Mineral oil and nitrox??

[Guy Manners]

Hi all
I just took over a dive-base on Bali - we're filling using a nice Bauer with the securus system; but it's been filled with Bauer mineral oil. We fill a lot of nitrox (O2 squirt and top-up) - now I see that the mineral oil is not supposed to be used with nitrox. My "expert" friends in Germany - normally sticklers for using the right kit - say that it doesn't matter.
Could someone explain why it might NOT matter? I can see why it should.....!
Or any other knowledgeable comments?
Thanks!

 

[rjack321]

If you are partial pressure filling it doesn't matter. This assumes you have adequate filtration after the compressor to produce OCA.

If you are continuous blending (entraining extra O2 into the compressor inlet) this should only be done with synthetic oils and only after the mineral oils and carbon deposits have been completely removed from the system.

Given that you are in Bali, I'd recommend switching to a synthetic oil with a higher flash point even if you are partial pressure blending. This will minimize your risk of CO production/contamination in hot weather. How involved this process will be depends on the age of the compressor and the degree of carbonization in the condensors and valves.

 

[captain]

Besides what Rjack32 said I switched from mineral oil to synthetic many years ago. I was always having carbon build up on valves and the need to clean them when using mineral oil. I haven't had carbon build up at all since switching to synthetic.

 

[Guy Manners]

More research later - all compressor manufacturers say that their compressors are NOT suitable to compress any air mix except 21%. With or without mineral oil.
Any comments?

 

[captain]

CYA, there are many things that are routine and accepted practices but equipment manufactures will not acknowledge as acceptable unless the whole system was designed, tested and built by them for a specific purpose such as continuous blending. It's all about product liability.

 

[iain/hsm]

IMHO Guy that's not strictly true, I am happy to run Nitrox at up to 50% 850 LPM and store at 300 bar and yet the Nitrox compressor uses a 6 ltr sump of standard mineral based machine oil ISO 150

During installation we entrained oxygen into the first stage intake at 85% purity while compressing up to 350 barg for three hours filling a bank as a sort of working pressure to test pressure procedure. While being verified by a third party insurer Det Norke Veritas. DNV.

Another smaller pump we have runs pure oxygen at 2.75 barg (40 psi) at the inlet and 207 barg (3000psi) at the outlet. Flow is 285 LPM, pure 100% oxygen.

The oil sump is 3 litres and the oil is again is just a cheap £10 ($15) worth of standard automotive ISO 150 40wt mineral based oil.

On both compressor we run for 5000 hours before oil change.

The only difference is that both compressors were designed for nitrox and oxygen.
and again this is plainly written on the label and in the manual.

Once again I guess the answer is look at the compressor and "Read the Label"

Not all compressors manufactures compress oxygen or offer oxygen compressors those that don't it would appear would be better sticking to what they know Air.

IMHO You may be better with less of an "expert" friend and more of an expert engineer and CYA has no part in it either. LOL Iain Middlebrook.

 

[captain]

IMHO Guy that's not strictly true, I am happy to run Nitrox at up to 50% 850 LPM and store at 300 bar and yet the Nitrox compressor uses a 6 ltr sump of standard mineral based machine oil ISO 150

During installation we entrained oxygen into the first stage intake at 85% purity while compressing up to 350 barg for three hours filling a bank as a sort of working pressure to test pressure procedure. While being verified by a third party insurer Det Norke Veritas. DNV.

Another smaller pump we have runs pure oxygen at 2.75 barg (40 psi) at the inlet and 207 barg (3000psi) at the outlet. Flow is 285 LPM, pure 100% oxygen.

The oil sump is 3 litres and the oil is again is just a cheap £10 ($15) worth of standard automotive ISO 150 40wt mineral based oil.

On both compressor we run for 5000 hours before oil change.

The only difference is that both compressors were designed for nitrox and oxygen.
and again this is plainly written on the label and in the manual.

Once again I guess the answer is look at the compressor and "Read the Label"

Not all compressors manufactures compress oxygen or offer oxygen compressors those that don't it would appear would be better sticking to what they know Air.

IMHO You may be better with less of an "expert" friend and more of an expert engineer and CYA has no part in it either. LOL Iain Middlebrook.

What are the compressor design differences to allow oxygen.

 

[rjack321]

Captain if you didn't know, Ian/hsm works for Rix in the UK. The oil sumps in question are isolated from the O2.

 

[captain]

I am very familiar with isolated oil sump compressors, At one time I operated 100% o2 isolated sump compressors when I worked for Praxair. Compressors so big you couldn't put one in a two car garage. We were religious about keeping the piston rod between the sump and the head oil free and had vacuum pumps on the sumps to suck oil vapors and discharge them outside the compressor building.
Pumping 100 % and blending 32% are two different situations.
Not everyone doing continuous blending uses isolated sump compressors and I can't say I read about compressors going bang all over the place so it would appear that it can be safety done with compressors other than ones with isolated sumps.

 

[rjack321]

I am very familiar with isolated oil sump compressors, At one time I operated 100% o2 isolated sump compressors when I worked for Praxair. Compressors so big you couldn't put one in a two car garage. We were religious about keeping the piston rod between the sump and the head oil free and had vacuum pumps on the sumps to suck oil vapors and discharge them outside the compressor building.
Pumping 100 % and blending 32% are two different situations.
Not everyone doing continuous blending uses isolated sump compressors and I can't say I read about compressors going bang all over the place so it would appear that it can be safety done with compressors other than ones with isolated sumps.

Yeah I have over 450 hours on my little 3.5cfm Alkins and no bang yet.

Been running synthetic since day 1. There is no way in 2011 I would recommend anyone use a mineral oil and least of all in the tropics.