Grasso

[seanf]

https://flic.kr/p/2mR1rgv

Grasso GR-G30S-28.
Fixed Vi.


When the suction to discharge pressure difference is high the noise gets worse. Starting about 2.6 bar suction, 9.8 bar discharge and 30% slide, itll go quieter on more slide.
But bigger diff louder it becomes and it stays even with more slide.
Smaller diff, say 9.0 bar and 3.5 bar the noise goes or very faint.
The noise mainly seems to be around the underside of the comp, under the loading solenoids area.
Its on a two comp pack, when running the second comp on its own you dont get any unusual noise out of it.

[Josip]

.... ?!? .....

[seanf]

Ive put it back up Josip. Might be something to learn from you guys.

[RANGER1]

Sean,
How many run hours on it?
Are you carrying out 5000 hr face gap checks to monitor thrust bearings?

[seanf]

Sean,
How many run hours on it?
Are you carrying out 5000 hr face gap checks to monitor thrust bearings?

Hi Ranger,

The four comps that are on the same system, were replaced over the last month or two as far as I know by another company.

Ran all four comps on manual, loading up and down the capacity range. It may just be thats the way it was left adjusted, but the noisy comp is the only one that seems to load and unload slowly.

[RANGER1]

Hi Ranger,

The four comps that are on the same system, were replaced over the last month or two as far as I know by another company.

Ran all four comps on manual, loading up and down the capacity range. It may just be thats the way it was left adjusted, but the noisy comp is the only one that seems to load and unload slowly.

Be under warranty!
What would warranty period be 3 or more months.
GEA I have seen, just replace compressor with new change over compressor.
Are you sure motor okay, was any work carried out on bearings etc?
What is block & solenoid on discharge end in video, never seen before.

[seanf]

Be under warranty!
What would warranty period be 3 or more months.
GEA I have seen, just replace compressor with new change over compressor.
Are you sure motor okay, was any work carried out on bearings etc?
What is block & solenoid on discharge end in video, never seen before.

Not sure on the warranty.
The other company (not GEA) may have done overhauls on them rather than new comps. Two comps data plates are dated 2008 and have damaged or missing rivits.
Motor sounds ok when the the high pitch noise isnt there, but theres no records of greasing on site so.
I assumed its for stopping oil flow to that comp as its on a two comp pack sharing the same sep and common oil supply from it. But I can check the wiring diagram the next time Im there and let you know.

[Josip]

Ive put it back up Josip. Might be something to learn from you guys.

Hi, Seanf

learning is endless process ... so

Not sure in your case but we had one Sabroe compressor SAB 163 with noise similar to rattling and we just made an overhaul and assembled it and start.

Unfortunately I do not remeber now, but at low capacity rattling were quite low and then at some higher capacity sound became quite high and then coming close to 100% capacity rattling were less but still present. System was NH3 -10/+35.

Then we dismantle compressor again to check for damage ... found nothing ... then start to ask questions to other people ... from an old friend dealing with Stal, Howden, Sabroe and other compressors we get an info that slide valve went worn and gap between slide valve and housing close to compressor discharge port was too big ... i.e. seems that high pressure discharge gas from one side and oil pressure from another side cause that strange behaviour (vibration) of slide valve and result was rattling noise from compressor.

We made metalisation of slide valve, but result was not so good (it is not possible to make a good metalisation on moveable parts becuse there we still have a housing which is also worn and not possible to repair with metalisation because both parts must be very precise). Only cure is to replace complete part of compressor discharge housing and of course new slide valve. Quite expensive steps and client did not agree to do that but rather listen noisy compressor.

Not sure now what kind of "happyend" was with that compressor. Must say there were four SAB 163 and 3 SAB 128 but only that one was noisy.

Best regards, Josip

[RANGER1]

Would make it problem for company that overhauled.
As Josip mentions could be rotor, slide valve contact, also causing slide to be slower.
Without out knowing condition before & how it sounded.
also be to much oil injection into rotors, Grasso have external adjustment to control discharge temperature.
If to much, can be noisy, which is easy to adjust to see.
Coupling, is it okay as well.
To be fair though, would not touch under warranty, as think minimum 3 months, once someone else touches it, assume they would not be happy, best put it on them first.

[seanf]

Hi, Seanf

learning is endless process ... so

Not sure in your case but we had one Sabroe compressor SAB 163 with noise similar to rattling and we just made an overhaul and assembled it and start.

Unfortunately I do not remeber now, but at low capacity rattling were quite low and then at some higher capacity sound became quite high and then coming close to 100% capacity rattling were less but still present. System was NH3 -10/+35.

Then we dismantle compressor again to check for damage ... found nothing ... then start to ask questions to other people ... from an old friend dealing with Stal, Howden, Sabroe and other compressors we get an info that slide valve went worn and gap between slide valve and housing close to compressor discharge port was too big ... i.e. seems that high pressure discharge gas from one side and oil pressure from another side cause that strange behaviour (vibration) of slide valve and result was rattling noise from compressor.

We made metalisation of slide valve, but result was not so good (it is not possible to make a good metalisation on moveable parts becuse there we still have a housing which is also worn and not possible to repair with metalisation because both parts must be very precise). Only cure is to replace complete part of compressor discharge housing and of course new slide valve. Quite expensive steps and client did not agree to do that but rather listen noisy compressor.

Not sure now what kind of "happyend" was with that compressor. Must say there were four SAB 163 and 3 SAB 128 but only that one was noisy.

Best regards, Josip

Cheers Josip

[seanf]

Aye, the plan seems to be to leave it to the other company. It would have been an interesting fault to look into though.

Cheers Ranger.

[Zeleman]

Hi,

maybe need check oil delta pressure!C D.jpg

[seanf]

What is block & solenoid on discharge end in video, never seen before.

Wasnt much info, wiring diagram just states its an oil solenoid, the compressors manual says it a special add-on with no detailed drawing. Thinks its just for the shared seperater arrangement.

[RANGER1]

Thanks for update,
Has other contractor been back to site to check?

[seanf]

Dont think so. I'm back on site tomorrow, see if its still noisy and double check the pressures.

[seanf]

Checked pressures today.

The noisy compressor,

Motor Current: 59A
Slide position: 53%
Suction Pressure: 2.48 bar
Discharge Pressure: 9.6 bar
Oil Pressure: 7.8 bar
Filter Pressure: 8.9 bar
Oil Diff Press: -1.8
Filter Diff Press: 0.7 bar
Oil Temp: 41.2 °C
Discharge Temo: 55.6 °C
Suction Temp: -10.8 °C


Other comp that doesnt make the noise,

Motor Current: 54A
Slide position: 29%
Suction Pressure: 2.48 bar
Discharge Pressure: 9.7 bar
Oil Pressure: 7.7 bar
Filter Pressure: 8.8 bar
Oil Diff Press: -1.7
Filter Diff Press: 0.6 bar
Oil Temp: 40.4 °C
Discharge Temo: 56.3 °C
Suction Temp: -12.8 °C