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A group of us went diving on Wednesday and the topic came up about compressor air testing during the surface interval. I thought I would post this on the board for curiosity sake.
If you are using a personal Scuba compressor are you having your air tested? Who do you use for testing and how often? What grade or test are you having performed?
What type of compressor, filtration and how often are you changing filters? ie: P4 filtration once a year. etc.
I'm using a Mariner 1 with a P4 Bauer filtration system. I change my filters once a year. I have had my air tested once by TRI-AIR testing. I normally fill 6-12 bottles a month.
Testing, no, I am of the opinion that only continuous monitoring would be of any value. A one time test is just a still picture of what the air quality was at the time the sample was taken and is no indication of what it has been in the past or what it will be in the future.
Having worked in the commercial compressed gas industry, continuous monitoring was the only sure way of maintaining gas quality. The only sampling we did was to verify the accuracy of the continuous analyzers and was done daily.
Know your compressor, monitor it when filling, change oil and filters media on a schedule that reflects how many tanks you fill in a certain time frame, weekly, monthly, yearly,etc. I change yearly.
43 year old Luchard 3.5 cfm, 2 hand packed towers, one with sieve and the other with carbon.
Testing, no, I am of the opinion that only continuous monitoring would be of any value. A one time test is just a still picture of what the air quality was at the time the sample was taken and is no indication of what it has been in the past or what it will be in the future.
I am working with a company outside of Houston to come up with a real-time monitor for air compressors. The gasses aren't a problem with the method they are using (to monitor stack gasses and ambient air in refineries), the problem will be controlling cost. These babies run about $100k each in a refinery situation. The other problem will be a chamber big enough to hold the sensor, yet stand up to 6000 PSI. The company thinks that they can get the price below the $10k mark. Still high dollar, but so is a bad air lawsuit.
I am working with a company outside of Houston to come up with a real-time monitor for air compressors. The gasses aren't a problem with the method they are using (to monitor stack gasses and ambient air in refineries), the problem will be controlling cost. These babies run about $100k each in a refinery situation. The other problem will be a chamber big enough to hold the sensor, yet stand up to 6000 PSI. The company thinks that they can get the price below the $10k mark. Still high dollar, but so is a bad air lawsuit.
Why not just continuously bleed off a small amount of gas into a low pressure chamber with the sensor.
Why not just continuously bleed off a small amount of gas into a low pressure chamber with the sensor.
Because it is as worthless to sample air that will be discarded as to sample at a point in time. Why not sample the air that someone will actually breath?
It is useful to test your compressor's output at various points and at various times to get a feel for what's going on in your system. For instance, one year I tested the air at the start of the season after I cleaned everything and replaced the filters, then I tested the output again just before it was time for filter changes and cleaning. I tested the air at various output points along the plumbing to see what was going on.
As a result, I now know that my filter changing schedule is right on, and, after a couple of years of testing, I know that I am reliably producing oxygen-compatible air.
Captain, how can you do any sort of partial-pressure blending if you have no idea what your compressor is spitting out? Testing your cylinders after it's filled is not a valid method of determining whether or not you have oxygen-compatible air. Oil and such are known to disperse and settle on cylinder walls, making the gas seem "clean." But no matter how "clean" your cylinder gas appears, who knows what kind of oil and contaminants have been spattered on the cylinder valve furing the filling process. Now titrate in some high-pressure oxygen during a partial-pressure fill and you've got a recipe for disaster.
After my cylinders have been filled, I always check the oxygen content (duh) but I also check for carbon monoxide at the same time. Since I solo on my own voodoo gas, I need to rest assured that my gas is uncontaminated.
Because it is as worthless to sample air that will be discarded as to sample at a point in time. Why not sample the air that someone will actually breath?
How is that not testing the air that will be breathed as long as the sample point is down stream of anything that could contaminate it. Once the air leaves the final filter it doesn't much matter.
Our analyzers weren't in the main line, they were in a remote location and sampled a metered flow off the main line.
Captain, how can you do any sort of partial-pressure blending if you have no idea what your compressor is spitting out? Testing your cylinders after it's filled is not a valid method of determining whether or not you have oxygen-compatible air. Oil and such are known to disperse and settle on cylinder walls, making the gas seem "clean." But no matter how "clean" your cylinder gas appears, who knows what kind of oil and contaminants have been spattered on the cylinder valve furing the filling process. Now titrate in some high-pressure oxygen during a partial-pressure fill and you've got a recipe for disaster.
I spend my money chaning my filters more often, not on gas analysis.
Same compressor as you an Alkins W31. I have a 16" tower as a second filter.
The first filter gets changed whenever the RH exceeds 20% by real time monitoring. Humidity is (reliably) the first contaminant to break through this filter.
The second gets changed every 60 hours (~12,000cf = roughly every 8 or 9 months). I would not go a year between filter changes regardless of how much or little use they've gotten. Their shelf/service life is not that long. I feel like 9 months on the secondary filter is pushing it a bit already.
Oil mist is honestly not at all on my radar screen of concern. Its easy peasy to meet OCA standards with 2 filters. I am much more concerned about volatile organics and to a lessor extent CO since I continuous blend 32%.
Originally Posted by diverdowndude
I'm using a Mariner 1 with a P4 Bauer filtration system. I change my filters once a year. I have had my air tested once by TRI-AIR testing. I normally fill 6-12 bottles a month.
Annually is a long time. I prefer dual filters too. The P4 is quite large for your volumes but the filters don't have that long a shelf life esp if left unpressurized or allowed to de-pressurize.
It is useful to test your compressor's output at various points and at various times to get a feel for what's going on in your system. For instance, one year I tested the air at the start of the season after I cleaned everything and replaced the filters, then I tested the output again just before it was time for filter changes and cleaning. I tested the air at various output points along the plumbing to see what was going on.
As a result, I now know that my filter changing schedule is right on, and, after a couple of years of testing, I know that I am reliably producing oxygen-compatible air.
Captain, how can you do any sort of partial-pressure blending if you have no idea what your compressor is spitting out? Testing your cylinders after it's filled is not a valid method of determining whether or not you have oxygen-compatible air. Oil and such are known to disperse and settle on cylinder walls, making the gas seem "clean." But no matter how "clean" your cylinder gas appears, who knows what kind of oil and contaminants have been spattered on the cylinder valve furing the filling process. Now titrate in some high-pressure oxygen during a partial-pressure fill and you've got a recipe for disaster.
After my cylinders have been filled, I always check the oxygen content (duh) but I also check for carbon monoxide at the same time. Since I solo on my own voodoo gas, I need to rest assured that my gas is uncontaminated.
Never said I partial pressure blend, if I did any type blending it would be continuous. Besides it a portable, I am not going to be blending in some dive site parking lot.
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Air testing personal SCUBA compressors
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Originally Posted by diverdowndude
