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  1. #1
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    Grasso SP2 duo packs



    Hi All, For some time now we have had two Grasso duo packs fitted to a new freezer plant. But now we have been tould that we should not charge oil into the suction line when adding oil with the compressors running. Have read the Grasso manual and can not find anything about charging oil to maintan the oil level. Sent an e-mail to Grasso UK but they seem not too want to pass on any infomation to us only to the GEA engineers in there group. So if you have any of the Grasso duo packs how do you top up the oil level ? please.



  2. #2
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    Re: Grasso SP2 duo packs

    aawood1.
    You can download the Manual that you need from my link below.
    Check out page 61 and a little further on!

    Also I will see if I can uploads page 61?
    Grizzly

    http://www.mediafire.com/?z5mdy4jnwmf

  3. #3
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    Re: Grasso SP2 duo packs

    Hi Grizzly, Thanks for your reply my problem is that we can not stop one of the units to pump in the oil as we lose freezer/product temp. The system was ment to run 7 days with out stopping and only then for 2 to 3 hours at a time, but we lose oil from the units at a rate of 60 to 70 lts in 30 to 40 days. When it stop's we would have other jobs to get done on the freezer and chillers fitted in the line. What we need to do is add oil with the plant running but even with the pump GEA said would work we can not get the oil in.

  4. #4
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    Re: Grasso SP2 duo packs

    Could you not drop the control set point so that you have a temperature buffer to buy time to add the oil.
    Speak to production and close off the cold room for an agreeable period.
    Is the oil at discharge pressure plus?
    So the oil pump is trying to push against this?
    How come you are loosing so much oil?
    Is the oil not being reclaimed?
    It sounds as if this is serious wear or is the comp running for long periods on low load?
    How can we help further?
    Grizzly

  5. #5
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    Re: Grasso SP2 duo packs

    Hi Grizzly, Yes the oil is at discharge pressure plus, We did every thing GEA said with the pump and one of there engineers was with our engineer trying to get the oil in to the compressor, as for why they are loosing so much oil can not say, the oil is reclaimed in that they are standerd compleat Grasso package units, I would hope its not serious wear as they are only one year old and ment to be serviced by GEA, All I want to know is why can you not charge oil into the lowside suction like on all the other 8 screw compressors we have on site.

  6. #6
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    Re: Grasso SP2 duo packs

    Woody (hope I can call you that)

    I must admit I am with the Grenco Engineers.
    I know with recips etc you charge
    into the crankcase which is at suction pressure. With the suction gases passing through the crank, and onward through the liner into the compression chamber!
    Therefore any oil introduced through the suction line / port will be deposited in the oil reservoir within the sump. (topping up the oil in the process.

    Whereas oil is injected between the lands of the screw maintaining a protective film between them and helping to maintain a gas-tight seal.
    If you introduce oil via the suction you are subjecting areas that would cope with a suction gas/ vapour to a heavy highly viscous liquid.... not good.

    Understanding the routes taken should help explain why everyone is saying don't do it!
    Your main dilemma is to somehow pressurise the oil which you wish to add above the oil pressure. to create a flow.
    This may require a rig making?
    More on that later.
    What do you think?
    Grizzly

  7. #7
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    Re: Grasso SP2 duo packs

    Hi Grizzley,
    I do not mind it's a lot better than some of the things I get called at work. As I said we charge oil into the suctions of 5 Grasso screws and 3 Howden 255 screws for the last 25 years, we started with 9 Grasso screws and what killed them was Liquid return and rear end bearing wear. At this time it seens to be a learning curve for us and some of the GEA engineers that come to this site, like I said each one of them has a driffrent way to try and charge the oil.
    Thanks Woody.

  8. #8
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    Re: Grasso SP2 duo packs

    Any screw you can add oil into suction when it is running . Screws pump that much oil in normal running anyway .
    In your case suction may be in vacuum so at worst a little air might enter system .
    The amount and speed you pump in oil would do no harm at all .
    Just don't do it while its not running as it will start up causing causing oil compression and possible damage .

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