1354 VPA – Practical

by Ajay Laghate
 Course Content
• Checks prior to start-up.

• Start-up.

• Calibration/validation and verification with laboratory analysis.

• Major parts recognition and removal/replacement .

• Stripping apart of critical parts for servicing.

• Routine Maintenance.

• Q&A Session.

The Precision Behind The Process

 Checks Prior to Start-Up
(Before carrying out the following checks please
ensure the power to the analyser has been
isolated)!

The Precision Behind The Process

 Type of Oil

The type of bath oil chosen is specific according to its heat transfer
properties. The oil that ATAC recommends is Shell Thermia Oil B,
however it is understood that alternative oils more readily available
may want to be used. As a general rule as long as the oil used has the
same characteristics and properties as the specification data sheet for
Shell Thermia Oil B then it will be ok to use. A copy of the specification
data sheet for Shell Thermia Oil B is in your training folders.
If at anytime you are in doubt then please contact ATAC for advice and
assistance.

The Precision Behind The Process

 Bath Oil Level

Lower the analyser bath

and fill with the appropriate
oil to this level. (Normally
11 litres).

The Precision Behind The Process

 Bath Oil Level - continued
As the bath has had to be lowered for filling now
is a good time to check the movement of the
stirrer and to check for fouling.

To do this remove the top cover of the motor by

removing the two retaining screws and manually
turn the fan.

Once the oil bath has been filled and checks completed return
the oil bath to its normal operating position and tighten all of
the oil bath retaining bolts and replace the motor top cover.

The Precision Behind The Process

 Control Enclosure
Incoming analyser power
supply terminated here.
Neutral Before switching on the
analyser, check that
Live power supply is of the
correct voltage and the
Earth live, neutral and earth
wires are terminated
correctly and securely.
Overload trip

Power fail relay connections (optional).

Two connections that can be either fail-safe
or non fail-safe. For fail-safe terminals 6 &1
are common and terminals 5 & 3 are N/C.

The Precision Behind The Process

Control Enclosure - continued

With the control enclosure open

further checks can be carried out.
Check the tightness of all wire
terminations and security of all
PCB’s.

The Precision Behind The Process

 Control Enclosure - continued
The Temperature Control Card has two sets of dip-switches, Gain & Reset,
which are Factory set and are for the heater PID. There is also a heater
on/off switch which is for Factory testing use only and should always be in
the OFF position.

Main fuse.

Factory use heater on/off switch.

Temperature Control Card.

Reset dip-switches

Gain dip-switches.

The Precision Behind The Process

 Start-Up
(Do not attempt to power up the analyser unless
the previous checks mentioned have been
carried out).

The Precision Behind The Process

Once the previous checks mentioned have been carried out and
everything is found to be satisfactory, power can be applied to the
analyser and the analyser can be powered up using the analyser
power on/off switch and at the same time the analyser motor on/off
switch can also be switched to the on position.
At this stage allow the analyser to reach the operating temperature of
37.8°C before any process is introduced to the analyser. While the
analyser is warming up prepare the SCS to supply process to the
analyser and check that the available inlet pressure to the analyser
will be sufficient to overcome the return line pressure and for
vaporisation of the product. For this to occur the analyser inlet
pressure needs to be: 2.5bar x return line pressure + 7bar.
To check if the analyser has reached operating temperature check the
reading on the mercury thermometer and at the same time check that
the amber heater light is pulsing on/off on a regular basis.
N.B. Never power on the analyser with the oil bath lowered as this will
cause damage to the analyser.
The Precision Behind The Process
 Introducing Process to the analyser
To begin with, ensure that the
analyser Forward Pressure Regulator
(FPR) and Back Pressure Regulator
(BPR) are closed and the Flushing
Valve is fully open. As the first
quantities of process that will have
gone through the SCS and from the
process line may be contaminated if
the lines were not previously flushed
this will ensure that the analyser will
not end up with contamination or
particulates in the analyser sample
lines and nozzle assembly.
Flushing Valve. Forward Pressure
Regulator
Back Pressure Regulator
The Precision Behind The Process
 Introducing Process to the analyser - continued
After approximately 5 minutes of
running process to the analyser with
the Flushing valve open, fully open the
BPR. Then close the Flushing valve
and slowly open the FPR until the
required pressure is seen at the
Nozzle Pressure indicator.
Then slowly increase the back
pressure to approximately 10psi,
according to the Back Pressure
indicator, using the BPR, having this
small amount of back pressure helps
to provide for a more stable output
Nozzle Pressure Indicator from the analyser.

Back Pressure Indicator

The Precision Behind The Process

 Introducing Process to the analyser - continued
Once the analyser has been running for
approximately 10 to 15 minutes
disconnect the tube line between the
Vapour Pressure indicator and the
transmitter while the analyser is still
running, this serves two purposes:
1) It is the means by which to bleed the
transmitter.
2) It is another check to ensure that
there is indeed vapour in the vapour
line and not liquid.

Vapour Pressure Vapour Pressure

Indicator line to Transmitter

The Precision Behind The Process

Calibration/Validation

The Precision Behind The Process

Once the analyser has been running for approximately one hour and has
stabilised then a laboratory sample can be taken for calibration/validation
purposes. The best way to calibrate or validate is by what is referred to as
the “grab sample” method.

The analyser, as supplied, will have been Factory calibrated using a standard
reference liquid and it should not normally require adjustment. However, it is
always good practice during the Commissioning phase to ensure the
analyser is calibrated to the laboratory analysis and once calibrated the
analyser output should need only validation/verification on a periodic basis.

The following is a guide to calibration/validation:

1. Confirm that the temperature of the oil bath is accurately set to the
specified value (normally 37.8°C +/- 0.01°C).

The Precision Behind The Process

2. Ensure that the analyser is running normally and producing a stable
vapour pressure output.

3. Record the reading on the analyser transmitter and immediately take a

sample of the sample at the sample take off point from the SCS, also making
a note of the date and time. This sample should be taken in a container
designed to minimise losses through vaporisation. Carry out several
laboratory tests to ensure that results are within the limits of the ASTM D323
Reid Vapour method.

4. If the analyser output is the same as the laboratory test and falls within the
ASTM limits, no further action is necessary. (ASTM limits: Dependent on
product and procedure used, on average 2kPa or 0.29psi or 0.02bar)

5. If it is necessary to make an adjustment then this can be carried out by

connecting a hand held communicator to the analyser transmitter and
“trimming” the transmitter according to the required amount.

The Precision Behind The Process

 Major Parts recognition
and removal/replacement

(Before carrying out any of the following work

please ensure the power and process to the
analyser has been isolated and that if required a
Hot Work Permit has been obtained).

The Precision Behind The Process

Oil Bath Thermal Fuse
Over-temperature of the oil bath is prevented
by a thermal fuse – this is mounted in a
thermo-well adjacent to the heater. To replace,
remove screw top from heater, disconnect
thermal fuse wires from connector block and
gently pull thermal fuse out of location holder.
Fitting is the reversal of removal.

Heater cover/access to Thermal Fuse

Thermal fuse location

The Precision Behind The Process

 Nozzle Assembly
The nozzle assembly can be removed
by unscrewing the nozzle assembly
holder and gentle pulling out of its
location. Once removed check the two
‘O’ rings for any signs of normal wear
or damage, check the nozzle for any
foreign debris and check the condition
of the filter.
Fitting is the reversal of removal with
the exception that a small amount of
silicon grease should be applied to the
two ‘O’ rings.

Nozzle Assembly holder

The Precision Behind The Process

 Sample Inlet Filter

The sample inlet filter is effectively a

‘Y’ – strainer, which allows for easy
removal of the filter element with the filter
body still in-situ.

Sample inlet filter

The Precision Behind The Process

 Motor
Power wires/cable
Removal of the motor is as
follows:
1) Lower the bath and remove
the two stirrers from the
stirrer shaft.
2) Disconnect the power
wires to the motor and
unscrew the cable gland.
3) Disconnect the earth wire.
4) Loosen and remove the
four retaining nuts and then
lift the motor vertically until
the shaft is clear of the Stirrers
bearing housing.
Earth wire 5) Fitting is the reversal of
removal.
Retaining Nuts
The Precision Behind The Process
Stripping apart of critical
parts for servicing

The Precision Behind The Process

• Nozzle assembly.

• Inlet filter.

• Thermal fuse.

• Temperature Control Chasis.

The Precision Behind The Process

Routine Maintenance

The Precision Behind The Process

Once commissioned, and provided the sample conditions are maintained and
checked, routine maintenance on the analyser is minimal.

The following checks should be carried out on a daily basis:

• Check that the bath temperature on the mercury thermometer is at 37.8°C

+/- 0.01°C .

• Check that the heater light is pulsing on/off on a regular basis.

• Check the process/sample pressures.

• Check for any leakages on fittings.

The Precision Behind The Process

The following checks should be carried out on a monthly basis:

• Check the bath oil level (middle of upper elbow).

• Operate the flush valve to clean the sample inlet filter.

The following should be carried out on an as required basis:

• Remove the inlet filter element for cleaning.

• Remove the nozzle assembly for cleaning.

• Validation checks.

The Precision Behind The Process

Thanks for listening.
Any questions?