4112 Dew Point Transmitter

Operations Manual

70-82-25-08
Rev. 2
2/99
 Copyright, Notices, and Trademarks
Printed in U.S.A. – © Copyright 1999 by Honeywell Inc.
Revision 2 – 2/99

While this information is presented in good faith and believed to be

accurate, Honeywell disclaims the implied warranties of
merchantability and fitness for a particular purpose and makes no
express warranties except as may be stated in its written agreement
with and for its customer.

In no event is Honeywell liable to anyone for any indirect, special or

consequential damages. The information and specifications in this
document are subject to change without notice.

Honeywell
Industrial Automation and Control
Automation College
2820 West Kelton Lane
Phoenix, AZ 85023
(602) 313-5669

ii 4112 Dew Point Transmitter – Operations Manual 2/99

 About This Document

Abstract
This manual provides technical description and installation and maintenance instructions for the
Honeywell 4112 Moisture Instrument.
Included are all circuit adjustment instructions required to verify proper electrical functions of the
instrument as well as system calibration for ambient temperature and moisture.

Revision Notes
The following list provides notes concerning all revisions of this document.

Rev. ID Date Notes

0 9/30/96 This document is the initial release of the Honeywell version of the L&N
manual p/n 278159 Rev. A.

1 10/97 Additions were made in Chapter 3 for Ferrite Bead installation and in
Chapter 12 for CE approval information.

2 2/99 Additions were made for the cooler option and the S200 and S201 dip
switches.

References
Non-Honeywell Documents
The following list identifies select non-Honeywell documents that may be sources of reference for the
material discussed in this publication.

Title Author Publisher ID/ISDN #

Installation of Intrinsically Safe ANSI/ISA RP 12.6

Instrument Systems in Class I
Hazardous Locations

Contacts
The following list identifies important contacts within Honeywell.

Organization Telephone Address

Honeywell TAC 1-800-423-9883 Voice 1100 Virginia Drive
Fort Washington, PA 19034

2/99 4112 Dew Point Transmitter – Operations Manual iii

 Contents

1. INTRODUCTION....................................................................................................1
1.1 Overview.........................................................................................................................................1
Transmitter Functions........................................................................................................................1
1.2 Filters ..............................................................................................................................................1

2. SPECIFICATIONS AND MODEL SELECTION GUIDE .........................................5

2.1 General Specifications ....................................................................................................................5
2.2 Model Selection Guide ...................................................................................................................6
Introduction .......................................................................................................................................6

3. INSTALLATION .....................................................................................................9
3.1 Storage and Shipment .....................................................................................................................9
3.2 Unpacking .......................................................................................................................................9
3.3 Rough Functional Check.................................................................................................................9
3.4 Dew Point and Wet Bulb Considerations .......................................................................................9
3.5 Mechanical Considerations...........................................................................................................10
3.6 Maintaining CE Mark Approval Procedure..................................................................................10

4. WIRING................................................................................................................13
4.1 Introduction...................................................................................................................................13

5. SYSTEM OPERATION ........................................................................................21

5.1 Introduction...................................................................................................................................21
5.2 Output 4 mA to 20.0 mA ..............................................................................................................22
5.3 Dry Bulb Temperature System .....................................................................................................22
5.4 A to D Conversion ........................................................................................................................22
5.5 Moisture Circuits ..........................................................................................................................22
5.6 Look Up Table ..............................................................................................................................22
5.7 Dew Point Output/Wet Bulb Output.............................................................................................23
5.8 Microprocessor Interface ..............................................................................................................23

iv 4112 Dew Point Transmitter – Operations Manual 2/99

6. DIP SWITCH FUNCTION.....................................................................................25
6.1 Introduction...................................................................................................................................25
S-200................................................................................................................................................25
S-201................................................................................................................................................26

7. TROUBLESHOOTING.........................................................................................31

8. MOISTURE LOOP CALIBRATION......................................................................33

9. TEMPERATURE LOOP CALIBRATION PROCEDURE......................................37

10. COOLER OPTION ...............................................................................................41

10.1 Introduction...................................................................................................................................41
10.2 Cooler Construction......................................................................................................................41
10.3 Installation ....................................................................................................................................42

11. HAZARDOUS LOCATIONS.................................................................................45

11.1 Introduction...................................................................................................................................45
11.2 Explosion Proof Installations........................................................................................................45
11.3 Intrinsically Safe Installations ......................................................................................................45

12. CE APPROVALS .................................................................................................49

Introduction .....................................................................................................................................49

2/99 4112 Dew Point Transmitter – Operations Manual v

 Tables
Table 4-1 DC Power Supply Requirement vs Load ________________________________________ 13
Table 4-2 120V ac Application Wiring__________________________________________________ 14
Table 4-3 DC Application Wiring______________________________________________________ 15
Table 6-1 S-200 (DP) Switch Functions _________________________________________________ 26
Table 6-2 S-201 Switch Functions _____________________________________________________ 27
Table 6-3 Switch Selectability of Output Units for the 4112 Transmitter _______________________ 29
Table 7-1 Troubleshooting ___________________________________________________________ 31
Table 8-1 Calibration Kit #4113-L60-0001 ______________________________________________ 33
Table 8-2 ZERO Calibration Procedure_________________________________________________ 34
Table 8-3 Span Calibration Procedure __________________________________________________ 35
Table 8-4 Temperature Dependence of Salt Solution Humidity Standards ______________________ 35
Table 9-1 Transmitter Cal. Procedure ___________________________________________________ 37
Table 9-2 Transmitter Cal. Procedure, continued __________________________________________ 38
Table 9-3 Transmitter Cal. Procedure, continued __________________________________________ 39
Table 10-1 Cooler Performance ________________________________________________________ 41
Table 10-2 Cooler Installation _________________________________________________________ 42

vi 4112 Dew Point Transmitter – Operations Manual 2/99

 Figures
Figure 1-1 – 4112 Assembly ____________________________________________________________ 3
Figure 2-1 D1 Dew Point Accuracy ______________________________________________________ 8
Figure 2-2 D2 Dew Point Accuracy ______________________________________________________ 8
Figure 2-3 D3 Dew Point Accuracy ______________________________________________________ 8
Figure 3-1-a Standard 4112 Mounting Configuration________________________________________ 11
Figure 3-2-b 4112 Transmitter with High Pressure Probe (option –110) Mounting Configuration _____ 12
Figure 4-1 AC Wiring Diagram with Temperature and Dew Point 4-20 mA Current Loops Monitored 14
Figure 4-2 AC Wiring Diagram with Dew Point Only 4-20 mA Current Loop Monitored ___________ 15
Figure 4-3 DC Wiring Diagram with External Supply for Temperature and Dew Point 4-20 mA Loops
Monitored______________________________________________________________________ 16
Figure 4-4 DC Wiring Diagram with External Supply with Dew Point Onlyy 4-20 mA Current Loop
Monitored______________________________________________________________________ 17
Figure 4-5 DC Wiring Diagram with Internal Supply for Dew Point and Temperature 4-20 mA Current
Loops Monitored ________________________________________________________________ 18
Figure 4-6 DC Wiring Diagram with Internal Supply for Dew Point only 4-20 mA Current Loops
Monitored______________________________________________________________________ 19
Figure 4-7 DC Wiring Diagram with Internal Supply for Dew Point and Temperature 4-20 mA Current
Loops Monitored ________________________________________________________________ 20
Figure 5-1 Simplified System Block Diagram _____________________________________________ 21
Figure 6-1 DIP Switch S-200 ON/OFF Configuration _______________________________________ 25
Figure 6-2 DIP Switch S-201 ON/OFF Configuration _______________________________________ 26
Figure 6-3 Dew Point Assembly - Key Component Locations _________________________________ 28
Figure 8-1 Electrical Test Setup ________________________________________________________ 36
Figure 9-1 Calibration Setup ___________________________________________________________ 40
Figure 10-1 Cooler Assembly __________________________________________________________ 42
Figure 11-1 Drawing A-21008, Sht 1 ____________________________________________________ 46
Figure 11-2 Drawing A-21008, Sht 2____________________________________________________ 47
Figure 11-3 Drawing A-21008, Sht 3 ____________________________________________________ 48

2/99 4112 Dew Point Transmitter – Operations Manual vii

viii 4112 Dew Point Transmitter – Operations Manual 2/99
 Introduction

1. Introduction

1.1 Overview
Transmitter Functions
The Honeywell 4112 unit measures and digitally displays Ambient Temperature and a moisture
measurement. The moisture measurement can be in units of Dew Point Temperature, Relative Humidity,
Humidity Ratio or Wet Bulb temperature, depending on a customer’s requirements. In addition this
transmitter unit outputs two 4 mA to 20 mA current loops, proportional to Ambient Temperature and
moisture measurement. Figure 1-1 shows an exploded view of the 4112 assembly.
The unit is packaged in an explosion proof housing with a window to permit viewing the digital displays.
Connection for Transmitter operation is available by unscrewing (counterclockwise) the windowed housing
cover and exposing a barrier strip with screw terminals on an inside cover.
A label adjacent to the barrier strip screw terminals identifies connections for 120 VAC or low voltage DC
operation of the unit. Wiring should be routed through conduit inlets on the housing to the screw terminals
exposed by removal of the windowed explosion proof cap.
A green grounding screw is mounted to the housing adjacent to the internal cap for system grounding.
A metal swing away plate is affixed to the side of the unit below the explosion proof cap. This plate may be
loosened and swung away to expose adjustment controls for field calibration. These controls may be
accessed without violating the explosion proof integrity of the housing.
The sensor may be inserted into the application via 1/2” NPT male threads at the root of the sensor probe
just under the base of the housing.
The probe stainless steel shaft is 3/8” diameter and may optionally be inserted into the application via a 3/8”
compression fitting.

1.2 Filters
Included with each dew point transmitter are two threaded filters and a fluted shield .
One of the filters is mounted on the end of the sensing probe. The other filter and the shield are packed in a
small plastic bag. Following is a description of these three parts.:

1.2.1 Sintered Stainless Steel Filter

This is the filter that is installed on the probe when it is shipped from the factory. This filter is generally
recommended for most industrial applications. It filters out airborne particulate as small as 60 microns in
diameter. It also provides protection against mechanical damage to the sensor. If necessary, it may be re-
moved and cleaned in any suitable cleaning agent. If the filter is cleaned, make sure that it is thoroughly dry
and free of any film before installing it on the probe.

1.2.2 Sintered Stainless Steel Filter with Hydrophobic Coating

This filter appears identical to the regular sintered stainless steel filter (see #1) except that it has a 1/16”
machined flat on the side of the cylindrical filter. This filter has been coated with a material which repels
liquids. It is recommended for those applications where the sensor probe might be exposed to temporary

2/99 4112 Dew Point Transmitter – Operations Manual 1

4112 Dew Point Transmitter Operations Manual

condensing or wet conditions. It will help keep liquid moisture off the sensor itself, allowing it to more
quickly respond when conditions return to a non-saturated state.

1.2.3 Black Fluted Shield

This is really a mechanical shield rather than a filter. It is constructed of a heat resistant composite. The
fluted shield is recommended for use where the air or gas to be measured is clean and/or where fast
response is a high priority. With the fluted shield, the sensor’s time constant in slow moving air at 25 deg
C. is reduced from 50 seconds with either of the stainless steel filter to 16 seconds.

2 4112 Dew Point Transmitter – Operations Manual 2/99

 Introduction

Window

Explosion Proof Cap

Window

Moisture Resistant Cap

5 Screw Terminals for
Transmitter and Power
Connections

Digital Display
Interface Cable Cap
Screw Terminals for
Temperature Sensor
Signal Conditioning
and Transmitter Ass’y
Co-Axial Connector
for Moisture Sensor

Supply Voltage Label Label & Cover Plate

and Xmtr Rating Label Swing Away for Adjustment

Conduit for Wiring

Neoprene O-Ring

1 1/4-16 UN-2A
to Have 8 Threads
Minimum Engagement
1/2-14 NPT Conduit with Housing
Material: 304 or 316 S.S.

1/2-14 NPT
Material: 300 Series S.S.

Sensor

a/n 23314
3/8"

Figure 1-1 – 4112 Assembly

2/99 4112 Dew Point Transmitter – Operations Manual 3

4112 Dew Point Transmitter Operations Manual

4 4112 Dew Point Transmitter – Operations Manual 2/99

 Installation

2. Specifications and Model Selection Guide

2.1 General Specifications

PERFORMANCE MOISTURE DRY BULB TEMPERATURE
o o
Display Resolution: 0.1 C or F, selectable 0.1oC or oF, selectable
Accuracy See Figures 2-1, 2-2 and 2-3
Input Voltage Effect: 0.002%/Vmax. (negligible) from 11 to 45 Vdc.
Time Constant 16 sec in slowly moving air @ 25°C with fluted shield
50 sec in slowly moving air @ 25°C with stainless steel filter

INSTALLATION
Transmitter Housing: NEMA 4X, IP65 cast low-copper aluminum fully anodized with aliphatic
urethane finish. Weight approximately 4.4 lb. (2.0 kg).
Sensor Housing: Stainless steel probe; fluted shield; porous stainless steel filters.
Mounting: Can be mounted on pipe or wall
Sensor Operating Environment: -40oC to 185oC (-58oF to 365oF); to 150°C (300°F) for –110 option
Transmitter Operating Environment: -40oC to 80oC (-40oF to 176oF); Display:-30oC (-22oF)
Storage Environment: -55oC to 85oC (-67oF to 185oF)
Power Requirements: 115 VAC ± 10%, 60 Hz with Rlmax 500 Ohm or 11Vdc + (Rload x 0.02 A)
min. to 45 Vdc max. for dual 2-wire operation
Operation requires three wires, even if using only one signal
Intrinsic Safety Entity Parameters: V max = 30 volts; I max = 360mA; Ci = 0.1 µF; Li = mH
Signal Connection: Screw terminals
Sensor Mounting: 1/2” NPT; ¾” NPT (-110 option)
Pressure: 0 to 350 psi dew point at pressure; 0 to 2000 psi (-110 option)

SERVICEABILITY
Periodic Maintenance: Verify calibration periodically. Wash sensor as needed.
Adjustments: Vernier, non-interacting, multi-turn potentiometers for zero and span control
of Dry Bulb temperature. Momentary rotary action switches for Dew Point
Calibration. Adjustments are on the outside of the transmitter housing under
a swing-away plate.
Sensor Break Indication: Dry Bulb Sensor: upscale both output signals
Dew Point Sensor: downscale on dew point signal only
Over Temperature Indication: Dew Point output at 100oC when Dry Bulb > 192oC
Sensor Cleaning: Wash with detergent solution. Rinse with de-ionized water. Camel hair
(organic) brush may be used during cleaning when required.

2/99 4112 Dew Point Transmitter – Operations Manual 5

4112 Dew Point Transmitter Operations Manual

2.2 Model Selection Guide

Introduction
The model number breakdown is presented in the tables that follow.
The basic model number consists of a key number. Appended to this key number are characters that
identify the features in various categories. The meaning of the characters in each category is presented in a
table identified below.
Key Number Table I Table II Table III Table IV (Optional)
_____ - __ - __ - _ - ___,___

KEY NUMBER Selection Availability

Description
4112 Dew Point and Temperature Transmitter 04112 ↓

TABLE I – PROBE LENGHTS

Standard Lengths 12 Inches 12 •
Non- Standard lengths – Specify in inches 02 •
04 d
06 •
24 •
30 •

TABLE I I – STANDARD RANGE AND OUTPUT OPTIONS

Application 4-20 mA Output
Dew Point – General Use, Dry Bulb Temp: 0°C to 204.7°C D1 •
including industrial drying (32°F to 400.5°F)
Dew Point Temp: -104.7°C to 100°C
(-156.5°F to 212°F)
Dew Point – Tight Mid-Range Dry Bulb Temp: 0°C to 40.94°C D2 •
control, as in clean rooms, etc. (32°F to 105.69°F)
Dew Point Temp: -12.8°C to 28°C
(-8.96°F to 82.67°F)
Dew Point – Ideal for trace moisture Dry Bulb Temp: -50°C to 52.3°C D3 •
measurements i.e., instrument air, (-58°F to 126.14°F)
dry gas, and outdoor measurements. Dew Point Temp: -60°C to 42.3°C
(-76°F to 108.14°F)
Dew Point – Trace moisture measurement Dry Bulb Temp: -17.8°C to 93.3°C D4 f
with higher dry bulb capability than D3. (0°F to 200°F)
Dew Point Temp: -17.8°C to 37.8°C
(0°F to 100°F)

6 4112 Dew Point Transmitter – Operations Manual 2/99

 Installation

Application 4-20 mA Output

Wet Bulb Output – valid at 1 atmosphere Dry Bulb Temp: 0°C to 204.7°C W1 •
total pressure (32°F to 400.5°F)
Dew Point Temp: -10°C to 100°C
(14°F to 212°F)
High Accuracy Relative Dry Bulb Temp: 0°C to 204.7°C R1 •
Humidity Output (32°F to 400.5°F)
Relative Humidity: 0 to 100%
Humidity Ratio Output – Valid at 1 Dry Bulb Temp: 0°C to 204.7°C H1 •
atmosphere total pressure (32°F to 400.5°F)
Humidity Ratio: 0 to 0.5lb H2O/lb
dry air (0-3500 grains/lb)
Humidity Ratio Output – Valid at 1 Dry Bulb Temp: 0°C to 40.94°C H2 •
atmosphere total pressure (32°F to 105.69°F)
Humidity Ratio: 0 to 0.24lb H2O/lb
dry air (0-168 grains/lb)
Humidity Ratio Output – Valid at 1 Dry Bulb Temp: -50°C to 52.3°C H3 •
atmosphere total pressure (-58°F to 126.14°F)
Humidity Ratio: 0 to 0.05lb H2O/lb
dry air (0-350 grains/lb)

TABLE III – TEMPERATURE DISPLAY (Select One)

Display in °C C •
Display in °F F •

TABLE IV – OPTIONS*
None 000 •
Pipe/Wall Bracket Kit 100 •
High Pressure Probe: up to 2000 psi 110 c
FM Intrinsically Safe (24 Volt only) 209 e
CE Compliant (24 Volt DC Power) 210 •
Stainless Steel Tag, up to 25 characters each of 3 lines 208 •
RESTRICTIONS
Restriction Letter Available Only With Not Available With
Table Selection Table Selection
c I 04, 12 IV 100, 104
II D3
d IV 110
e IV 210
f IV 209, 210
*See 4113 Accessories for coolers, insertion removal device, etc.

2/99 4112 Dew Point Transmitter – Operations Manual 7

4112 Dew Point Transmitter Operations Manual

Dew Point Accuracy, D1 Version

6.0
-10

FP
H 0°C

Dew Point Accuracy ±°C

1% R

°C
-75
4.0 °C

FP
-50

°C
3.0

- 25

DP
DP
H
3% R

DP
2.0 -50
DP

°C
0°C

°C
°C

50
°C

25
75 DP
0°C
1 .5 10
RH
1 .0 10%

0.8
-25°C
0.6 0°C

0.5
0 25 50 75 100 125 150 175
Dry Bulb Ambient - °C a/n23315

Figure 2-1 D1 Dew Point Accuracy

Dew Point Accuracy for D2 Version

1 .1
Dew Point Accuracy, ±°C

FP
F)
4°
0.9 C
(1
0°
-1 P
)F
0.8 3 °F
it) (2
Lim °C
-5 DP
mA )
0.7 (4 2°F
(3
C
0° DP
°F)
(50
0.6 10°
DP
(68°F)
20°C
0.55
0 10 20 30 40
Dry Bulb Temperature, °C a/n 23326

Figure 2-2 D2 Dew Point Accuracy

Dew Point Accuracy for D3 Version

8
Dew Point Accuracy ±°C

) FP
4 6°F FP P FP
(-7 F) )F F)
C 8° 0°F 2°
0° (- 5 (-4 (- 2
-6 °C °C 0 °C
-5
0 -4
0
-3 FP
2 ° F)
(-4 FP
-2 0°C 14°
F)
P
0°C( 2°F) D
1 -1
0°C
(3
DP
20°C (68°F)
0.5
-40 -20 0 20 40
Dry Bulb Temperature - °C a/n 23327

Figure 2-3 D3 Dew Point Accuracy

8 4112 Dew Point Transmitter – Operations Manual 2/99

 Installation

3. Installation

3.1 Storage and Shipment

CAUTION
For prolonged storage or for shipment, the Transmitter should be kept in its shipping clamps or
o
covers. Store in a suitable environment with temperature between –55 and 85 C and relative
humidity that excludes moisture condensation on the unit.

3.2 Unpacking

Step Action

1 If there are visible signs of damage, do not remove the transmitter from its packing material. Notify
the carrier and Honeywell immediately.

2 If there is no visible damage, compare the contents with the packing list. Notify the carrier and
Honeywell immediately if there is a or shortage.

3 Please do not return goods without contacting Honeywell.

4 Carefully remove the Transmitter from its packing case and then remove any shipping ties on
packing material. Follow the instructions on any attached tags and then remove such tags.

3.3 Rough Functional Check

A functional check may be performed on the instrument to evaluate the unit for catastrophic damage when
unpacked.

Step Action Result

1 Connect the “H2O”, “TEMP”, and “COM” screw The display should indicate ambient temperature and
terminals on the internal cap together. Apply dew point temperature.
120 VAC 60 Hz to the L1 and L2 screw
terminals.

2 Hold the sensor tip close to your open mouth Observe that the temperature display of ambient and
and breathe on it. dew point temperature responds.

3.4 Dew Point and Wet Bulb Considerations

Dew Point engineering units are expressed in degrees of temperature.
The 4112 is calibrated in degrees Centigrade or Fahrenheit. The wet bulb temperature may also be selected
to display and output in degrees Centigrade or Fahrenheit. The Dew Point temperature is that which will
cause water condensation to form when the water vapor in the measured gas is cooled.

2/99 4112 Dew Point Transmitter – Operations Manual 9

4112 Dew Point Transmitter Operations Manual

The highest temperature at which water can exist as a liquid at one atmosphere of pressure is 100oC, hence
the maximum dew point range of the 4112 is 100oC or 212oF.
There is no theoretical practical upper limit of temperature at which water vapor can exist as a gas.
The real practical upper limit of gas ambient temperature for in situ dew point measurement is the 4112
sensor technology. This is limited to 185oC.
The 4112 calibrated upper limit of ambient temperature, sometimes referred to as dry bulb temperature, is
204.7oC.
Figure 2-3 illustrates the temperature range for which dew point measurements may be taken by the 4112.
When choosing a site for sensor installation within a system consideration should be given to select a point
where the gas will be the coolest without the formation of condensation.
The reason for the above consideration is that accuracy is dependent on the difference of temperature
between the ambient or dry bulb and dew point temperature (see accuracy chart Figure 2-1). This
temperature difference is referred to as temperature depression.

3.5 Mechanical Considerations

Probe lengths from 2” to 30” are available to reach into various application depths.
Sealing of the application environment ordinarily may be achieved by the 1/2” NPT fitting at the base of the
4112 probe. Should the application environment wall thickness not permit use of a 1/2” NPT fitting, then a
3/8” diameter bulkhead compression fitting may be used to clamp the 3/8” stainless steel probe and use
option 100 brackets to support the transmitter housing .

ATTENTION
This conduit connection can not exceed 30”.

3.6 Maintaining CE Mark Approval Procedure

ATTENTION
To maintain CE mark approval the supplied Ferrite Bead must be installed on the field wiring per the following
installation notes when installing option code –210 units.

Step Action
1 These installation notes apply to CE marked direct current loop powered units only (option code –
210). The ferrite bead is not required for CE marked AC line powered units (option –212). The ferrite
bead is not required for any units not bearing the CE mark.
2 Install the 4112 per the installation instructions. Before connecting the field wires to the terminal
block, slip the supplied ferrite bead over all wires. The ferrite bead is installed inside the threaded
explosion-proof housing of the 4112 unit.
3 Push the ferrite bead over the field wires as far as possible to the lower part of the enclosure.
4 Secure a plastic cable tie around the field wires just above the ferrite bead to retain the ferrite bead (
the exact location of the ferrite bead is not critical to its function.).
5 Connect the field wires to the terminal block per the installation instructions.

10 4112 Dew Point Transmitter – Operations Manual 2/99

 Installation

Allow 3.2" (81.3mm) for

Removal of Cover

4.4
4.6" Dia (111.8mm)
7.3
(116.8mm) (185.4mm)

ZSD

Swing Away Nameplate

Allows External Access
to the Calibration
Adjustments 1-1/2"
(38.1mm)

1/2" NPT
Optional Pipe/Wall Mount
12" Hardware Kit
(305mm)
STD

3/8 (9.53mm) Dia

Figure 3-1-a Standard 4112 Mounting Configuration

2/99 4112 Dew Point Transmitter – Operations Manual 11

4112 Dew Point Transmitter Operations Manual

Allow 3.2" (81.3mm) for

Removal of Cover

4.4
4.6" Dia (111.8m
7.3
(116.8mm) (185.4mm)

ZSD

Swing Away Nameplate

Allows External Access
to the Calibration
Adjustments 1-1/2"
(38.1mm)

3/4" NPT

12"
(305mm)
STD

Allow 0.75" clearance

Figure 3-2-b 4112 Transmitter with High Pressure Probe (option –110)
Mounting Configuration

12 4112 Dew Point Transmitter – Operations Manual 2/99

 Wiring

4. WIRING

4.1 Introduction
The 4112 has two transmitter outputs and an internal 120 VAC 60 Hz power supply to power these two
transmitters.
The two transmitters are internally connected together at their (+) positive terminals and when powered by
120 VAC 60 Hz can drive a maximum wire and load resistance of 500 ohms.
Should 120 VAC 60 Hz operation not be desired the 4112 may be powered by an external low voltage DC
power supply.

ATTENTION
The intrinsically safe model is DC powered only.

Table 4-1 DC Power Supply Requirement vs Load

Voltage Wiring and Load Resistance

45 Vdc 1700 Ohms

35 Vdc 1200 Ohms

24 Vdc 650 Ohms

15 Vdc 200 Ohms

The above values are derived from the relationship 11 Vdc + (Rload x 0.02A) = Vdc loop min..
11 Vdc is required to keep the transmitter in regulation while the load(resistor + lead wires) creates the
balance of the voltage drop incurred at the 20 mA level.

ATTENTION
Determine load resistor values and mounting location per the requirements of your readout device(s).

REFERENCE
Figure 1-1, screw terminal label on inner cap.

CAUTION
Both outputs must be connected to the negative side of the power supply even if no 4-20 mA input device is
used for one or both outputs.

2/99 4112 Dew Point Transmitter – Operations Manual 13

4112 Dew Point Transmitter Operations Manual

Table 4-2 120V ac Application Wiring

Step Action Result/Notes

1 Connect ground lead to green ground screw

2 Connect AC Line wires to L1 and L2 Hot lead to L1 and neutral to L2

3 Connect one end of the Dew Point load Maximum load resistance for ac powered
resistor to the H2O Terminal, and wire to the transmitters is 500 ohms, 250 ohms per channel.
Positive Terminal of the readout device.

4 Connect the other end of the Dew Point load

resistor to the COMM Terminal. And to the
Negative terminal of the readout device.

5 Connect one end of the Dry Bulb load resistor If Dry Bulb read out is not used, use a jumper
to the TEMP Terminal, and wire to the Positive between TEMP and COMM in place of the
Terminal of its readout device. resistor and disregard step 6 below. See Figure 4-
2.

6 Connect the other end of the Dry Bulb load

resistor to the COMM Terminal. And to the
Negative terminal of its readout device.

4112
Terminal
Block

L Hot (Black)
1
120 VAC Power
L
Neutral (White) 4 - 20 mA
2 Input Device
_
Com Loop Com
(-)

H2 O
AI 1
{ + Dew Point
4 - 20 mA
Input

+
Temperature
Temp 4 - 20 mA
AI 2
{ _
Input

Gnd Jumper
Water Pipe
Load Resistors
if Required
a/n 23317

Note: Always consult the manual of these devices for correct jumper configuraiton and wiring connections.

Figure 4-1 AC Wiring Diagram with Temperature and Dew Point

4-20 mA Current Loops Monitored

14 4112 Dew Point Transmitter – Operations Manual 2/99

 Wiring

4112
Terminal
Block

L Hot (Black)
1
120 VAC Power
L
Neutral (White) 4 - 20 mA
2 Input Device
_
Com Loop Com

H2 O
(-)
AI 1
{ + Dew Point
4 - 20 mA
Input

Jumper
+
Load Resistors Temperature
Temp if Required 4 - 20 mA

{
AI 2 _
Input

Gnd
Water Pipe

Note: Always consult the manual of these devices for correct jumper configuraiton and wiring connections.

Figure 4-2 AC Wiring Diagram with Dew Point Only

4-20 mA Current Loop Monitored

Table 4-3 DC Application Wiring

Step Action Result/Notes

1 Connect ground lead to green ground screw

2 Connect power supply Positive lead to COMM

3 Connect one end of the Dew Point load

resistor to the H2O Terminal, and wire to the
Positive Terminal of the readout device.

4 Connect the other end of the Dew Point load

resistor to the power supply Negative and to
the Negative terminal of the readout device.

5 Connect one end of the Dry Bulb load resistor If Dry Bulb read out is not used, use a jumper
to the TEMP Terminal, and wire to the Positive between TEMP and power supply Negative in
Terminal of its readout device. place of the resistor and disregard step 6 below.
See Figure 4-4.

6 Connect the other end of the Dry Bulb load

resistor to the power supply Negative and to
the Negative terminal of its readout device.

2/99 4112 Dew Point Transmitter – Operations Manual 15

4112 Dew Point Transmitter Operations Manual

Current Loop
Power Supply

4112 24 VDC Typ

Interface @ 40 mA Min
Wiring
Block 4 - 20 mA
Input Device
+ - _
Loop Com
Com
(+)

H20
AI 1
{ Dew Point
+ 4 - 20 mA
Input

+
Temperature
Temp 4 - 20 mA
AI 2 { _
Input

Gnd Load Resistors Jumper

Water Pipe If Required

Note: Always consult the manual of these devices for correct jumper configuraiton and wiring connections.

Figure 4-3 DC Wiring Diagram with External Supply for Temperature

and Dew Point 4-20 mA Loops Monitored

16 4112 Dew Point Transmitter – Operations Manual 2/99

 Wiring

External Power Supply

Current Loop

4112 24 VDC Typ

Interface @ 40 mA Min
Wiring
Block 4 - 20 mA
Input Device
+ - _
Com
(+) Loop Com

H2O
AI 1
{ + Dew Point
4 - 20 mA
Input

Temp

Load Resistor
If Required
Gnd
Water Pipe

Note: Always consult the manual of these devices for correct jumper configuraiton and wiring connections.

Figure 4-4 DC Wiring Diagram with External Supply with

Dew Point Only 4-20 mA Current Loop Monitored

When the monitoring device supplies power for the 4112 Transmitter, both loops must be activated. This is
necessary for the proper operation of the instrument. Wiring diagrams covering monitoring devices with
internal power supplies are shown in Figures 4-5, 4-6 and 4-7.

2/99 4112 Dew Point Transmitter – Operations Manual 17

4112 Dew Point Transmitter Operations Manual

4 - 20 mA
Input Device

4112
Terminal + 24VDC
Block Internal
- Supply
-
Loop Com
Com
(+) Jumper

H2 O
AI 1
{ +
Dew Point
4 - 20 mA
Input
+
Temperature
Temp 4 - 20 mA

Gnd Water Pipe

Load Resistors
If Required
AI 2
{ -
Input

Note: Always consult the manual of these devices for correct jumper configuration and wiring connections.
Two inputs are needed for proper operation. Both outputs must be connected to the negative side of
the power supply, whether one or both outputs are used. If 2 inputs are not available call the
Technical Assistance Center (T.A.C.) @ 1-800-343-0228 for assistance..

Figure 4-5 DC Wiring Diagram with Internal Supply for Dew Point
and Temperature 4-20 mA Current Loops Monitored

18 4112 Dew Point Transmitter – Operations Manual 2/99

 Wiring

4 - 20 mA
Input Device

4112
Terminal + 24VDC
Block Internal
- Supply

Jumper
Com -
(+)

H 2O
AI 1
{ +

Dew Point
4 - 20 mA
Temp Input

Load Resistor
Gnd Water Pipe If Required

Note: Always consult the manual of these devices for correct jumper configuration and wiring connections.
Two inputs are needed for proper operation. Both outputs must be connected to the negative side of
the power supply, whether one or both outputs are used. If 2 inputs are not available call the
Technical Assistance Center (T.A.C.) @ 1-800-343-0228 for assistance..

Figure 4-6 DC Wiring Diagram with Internal Supply for Dew Point only
4-20 mA Current Loops Monitored

2/99 4112 Dew Point Transmitter – Operations Manual 19

4112 Dew Point Transmitter Operations Manual

Typical Mointoring Device

4112 with Internal Power Supply
Terminal without PS (+), PS(-) terminals
Block (e.g. DCS, PLC, Recorders)

Com - + V-
-
(+) AI 1

+ V+
H2 O
Excitation
Voltage
AI 2

Temp - +
-

Gnd Water Pipe

Load Resistors
If Required

Note: Always consult the manual of these devices for correct jumper configuration and wiring connections.
Two inputs are needed for proper operation. Both outputs must be connected to the negative side of
the power supply, whether one or both outputs are used. If 2 inputs are not available call the
Technical Assistance Center (T.A.C.) @ 1-800-343-0228 for assistance.

Figure 4-7 DC Wiring Diagram with Internal Supply for Dew Point
and Temperature 4-20 mA Current Loops Monitored

20 4112 Dew Point Transmitter – Operations Manual 2/99

 System Operation

5. System Operation

5.1 Introduction
Figure 5-1 Simplified System Block Diagram shows transmitter connections labeled L1, L2, COM, H2O
and Temp.

EO +5.0
+
DC to DC
Convertor
5.0 VDC RTD

-
+ COMM
+ Digital Display
Temp CCT
Zero Span 204.7°C
-104.7°C
Temp. D.P.
24 VDC A to D RH OSC
I2 Freq
6.9 Zero Span
F101 CR VDC RV301 RV302
T 100 C101 RV300 Moisture
100
Sensor
VR
-
BR100 402

D.P.
F100 D to A S-201
-
EO -6.9

MICROPROCESSOR
Display °C/°F
Zero Span
4 mA Temp. RV200 RV201 Cal Protect
I1 I3 4 mA D.P. I4
Scale H.B./D.P.

Not Used
RV400
RV202
Ext.
Micro
Interface
Conn.

E ² Memory
Set Zero RH + DP Look Up
AC Powered Function/Mode Ta ble
Connections Switches
Down Up
DC Powered See S-200
Connections Figure 4-1 DP Calibration
See
Figure 4-2

a/n 23319

Figure 5-1 Simplified System Block Diagram

When powered by 120 VAC through F101 to T100 a step down transformer, BR100 rectifies T100 output
to 24 Vdc at C101. The DC minus (-) of this C101 voltage is routed to the COM screw of transmitter
connections on the inner cap.
When CH#1 and CH#2 are connected to COMM through a short or load resistor, a 4.0 mA current is drawn
by each current source I1 and I3 causing 8 mA to be supplied to shunt regulator VR 402 resulting in a –6.9
Vdc to be generated, referenced to the plus (+) terminal of C101’s voltage.
The –6.9Vdc is inverted by a DC to DC converter and regulated to +5.0Vdc referenced to the common (+)
voltage rail of C101’s voltage.

2/99 4112 Dew Point Transmitter – Operations Manual 21

4112 Dew Point Transmitter Operations Manual

5.2 Output 4 mA to 20.0 mA

This +5.0V DC and –6.9V DC is used to power circuitry that controls the current modulator I2 and I4 in the
range of 0 mA to 16 mA in parallel with I1 and I3 the 4 mA current sources.
This results in 2 ea. 4 mA to 20 mA transmitter outputs that route a sensor determined current to output
connection common.
A load resistor in series with either output connected to common can now read the loop current.

5.3 Dry Bulb Temperature System

The temperature circuit sensor is a platinum RTD element affixed to the rear surface of the moisture sensor.
The resistance change of the RTD is standardized by temperature circuits that are set by zero and span
temperature controls behind a swing away front panel, to provide a calibrated range of 000.0oC to 204.7oC
corresponding to 4mA to 20 mA available at screw terminals labeled TEMP and COM.

5.4 A to D Conversion
Once the current output is calibrated a voltage in the temperature circuit proportional to output current
calibration is routed to 12 bit A to D converter circuitry that digitizes the temperature signal to the
microprocessor.
This digitized value is displayed on a microprocessor controlled LCD display.
Calibration of the A to D converter is accomplished by RV301 and RV302, zero and span controls.

5.5 Moisture Circuits

A moisture sensor mounted at the tip of the 4112 probe produces a capacitance change as a function of
moisture.
This capacitance change is converted to a frequency change by an oscillator whose base frequency at
000.0% RH is set by RV300.

As moisture levels change and the capacitance of the moisture sensor changes, the RH oscillator changes
frequency.
This frequency change is monitored by the microprocessors timer input and provides digitized moisture
information to the microprocessor.

5.6 Look Up Table

The moisture sensors response characteristics are stored in an E2 memory in the form of a lookup table.
The microprocessor evaluates the temperature and moisture digitized signals by interrogating the E2
memory lookup table to determine the dew point that is being applied to the dew point sensor.

22 4112 Dew Point Transmitter – Operations Manual 2/99

 System Operation

5.7 Dew Point Output/Wet Bulb Output

The microprocessor then outputs a digital value to a 12 bit D to A converter that drives current source I4 in
the range of –104.7oC to +100oC (-156.46oF to 212oF). This produces a calibrated 4mA to 20 mA current,
proportional to dew point, available at screw terminals labeled H2O and COM.
RV200 zero control and RV201 span control set the Dew point calibrated output current to correspond to
the value on the microprocessor controlled LCD display.
Dew point calibration may be altered by activation of up and down calibration switches connected to the
microprocessor.
Activation of these switches is accomplished by rotation of screw driver operated actuator located behind a
swing away front panel.
Clockwise detention of this actuator (embossed “D”) will cause an upward incrementing of Dew Point
calibration. Counter clockwise will cause a downward incrementing of Dew Point calibration.
An internal DIP switch may be activated to change the output to calculated Wet Bulb temperature.

5.8 Microprocessor Interface

The 4112 is fitted with an external micro interface connector which is used at the factory.
When interfaced with suitable isolation circuitry and an IBM P.C. resident program, test of the
microprocessor, interrogation and re-programming of the look up table in the E2 memory is made possible.

2/99 4112 Dew Point Transmitter – Operations Manual 23

 DIP Switch Function

6. DIP Switch Function

6.1 Introduction
Two single – pole, single – throw DIP switch packs are mounted on the microprocessor board and
interfaced to the microprocessor. S-200 consists of two switches and S-201 consists of four switches.
The location of the S-200 and S-201 on the dew point assembly is shown in Figure 6-3

S-200
DIP switch S-200 contains two switches and is located on the microprocessor board perpendicular to the
display board and directly behind the upper display (dry bulb temperature). S-200 has the letters D.P.
inscribed in white letters directly beside it (see Figure 6-3). Figure 6-1a illustrates the correct method for
configuring the switches of DIP switch S-200 in the off position. Each individual switch is OFF when it is
pointing up toward the white dot and the word OFF located on the DIP switch block. Figure 6-2b illustrates
the correct method for configuring the switches of DIP switch S-200 in the ON position. The switch is ON
when it is pointing down toward the switch numbers inscribed on the DIP switch block.

O FF O FF
A. B.
OFF ON

2 2
1 1

Figure 6-1 DIP Switch S-200 ON/OFF Configuration

2/99 4112 Dew Point Transmitter – Operations Manual 25

4112 Dew Point Transmitter Operations Manual

Table 6-1 S-200 (DP) Switch Functions

Switch Number Setting Action/Result

1 ON Switch S-200-1 ON at all times unless performing a zero

calibration.

OFF 2 sec, back Switch S-200-1 OFF only when performing a zero %RH
to ON calibration. When switch 1 of S200 is turned OFF and then
back ON, the transmitter assumes a zero %RH standard is
being applied to the sensor and stores this data in memory.
Note: Switch 3 of DIP switch S-201 must be in the ON
position to allow the transmitter to store the zero calibration
data. If this switch is in the OFF position when activating
switch 1 of S-200, the lower display will quickly 0.0% RH for
approximately one second, and then continue displaying the
value observed before configuring switch 1 of S-200.

2 ON Moisture analog output scaling (4-20 mA) and reading are

per the position of switches 1&2 of DIP switch S-201 (See
Table 6-2).

OFF Moisture reading and analog output scaling are 0-100% RH

over 4-20 mA.

This is NORMAL position if R1 range is specified.

S-201
DIP switch S-201 contains 4 switches and is labeled S201and is located on the reverse side of the
microprocessor board than S200. See Figure 6-3. Figure 6-2 illustrates the correct method for configuring
the switches of DIP switch S-201 on and off. Figure 6-2a illustrates the correct method for configuring the
switches of DIP switch S-201 in the off position. Each individual switch is OFF when it is pointing up
toward the white dot and the word OFF located on the DIP switch block. Figure 6-2b illustrates the correct
method for configuring the switches of DIP switch S-201 in the on position. The switch ins ON when it is
pointing down toward the switch number inscribed on the DIP switch block.

O FF
A. B. O FF

OFF ON

4 4
3 2 3
2
1 1

Figure 6-2 DIP Switch S-201 ON/OFF Configuration

26 4112 Dew Point Transmitter – Operations Manual 2/99

 DIP Switch Function

Table 6-2 S-201 Switch Functions

Switch Setting Range Action/Result
Number

D1, D2, D3, W1, R1 Switch 1 of S-201 comes configured in the OFF position from
the factory for models D1, D2, D3, W1 & R1. The position of
switch 1 for these models has no effect on the transmitter
reading/output.

1 OFF H1, H2, H3 When in the OFF position and switch 2 of S-201 is in the ON
position, the transmitter moisture display and output scaling
units are lb/lb. When switch 2 of S-201 is in the OFF position,
switch 1 of S-201 has no effect on the transmitter
reading/output.

ON When switch 1 of S-201 is in the ON position, and switch 2 of

S-201 is in the ON position, the transmitter moisture display
and output scaling units are grains/lb. When switch 2 of S-201
is in the OFF position, switch 1 of S-201 has no effect on the
transmitter reading/output.

OFF D1, D2, D3, H1, H2, H3, W1 When switch 2 of S-201 is in the OFF position, the moisture
display and output scaling are proportional to Dew Point
temperature.

2 W1 When switch 2 of S-201 is in the ON position, the transmitter

display and output scaling are proportional to Wet-bulb
temperature.

ON D2, D3, H1, H2, H3 When switch 2 of S-201 is in the ON position and switch 1 of S-
201 is in the ON position, the transmitter moisture display and
output scaling units are grains/lb. When switch 2 of S-201 is in
the ON position and switch 1 of S-201 is in the OFF position,
the transmitter moisture display and output scaling units are
lb/lb.

ON ALL When switch 3 of S-201 is in the ON position, a Humidity

Calibration (Zero and/or Span) is allowed. The transmitter will
ignore any calibration attempts if switch 3 is in the OFF
position. During a Span calibration attempt when switch 3 is in
the OFF position, the upper display will read PPP.P.

3 OFF When switch 3 of S-201 is in the OFF position while power is

being applied, the transmitter uses/restores factory Humidity
Calibration values (Zero and Span).

4 ON ALL Dry Bulb and Dew Point/Wet Bulb Displays are in degrees
Fahrenheit on the transmitter.

OFF Dry Bulb and Dew Point/Wet Bulb Displays are in degrees
Celsius on the transmitter.

2/99 4112 Dew Point Transmitter – Operations Manual 27

4112 Dew Point Transmitter Operations Manual

RV300 RH Frequency Adj.

RV301 Temp Display Zero

RV302 Temp Display Span
Display
Dip Card A/D Card
Switch

S201 4 Display On = °F
S200 Off = °C
1 Zero = Cal 3 Cal Prot. On = Fact
Off = Oper Off = Usr
RTD Temperature
2 Scale On = W.B.
Sensor Locations
Off = D.P.
Span RV201 1 Not Used
Zero RV200
2 Display On = D.P. RV400 4mA Temp
Off = %RH
DP Loop 4mA
Dew Point Up/Down Span
RV202
Counts Pushbuttons
RTD Card
External Micro
Span Temp 20mA
Interface Connector

Zero Temp 4mA

Mother Card
a/n 23320

Figure 6-3 Dew Point Assembly – Key Component Locations

28 4112 Dew Point Transmitter – Operations Manual 2/99

 DIP Switch Function

Table 6-3 can be used to convert the 4112 transmitter from one model type to another. For example, if we
take a D1 model type transmitter, the table shows that it can be converted to an R1 or H1 unit by
appropriately configuring DIP switches S-200 and S-201.
Table 6-3 Switch Selectability of Output Units for the 4112 Transmitter

Model Type D1 D2 D3 D4 H1 H2 H3 R1 W1

D1 X — — — X — — X —

D2 — X — — — X — *X —

D3 — — X — — — X *X —

D4 — — — X — — — *X —

H1 X — — — X — — X —

H2 — X — — — X — *X —

H3 — — X — — — X *X —

R1 X — — — X — — X —

W1 X — — — — — — X X

NOTE: *X indicates a non-temperature compensated relative humidity output signal which is provided
only for purposes of calibration against a relative humidity reference at room temperature. RH is always 0-
100% over 4-20 mA. Dry bulb temperature ranges always remain fixed.

ATTENTION
• The RH output is temperature compensated only if the instrument is configured with D1, W1, H1 or R1
output options.

• With other ranges, RH output reads low above room temperature, and high below room temperature.

2/99 4112 Dew Point Transmitter – Operations Manual 29

4112 Dew Point Transmitter Operations Manual

30 4112 Dew Point Transmitter – Operations Manual 2/99

 Troubleshooting

7. Troubleshooting
Table 7-1 Troubleshooting
Symptom Probable Cause Action

Transmitter does not function. Incorrect connections, reversed Review Figure 4-1and
Display is blank. polarity
Figure 4-3. Try reversing the
polarity

Humidity output is locked at 20ma, Water vapor has condensed on Withdraw sensor from process. Dry
dew point reading tracks at or very the sensor and or the filter the filter *. Use the sintered
close to dry bulb temperature stainless steel filter with
reading. Display reads HHH.H. hydrophobic coating

Water vapor has condensed Use the fluted shield

inside the filter. Sensor reads
saturated condition when sample
gas is not saturated.

Mechanical damage of the Visible scratches, abrasion, etc. Use screens or baffles to deflect
sensor surface high flow rates, greater than 30 high speed airborne particulate,
m/sec (100 fps) relocate transmitter.
Damaged sensors must be replaced
and the transmitter recalibrated.

Transmitter humidity output is Filter is plugged Clean and or replace filter

changing very slowly or even locked
at some level.

Sensor is dirty Clean sensor, see Sensor Cleaning

Humidity output is locked Break in the electrical Return transmitter to Honeywell for
permanently, typically at 4ma. connection between the sensor service.
and the transmitter electronics:

Overheating return transmitter to Honeywell for

service. relocate transmitter or use
the cooler option

Chemical damage Diminish sensor exposure to

harmful chemicals, consider
periodic sensor replacement.

Strong vibration or flexing or Install support bracket etc. to

bending of probe prevent probe flexure.

Dew point reading does not agree Reference dew point value is Convert each reading to the
with the reading from another referenced to atmospheric equivalent humidity ratio (mixing
reference instrument. pressure, while the transmitter’s ratio) value and then compare the
sensor is reading the gas at humidity ratio values **
elevated pressure

* After an hour or so, depending on the amount of condensation, the unit output should be between 4 and 20ma.
One way to speed the drying of the sensor and filter is to spray them with an isopropyl alcohol solution from a
simple plastic pump spray bottle.

2/99 4112 Dew Point Transmitter – Operations Manual 31

4112 Dew Point Transmitter Operations Manual

** The partial vapor pressure of a compressed gas mixture is higher than the partial vapor pressure of the same
gas mixture at atmospheric pressure. Because dew point is directly related to vapor pressure, the dew point of a
compressed gas will also be higher than the dew point of that same gas at atmospheric pressure. One way to
compare two dew point readings of the same gas but at different pressures is to convert each reading to the
equivalent humidity ratio (mixing ratio) value and then compare the humidity ratio values. Given total pressure
and dew point, the humidity ratio can be calculated. The humidity ratio is commonly expressed as pounds of
H2O per pound of dry air, grains per pound, kilogram per kilogram, etc.

Sensor Cleaning
The surface of the sensor may be coated with a film or with a heavy layer of contaminants. This is usually,
though not always, evident by visual inspection of the sensor surface. The sensor surface is green in color and
normally appears shiny, sometimes iridescent depending on lighting. A good procedure for cleaning the sensor
is as follows: Obtain three simple pump spray bottles, Fill the first with a solution of distilled water and mild
detergent like Ivory soap. Fill the second with distilled water, and the third with a solution of water and
isopropyl alcohol. Spray the sensor directly with the soap solution, and follow that with distilled water spray to
rinse it off. Finally a spray of alcohol will help to dry out the sensor quickly. As an alternative to the three
bottles, the alcohol alone will often be adequate to clear the sensor of surface contaminants. Avoid touching the
sensor surface directly as it is possible to scratch the sensor’s top protective layer. If necessary, a soft camel hair
brush may be used to help remove surface dirt.
For convenience, the sensor may be removed from the end of the probe before cleaning. The sensor connects to
the probe via four gold-plated pins. When reinstalling the sensor assembly, be sure to match up the notch on the
sensor assembly housing with the machined flat at the end of the probe.

32 4112 Dew Point Transmitter – Operations Manual 2/99

 Moisture Loop Calibration

8. Moisture Loop Calibration

The 4112 Transmitter is calibrated at the factory prior to shipping. A Certificate of Calibration is supplied
with each unit. Honeywell does not make any specific recommendation as to the re-calibration interval. The
Honeywell moisture sensor is constructed of an inert thermoset polymer. There is nothing inherent in the
sensor material or construction that dictates re-calibration after a specific interval of time. Many Honeywell
moisture sensors have been in service in harsh environments for several years without requiring re-
calibration. The users’ own quality system requirements or regulatory requirements are the factors that
commonly drive the need for re-calibration.
There are two calibrations that can be done in the field, moisture loop and temperature. In most cases, even
when replacing the sensor, it is only necessary to perform the moisture calibration. The moisture
calibration consists of a zero and span. The temperature calibration is not recommended.
For many companies, up-to-date traceable instrumentation calibration is a necessity. In such cases, the
instrument can be returned to Honeywell for a full factory calibration. The instrument will be calibrated by
Honeywell and returned to the customer with an NIST traceable Certificate of Calibration. Before returning
the instrument to Honeywell, call for a Return Merchandise authorization (RMA) and instructions for its
return.

REFERENCE
(Table 6-1 , 6-2 ), Fig. 1-1 , Fig. 6-3, Fig 8-3, and Fig. 9-1

Table 8-1 Calibration Kit #4113-L60-0001

Quantity Description

1 Aluminum Calibration Canister with Appropriate Fittings (2) and stopper

1 Plastic Calibration Bottle

1 Packet of Reagent Quality Sodium Chloride (RH-75.3%)

3 Packets of Molecular Sieve/Desiccant

2/99 4112 Dew Point Transmitter – Operations Manual 33

4112 Dew Point Transmitter Operations Manual

Table 8-2 ZERO Calibration Procedure

Step Action Result/Notes

1 Obtain a screwdriver, suitable power supply, The Calibration Kit provides the necessary
Calibration Kit or alternate 0% and 75.3% RH standards. Near 0% RH can also be obtained
standards. from bottled Nitrogen gas. A 75.3% RH standard
may be made by mixing a saturated solution of
sodium chloride in a suitable container.

2 Remove outer cover from the transmitter. Turn cover counterclockwise.

3 Remove inner cover from the transmitter. Loosen mounting screws(3) and one ground
screw.

4 Power the transmitter Make sure terminals are covered with black shield

5 Set S-200-2, labeled DP-2 to OFF; make sure Bottom display of transmitter will display %RH
S-201-3 is ON

6 Prepare dry gas(0 %RH) Add packet of desiccant to aluminum canister .

Use desiccant only once.

7 Insert the probe into the canister with the Let stand for 30 to 60 minutes. RH reading should
attached compression fitting, and fasten the be 0 to 0.1 % after time has elapsed. If so, go to
fitting around the probe end. step 9. If higher, go to step 8.

8 Activate DIP switch S-200-1,labeled DP-1 to S-200 is on the top edge of the microprocessor
OFF position for approximately 2 seconds then board in Figure 6-3. The display should be
return to ON position. reading 0.0% RH.

9 Remove the 0% RH standard. Go to Table 8-3 for span calibration

Note: Factory calibration values can be restored by setting DIP switch S-201-3 to OFF, while power is applied to
transmitter.

34 4112 Dew Point Transmitter – Operations Manual 2/99

 Moisture Loop Calibration

Table 8-3 Span Calibration Procedure

Step Action Result/Notes

1 Add a portion of the salt(NaCl) to the empty

plastic Calibration Bottle. (Use about ¼ of salt
packet.)

2 Add distilled water (about 10 ml) to form a Slush/slurry appearance, salt crystals should be
saturated solution. visible in solution Avoid wetting the plastic filter in
the bottle.

3 Insert the probe via the plastic filter fitting. Let stand for approximately two hours. The lower
Insert the bottle into a temperature stable transmitter display should read 75.3% RH @
environment, see Figure 9-1 Calibration Setup 75°F/24°C after the two hours.

4 If the transmitter does not read 75.3% RH;

proceed to step 5. If the transmitter is reading
75.3% RH, proceed to step 7.

5 Remove the Honeywell nameplate from the Moisture display increments up or down. CAL is
face of the transmitter. displayed until actuator is released. After
adjustment, CCC.C appears in the display.
Use a flathead screwdriver to rotate slot D
clockwise to increase, counter clockwise to
decrease display of %RH until lower displays
read 75.3% RH.

6 Momentarily press and release again. If CCC.C does not clear, the switch button is
stuck, or there is an internal fault. Have the
transmitter serviced.

7 Set S-200-2 back to the ON position. The Do not turn OFF S-201-3 or the original factory
calibration is complete. span and zero calibration will be restored.

Table 8-4 Temperature Dependence of Salt Solution Humidity Standards

Salts 15°C (59°F) 20°C (68°F) 25°C (77°F) 30°C (86°F) 35°C (95°F)

Sodium Chloride %RH 75.61 75.47 75.29 75.09 74.87

Lithium Chloride %RH 11.30 11.31 11.30 11.28 11.25

Potassium Carbonate %RH 43.15 43.16 43.16 43.17 N/A

2/99 4112 Dew Point Transmitter – Operations Manual 35

4112 Dew Point Transmitter Operations Manual

Dew Point Temperature

Channel Channel
R Load R Load
4 - 20 mA 4 - 20 mA

N.C. L1
120 VAC R1 R2
N.C. L2 60 Hz DVM DVM
Comm Comm
H2 O H2 O

Temp Temp

INC

Z S D

Ambient Temp. Zero

Dew Point
(±Multiturn Pot.)
Cal. Actuator
(±10° multiturn Only)
Ambient Temp. Span
(±Multiturn Pot.)

R1, R2 = Precision Wirewound

Load Resistor 250 Ohm
.01%, 1/2 Watt

DVM = 5 1/2 Digit Data Precision

Model 3500

Range = 4 - 20 mA = 1-5 VDC

a/n 23321

Figure 8-1 Electrical Test Setup

36 4112 Dew Point Transmitter – Operations Manual 2/99

 Temperature Loop Calibration Procedure

9. Temperature Loop Calibration Procedure

CAUTION
• Do not attempt this procedure unless temperature bath can be measured and controlled to 0.01deg c via
NIST traceable standards.

• Do not remove the P.C. assemblies from the lower housing as this affects calibration

REFERENCE
(Table 6-1, 2 ), Fig. 1-1 , Fig. 6-1, fig 8-1, and Fig. 9-1

Table 9-1 Transmitter Cal. Procedure

Step Action Result/Notes

1 Obtain a power supply, resistance decade Connections are shown in Fig. 8-1, electrical test
box(0-5000 ohms, settable to .01 ohm), load set up
resistors and DVM. Also tip cover( Honeywell
part number 225-0158)

2 Remove both transmitter covers.

3 Unplug RH coax cable from A to D board

4 Disconnect RTD wires from RTD terminal

block

5 Connect resistance box to RTD block Set for zero ohms(or short box terminals)

6 Turn the Zero trimpot located on the Mother

Board, fully counter clockwise.

7 adjust RV-400 trimpot on the RTD Board Temperature Channel output of 3.98 to 4.00
milliamps cutoff

8 adjust RV-301on the A to D Board Temperature Display reading of 000.0. Dew Point
display should now read -104.7.

9 adjust RV-200 trimpot on the Microprocessor 0.000 millivolts output +/- 50 microvolts at pins 1
Board and 2 of U-200 IC

10 adjust RV-202 trimpot on the Microprocessor Dew Point Channel output of 3.98 to 4.00
Board milliamps cutoff.

11 Set decade box to 1000 ohms

2/99 4112 Dew Point Transmitter – Operations Manual 37

4112 Dew Point Transmitter Operations Manual

Table 9-2 Transmitter Cal. Procedure, continued

Step Action Result/Notes

12 adjust the Zero trimpot on the Mother Board for slightly over 4 milliamps Temperature Channel
output and then slowly back to 4.00 milliamps

13 adjust RV-301 trimpot on the A/D board Temperature Display reading of 000.0.

14 Set the decade box for 1754.89 ohms

15 adjust the SPAN trimpot on the Mother Board 20.00 milliamps output on the Temperature
Channel

16 adjust trimpot RV-302 located on the A/D Temperature Display to read 204.7.
Board

17 Remove decade box (open circuit)

18 adjust RV-201 trimpot on the Microprocessor for Dew Point channel 20.00 milliamps output
Board

19 Reconnect the RTD Sensor wires to the RTD

Board

20 set S-200-2 (DP/RH DIP switch) to OFF sets moisture to RH display

21 Reconnect the RH Sensor coax cable to the

A/D Board

22 Place protective tip cover on end of probe prevents water/oil Sensor contamination

23 immerse probe into a standard 0 degree

centigrade ice bath for 30 minutes

24 adjust the Zero trimpot located on the Mother for slightly over 4 milliamps Temperature Channel
Board output then slowly back to 4.00 milliamps output.

25 Remove probe from ice bath, then place probe

into oil bath approximately 100 degree
centigrade for 30 minutes

26 adjust the Span trimpot located on the Mother for the Temperature Channel milliamps output by
Board using the following transfer equation:
o
milliamps output = (( Bath Temp C / 204.7 ) x 16
mA )) + 4 mA.

27 Remove the protective tip cover from end of

probe and expose the Sensor to a dry gas
calibration source for 15-20 minutes or
Honeywell PK-2 dry gas calibration source for
thirty(30) minutes.
2
28 Set S-200-1OFF for a minimum of 2 seconds, Stores zero cal value in E ROM
to ON.

38 4112 Dew Point Transmitter – Operations Manual 2/99

 Temperature Loop Calibration Procedure

Table 9-3 Transmitter Cal. Procedure, continued

29 Expose the sensor to a sodium chloride Salt
Bath Standard in approximately a 25 degree
centigrade ambient temperature environment
of gravel mass per Figure 9-1 for 120 minutes

30 using screw driver slot switch activator D (Fig. read 75.3 % RH.
8-1), increment or decrement the Display

31 re-assemble unit Calibration is completed

2/99 4112 Dew Point Transmitter – Operations Manual 39

4112 Dew Point Transmitter Operations Manual

N.C. L1
120 VAC
N.C. L2 60 Hz
Comm Comm
H 2O H 2O
Temp Temp

Jumper

INC

Z S D
Ambient Temp. Zero
(±Multiturn Pot.) Dew Point
Cal. Actuator
(±10° multiturnOnly)
Ambient Temp. Span
(±Multiturn Pot.)

Any Container

Fine Gravel
Thermal Mass
(I.E. Aquarium Gravel)

3"

Place bottle 3" below

gravel level

Relative Humidity Bottle

HY-CAL HC-60-75

2" min 2" min

Solution with
Sodium Chloride
2" min Crystals in a
Saturated Solution

a/n 23322

Figure 9-1 Calibration Setup

40 4112 Dew Point Transmitter – Operations Manual 2/99

 Cooler Option

10. Cooler Option

10.1 Introduction
The Dew Point Transmitter has a maximum sensor operating temperature of 185°C. The optional Cooler
allows the safe operation of the sensor at process temperatures of up to 540°C (1000°F).
The Cooler surrounds the Dew Point probe with a jacket of flowing external air. Customer supplied air is
directed through the inlet port on the Cooler. The air is vented through a muffler on the outlet port. A safe
operating temperature can be maintained by controlling the air pressure.
Table 10-1 Cooler Performance, shows the cooling capability of the cooler. The data was obtained by
inserting the Dew Point Transmitter and Cooler into an oven in still air. The table lists sensor temperatures
for various oven temperatures and inlet pressures. For example, with oven temperature at 427°C and inlet
pressure at 20 psig, the dew point sensor temperature is 109°C, well below the 185°C maximum sensor
rating.

Table 10-1 Cooler Performance

Inlet Pressure (psig) Air Flow (scfm) Ambient Static Air Temperature

538°C 427°C 316°C 204°C

w/muffler w/o muffler Dew Point Sensor Temperature (deg C)

50 ----- ----- 89 62 49 37

40 23 3 102 74 53 39

30 16 2.3 120 88 60 43

20 10 2 152 109 75 50

10 ----- ----- 148 99 62

CAUTION
Maximum sensor temperature is 185°c. exceeding this temp. will damage the sensor and void the warranty.

REFERENCE
Data Developed using a 12 in. probe and cooler with 5 (0.187 dia.) vent holes. Actual sensor temperatures
depend upon actual process ambient (moving vs static air) and inlet process air temperature.

10.2 Cooler Construction

The Cooler is made from 304 stainless steel. All joints are welded or brazed. The mounting thread of the
Cooler is 2 ½” male NPT. The inlet port is ¼” female NPT. A muffler is factory installed on the outlet port.
The center mounting hole for the Dew Point Transmitter is ½” female NPT. See Figure 10-1.

2/99 4112 Dew Point Transmitter – Operations Manual 41

4112 Dew Point Transmitter Operations Manual

11.085" +/- 0.300 1/4" 18 FNPT

1.875 (Air, In)

.700

90 o Street Elbow
1.25" 304 SST
DIA.

.187" DIA. 4 PLC’s

.18" DIA Equally Spaced Muffler 1/4" NPT
2 1/2"" 8 NPT constructed of Porous
Process Connection Sintered Bronze Bonded
NOTES:
to Copper Pltd Steel Pipe
- Operating Temperature: 1000 o F Max (Air, Out)
- Operating Pressure: 100 psig Max.
- If the cooling air supply is interrupted long
enough for the cooler interior to overheat,
the Dew Point sensor will be damaged.

Figure 10-1 Cooler Assembly

10.3 Installation
CAUTION
Installation must not permit exceeding the 185°C sensor limit or the 80°C max electronics operating limit. To
protect the sensor, the air supply must be reliable and over -temp and loss of air alarms are recommended.

Table 10-2 Cooler Installation

Step Action

1 Obtain a pressure regulator and gauge capable of delivering 5 scfm @ 50 psig., suitable tubing to
connect the air supply to the ¼ “ NPT inlet port, and a means to measure the cavity temperature.

2 Remove the Cooler from the transmitter. Loosely plug the ½” NPT mounting port temporarily.

3 Thread only the Cooler into the process environment.

4 Install the pressure regulator and gauge from the air supply to the Cooler inlet.

5 Turn on the air supply and set the regulator to 50 psig.

6 When the process temperature is at its hottest, allow 30 minutes for the Cooler cavity to reach its
maximum.

7 Measure the cavity temperature. Make sure it does not exceed 185°C.

8 For best performance, adjust the pressure to make the cavity temperature about 25 deg. above the
normal process dew point. See

9 Complete the transmitter installation.

42 4112 Dew Point Transmitter – Operations Manual 2/99

 Cooler Option

2/99 4112 Dew Point Transmitter – Operations Manual 43

 Hazardous Locations

11. Hazardous Locations

11.1 Introduction
The Honeywell model 4112 Dew Point Transmitter is approved by Factory Mutual:
Case: NEMA 4X, approved units have FM labeling.
Explosion proof: Class I, Division 1, Groups B, C, and D; dust-ignition proof for Class II, Division 1,
Groups E, F, and G indoor and outdoor locations.
Intrinsically Safe: Class I, Division 1, Groups A, B, C, and D; dust-ignition proof for Class II, Division 1,
Groups E, F, and G indoor and outdoor locations in accordance with Drawing No. A-21008, Rev 4-7-94

11.2 Explosion Proof Installations

In order to maintain an explosion proof installation, adhere to the following guidelines:
1. Unused conduit entrances must be plugged. Plugs must be installed with at least 5 threads engaged.
2. Conduit seal must be used within 18 inches of conduit entry.
3. All wiring must comply with the National Electrical Code(ANSI/NFPA 70) in addition to local
electrical codes, regulations and ordinances. Explosion proof conduit must be used.
4. Do not apply power to the transmitter with top housing cover removed. Do not remove the cover with
power on.
5. Modification to equipment or substitution of components by other than authorized factory
representative will void hazardous location ratings.

11.3 Intrinsically Safe Installations

The model 4112 must be specified with Option 209 in order to be intrinsically safe.
For guidance on installation, see ANSI/ISA RP 12.6, “Installation of Intrinsically Safe Instrument Systems
in Class I Hazardous Locations.” These installations require the use of approved safety barriers.
See Drawing A-21008 (three pages) :
Page 1, Installation per FM Entity Parameter Concept.
Page 2, Two Installations using Stahl barriers.
Page 3, An installation using MTL barriers.

2/99 4112 Dew Point Transmitter – Operations Manual 45

4112 Dew Point Transmitter Operations Manual

3 Positive
2 Loop Barriers
24V (40 mA MIN) (Notes 3 & 4)
DC Supply
0.1A 8-40 mA
Fuse
COM
Notes:
Power Supply Ground 1. Vmax must be greater than Vt of the FMRC approved
4-20 mA + barrier combination.
H2 O
Imax must be greater than It of the FMRC approved
Alternate Load Resistor
Location (Note 2) barrier combination.
4-20 mA + Ci plus interconnecting wiring must be less than C0 of the
TEMP FMRC approved barrier combination.
2. Preferred location of 2500 load resistor is for high
CAT 4112 impedence receiver input circuit for less than 250k Ohm
Signal Common Dew Point/ input impedance move load resistor to receiver terminals.
Temperature This adds barrier resistance to transmitter load.
1-5V Receiver Transmitter 3. Install in accordance with manufacturers instructions and
Input Terminals (Note 1) NEC Article 504 and ANSI/ISA RP12.6.
Dew Point 4. Typical connections are shown to barrier unit terminals.
Alternate Load Resistor Maximum fault voltage in any circuit connected to barrier
Location (Note 2) Preferred Load terminals must not exceed 250V RMS or 250VDC.
Resistor Location 5. A Approved transmitters:
(Note 2) 4112 02-D1.d2-C-100 207
to D3H1-f-104 208
Signal Common 60 H3W1 209
1/4 X 1 3/4 Copper Bus Bar B See sheet 2 of this drawing for Stahl barrier system
1-5V Receiver and sheet 3 for MIL barrier system.
for Mounting Barriers. Must 6. Use only NRTL listed dust tight fitting or threaded conduit
Input Terminals Have 2 Earth Ground
Temperature Connections. Bus Bar to for installation in Class II, Division I, Groups E, F, and G.
Ground Resistance 1 Ohm
Maximum.
Intrinsic Safety Entity Paramters:
NONHAZARDOUS LOCATION Vmax = 30 volts
HAZARDOUS LOCATION
Class I, II, III Imax = 360 mA
Division 1 Ci = 0.1uF
Groups A, B, C, D, E, F, G Li = mH

Cat 4112 Entity Intrinsically Safe Installation

Dew Point/Temperature Transmitter with Negative Ground Supply a/n 23323

Figure 11-1 Drawing A-21008, Sht 1

46 4112 Dew Point Transmitter – Operations Manual 2/99

 Hazardous Locations

OPTION I

HAZARDOUS LOCATION NONHAZARDOUS LOCATION

Class I, II, III
Div 1
Groups A, B, C, D, E, F, G

COM 8-40 mA 3 2 Loop

9002/13-280-110-00 1 + Notes:
H 2O 4-20 mA 4 24V (40 mA MIN)
2 - 1. Intrinsic safety barrier specifications as follows:
DC Supply
+/PA PA/+ R Stahl 9002/13-280-110-00 Intrinspak
4-20 mA + 1-5V Receiver Rated Voltage +24 to 26 VDC per channel
TEMP 3
1 Input Terminals Resistance 280 Ohm Channel I
4 9001/03-280-000-10 -
2 Dew-Point 1V Drop Channel II
+/PA 1-5V Receiver
PA/+2 -
+ Input Terminals R Stahl 9001/03-280-000-10 Intrinspak
Temperature Rated Voltage +24 to 26 VDC
Resistance 1V Drop
250 Load
CAT 4112 I S Ground Resistor
Dew Point/ R Stahl 9004/01-280-050-00 Intrinspak
Temperature Rated Voltage +24 to 26 VDC per channel
Transmitter Resistance 53 Ohm plus 0.9V Drop

OPTION II 2. Install in accordance with manufacturers instructions

and NEC Article 504 and ANSI/ISA RP12.6.

COM 8-40 mA 3 2 Loop

9004/01-280-050-00 1 + 3. Use only NRTL listed dust tight fitting or threaded
H 2O 4-20 mA 4 24V (40 mA MIN)
2 - conduit for installation in Class II, Division I,
DC Supply
+/PA PA/+ Groups E, F, and G.
4-20 mA + 1-5V Receiver
3 1
TEMP Input Terminals 4. Maximum fault voltage in any circuit connected to
4 9001/03-280-000-10 2 - Dew-Point barrier terminals must not exceed
+/PA PA/+ 1-5V Receiver
- 250V RMS or 250 VDC.
3 1 + Input Terminals
4 9001/03-280-000-10 2 Temperature

+/PA PA/+ 250 Load

Resistor

I S Ground

Cat 4112 with Stahl Barrier System Intrinsically Safe Installation

Dew Point/Temperature Transmitter with Negative Ground Supply a/n 23324

Figure 11-2 Drawing A-21008, Sht 2

2/99 4112 Dew Point Transmitter – Operations Manual 47

4112 Dew Point Transmitter Operations Manual

HAZARDOUS LOCATION
NONHAZARDOUS LOCATION
Class I, II, III
Div 1
Groups C, D, E, F, G

COM 8-40 mA 3 1 2 Loop

+
4-20 mA MIL787SP 24V (40 mA MIN)
H 2O 4 2 - DC Supply
3 1 1-5V Receiver
4-20 mA MIL787SP +
TEMP 4 2 Input Terminals
-
Dew-Point
- 1-5V Receiver
+ Input Terminals
Temperature
CAT 4112 I S Ground
Dew Point/ 250 Load
Temperature Resistor
Transmitter
Notes:
1. Install in accordance with manufacturers instructions and
NEC Article 504 and ANSI/ISA RP12.6.
2. Maximum fault voltage in any circuit connected to barrier
terminals must not exceed 250V RMS or 250VDC.
3. Use only NRTL listed dust tight fitting or threaded conduit
for installation in Class II, Division I, Groups E, F, and G.

Cat 4112 with MIL Barrier System Intrinsically Safe Installation

Dew Point/Temperature Transmitter with Negative Ground Supply a/n 23325

Figure 11-3 Drawing A-21008, Sht 3

48 4112 Dew Point Transmitter – Operations Manual 2/99

 CE Approvals

12. CE Approvals

Introduction
The following statements covers the subject of CE approvals for the 4112 Dew Point Transmitter.

CE conformity: This product is in conformance with the protection requirements of the following
European Council Directive: 89/336/EEC, the EMC directive. Conformance of this product with any
other “CE Mark” Directive(s) shall not be assumed.

Attention
The emission limits of EN 50081-2 are designed to provide reasonable protection against harmful
interference when this equipment is operated in an industrial environment. Operation of this equipment in a
residential area may cause harmful interference. This equipment generates, uses, and can radiate radio
frequency energy and may cause interference to radio and television reception when the equipment is used
closer than 30 meters to the antenna(e). In special cases, when highly susceptible apparatus is used in close
proximity, the user may have to employ additional mitigating measures to further reduce the
electromagnetic emissions of this equipment.

2/99 4112 Dew Point Transmitter – Operations Manual 49

Industrial Automation and Control Helping You Control Your World
Honeywell, Inc.
1100 Virginia Drive
Fort Washington, Pennsylvania 19034