bitzer screw compressor fault

[yair be]

Dear friends
Why is the suction pressure rises with bitzer screw compressor starting.
This is a freez compressors rack for supermarket application.
When closing the tap down the compressor suction goes to vaccum.
thanks
yair

[Coorsman777]

Right rotation?

[yair be]

Right rotation?

yes the rotation right.
also i can say that the compressor has been worked in right condition for a 500 hr with out eny fult. and the oil prssure was right to.

[RusBuka]

May be he doesnt loading?

[NoNickName]

Internal safety valve leaking from high to low side.

[yair be]

dear friend
the safty valve is new we replace it .
we steel have the problem.
thaks,
yair

[yair be]

dear friend ,
I checked and it looks normal unloading.
anyway on Starting there is a trend of moving high pressure towards the suction pressure .
thanks,
yair

[NoNickName]

You've still got a bypass somewhere. Sometimes is installed on purpose to reduce the inrush current.