Dive Hookah Regulator Question

[DeborahLee]

Try this phone # 954 462 5570
Trebor Ind.
940 NW First St
Ft Lauderdale FL
I got a ddiaphram for my Brownie from them

[chrisjs]

Tell me what type of 12V compressor typically available to us non-military types will provide adequate air flow for diving and achieve 150psi at the same time???????

[s/vPainkiller]

This is a great thread. I'd like to put together one of these as well. It's not just PSI, there is also CFM to consider right? I'd also like to run a 12V compressor but have been worried about getting enough air flow.

Scott

[chrisjs]

You can buy a suitable oil-free 110V compressor for about $100 that will more than meet your needs for air flow and pressure. I bought mine from Sears but there are many available. Get one with a 2-3 gallon tank to even out air flow and avoid having to "suck" air. I am guessing this will cost less and be more reliable than a 12V compressor, even if you could find a suitable unit. Just run your inverter for the 30 minutes or so that you need to use the compressor. If you do not have an inverter buy a small portable unit for this and other tasks.

[fstbttms]

Originally Posted by s/vPainkiller

This is a great thread. I'd like to put together one of these as well. It's not just PSI, there is also CFM to consider right? I'd also like to run a 12V compressor but have been worried about getting enough air flow.

Scott

To breathe comfortably while exerting one's self, I find that a compressor needs to be rated to deliver 2.0+ CFM at around 90-100 psi.

[Matt sachs]

fstbottoms, do you use a standard second stage regulator?

[skipmac]

Originally Posted by Matt sachs

Maybe I'm confused about hooka, but the typical open circuit first stage reg its set to reduce tank pressure to 140 - 145 psi. The second stage reduces pressure to slightly over abient pressure. Why do you need a special hooka reg if you have 150 at the compressor?

That's what I recall, intermediate pressure (IP) ie after the first stage regulator (the one on the tank) feeding the second stage (the one in your mouth) is max 140-150. So any standard second stage regulator should handle up to 150 psi from a compressor.

When I was tech diving I adjusted the IP lower as it is easier on the seats in the second stage and you are less likely to get a free flow. Since I was breathing trimix it didn't effect breathing effort but a lot of air divers would tune the first stage as high as possible to make the second stage easier to breathe.

And correct, a regulator used with Hookahs is no different than a regular SCUBA regulator.

[fstbttms]

Originally Posted by Matt sachs

fstbottoms, do you use a standard second stage regulator?

No, I use the Zeagle I mentioned earlier. It has been modified for use in a hookah rig.

[Albro359]

Its not just a reg, its a regulated demand valve...you need this ti shut off the air suply while you exhale, o'wise you can't....

[Matt sachs]

I guess what I wanted to know is what modifications? Is it just the breaking pressure because of the lower pressure in the line?

[Dsanduril]

Originally Posted by skipmac

And correct, a regulator used with Hookahs is no different than a regular SCUBA regulator.

Yes and no. As you say, the typical SCUBA regulator second stage works at an input pressure of about 150 psi. For example, here are some specs from a ScubaPro:

MK25 First Stage
Intermediate pressure: 9-9.8 bar / 130-142 psi
G260 Second Stage
Maximum low pressure: 14 bar / 203 psi

However, several vendors sell hookah versions with lighter springs that work at lower inlet pressures. The Oceanic GT3, for instance, is available in a version that has a maximum inlet pressure of 125 psi. These regulators are intended for use with small compressors that can't easily reach 150 psi. And, if you are only diving to 30 ft/10 meters you probably don't need the excess pressure. Some reg. manufacturers sell hookah spring kits for use at lower pressures, others don't.

So, to the OP's questions, you have two options:

1. Regulate the air supply down to what your regulator expects. If you are comfortable that the spec is 60 psi, put a standard air regulator on the compressor that is set for 60 pounds. You'll want one with a large enough orifice that your breathing doesn't result in a large pressure drop on the low side. Should be able to pick one up at any big box hardware store for $50 or less. You're basically building a two-stage regulator, the standard compressed air regulator is your first stage, then the hookah second stage.
2. Use a standard SCUBA second stage, which will be happy with your 150 psi. Just get a second stage from any SCUBA shop and adjust to match your output pressure. Nothing else should be required.

[skipmac]

Originally Posted by Dsanduril

Yes and no. As you say, the typical SCUBA regulator second stage works at an input pressure of about 150 psi.

Well to be nit picky I think I said max 140-150. Conservative divers recommend adjusting the first stage IP lower, 130-135 I think is common. I usually set my first stages to about 110-120 and adjusted the second stages accordingly.

I had Zeagles, Scubapros and Oceanics and no problem with any.

[fstbttms]

Originally Posted by Matt sachs

I guess what I wanted to know is what modifications? Is it just the breaking pressure because of the lower pressure in the line?

Honestly- I'm not sure what the mods consist of.

[Dsanduril]

The mod is a replacement of the spring in the second-stage that balances against the inlet pressure. Keene sells an awful lot of hookah equipment (Intro to Hooka!), this is what they have to say:

A prospective Hookah diver must realize that SCUBA regulators CANNOT be used for Hookah applications without special modifications. A typical Hookah compressor operates in an average pressure range of 30 to 50 p.s.i., which is not enough pressure to drive the spring loaded downstream valve of a SCUBA regulator. A diver who already owns a SCUBA regulator, but who wishes to use it for Hookah applications, must take his regulator to a competent dive shop or repair station and get the regulator converted over for low pressure use; he should not attempt to do it himself. The conversion can be made by installing a set of low tension springs which will give maximum efficiency when operated at low Hookah pressures. A dive shop or repair station will also have the necessary test gauges, etc., to make certain the adaptation has been effective.

It's really not that hard, you don't need a professional dive shop, but you do need the proper spring.

[Dsanduril]

Originally Posted by skipmac

Well to be nit picky I think I said max 140-150. Conservative divers recommend adjusting the first stage IP lower, 130-135 I think is common. I usually set my first stages to about 110-120 and adjusted the second stages accordingly.

I had Zeagles, Scubapros and Oceanics and no problem with any.

In principle I think we are pretty much in agreement. The IP of a SCUBA second stage is somewhere in the mid 100 pound range, and there is a fair amount of latitude in the adjustment of that IP.

However, most regulators make this adjustment by increasing or decreasing pressure on a spring by use of a threaded assembly. At some point you run out of thread, and that is the lowest tension you can get. IME that is somewhere north of 100 pounds, but is depends on the regulator. Once you get to that point you have to put in a lighter spring, then you can adjust the regulator to lower pressures. A lot of hookah rigs work in the sub-100 range, you can get more air with less power from a cheaper compressor if you do. The downside is you need a larger diameter hose to move the same volume. Not uncommon however. As Keene says, theirs run at 30-50 pounds, and many others I have seen run 60-80. Most standard SCUBA springs just don't have enough adjustment to go that low.

For the OP, with 150 pounds available, no reason he couldn't use a standard SCUBA second-stage. For the others who have questions about lower pressures, at some (unknown) pressure you will need a lighter spring.