help with Hookah compressors...

[wolfaroo]

G'day all

Next year I plan to clean my boat using the increasingly popular hookah-type setup and would like to ask some advice about the compressors people use before purchasing one. I need to get a compressor for paint spraying in a couple of weeks so rather than get two, I'm looking for one that can be used for both purposes (paint spraying now & very occasional shallow diving in the future). I should point out that the diving will only be a couple of hours every couple of months (to clean a hull with draft of 2m). I plan to get all the proper equipment and take a course prior to doing anything dive-related, including getting the other components (I'll also be hoping for advice on these in due course), but I'm ready to get the compressor now.

My question is, would a compressor with the following spec be suitable as a hookah-type compressor to be used as outlined above (assuming all the correct filters/hose/regulators etc):

2.5HP oil-free w/ 50 litre reciever tank
f.a.d. 8.8cfm
10 bar max pressure

Any feedback on suitable compressor spec would be gratefully received, thanks.

Wolf

 

[frogman62]

When you describe oil free, do you mean a diaphragm compressor : not an piston type compressor (usually oil lubricated but might have sealed bearings) Safe hookah compressor should be a diaphragm compressor where there is no open connection between the crankcase and the air being compressed. The connecting rod should be a sealed bearing type. Some had a gas engine with an extended exhaust tube or had the exhaust vented under water which reduces the possibility of CO entering the air intake.
IF the compressor is electric powered then CO should not be a problem.
IF you are only using the hookah to a depth of 20 feet maximum. The air pressure for the hookah regulator should be about 100-125 PSI over the surrounding water pressure at 20 feet (roughly 9 PSI plus 14.7 or 24 PSI). The compressor is pumping max at 10 BAR or 145-150 PSI so you will have no safety factor at 20 feet. IF you don't work hard and need heavy breathing this is still not acceptable because the compressor probably cycles max at 150PSI and shuts off then restarts at 110 PSI so you might not have a sustained breathing safety margin. Also 8.8 CFM is probably not the delivered free air at 150 PSI but at 90 PSI so you have absolutely no safety margin with this compressor.
The compressor also needs a one way valve in the hose at the divers regulator location because if the hose breaks the water pressure on the diver will be sufficient to squeeze the diver and exhaust almost all air from the lungs.
IF you are only going to use it to clean the boat bottom at 6-10 feet maximum depth you could get away with this and be marginally "safe". Also you are only one breath from the surface. , so risk is not very high.
Jim Shelden

 

[wolfaroo]

Thanks for the detailed info Jim. I'm totally new to diving so please forgive me if I've misunderstood your reply, but I think we must be talking about different systems or something... The commercially available hookah diving systems operate at much lower pressures & air volumes than you have indicated. For example, one of the Air Line compressor's is 2.18cfm @ 50psi but is reportedly good for one diver down to 50ft (Air Line Diving System | The Air Line by J. Sink) & the hookahmax compressor is 2.55cfm @ 65psi, which they advertise as enough for 2 divers to 30ft (Hookamax Dive Systems). Am I missing something here?

To answer your other questions: the compressor I was looking at is an electric single head piston, oil-less operation but not a diaphragm compressor, so I will continue searching.

Thanks again.
Wolf

 

[frogman62]

I looked at the two sites you mentioned and agree I am not thinking of sport diving. The water pressure at 33 feet is 1 atmospheres of pressure or 14.7 PSIG --66 ft 29.4PSIG. If you have an air hose from the surface with only a demand (2nd stage regulator) with 50 PSIG then the air supply is roughly twice the pressure at depth so the air supply is limited only by the volume supplied through the hose. You do not have a 1st stage scuba regulator to contend with supplying air to the 2nd stage demand regulator.
The compressor you are considering has more than enough pressure and volume, but I don't know about the air quality.
My "old" military equipment explanation is all wet in the application you are considering. I am completely "off base". Sorry to confuse you.
Jim Shelden

 

[wolfaroo]

No need to apologise buddy - I'm grateful for any & all info. Your post prompted me to learn about the different pressures used in scuba & hookah diving & the different regulators/regulator settings too, which isn't immediately obvious to newcomers like me, so thank you. I found some useful websites along the way, which I'll post here in case others are interested. It seems hookah diving typically uses compressed air in the range 30-50 psi @ volumes between 2-4cfm per diver for dives <33ft.

As for the compressor, diaphragm seems to be the preferred as you pointed out but several systems do also use piston-type compressors, but only those that are oil-free and have an inline <40 micron filter & water/oil trap and stainless steam hose. I was hoping to be able to use the same compressor for odd jobs and the occasional dive but so far I can't find an oil free with enough power to spray or a suitably powered diaphragm compressor. I'll keep searching but it's looking like I might end up with two compressors atm...

Useful websites:
Intro to Hooka!
Hookah Diving Systems
Cool Stuff You Can Make or Buy for Your Boat (caution: some good info here but possibly a bit blasé on safety)
http://underwaterprojects.741.com/myfiles/buildhookah1.pdf

Cheers,
Wolf

 

[frogman62]

There is a low cost solution to your compressor issue, Does the compressor you are considering purchasing have an adjustable pressure regulator on the outlet that can be adjusted to less than 50 PSI?
IF so, Schedule 40 PVC will easily stand up to 80 PSI (rated at much higher by we are looking at safety) You can go to ACE hardware and purchase two feet of 2 inch inside diameter PVC and also the end caps that have threads on one side and make an inline filter containing desiccant 13X and charcoal that will give you clean, oil free air for several hours.
Replacing the chemical would not be difficult and would be much less expensive than buying two compressors.
Jim

 

[iain/hsm]

It gets worse I'm afraid.

Taking the opposite approach first and considering your painting requirement.
In the UK there is a small requirement for Hookah compressors on a 15CFM 425 l/min block and 150psig 10 barg discharge pressure, oil lubricated. Mostly used for shallow civil engineering diving and normally have a Yanmar L48 diesel engine, weight is around 200 lbs 100 kg

Would work just OK as a wet paint compressor, The filtration is to BS4001 this has high humidity but less than 5ppm oil vapour. CO and exhaust fumes are covered only by a long 15 foot 4 metre air intake hose.

A better paint compressor would be an oil free block again size options would be from 7cfm 200 l/min 2BHP 1.5Kw to a maximum 30 cfm 850 l/min 10HP 7.5Kw, All 10 bar 145 pig

The largest of which the 30 cfm as a diving compressor uses a Lister diesel engine and weighs in at some 700 lbs 300kg with engine frame, filtration and motor.

So as for using a paint compressor on a yacht I guess weight is your penalty.

Now consider that the smallest 5 cfm 140 l/min pump will not work as a paint compressor unless you are prepared for long waits for the pressure to build up and use a pressure reducer and a gun that can work at reduced pressure or be prepared to have uneven wet film paint coverage. Iain Middlebrook

---------- Post Merged at 01:08 AM ---------- Previous Post was at 12:42 AM ----------

There is a low cost solution to your compressor issue, Does the compressor you are considering purchasing have an adjustable pressure regulator on the outlet that can be adjusted to less than 50 PSI?
IF so, Schedule 40 PVC will easily stand up to 80 PSI (rated at much higher by we are looking at safety) You can go to ACE hardware and purchase two feet of 2 inch inside diameter PVC and also the end caps that have threads on one side and make an inline filter containing desiccant 13X and charcoal that will give you clean, oil free air for several hours.
Replacing the chemical would not be difficult and would be much less expensive than buying two compressors.
Jim

IMHO the idea of an in line molecular sieve and charcoal filter in a home made "lash up" in line filter is a non starter.

The heat generated alone by the liquid water droplets on 13X molecular sieve from a low pressure compressor will melt your PVC tube fist time out, an exothermic reaction I would expect to exceed 100C

In addition activated carbon/charcoal acts to adsorbed oil vapour, any water carry over will simply "wash out" the retained hydrocarbon in one huge slug of slime if the plastic pipe don't melt first that is LOL

IMHO for these low pressure applications if you must use a chemical filter use activated alumina, better than silica gel, is more effective at higher temperatures and tolerates water droplets without the exothermic reaction of molecular sieve. Iain Middlebrook

---------- Post Merged at 01:27 AM ---------- Previous Post was at 12:42 AM ----------

---------- Post Merged at 01:28 AM ---------- Previous Post was at 12:42 AM ----------

G'day all (SNIP)

My question is, would a compressor with the following spec be suitable as a hookah-type compressor to be used as outlined above (assuming all the correct filters/hose/regulators etc):

2.5HP oil-free w/ 50 litre reciever tank
f.a.d. 8.8cfm
10 bar max pressure

Any feedback on suitable compressor spec would be gratefully received, thanks.

Wolf

Wolf.
My guess it's a small high RPM intermittent duty paint shop hobby compressor
If so it will have a short, hot and hard life then die,

My concern is that you don't follow suit.

There is a reason why commercial diver hookah units have a bigger capacity than demand to allow the plant to operate in an "unloader" condition and incorporate aftercoolers and heat exchangers also a large receiver all to allow for cooling and water condensing separating before any consideration of chemical filtration.

After this the pressure is reduced further by a regulator to effectively cool the gas post filtration by pressure expansion before a final micronic particle filtration mesh cleans up the gas prior to dispensing to the diver.

Now if you can separate the "paint spray and dive" idea then there is IMHO some merit in a micro pump with a tilt valve mouthpiece regulator or "Jack Browne" type facemask that could be both cheap and fun provided some safety considerations were debated. Iain Middlebrook

 

[frogman62]

Interesting,
If you are considering a small pancake tank on a $100 compressor, Iain is right on the money.
IF you purchase a compressor that pumps 150 PSI into a 30 gal or bigger tank--now you can paint till your hearts content and you can use it for a hookah compressor, because the air will have a condensation and cooling period in the large tank. IF the compressor is a 2 stage even better because it usually has cooling coils between stages and also between the compressor and storage tank. I also agree that activated alumna is better and cheaper by quite a bit.
Jim Shelden

 

[iain/hsm]

Look also at your paint gun options.

A typical suction pressure gun designed for 40 psi needs 9-14 cfm for a 10"-14" spray pattern. Again not knowing what your painting or paint used. Synthetics, enamels, epoxy's etc, but say for a car finish you may prefer a gravity fed gun, again can be down to 30psi but still 12-16 cfm. Try this site for some options check the DeVilbiss range under technical for the various flows and pressure options.

Devilbiss Automotive Refinishing | Automotive Paint Supplies

Then consider the power generator spare capacity on your yacht, this will dictate the size of compressor you can run by the electric motor size.

When diving the thing no point loosing your gas when your wife puts the kettle on and cuts the generator out, and IMHO avoid diesel or petrol on a pleasure vessel if you can. All I know about is commercial diving stuff.

But if you can balance all this with these little oil free single stage micro pumps used by river divers and popular with the private gold prospectors (I understand) this may be a better option for you to investigate.

Incidentally the company I represent started off making compressors for the Californian gold rush in 1878 I guess I should try the back of the stores LOL

But I have to agree with Jim that little pancake pumps sounds like a lot of fun, for hull inspection save for one consideration to never use hookah on a yacht diving a reef.

As it can be a real pain happily diving the reef then stumbling on a virgin wreck you slowly as your air runs out. ........... kind of recognise. LOL Iain Middlebrook

 

[fstbttms]

FYI- most hull cleaners use oil-less piston-type compressors in their hookah rigs. The Thomas 1020 is the industry standard. Diaphragm compressors are not necessary. Don't let these hardhat guys scare you about what you need. They may know what is used in a full-on commercial setting, but not for working off the dock in your marina. For hull cleaning, 3/4 hp is plenty. You may need more get-up-and-go to do the spray work you have in mind, but not for diving.