TI00471C/07/EN/02.
16 Products Solutions Services
71316927
Technical Information
OUSAF21
Optical sensor for the measurement of low color
concentrations
Application
The sensor is used to measure color concentrations in the low measuring range of the
visible electromagnetic spectrum.
• Color scale measurement
APHA/Hazen, potassium permanganate in water
• Measurement of color concentration
– Outgoing goods inspection/purity monitoring
– Color assurance
– Discoloration control
– Distillation monitoring
Your benefits
• As slightest color changes are detected, production quality is guaranteed
– Measuring range up to 2.5 AU or 50 OD (depending on optical path length)
– Can be configured to measure color concentration at discrete wavelengths in the
visible regionregion
– Outstanding filter properties for highest linearity
– Direct concurrence with laboratory values
– Integrated reference detector for the compensation of particles, bubbles and
lamp aging
– Incandescent lamp for long service life and stable measured values
• Cost-effective, time-efficient verification (liquid-free)
• FM- and ATEX-approved lamps for applications in the hazardous area
• Broad variety of window materials and seals for resistance to a wide range of
process media
• Optional air purge ports to prevent the formation of condensate on the optical
windows
OUSAF21
Function and system design
Measuring principle Light absorption
The measuring principle is based on the Lambert-Beer law.
There is a linear dependency between the absorption of light and the concentration of the absorbing
substance:
A = -logAm = ε . c . OPL
A ... absorption, Am ... absorption measured by detector
ε ... Extinction coefficient
c ... Concentration
OPL ... Optical path length
A light source emits radiation through the medium and the incident radiation is measured on the
detector side.
A beam splitter splits the light into two beams. One beam is used for measuring while the other acts
as a reference to compensate for particles, bubbles and lamp aging.
Once the light has passed through a filter for wavelength selection, the intensity of the light is
determined by a photodiode and converted to a photocurrent.
The subsequent conversion to absorbance units (AU, OD) is performed in the associated transmitter.
1 OPL AR 2 3
Am
6 8 7 6 5 4
A0029408
1 Absorption measurement (double wavelength) with reference
1 Light source
2 Reference detector
3 Reference filter
4 Measuring detector
5 Measurement filter
6 Beam splitter
7 Optical windows
8 Medium flow
Measuring system An optical measuring system comprises:
• OUSAF21 sensor (photometer) with flow assembly
• Liquiline CM44P transmitter
• CUK80 cable set
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OUSAF21
1 2 3
6 5 4
A0029658
2 Example of a measuring system with OUSAF21
1 CUK80 cable set 4 OUSAF21 detector unit
2 Medium outflow from assembly 5 Medium inflow to assembly
3 CM44P transmitter 6 OUSAF21 lamp unit
Input
Measured variable process absorption
Measuring range • 0 to 2.5 AU
• Max. 50 OD (depending on the optical path length)
Wavelength Measurement 400 nm, 420 nm, 520 nm
Reference 720 nm
Power supply
Electrical connection The sensor is connected to the transmitter using the pre-terminated or labeled cable set CUK80 (for
connection to CM44P) or OUK20 (for connection to CVM40). The terminals and labeling may vary
depending on the transmitter in use. The cable set must be ordered separately.
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OUSAF21
A B
GY
YE RD
YE BK
BK WH
BK GN
GY
A0029436
3 OUSAF21 connecting cable
A Light source (lamp) power supply
B Signals of detector
CM44P terminal CVM40 terminal Cable color Assignment
P+ V1.1 YE (thick) Lamp voltage +
S+ V1.3 YE (thin) Detection of lamp voltage +
P- V1.2 BK (thick) Lamp voltage -
S- V1.4 BK (thin) Detection of lamp voltage -
A (1) S1.1 RD Measuring detector sensor +
C(1) S1.2 BK Measuring detector sensor -
SH (1) S1.S GY Shield
A (2) S2.1 WH Sensor reference +
C(2) S2.2 GN Sensor reference -
SH (2) S2.S GY Shield
Cable length Maximum 100 m (330 ft)
Lamp voltage Sensor version Lamp type Lamp voltage [V]
OUSAF21-xxxxx Dual beam, high-luminescence or gas-filled high- 4.9 ± 0.1
performance lamp
Versions for use in Safety instructions for electrical apparatus in explosion-hazardous areas, XA01403C
hazardous areas
Connecting the detector using a safety barrier
The photometer sensors use silicon photovoltaic cells as detectors which are operated in the current
mode. The detectors are intrinsically safe and can be deployed in Zone 1 environments.
The safe area is separated from the hazardous area by two safety barriers MTL7760AC.
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OUSAF21
90 (3.54)
12.6 (0.5)
105 (4.13)
4 Safety barrier, dimensions in mm (inch)
The safety barrier may only have a very low leak current since the optical signals from the
sensor can be in the nanoampere range. Therefore, the sensor cable shield is connected to the
ground terminal of the barrier.
On delivery, the CUK80 detector cable is permanently wired to the safety barriers. All you have to do
is simply connect the individual cable ends to the detector and transmitter.
Photometer 2x MTL7760ac CM44P
(Det.)
BK
BK C (1)
3 1 RD
RD A (1)
4 2 SH (1)
GN GN
3 1 C (2)
WH
WH A (2)
4 GY 2 GY
SH (1)
Connecting the hazardous area lamp using a junction box
The hazardous area lamp (EXP-1) must be connected to the transmitter using a certified junction
box.
For versions with FM approval, the junction box is included in the delivery and already pre-
terminated on the lamp side. You simply have to connect the cable of the transmitter (CUK80)
to the terminals of the junction box.
For versions with ATEX approval, the junction box is not included in the delivery and it and the
cable glands required must be provided by the customer at the place of installation. You must
connect the cables entirely on your own (CUK80 of transmitter and lamp cable of photometer
sensor).
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OUSAF21
EXP-1 CM44P
ATEX II 2G Ex db IIC T5 Gb
FM Cl.1, Div. 1, Groups B, C, D
YE
P+
YE
S+
BK
S-
BK
P-
PE
27
30
A0029440
5 Connecting the hazardous area lamp to CM44P using a junction box
Installation
Installation instructions
A C
A0029247
6 Mounting angles. The arrows indicate the direction of medium flow through the assembly.
Environment
Ambient temperature range 0 to 55 °C (32 to 130 °F)
Storage temperature -10 to +70 °C (+10 to +160 °F)
Humidity 5 to 95 %
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Degree of protection IP 65 (NEMA 4) for all optical parts
Process
Process temperature 0 to 90 °C (32 to 194 °F) continuous
Max. 130 °C (266 °F) for 2 hours
Process pressure Max. 6 bar (84 psi) absolute, depending on the material, pipe size and process connection of the flow
assembly
Mechanical construction
Design, dimensions Lamp type Dimension A in mm (inch)
Detector type Dimension B in mm (inch)
The total length of the sensor module is derived from the lengths of the lamp, the detector and
the assembly.
The dimensions of the OUA260 assembly are provided in Technical Information, TI00418C.
A B C
A0029245
7 Dimensions, see table
A Lamp module
B Flow assembly
C Detector module
Lamp module Dimension A in mm (inch)
High-luminescence lamp and standard incandescent lamp 33.78 (1.33)
Gas-filled lamp 33.78 (1.33)
Flow assembly Dimension B in mm (inch)
Path length 100 mm 150 (5.9)
Path length 150 mm 200 (7.9)
Path length 200 mm 250 (9.8)
Path length 250 mm 300 (11.8)
Detector module Dimension C in mm (inch)
Standard version 101.6 (4.0)
‣ When connecting the sensor cable, make sure you maintain an additional distance of 5 cm (2")
on both the lamp side and the detector side of the sensor.
Weight 1.225 kg (2.7 lbs.), without flow assembly
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OUSAF21
Materials Sensor housing Stainless steel 316L
Cable connection ends Nickel-plated brass
Light source High-luminescence lamp (wavelength filter 450 nm and above)
Gas-filled high-performance lamp (wavelength filter below 450 nm)
Lamp operating life: typically 10 000 h
Detector UV silicon detectors, hermetically sealed
Filter Multilayer narrow-band interference filter
Certificates and approvals
mark Declaration of Conformity
The product meets the requirements of the harmonized European standards. As such, it complies
with the legal specifications of the EC directives. The manufacturer confirms successful testing of the
product by affixing to it the mark.
Ex approvals • ATEX II 2G Ex db IIC T5 Gb
• FM Cl.1, Div. 1, Groups B, C, D
Ordering information
Product page www.endress.com/ousaf21
Product Configurator On the product page there is a "Configuration" button to the right of the product image.
1. Click this button.
The Configurator opens in a separate window.
2. Select all the options to configure the device in line with your requirements.
In this way, you receive a valid and complete order code for the device.
3. Export the order code as a PDF or Excel file. To do so, click the appropriate button on the right
above the selection window.
For many products you also have the option of downloading CAD or 2D drawings of the
selected product version. To do so, click the "CAD" tab and select the desired file type using drop-
down lists.
Scope of delivery The scope of delivery consists of the following :
• sensor
• Detector and lamp module mounted on OUA260 flow assembly
• Operating Instructions
If the sensor is ordered with a transmitter, the complete measuring system is factory-calibrated and
shipped as one package.
If you have any questions, please contact your supplier or your local sales center.
Accessories
The following are the most important accessories available at the time this documentation was
issued. For accessories not listed here, please contact your service or sales office.
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Cable CUK80 cable set
• Pre-terminated and labeled cables for connecting analog photometer sensors
• Product Configurator on the product page: www.endress.com/cuk80
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