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Dirk_Bracke
14-05-2013, 11:01 PM
Hey guys, i'm working for a large chemical company. Today, we're evaluating quotes for a new industrial refrig on R290. Upto now, we've always had good experiences with Howden Wrv machines on R22. Apart of its flammability, we're wondering if any specific considerations have to be taken for R290 with respect to lubrication of the sleeve bearings and the double mechanical seal ? Miscibility, viscosity effects on oil? Any thoughts on this? Thanks.

RANGER1
15-05-2013, 11:10 AM
Hey guys, i'm working for a large chemical company. Today, we're evaluating quotes for a new industrial refrig on R290. Upto now, we've always had good experiences with Howden Wrv machines on R22. Apart of its flammability, we're wondering if any specific considerations have to be taken for R290 with respect to lubrication of the sleeve bearings and the double mechanical seal ? Miscibility, viscosity effects on oil? Any thoughts on this? Thanks.

Dirk, You may have to check "0" ring material is suitable for propane & would suggest replace shaft seal or elastomers anyway. I think also oil lube to main bearings should use all 4 main bearing connections due to possible flashing of refrigerant in oil galleries. Also you may expect a capacity reduction with propane.

Dirk_Bracke
15-05-2013, 10:18 PM
to RANGER1 : Capacity reduction in not really an issue, as we are dealing with a complete new installation.
I read somewhere that R290 has a bigger vapor cloud compared to R22, when it comes to degasification in the lube oil. Therefore my question with respect to sleeve bearings lubrication. When experience is good for R22, on other existing applications, can I extrapolate to good expected behaviour on R290.
Also R290 seems to have tendency to lower viscosity of mineral oils. I wonder if this effect is worse then compared to R22. Some manufacturer move to higher viscosity oils, when converting to R290.

The questions are also related to whether I should move cylindrical roller bearing compressors, from sleeved bearing supported rotors (API619), or not, for R290 refrigerants. Rolling elelemnt bearings seems to be less sensitive to lubrication disturbance due to vaporisation.

Can somebody provide me some charts like :
viscosity to temperature relations for different solutions oil/R290 and oil/R22,
solubility of R290 and R22 in mineral oil or other types of oil, like PAG, for various temperatures and pressures
Thx

ISEL
24-06-2013, 09:54 PM
Propane is an interesting subject for lubrication. Solubility of the refrigerant into the oil will go up with a decrease in temperature or increase in pressure. Propane is also very soluble with POE, PAO, and AB oils. There is a lot of special consideration for propane compression and the lubricant requirements. Watching the solubility and miscibility is key to ensuring you have that 7-9cSt minimum viscosity on your bearings. Since propane dilutes very easily into most lubricants, some people even go from a standard 68cSt up to a 100cSt to work around the viscosity dilution.

Feel free to private message me for more information. I think I'm one of the few manufacturers on the forums.