The AMIAD Micro-Strainers are a fine filter that are designed to be an initial screen for many different processes. In this case they had been installed on the inlet pipe at Aurora A-Class Treatment Plant. I was engaged to investigate these filters that had been causing intermittent alarms. After my analysis, I recommended that the filters get an upgrade and full maintenance check. See my LinkedIn post for more info; https://www.linkedin.com/today/post/article/project-3-class-treatment-plant-amiad-david-list?trk=prof-post

1. Field Service Report
RTP074
Field Service Report
Recycled (A Class) Treatment Plant
Aurora
Completed by
David List
On behalf of YVW
June, 2016
Employed by Ventia

2. Field Service Report
RTP074 Aurora Recycled Treatment Plant
Field Service Report
The aim of this report is to outline the root cause of the original fault involving the
AMIAD Micro-Strainer. Then identify the improvements that were implemented to
rectify the fault.
Contents
AMIAD SAF-4500 Micro-Strainers Operation..............................................................................- 1 -
Problem..............................................................................................................................................- 5 -
Cause.................................................................................................................................................- 6 -
Cause - Low Operating Pressures ............................................................................................- 7 -
Remedy - Low Operating Pressures.........................................................................................- 7 -
Cause – Control Board Failure...................................................................................................- 8 -
Remedy – Control Board Failure ...............................................................................................- 8 -
Cause – Pause Function...........................................................................................................- 10 -
Remedy – Pause Function .......................................................................................................- 10 -
Cause – Differential Pressure Switch......................................................................................- 11 -
Remedy – Differential Pressure Switch ..................................................................................- 11 -
Maintenance....................................................................................................................................- 14 -
Improvements .................................................................................................................................- 18 -
Regular Maintenance.................................................................................................................- 18 -
Inlet Filter.....................................................................................................................................- 19 -
Conclusion.......................................................................................................................................- 20 -
References......................................................................................................................................- 20 -
Enquiries..........................................................................................................................................- 21 -

3. Field Service Report
- 1 -
AMIAD SAF-4500 Micro-Strainers Operation
The operation of the strainers is important to understanding how decisions were
made in regards to its ultimate rectification. Below is a brief description on its
intended operation;
1. The AMIAD Micro-Strainers is located in the A-Class building at Aurora STP.
The strainer is situated on the inlet side of the Ultra Filtration (UF) Skids.
Below shows a screen shot of the UF feed system, including strainers;
2. The strainers are designed to filter the B-Class effluent to within 200 microns.
This is ensuring that no large particles enter the inlet of the UF Skids.
3. There are two strainers is parallel that operated simultaneously. At any time
one strainer can be isolated for maintenance purposes.

4. Field Service Report
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4. The filtering process is as follows;
For a more in depth view please see the link below;
http://www.amiad.com/catalog.asp?type1=1&cat=13

5. Field Service Report
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5. As suggested in point 4 “The Self-Cleaning Process”. The exhaust valve
opens to expel all the “cake” that is removed by the suction nozzles. In the
case of this particular installation the exhaust valves feature an inline pump
and pressure reducing valve.
This assembly was installed to accommodate the low operating pressures.
Without the pump installed the operating pressure alone would not be able to provide
enough suction to remove an adequate amount of “cake”. Though, with the pump
installed by its self it would provide too much suction and may damage the micron
filter inside.
So the pressure reducing valve is installed to sustain the correct pressure whilst
exhausting.

6. Field Service Report
- 4 -
6. The original controls for the strainers were provided by 2 control panels, one
for each strainer. These operated as a master/slave or duty standby
operation. The control for its operation was via the mode selector located
between the two controllers.
During the operation of either mode a pause function was used to prevent
scanning whilst the UF Skids were not requesting effluent.
This concludes the brief explication of how the AMIAD SAF4500 Micro-Strainer were
intended to operate.
For further information, please see the manual attached to this PDF.

7. Field Service Report
- 5 -
Problem
On Friday the 26th of February 2016 Ventia was engaged by YVW to investigate low
flow alarm on the AMIAD Micro-Strainers Flushing Controller at RTP074. By all
accounts this problem had persisted for many months and its operation was never
fully clear.
 The picture below shows the controller that was going into low flow. Every
time the low flow alarm sounds it must be reset locally before the strainers
could be operational.

8. Field Service Report
- 6 -
Cause
The cause of the low flow alarm was a combination of 4 main factor;
1. At low operating pressures the exhaust valves were unable to expel “cake”.
2. The control board for the master strainer was faulty.
3. The pause function was not correctly installed. Allowing the strainers to scan
at any time.
4. The differential pressure switches had failed due to lack of maintenance. This
would override the timed scan function and consecutively run a scan.
Either one of the faults could have cause the low flow alarm.
With the combination of the above faults not only did the flushing operation fail but
the overall straining operations also failed.
The following points will attempt to explain the “cause” & “remedy” as listed above.
Further improvements made on the strainers will then be listed and future
maintenance suggested.

9. Field Service Report
- 7 -
Cause - Low Operating Pressures
The exhaust valves installed were only designed to expel process fluid at a certain
pressure. When air is released from the diaphragm the process fluid must overcome
the piston and seat attached to the diaphragm. See picture below;
Remedy - Low Operating Pressures
The valves were replaced with butterfly actuator valves. This allows effluent to pass
through the valve at any pressure. All the air supply lines were also modified and
now feature isolation for maintenance purposes. See picture below;

10. Field Service Report
- 8 -
Cause – Control Board Failure
The printed circuit board inside the master controller had failed. The auxiliary power
that is supplied to the exhaust valves was not adequate to open them 100% of the
time. Hence giving and intermittent no flow fault on the flushing controller.
The picture below shows the failed transformer that caused the auxiliary power fault;
Remedy – Control Board Failure
After several conversations with AMIAD technical support. It was decided to remove
both controllers as only one is required.
The reason for this is that one controller can accommodate up to four
filters/strainers. The picture below is an exert from the SAF-4500 manual;

11. Field Service Report
- 9 -
The picture below shows the newly installed controller;
By changing the wiring configuration, a single controller was now able to
accommodate both filters/strainers. So by removing the master controller and only
using the slave controller we were able to overcome the broken circuit board.
NOTE: A spare circuit board was ordered in case this happens again.

12. Field Service Report
- 10 -
Cause – Pause Function
The pause function that causes the strainers to stop flashing whilst the UF filters are
not operational, was not wired correctly. This meant that the strainers were flushing
on a timed cycle but did not have sufficient operational pressure (feed pumps were
not running). Hence the flashing controller would go into no flow.
Remedy – Pause Function
When the master and slave controllers were merged into one. The opportunity was
taken to correctly wire the pause function.
The picture below shows what the local controller now displaying when the pause is
active;

13. Field Service Report
- 11 -
Cause – Differential Pressure Switch
The differential pressure switches are located directly on the strainers. They are
designed to measure the differential pressure across the micron filter and force a
flush at a pre-determined pressure (7psi).
Both switches had not been serviced for some time and had failed closed. As a
result the strainers were flushing all the time. The picture below shows the
differential pressure switch;
Remedy – Differential Pressure Switch
Whilst the concept of the pressure switches is necessary. They are very limited in
their functionality. So to increase diagnostics and operational efficiency the
discussion was made install differential pressure transmitters.
These transmitters were installed on both strainers and give real time values of the
differential pressure across the filters. See picture on the next page;

14. Field Service Report
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The existing switches were then decommissioned and the transmitters brought
online. Both of these transmitters can now be viewed and managed from CITEC, see
below;

15. Field Service Report
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The new differential pressure transmitters no longer immediately induce a flush/scan.
The differential set point and alarm delay is now variable via CITEC and once these
set points are reached it will only request that the operator force a flush/scan. See
below;
The example to the right shows a set point of 0.9
kPa and a time delay of 20 seconds.
If the differential pressure in either strainer exceeds
0.9 kPa for longer than 20 seconds, then and a
“WASH REQUIRED” label will appear.
This will not automatically initiate a flush/scan, this
will need to be done by the operator via the “RUN
REQUEST” button.
Any faults associated with the strainers are now also
shown and can be reset via CITEC. See below;

16. Field Service Report
- 14 -
Maintenance
Whilst the upgrades to the strainers were being performed. They also under went
some general maintenance.
1. The internal micron filters were removed and cleaned. Below is the dirty filter;

17. Field Service Report
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2. The course filters on the motor side of the strainers were removed and
cleaned. Below is the dirty filter;

18. Field Service Report
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3. All the rubbers and O-rings were replaced. Below is a crushed rubber seal;

19. Field Service Report
- 17 -
4. All new scanning nozzles were replaced. Below is a refurbished scanner;
NOTE: Spare service kits have been left in the A-Class building for future maintenance.

20. Field Service Report
- 18 -
Improvements
Regular Maintenance
Upon first impressions of the strainer system it was evident that they have not been
serviced for some time. The overall breakdown of these strainers can directly be
contributed to the lack of maintenance.
The AMIAD SAF-4500 Micro-Strainers are an important part of the A-Class process.
When not properly maintained they can put unnecessary strain on the rest of the
plant.
The most integral part of the strainer is the suction nozzles (#7). If these are not
serviced, the “Cap-SLN” wears down to bear stainless steel. This can then tear the
micron filter which becomes irreparable. A new micron filter is worth over $7000.00.

21. Field Service Report
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Inlet Filter
Currently there is no filter before the strainers. There is a course filter of the strainer
but this not very practical for serviceability. See picture below;
An inlet strainer like the “C In-Line” type show below, would be easy to maintain and
access for service. Ideally it would be located between the feed pumps and the
AMIAD SAF-4500. See the link below for more information;
http://www.amiad.com/catalog-in.asp?type1=1&num=96&cat=18

22. Field Service Report
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Conclusion
The AMIAD SAF-4500 Micro-Strainer is now fully operational.
Before being upgraded, it had been neglected and was inefficient. By installing more
diagnostics and remote operations the strainers should now operate as intended.
The ability to now see the differential analog value will now enable the operator to
assess the integrity of the micron filter and request serviceability based on real
figures.
It is crucial that these strainers remain properly maintained or it will result in
additional operational costs.
References
The following documentation is attached to this PDF;
 ABB 2600T Differential Pressure Transmitter Manual
 AMIAD SAF-4500 Manual
 ABB 2600T Calibration Certificates

23. Field Service Report
- 21 -
Enquiries
Should you need any clarification on this document or if you wish to discuss a site
upgrade please contact myself or Anthony Crowther.
David List
Mob: 0408 006 344
Email: David.List@ventia.com.au
Anthony Crowther
Mob: 0439 619 314
Email: Anthony.Crowther@ventia.com.au