Advice on new set up

[oxyhacker]

An interesting experiment! I find it hard to believe, that your raw ouput could meet OCA standards. Where did you take the sample from?

BTW, the statement has been made at various times in this thread that no scuba compressor manufacturers approve the use of their compressors for continuous mixing. Coltri does, and the US Alkin distributor says that Alkins are "approved for Nitrox up to 40%". Actually, Bauer USA did at one time, but they seem to have changed their mind.


QUOTE=Doc Harry;4537946]I know that the Alkin W31 is not approved for Nitrox, but.... I just the air test results. The compressor has been in use for one year now. Before I performed my annual maintenance and filter changes, I decided get two air samples after warming up the compressor for one hour:

1) the raw compressor output
2) the air after it passed through the filters.

Both samples qualify as Grade E oxygen-compatible air.

So it is possible to mix your own Nitrox without having to spend $10,000 on a compressor.[/QUOTE]

 

[rcontrera]

BTW, the statement has been made at various times in this thread that no scuba compressor manufacturers approve the use of their compressors for continuous mixing. Coltri does, and the US Alkin distributor says that Alkins are "approved for Nitrox up to 40%". Actually, Bauer USA did at one time, but they seem to have changed their mind.

Just a little update on the Coltri policy. About a year and a half ago Carlo Coltri revised his statement to read that the Coltri compressors can handle up to 40% MEMBRANE made Nitrox up to 3800 psi and has said that mixing will void the warranty (of course he forgot to tell us distributor peons until last DEMA). Seems that they were having problems in the EU with cheesy mixing outfits putting slugs of O2 through the machines and toasting them.

 

[dannobee]

Harry.
You really think so? Just print out or PDF the test results of both of these tests and we shall see, shall we? Iain Middlebrook

Instead of continuing to criticize Harry's HOME system, why don't you show us pictures of your HOME system? Otherwise, Shut The **** Up.

 

[veriqster]

Instead of continuing to criticize Harry's HOME system, why don't you show us pictures of your HOME system? Otherwise, Shut The **** Up.

NICE!!!!!!
People take their time to give you / us for FREE advice, technical expertise and (quite informed) opinions and you tell them off, .....
How about you do it in another place so we can benefit from their help in the future too.
P.S. Nothing is perfect and if you can leave with it nobody tells you not to use it but it's nice to know how a perfect solution would have to look.
P.P.S. My "fill station" looks nothing like the pictured one - it's a "piece of trash' put together for cheap and in a hurry but it does it's job and is safe, mostly thanks to info from people that you tell off.
P.P.P.S. No pun intended.

 

[dannobee]

An interesting experiment! I find it hard to believe, that your raw ouput could meet OCA standards. Where did you take the sample from?

Look at the picture, I believe the "raw" compressor outlet has passed through the factory filters. His "filtered" outlet has passed through the hyperfilter mounted to the wall.

 

[oxyhacker]

You are probably right, but one would not normally take "raw" to mean air that has already gone though a Grade E filter system, So I thought it was important to seek clarification, lest anyone stop using their filter stack on the impression it is not necessary!

We find a lot of the dumb things that get done in gas mixing are done as a result of someone misunderstanding directions that are a little less than clear.

Look at the picture, I believe the "raw" compressor outlet has passed through the factory filters. His "filtered" outlet has passed through the hyperfilter mounted to the wall.

 

[Doc Harry]

Harry.
You really think so? Just print out or PDF the test results of both of these tests and we shall see, shall we? Iain Middlebrook

dannobee is correct, the "raw" output goes through a factory water separator and 10-inch factory filter. The other filter is not a "hyperfilter," it's just a regular 24-inch LF filter.

FYI, I change the factory filter in half the time (every 12 hours) recommended by the manufacturer (every 25 hours) since I typically see 75-90% humidity here in the summer.

My actual written gas analysis reports are slightly different from the verbal I got from the lab. The "raw" output is CGA Grade E but didn't make OCA because the dew point was -38 degrees F (OCA requires a dew point colder than -50 degrees F). The rest of the criteria were similar between the two samples (range shown) and otherwise were OCA.

What I find most interesting is that the lab recorded carbon monoxide at 1.0 ppm ("raw" air sample) and 1.6 ppm (filtered air sample). I test every one of my cylinders for CO (since the compressor uses oil and I dive solo on my home brew) and I consistently get 0 ppm on my meter. I use a BW Technologies Gas Alert Extreme CO detector calibrated 2-3 annually with 10 ppm calibration gas. I do a "bump test" by breathing into the analyzer and get 3 ppm CO, so I know it works.

My Gas

Oxygen: 21% (OCA Limits 20-22%)
Nitrogen: 79% (OCA Limits 75-80%)
CO2: 315-384 ppm (OCA Limit 1000 ppm)
CO: 1.0-1.6 ppm (OCA Limit 10 ppm)
Volitile hydrocarbons + Methane: 5.9-6.9 ppm (OCA Limit 25 ppm)
Oils: <0.013 (OCA Limit 0.1 mg per cubic mm)
Solid particles: 3-0-0 (OCA Limits 93-3-0)*
Fibers: 0-0-0 (OCA Limits 20-3-0)**
Dew Point: -95 deg F (OCA Limit -50 deg F)
Odor: None (OCA Limit None)

*NASA solid particle limits 93-3-0
101-250 microns: 93 maximum
251-300 microns: 3 maximum
>300 microns: 0 maximum

**NASA fiber limits 20-3-0
0-500 microns: 20 maximum
501-1000 microns: 3 maximum
>1000 microns: 0 maximum


So... I think it's just fine to homebrew Nitrox/Trimix on these small compressors. I understand the theortical risks, but in practical terms.... it works just fine for me. I keep the system clean and well-maintained.

You think I want a fire in my garage, fueled by high-pressure oxygen?

 

[iain/hsm]

Instead of continuing to criticize Harry's HOME system, why don't you show us pictures of your HOME system? Otherwise, Shut The **** Up.

With respect, and with a degree of restraint on my part. Please try to comprehend that my quoted list was taken from a European Written Scheme of Examination.

I trust that is crystal clear, you insolent little man.

In case you are having difficulty with the concept, this is a legal requirement in Europe written in the plainest of Queen’s English outlining what is in effect a legal requirement for compressors in Europe that have to comply in there design with the said Written Scheme of Examination.

As the OP was from Ireland not the USA I think it only fair that we consider that salient fact. It is further only reasonable as we discuss that at the very least we consider his geographic location and any required legislation relevant to him.

You will find on the Scubaboard forum we European divers are made welcome and as part of a global diving community understand that you have different legislation to us in Europe. Please try to comprehend that also.

As a forum member it is commonly understood that different specific legal requirements are required with equipment over the world. We just have tighter standards, for example EN 250 for regulator performance EN 12021 for divers breathing air and EN 8478 for Nitrox and Heliox breathing mixtures.

To us and other member states of the “common market” also called the EU of which the original poster is a member we are therefore subject to that legislation.

 

[iain/hsm]

dannobee is correct, the "raw" output goes through a factory water separator and 10-inch factory filter. The other filter is not a "hyperfilter," it's just a regular 24-inch LF filter.

FYI, I change the factory filter in half the time (every 12 hours) recommended by the manufacturer (every 25 hours) since I typically see 75-90% humidity here in the summer.

My actual written gas analysis reports are slightly different from the verbal I got from the lab. The "raw" output is CGA Grade E but didn't make OCA because the dew point was -38 degrees F (OCA requires a dew point colder than -50 degrees F). The rest of the criteria were similar between the two samples (range shown) and otherwise were OCA.

What I find most interesting is that the lab recorded carbon monoxide at 1.0 ppm ("raw" air sample) and 1.6 ppm (filtered air sample). I test every one of my cylinders for CO (since the compressor uses oil and I dive solo on my home brew) and I consistently get 0 ppm on my meter. I use a BW Technologies Gas Alert Extreme CO detector calibrated 2-3 annually with 10 ppm calibration gas. I do a "bump test" by breathing into the analyzer and get 3 ppm CO, so I know it works.

My Gas

Oxygen: 21% (OCA Limits 20-22%)
Nitrogen: 79% (OCA Limits 75-80%)
CO2: 315-384 ppm (OCA Limit 1000 ppm)
CO: 1.0-1.6 ppm (OCA Limit 10 ppm)
Volitile hydrocarbons + Methane: 5.9-6.9 ppm (OCA Limit 25 ppm)
Oils: <0.013 (OCA Limit 0.1 mg per cubic mm)
Solid particles: 3-0-0 (OCA Limits 93-3-0)*
Fibers: 0-0-0 (OCA Limits 20-3-0)**
Dew Point: -95 deg F (OCA Limit -50 deg F)
Odor: None (OCA Limit None)

*NASA solid particle limits 93-3-0
101-250 microns: 93 maximum
251-300 microns: 3 maximum
>300 microns: 0 maximum

**NASA fiber limits 20-3-0
0-500 microns: 20 maximum
501-1000 microns: 3 maximum
>1000 microns: 0 maximum


So... I think it's just fine to homebrew Nitrox/Trimix on these small compressors. I understand the theortical risks, but in practical terms.... it works just fine for me. I keep the system clean and well-maintained.

You think I want a fire in my garage, fueled by high-pressure oxygen?

Interesting stuff. Although our European minimum test standard is very near to yours we would still not be able to use an oil lubricated compressor with entrained oxygen.

The two standards we have are split into two Breathing Air which is a pretty basic standard and the later Breathing Gas. I will sort out the degree F and Degree C and convert Mg M3 to ppm later as follows:

BS8478:2006 Breathing Gases Component Concentration
at 1.013bar and 20°C

Oxygen (%)
Mixtures containing <40% by volume
Mixtures containing >40% by volume
Stated A) ±0.5B)
Stated A) ±1.0 B)
Nitrogen (%) Remainder

Water (Mg/m3) <5
Carbon dioxide (ppm) <400
Carbon monoxide (ppm) <3
Oil (Mg/m3) <0.01
Methane (ppm) <30

Total volatile non-substituted hydrocarbons
(vapour or gas) as methane equivalent (ppm) <50

Total other non-toxic gases (including argon and other group
18 noble gases) (%) <0.5

A) Percentage as stated by the supplier
b) Tolerance value is a percentage of the total gas mixture
The above table relates to Nitrox/Oxygen breathing gases for Hyperbaric Use. (NOT BREATHING AIR)

2nd Part is the standard breathing air:

BS EN12021 Divers Breathing Air
Component Concentration at 1.013bar and 20°C
Oxygen % by volume (dry air) 21±1%
Lubricant content (droplets or mist) (Mg/m3) 0.5
Carbon dioxide (ppm) 500
Carbon monoxide (ppm) <15
The air shall be without significant odour or taste.
There shall be no free liquid water.

The maximum water content of the air measured at: <30
- a compressor system outlet for filling cylinders (Mg/m3) 25

 

[dannobee]

With respect, and with a degree of restraint on my part...

It was you who called our US systems "cobbled" and stated there was no way they would pass EU tests and further stated continuous blending would cause sufficient degradation of the oil that high levels of CO would be produced.

The results of Harry's test proved you wrong.

Then your reply included an ad hominem attack.

Harry was kind enough to show a picture of his home setup. You criticized that, nitpicking several points including such minutia as the wiring of his lights.

With respect to differing laws governing installations, Harry, Craig, et al, simply showed different methods irrespective of these constraints. I trust the original poster is intelligent enough to take that into consideration.

Now, where are the pictures of YOUR home system? Or at least pictures of any system that you have installed.