SCBA to SCUBA yoke adapter?

[otter-cat]

I just saw an adapter designed for using an SCBA fill station to fill yoke style scuba tanks. My question is this: Are SCBA fill stations designed to filter the air to the same purity as oil-free scuba compressors? I know that scuba requires a higher purity of air than we can breathe safely at the surface, due to the effects of the higher partial pressures of the gases at higher ambient pressure.

Thanks for any input!

Moderators: If this question is in the wrong forum, please feel free to move it to the appropriate one!

 

[divenutny]

A SCBA fill station should provide air clean enough for scuba. You might need better filters, most likely, the SCBA fill station has sufficient filtering. I recommend you ask the SCBA mechanic who maintans the station. They would know best.

Several years ago, my friends and I purchased an old SCBA fill station to fill our tanks. We got tired of driving 12 - 18 tanks to a LDS to get fills for the next day of diving. Plus the LDS had a attitude when we would show up with so many tanks in the afternoon. We have the compressor checked regularly. No problems so far.

Good luck - Tom

 

[otter-cat]

You might need better filters, most likely, the SCBA fill station has sufficient filtering. I recommend you ask the SCBA mechanic who maintans the station. They would know best.

First off, thanks for your input. I am concerned that a mechanic for an SCBA fill station (for firefighters, for example) may not be aware of the additional air purity needs for scuba diving as opposed to firefighters breathing that air at one atmosphere.

Also, can anyone tell me what kind of filters the SCBA station would need to have in order to ensure that it was providing air safe enough for scuba diving?

Thanks.

 

[deadend]

Most scba fill stations worthy of using will filter the air to the same or greater level of purity as a scuba fill station. I have verified this with my own and several other departments I know of. I can't see why it would be OK to breath bad air on scba and not on scuba. If anything I am far more stressed when breathing from scba than scuba and can be on it for far longer than scuba.

First off, thanks for your input. I am concerned that a mechanic for an SCBA fill station (for firefighters, for example) may not be aware of the additional air purity needs for scuba diving as opposed to firefighters breathing that air at one atmosphere.

Also, can anyone tell me what kind of filters the SCBA station would need to have in order to ensure that it was providing air safe enough for scuba diving?

Thanks.

 

[scubatoys]

If you are trying to buy an adapter... remember there are 2 different SCBA ends... One is a 346, one is a 347. 346 is for the 2200 bottles, 347 is for high pressure, 4500 and has about 4 more threads... so just make sure you get the right stuff to match up with whatever threads they are using - and make sure whoever is filling watches the pressures as if they are filling the 4500's - their compressor will probably not shut off until then. That may not work out all that good for the burst disk in a 3000 tank...

To do it up real slick... you could build a little station with one input, put an adjustable reg in line to turn it down to 3000 psi, then break out to as many whips as you want to run... But ball park... that filter, reg, manifold, whip setup would probably run about a grand...

If doing one now and then, that might be a bit over kill... but if a department wanted to set up to do a lot of tanks... that would be a nice setup.

 

[Firefyter]

I fill my own cylinders from our cascade system, and I'm perfectly comfortable doing so. We have a Bauer compressor that is a LOT better system than some dive ops and shops use, plus ours is regulated and checked to be within standards on a regular basis. I know some dive shops that have never been checked fo air quality, so which one do you think I'm going to trust? I know that this is not always the case, and that lots of shops have top of the line equipment, I'm just saying that I know what I'm getting for sure when I use our compressor. YMMV.

Oh, Larry is right about the threads being different. However, you can hook a 2216 psi bottle up to a system that uses 347 threads, you can just can't go the other way, i.e. 4500 psi bottle to 346. If you're building an adapter, use the 346 threads and it will work either way

 

[otter-cat]

I can't see why it would be OK to breath bad air on scba and not on scuba.

The problem is not that the air used for SCBA is "bad air" -- clearly it wouldn't make any sense to use on either SCBA or SCUBA if it is actually bad air. The difficulty about which I am concerned is that air that is absolutely safe for use on land (with the SCBA) may not be safe to use underwater, since the ambient pressure, and therefore the partial pressure of any "minor" contaminents will also increase. In other words, because of the LOWER partial pressures involved with using SCBA as compared to SCUBA, SCBA may allow for greater tolerance of slight levels of contaminents.

Basically, what it boils down to is this: Are the standards for air purity for SCBA as stringent as those for SCUBA?

 

[Firefyter]

Basically, what it boils down to is this: Are the standards for air purity for SCBA as stringent as those for SCUBA?

As I said in my first post, the standards for purity at our department are a LOT higher than those at most of the ops and shops I've seen. We're checked on a regular basis, whereas some of the quarries and such are NEVER checked. It's hard to say that ALL SCBA fill stations are better, because I'm sure that some of the smaller departments may fall through the cracks and never get get checked as well, but if it's a bigger department I wouldn't have a problem using their air. I've been using ours for years, as have most of the local divers, and there's never been a problem.

 

[jamiep3]

The short answer to your question is to check your departments testing records for the air quality. Most fire departments have their air tested routinely for quality. I know that our department maintains our air system to grade E, which I believe is the same standard as most Air fill stations for SCUBA.