Danfoss ICAD/ICM Valve problem

[piewie]

Hello Everyone

I have 2 Danfoss ICAD modulating valve actuators fitted on ICM valves wired back to EKC347 controllers and ICAD UPS. The EKC 347 is wired to a 4-20mA level probe (which also indicates level back to the SCADA system)

No.1 is fitted on the HP feed from the receiver to the -10 surge vessel this one never gives any problems at all.

No.2 fitted on the liquid feed from the -10 vessel to the low stage -32 vessel (differential feed line). This valve set is fairly reliable however every once in a while it seems that the valve and the actuator lose their synchronisation. It normally shows up as a level problem and when investigating I always find the actuator at 100% but on removing the actuator the valve will be in a closed position. I normally open the valve manually then close it manually, drive the actuator to 0% and re-fit the actuator and the problem is cleared.

The original systems did not have modulating valves but were fitted with a Danfoss PM1 type valve and EVM solenoid control. The contractor at the time just fitted the new modulating valves in line but after the PM1. The PM1 is still operational set at 10% higher level than the ICAD/ICM valves and are interlocked to the plant, they are de-energised at high level and if there are no compressors running.

There is no pattern to the problem with the valves and initially it was thought that it was power problem. We then fitted the UPS (which is cheaper if you buy it from RS) however the problem still persists.

My thoughts are that perhaps if the ICAD/ICM closes and then the PM valve closes that the liquid in between expands and that this pressure stops the valve from opening as the pressure is pushing down on the valve plug. The actuator continues to open as it is not physically connected to the valve and the valve remains closed. However why does it only happen on the No. 2 valve set and not on the No.1 valve set?

Another reputable contractor who we use has told me that they also have the same problem on another of their sites also on a -10 to -32 feed. Apparently they do not have a PM1 fitted before the ICAD/ICM.

If anyone has had this sort of problem before it would be great to hear how they solved it or not.

Many Thanks

[RANGER1]

Low temp around ICAD / ICM probably needs Danfoss heater installed to prevent ice build up or freezing .
I think in situations under -15 C they recommend to instal it .

[rvmitch9927]

The ICAD has to be setup for the size of the ICM. On the ICAD HMI you can change the span in which the actuator moves. It is menu option "26" you will set it to the size of the ICM, for example 40, 50 or 65. We had this problem with a new install. This might be worth checking. We have tried the heaters for operations at -25 F, didn't work too well.

[cricri]

Hello piewie,
I post a replie for the same trouble on a CO2 plant. I believe that you are getting the same problem and you should check if the grease supplied by Danfoss has been applied by our contractor.
I am using ICM 65 on ammonia at -35 without any problem.
If the PM1 is in line before the ICAD you can't get liquid expansion as the the PM don't stay closed with a counter flow. in the other case it's very dangerous as the ICAD stay closed and the PM also.
please see post 184294 on CO2 forum