Results 1 to 5 of 5
  1. #1
    Join Date
    Feb 2016
    Location
    egypt
    Age
    26
    Posts
    2
    Rep Power
    0

    Grasso 2 stage package



    I have a 2 stage Grasso package P & W frames, when the compressor stops suddenly the check valve doesn't close right and it rotates in the reversed direction with a noisy voice. when the service engineer arrived he changed the discharge pressure from 10.5 bar to 13 bar to avoid this action.
    this change decreased the refrigeration capacity and made the oil temperature higher than 55 C
    what should I do to solve these problems?



  2. #2
    Join Date
    Sep 2007
    Location
    Somerset
    Age
    63
    Posts
    4,465
    Rep Power
    38

    Re: Grasso 2 stage package

    Welcome ebaid.
    I fail to understand how increasing the discharge pressure and therefore the pressure / gas volume differential.
    Would make the compressor Scream any less! (As the higher discharge gas pressure balances out it will drive the screw backwards!)
    Or has the higher discharge setting meant that the compressor no longer reaches set point.
    So it does not stop?
    Whatever! The real answer is get the Non Return Valve fixed.
    The extra energy consumed by the compressor alone will more than pay for the repair!

    You do say when the comp stops suddenly?
    Could you explain?

    Thanks Grizzly
    Despite the High Cost of Living it still remains Popular!

  3. #3
    Join Date
    Aug 2007
    Location
    Adelaide Australia
    Age
    63
    Posts
    536
    Rep Power
    17

    Re: Grasso 2 stage package

    Hi ebaid
    Agree with Grizzly, putting the discharge pressure up will make it worse. Put the discharge back to 10.5 bar and fix the non return valve.
    Paul
    Born to fish, forced to work

  4. #4
    Join Date
    Feb 2016
    Location
    egypt
    Age
    26
    Posts
    2
    Rep Power
    0

    Re: Grasso 2 stage package

    the check valve has internal piston to close using the discharge gas pressure from oil separator, when we dismantled the check valve we found that it works well by using compressed air to actuate the valve.
    so, the best choice is to decrease the pressure and neglect reversed rotation or to keep the pressure high??

    I have also another problem in the other package:
    during starting up;when the HP compressor starts it makes the LP compressor rotate with high speed for long time (without starting LP drive motor) so that there is no oil lubrication in LP compressor during that period

    what do you think about this fault?

  5. #5
    Join Date
    Dec 2007
    Location
    australia
    Posts
    2,417
    Rep Power
    26

    Re: Grasso 2 stage package

    Ebaid,
    Can I ask which check valve you are referring too.
    Mic machine runs backwards on shut down its suction check & replace as previously stated for reliability.
    As for other package not sure how GEA set up duo, but see that first stage compressor has to rotate if only high side running.
    I would have thought first stage should run promptly after second stage high side compressor starts.
    Is there another line from low side suction going to high side suction with check valve in it as well?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •