which lubricant on co2

[ruskas]

Hi, im having trouble selecting the lubricant for a CO2 reciprocating compressor forma fertilizer plant. Which cylinder oil to use? Wet CO2 produces a weak acid, which will dilute the lubricant, and will react with EP addtives forming deposits. ISO VG220?
Also how can i calculate the amount of dilution i can expect with the gas? Is it possible?

 

[MolaKule]

What type and how large a compressor? What does the compressor literature specify in terms of viscosity and type?

Unless you know how much blowby gas in ppm gets past the rings on each stroke there is no way to determine the concentration.

Generally, compressors use a non-detergent oil with no EP additives. Some compressor oils contain a small amount of phosphorus anti-wear additive.

 

[ruskas]

Hi, usually the viscosity for these types of compressors is ISO VG150. what would be the cases of using a ISO 220? or higher? majority of compressors oils the manufacturers do not allow ZDDP or similar anti wear additives.

the compressor is an API618 machine, up to 250bar, only last stage piston gives problems.
How would i performed the calculation? any references?
Regards

 

[MolaKule]

Originally Posted By: ruskas
Hi, usually the viscosity for these types of compressors is ISO VG150. what would be the cases of using a ISO 220? or higher? majority of compressors oils the manufacturers do not allow ZDDP or similar anti wear additives.

the compressor is an API618 machine, up to 250bar, only last stage piston gives problems.
How would i performed the calculation? any references?
Regards


Quote:
Unless you know how much blowby gas in ppm gets past the rings on each stroke there is no way to determine the concentration.


As I stated above. Perhaps the manf. would know but I doubt it since much depends on the ring wear, cylinder compression, and valve sealing which would in turn affect compression.

A specialized oil analysis might be able to determine the amount of gas intrusion as a function of TAN increase.

The only other option for excessive blowby is re-ringing and cylinder honing.

 

[camelCase]

In the gas compression world, PAG based fluids have somewhat dominated because they are less susceptible to gas dilution compared to others.

Molakule is right though, there are a lot of factors that go into it. I'd give a good oil supplier like SLFi (slfi.net) or similar a shout. They are my go-to when I have hard questions.