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Dear friends
we are having an abnormal vibration on our new installed project for 3 cylinder Grasso compressor working on high stage. compressor is overhauled and unlikely to be the reason of vibrations.
the vibration is mostly for discharge of compressor and also will increase when the make up liquid line valve open the way from liquid receiver to intercooler.
any idea what could possibly cause that?
12embo,
Could be a number of things due to very limited information.
- Compressor or it’s base not mounted correctly.
- Loose belts or coupling alignment.
- Pipework supports inadequate.
- pipework to rigid.
- counterweights on crankshaft mixed up.
https://www.gea.com/docnav/Product%20Documents/Grasso%20Discontinued%20Models/ca0191_0089000_pl_rc11_v006_gbr_.pdf
12embo,
these series of compressors are out of production since about 30 years; so it's a second hand compressor.
Is it a bare compressor or a package from Grasso?
belt or direct? direct with flywheel?
a picture could help.
These old compressors were fitted with cast-iron connecting rods, the late ones with aluminium connecting rods.
No mixt during overhaul?
Do you have any experience of Grasso piston compressors plants?
Installations instruction are different compared to other brands made of cast-iron instead of .....pipes.
RC311 is not the best balanced one.
Actually that could be the reason.Quote:
Originally Posted by l2embo
Dear RANGER1
Thanks for your advice. We checked the coupling timing and bolts which were in good condition.
we are re-arranging the pipework also adding more support to check if they were the reason.
at the end we will go for the crank shaft mixing weights.
Yes we are using them here in Iran yet. ;)
It is grasso belt packaged compressor but overhauled with new parts. I am aware of difference weigh between connecting rod materials could cause that. We still trying to find the problem outside of compressor otherwise we go for compressor investigation.
we have worked many times with Grasso piston compressors. pipes are steel material.
Thanks for advice
I2embo,
what I mean was:
a RC11 crankcase is made of pipes. 1 pipe & 2 caps for the casing, 3 others for each row of cylinders.
it's light compared to cast-iron.
So this type of compressor need a good base and must be anchored to the concrete.
more cylinders = smoother operation.
direction of connections to headers have to be parallel to the axis of the compressor. sufficient length.
no valve between compressor and oil separator.
and so on......
we installed Sabroe compressors during 50 years and then switched to Grasso during now 30 other years, I can say that the setting of the unit is very important to prevent the issue you are facing to.
again, a picture of your unit could help.
Dear friends
Thanks to your time and advice.
The problem has been solved. it was because of the rigidity of compressor pipes. we dismantle the pipes and weld it again more carefully to avoid any twist and this fulfill the vibration problems so far.
Best Regards
Well done, good result and thanks for letting us know.