Welcome to ScubaBoard, an online scuba diving forum community where you can join over 205,000 divers from around the world discussing all things related to Scuba Diving. To gain full access to ScubaBoard (and make this large box go away) you must register for a free account. As a registered member you will be able to:
Participate in over 500 dive topic forums and browse from over 5,500,000 posts.
Communicate privately with other divers from around the world.
Post your own photos or view from well over 100,000 user submitted images.
Gain access to our free classifieds marketplace to buy, sell and trade gear, travel and services.
Use the calendar to organize your events and enroll in other members' events.
All this and much more is available to you absolutely free when you register for an account, so sign up today!
If you have any problems with the registration process or your account login, please contact the ScubaBoard Support Team.
It would benefit you to make sure the SCBA fill station has had it's air analyzed, and it is at least Grade E compliant.
...of course, this assumes you only want air, and that particular cylinder will not be used for partial-pressure (PP) blending for nitrox. If your cylinder has a sticker on it that says "Cleaned to Oxygen standards" then I wouldn't reccomend using SCBA station air, as it is rarely intentionally filtered to the quality of "Oxygen Clean Air", and using non-O2 clean air will contaminate the cylinder such that it could not be used for PP blending. (But, it would be perfectly fine as plain old air)
If you are talking about a containment fill station, you should make sure that it is designed to accept the bottles you intend to fill. Some units will accept 80's but nothing bigger. As far as air grade, what makes you so sure you are only getting Grade D. Have you had it tested or is your compressor a small portable?
sampling good bourbons while waiting for the ice to melt...
Join Date
Feb 2011
Location
"La Grande Ile"
Posts
1,096
Dives
100 - 199
the local VFD saved our bacon on a dive trip way too long ago... Our compressor (which we had brought along with us) would not work (3-phase on 1-phase service - yes, we were dumb!). We brought our whip to them, they hooked it up to their system, and filled out tanks.
SUPPORT YOUR LOCAL VFD - THEY DO MORE THAN YOU WILL EVER KNOW!!!!!!
Yes. Breathing air at depth changes the effects that contaminants have on your body. Grade D has no spec for hydrocarbons, and Grade E has a rather tight limit; and, there's a narrower limit on O2 percentages. Here's a good reference.
Originally Posted by Sm0g
well, is there anyway to convert or make a grade d filling station to put out grade e air? maybe buy a new filter or something?
There's many factors that affect filtration. Simply dropping in a different filter cartridge is rarely the answer.
The biggest factor, surprisingly, is cubic feet per minute. This governs the dwell time, or, how long the air stays in contact with each layer of the filter. Air that passes through too quickly has insufficent time to allow the media to absorb the contaminants. Hence, filter stacks are rated for a particular filtration grade at a particular CFM. A small filter can become surprisingly efficient at very low CFM rates (say, 2 CFM); a large filter can produce very poor filtration when pushed to double its rated capacity.
I presume you work for a fire department, and this is why you're asking all this, because you'd like to fill your SCUBA cylinders from the SCBA fill station at work. As a point of reference, our fire department has three mobile SCBA fill apparatus. About 10 years ago they were all updated to produce Grade E air. The filter stacks roughly doubled in size.
There are aftermarket filters you can place in-line with your cylinders as you fill them. It's been a while since I looked them up but they were expensive, in the range of $600 IIRC, and they had amazingly slow CFM rates, (maybe 3 CFM? Can't recall here, sorry) so they were more a PITA than a real help.
Soooo, the short version is if you want Grade E air, then you really need a compressor/filter stack assembly that's designed as a whole to produce that grade.
Probabally not the answer you're looking for, but so be it. For the record, I fill SCBA's at work, and all my SCUBA cylinders at the dive shop.
I look after the scba fill station for our fire dept. same filter... molecular sieve ..Hopcalite ... charcoal ....same commpressor as a dive shop so the air quality is good the only thing is our scba bottles are 2250 and our fill station can not be changed above this foir saefty reasons ..that is the only issue I see
Last edited by scubaboat; October 27th, 2011 at 12:50 AM.
LinkBack URL
About LinkBacks
Reply With Quote
Originally Posted by Sm0g
As a point of reference, our fire department has three mobile SCBA fill apparatus. About 10 years ago they were all updated to produce Grade E air. The filter stacks roughly doubled in size.
