View Full Version : oil dilution+high pressure and temp.

25-04-2006, 02:39 PM
Hi, I would appreciate any input on this observation I made.
A scroll compressor that works with R-22 was vibrating during operation a bit more than normal. This caused the pipes to break. I noticed that the heat pump was operating on heat at 24-25 bar discharge pressure due to dirty, blocked air filters. My opinion is that that the oil in the faulty compressor was diluted due to working at high pressure and temperature for 18 months. This resulted in the eventual breakdown of the compressor which resulted in the vibration.

US Iceman
25-04-2006, 03:36 PM
I don't think I would call this a dilution problem. This occurs when the oil has liquid refrigerant in it. The oil viscosity is lowered when the refrigerant is mixed with the oil.

In your example the oil viscosity was decreased by the high temperatures due to the air flow restriction. In addition to the lower oil viscosity issue the higher operating pressures would apply additional forces to the compressor bearings and other lubricated parts.

25-04-2006, 08:48 PM
Thanks for your input Iceman. I meant the viscosity but my English was incorrect. Thanks for pointing it out.

26-04-2006, 06:50 AM
I personally think that the chemical engineers make that the oil holds it lubrification capacities while working under different conditions.
24 to 25 bar (348/362 psi) is high but is for the oil not such a big deal.
Oil can decompose as soon discharge temperature reaches 140C (284F)

Johnny Rod
27-04-2006, 11:00 AM
24bar? Blimey. You could have had some air in there, raising the head pressure and making the compressor have to work very hard, hence the vibrations.