Sab 128 hf

[Josip]

Hi,

need some help, suggestion ... tip ... whatever we call that ... do not know anything about history of this compressor, but here we are ...

SAB 128 HF possible Mk3 but not sure ...
installed: about 1999-2000
refrigerant: ammonia
evaporating temperature -10*C
condensing I assume 30/35*C
working time around 38000 hours
equipped with UNISAB II ... nothing about configuration
oil ... maybe synthetic, but not sure
about other maintenance ... have no idea ... have been told ... servicing was more or less normal with changing of oil, oil filters, other details unknown...


Received request to help, with below description by phone from operator or owner:

Compressor can start normally, but oil pressure from the first moment is slowly going down, oil temperature is going up to 60*C and discharge temperature is very high up to 100*C, when oil pressure is coming down to 1.2 bar UNISAB shut down ....

I have some ideas (never saw that compressor, even above description received by phone), but I would like to hear your inputs, assumptions, thoughts, maybe someone had some recent case similar to this .... any help is welcome ... thanks for your time ...

We are still negotiating about this job and if we get it next week I'm going on site to check all about ... than I can update this thread with real on site situation....

Best regards, Josip

[RANGER1]

I would stick to the basics first

New oil filter
Clean oil pump pre-filter
Check oil cooler type & configuration ie clean water cooled etc.

Compressor is due for overhaul anyway.

[Josip]

Hi RANGER1

I would stick to the basics first

New oil filter
Clean oil pump pre-filter
Check oil cooler type & configuration ie clean water cooled etc.

Compressor is due for overhaul anyway.

thanks for your input

.... one update received today by phone again ....

compressor is running fine up to 80-85-90% of capacity .... coming close to 100% capacity became crazy ....


Best regards, Josip

[Jahangir]

Hi, First of all oil quality is very important. i should mention that i see fake oil that filled in original vg68 barrel .
i think you should check 3-way valve of oil cooler (if have in this type of compressor, may be rt5) and check if piston and spring works correctly.also oil return valve and it's filter should be checked.
if both are correct and oil filter is also clean, check oil pump for working properly.
i think check the compressor closely will have better results.
regards.

[josef]

Josip, I'll be a fool again here, but if your compressor HF 38,000 hours and has a nice sound 80-100% capacity-cut into a suction cover-sorry my opinion, but I believe it.
Give us your feedback message, thank you.

[RANGER1]

Awhile ago this happened to a similar machine.
Male rotor driven into suction end housing. In doing this, then suction roller bearings had no oil path, so bearings collapsed & rotor dropped into rotor casing wearing tips off rotors.

A small trap in this scenario is the rotor timing marks can be ground off, so best mark them before taking them out (if this is the case).
Maybe if oil filter is checked it might show metal paticles.

[Josip]

Hi, thanks for your inputs

Josip, I'll be a fool again here, but if your compressor HF 38,000 hours and has a nice sound 80-100% capacity-cut into a suction cover-sorry my opinion, but I believe it.
Give us your feedback message, thank you.

I did not hear that compressor running and cannot say exactly what is going on at 80 - 100% capacity, I believe that you have experience and you can be right ....

Awhile ago this happened to a similar machine.
Male rotor driven into suction end housing. In doing this, then suction roller bearings had no oil path, so bearings collapsed & rotor dropped into rotor casing wearing tips off rotors.

A small trap in this scenario is the rotor timing marks can be ground off, so best mark them before taking them out (if this is the case).
Maybe if oil filter is checked it might show metal paticles.

Must say those are not a nice scenarios ... until now have not experience with such damage (happened with S57 many years ago due to failure of axial bearings), because we insist and force owners to make an overhaul before i.e. 30000-35000 as per manuals even with regular maintenance ....

Anyhow, dear friends, your inputs are very valuable ....

I was thinking there is maybe some problem with oil cooler .... refrigerant side of oil cooler with oil and at high compressor capacity not enough area to cool the oil properly ... another possibility ... some discrepancy within plant ... lack of ammonia ... and normally as you mentioned ... dirty oil filter/s ...

Seems, we made agreement with owner to visit site next week ... than I'll update this ...

Thanks again...


Best regards, Josip