Compressor humidity indicator

iain-hsm · 10th May 2007, 21:45

Humidity indicators are available world wide. I thought every dive shop had one. The idea of monitoring humidity before it gets into your cylinder is cheaper in the long run than having to shot blast the rust out of rusty cylinders at your cost. That way the dive shop at the point of dispensing the “product” has a duty of care to provide air fit for purpose. However as the 3 month or 6 month air purity checks are always done after putting in a new filter cartridge it’s not quite the same for the customer that gets his fill at the end of the filter life. I know I will get flamed for this but there are some shops that keep a “good cylinder” to one side as the “test cylinder” that is used when an air sample is needed to be sent off for analysis.

The indicator shows both the compressor operator and the diver the purity of the air at the point of dispensing into the divers own property ie his cylinder.

The theory is simple as the largest impurity in an compressed air stream is water, and this is simply monitored by the blue disc that is “calibrated” both for ambient air temperature against the back pressure setting of the BPR valve on the filter stack. The relative humidity is shown on a segmented 10/20/30% relative humidity indicating card, each section in turn changes colour from blue (dry) to pink (wet)

The working pressure is 414 bar 6000psig we originally tested the design to 2070 barg 30,000psig when the 0-ring extrudes out of the housing. So with a 4:1 safety design they are good for pretty much all HP compressors.

The jpeg shows the small visual indicator and two longer tubes, one with a BNC plug and the other hard wired, these are for electronic monitoring the water vapour. The two electronic boards show a LED display option the other a digital display. Both can be calibrated for any of the European or American air purity standards. Packaging, the enclosure, display type etc is normally as per each compressor company specification.
The visual indicators are £30 ($50) and the electronic displays are £450 ($800) ARO, fittings are extra Swagelok etc are fine but they must be fitted upstream of the BPR and be pressurized as the filter at all times.

Dave Sutton · 10th May 2007, 23:54

Quote: (Originally Posted by Genesis)

Note that a lot of the "compressor guys" will sell you 20/40% cards. Those are completely worthless as once the 20% one turns your stack is already rubbish and by the time the 40% one turns you're not only pumping water-laden gas but LOTS of oil vapor as well!....

Really? Didn't know my Rix had any oil in it... If I can get it to pump oil, I'll be rich, as it'll have figured out a way to make oil from water....

I do monitor though, for the reasons that Ian has explained.

Dave

Sutty · 11th May 2007, 12:06

Quote: (Originally Posted by iain-hsm)

The jpeg shows the small visual indicator and two longer tubes, one with a BNC plug and the other hard wired, these are for electronic monitoring the water vapour. The two electronic boards show a LED display option the other a digital display. Both can be calibrated for any of the European or American air purity standards. Packaging, the enclosure, display type etc is normally as per each compressor company specification.
The visual indicators are £30 ($50) and the electronic displays are £450 ($800) ARO, fittings are extra Swagelok etc are fine but they must be fitted upstream of the BPR and be pressurized as the filter at all times.

How do I order one of the visual indicators and cards to match?

Thanks,
Neil

***Beanie*** · 11th May 2007, 12:14

Quote: (Originally Posted by Sutty)

How do I order one of the visual indicators and cards to match?

Thanks,
Neil

same here £30 a reasonable price tell us more.

10th May 2007, 23:54	#22 (permalink)
Dave Sutton Membership Cancelled Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,637	Re: Compressor humidity indicator Quote: (Originally Posted by Genesis) Note that a lot of the "compressor guys" will sell you 20/40% cards. Those are completely worthless as once the 20% one turns your stack is already rubbish and by the time the 40% one turns you're not only pumping water-laden gas but LOTS of oil vapor as well!.... Really? Didn't know my Rix had any oil in it... If I can get it to pump oil, I'll be rich, as it'll have figured out a way to make oil from water.... I do monitor though, for the reasons that Ian has explained. Dave
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11th May 2007, 12:06	#23 (permalink)
Sutty Classic Kiss diver Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Jun 2005 Location: Glossop, Derbyshire, UK Posts: 786	Re: Compressor humidity indicator Quote: (Originally Posted by iain-hsm) The jpeg shows the small visual indicator and two longer tubes, one with a BNC plug and the other hard wired, these are for electronic monitoring the water vapour. The two electronic boards show a LED display option the other a digital display. Both can be calibrated for any of the European or American air purity standards. Packaging, the enclosure, display type etc is normally as per each compressor company specification. The visual indicators are £30 ($50) and the electronic displays are £450 ($800) ARO, fittings are extra Swagelok etc are fine but they must be fitted upstream of the BPR and be pressurized as the filter at all times. How do I order one of the visual indicators and cards to match? Thanks, Neil __________________ Never forget that life is a finite resource.
(Online)

11th May 2007, 12:14	#24 (permalink)
*Beanie* Close to that red button Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Vision Join Date: Jan 2005 Location: In da house! yeah baby! Posts: 3,207	Re: Compressor humidity indicator Quote: (Originally Posted by Sutty) How do I order one of the visual indicators and cards to match? Thanks, Neil same here £30 a reasonable price tell us more. __________________ Beanie Gallery Admin & Library Assistant. www.outlawdivers.org.uk www.beandiving.co.uk www.beanengineering.co.uk www.divelife.co.uk
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