Hansen HMSV Problems

[THE DUDE]

Hello all
I am seeking some feedback on some problems I am having with some Suction Stop Valves.

The System is a Low temp R-404A Parallel Rack for a Cold storage WHSE.

* 3 60HP Bitzer Screws running @ 0 degf SST
* 20psi suction 180 psi head
* Average superheat @ Suction header 15-25 degf

* Reverse Cycle Defrost with a 35psi differential

* 5 Hansen SHMSV suction stops ( running off Floating point control..Open or Closed)
When a defrost is initated the LLSV is closed for 10 min to boil off liquid. After 10 min the Suction Stop is closed/ HGSV is opens/ Defrost Differential is energized.

Upon Defrost Termination the HGSV shut/ Defrost Differential is denergized and 1/2" pilot line is open (10min) to slowly bleed the pressure down to suction before opening the Suction Stop.

Previously I had lots of conednsate ( floodback) returning after defrost and this was damagaing the Suction Stops ( internal damage to pistons and Stator). After some control programing and installing the pilot pump outs this problem has been corrected. I just had a recent valve failure...broken Stator.
The rest of the overall system seems to be running fine...I am missing something.

[THE DUDE]

Victory!