DIY - discussion on building a DIY hookah diving compressor - Page 7 - SailNet Community
Old 02-01-2013
Senior Member

Join Date: Jun 2008
Location: Tampa, FL
Posts: 1,223
Thanks: 0
Thanked 37 Times in 37 Posts
Rep Power: 9

Re: DIY - discussion on building a DIY hookah diving compressor

My concern would be the 17.4 psi limitation. Standard air pressure is 14.7 psi. At a depth of 10 feet, the water pressure is 1.3 atmospheres, or about 19.1 psi. So this compressor cannot even pump air down 10 feet underwater, let alone get enough volume down to a diver that deep.

And then, is the flow rating at the full 17.4 or is that "free flow." A lot of compressors, in order to "pump up" their numbers, will list free flow volume and maximum psi, and not mention that at maximum psi the flow is going to be WAAAAY less.

Edit:

Oops! Just realized that my math is wrong. I was including the 1 atmosphere of pressure that we start with at sea level. So, if this thing can pump 17.4 psi then it can pump air down almost 40 feet. The question remains, though, if it will actually deliver the full flow at that depth.

And then, most of the regulators that I've seen that are made for hookah diving are adjusted to work with 40-60 psi of delivered air pressure. "Normal" scuba regulators work with around 100 psi of delivered air pressure. Obviously, these regulators would not work with that compressor, which may be why the ebay sellers plumb it to a snorkel, instead of a real regulator.

Last edited by denverd0n; 02-01-2013 at 02:46 PM.
denverd0n is offline

Old 02-01-2013
I don't discuss my member

Join Date: Feb 2003
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 2,419
Thanks: 13
Thanked 44 Times in 41 Posts
Rep Power: 15

Re: DIY - discussion on building a DIY hookah diving compressor

Quote:
Originally Posted by denverd0n View Post
...which may be why the ebay sellers plumb it to a snorkel, instead of a real regulator.
I guarantee that's the reason. And since there is no regulator, excess air (assuming there is any) must be continuously exhausted. If you ever dived with a regulator that was "free-flowing", you know what a PITA this is.
Fstbttms is offline
Old 02-01-2013
Member

Join Date: Nov 2012
Posts: 40
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0

Re: DIY - discussion on building a DIY hookah diving compressor

Wow, now we really have the (inappropriate language for a sailing thread removed by tdw) : 40 feet on a McGuivered Wallmart Hooka! Ouch!

For anyone considering such a thing: DON'T.

When I was saying the el cheap hookah might work, I meant FOR SHALLOW HULL WORK.
Less than 12 feet, depths that one can easily surface from if the thing stops.

Someone who is looking at 40 feet+ dives, should really heed ALL the safety advice given by others earlier in the thread.
Get certified, or at least read and understand the book.
Understand dive times.
Get reasonably fail safe equipment.

etc.

[and girls: the current post BELONGS above the quoted text.
That's how it is done.
Reason is that one re-reads the quoted text only when he has to.
Like you two should have. ]

Quote:
Originally Posted by denverd0n View Post
My concern would be the 17.4 psi limitation. Standard air pressure is 14.7 psi. At a depth of 10 feet, the water pressure is 1.3 atmospheres, or about 19.1 psi. So this compressor cannot even pump air down 10 feet underwater, let alone get enough volume down to a diver that deep.

And then, is the flow rating at the full 17.4 or is that "free flow." A lot of compressors, in order to "pump up" their numbers, will list free flow volume and maximum psi, and not mention that at maximum psi the flow is going to be WAAAAY less.

Edit:

Oops! Just realized that my math is wrong. I was including the 1 atmosphere of pressure that we start with at sea level. So, if this thing can pump 17.4 psi then it can pump air down almost 40 feet. The question remains, though, if it will actually deliver the full flow at that depth.

And then, most of the regulators that I've seen that are made for hookah diving are adjusted to work with 40-60 psi of delivered air pressure. "Normal" scuba regulators work with around 100 psi of delivered air pressure. Obviously, these regulators would not work with that compressor, which may be why the ebay sellers plumb it to a snorkel, instead of a real regulator.

Last edited by tdw; 02-04-2013 at 09:13 PM.
Navigator Wannabe is offline

Old 02-01-2013
I don't discuss my member

Join Date: Feb 2003
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 2,419
Thanks: 13
Thanked 44 Times in 41 Posts
Rep Power: 15

Re: DIY - discussion on building a DIY hookah diving compressor

Quote:
Originally Posted by Navigator Wannabe View Post
Wow, now we really have the retarded leading the blind
Buh-bye
Fstbttms is offline
Old 02-02-2013
Wish I never found SN!

Join Date: Jul 2006
Location: Presently in Brisbane, Australia
Posts: 2,114
Thanks: 9
Thanked 6 Times in 6 Posts
Rep Power: 11

Re: DIY - discussion on building a DIY hookah diving compressor

THE MATH BEHIND OPEN END SYSTEMS
One way to measure the volume is how long it takes to empty an inverted container, corrected for a pressure of 15 psi,
the pressure at 32 feet deep, above atmospheric pressure at the surface of the water. One foot of water is about 1/2
psi.(Actually, it's closer to 14.7/32=0.459 psi per foot of water depth)
The absolute pressure(Pabs.) would be:
Pabs=14.7(sea level) + 1/2d, where d=the depth of water to the discharge depth
of the compressor hose.
Using:
(P1)(V1)(T1)=(P2)(V2)(T2) (gas law), where pis pressure, V is volume and T is temperature
in degrees absolute.
V2=(P1)(V1)/(P2) where T1=T2 and the pressures are absolute pressures.
Let P2=pressure of water at the discharge depth, and let P1 = 14.7
P2= (14.7 + 0.459d), so the equation becomes:
V=(14.7)(V1)/(14.7 + 0.459d)
So, if your compressor produces 200 cuft/hr at the surface, at a depth of 20 feet,
it will produce:
V(@20 ft)=(14.7)(200)/(14.7 + 0.459 x 20)
=2940/(14-7 + 9.18)
=2940/23.88
=120(approx) cuft.
If there is any heating of the air, during compression and subsequent cooling
of the air, in the diver's supply line, then temperature must be taken into
consideration and the T2 = the discharge air temperature (measured) and
T1=exit air from the compressor output port. I don't think that the difference
is too significant to the calculation, pressures are the overriding
factors, since on the absolute temperature scale (459 degrees Absolute, Rankine,
= zero Fahrenheit, so (example) 60 degrees F =519 degrees R).
The minimum needed at 32 feet is 100-120 cuft/hour, but 150-180 cufh would
BE SAFER.

Simon

I miss my boat
Brisbane
DELIVERY SKIPPER
Drinking Rum before 10am makes you a Pirate NOT an alcoholic
SimonV is offline
Old 02-06-2013
Senior Member

Join Date: Jun 2008
Location: Tampa, FL
Posts: 1,223
Thanks: 0
Thanked 37 Times in 37 Posts
Rep Power: 9

Re: DIY - discussion on building a DIY hookah diving compressor

Wow. Talk about misinterpreting something, Navigator Wannabe!

I simply said that the compressor was capable of pushing air down 40 feet. I did not recommend that it be used at that depth. I didn't even come close to IMPLYING that it could be used at that depth. In fact, I specifically expressed my doubts about its ability to supply adequate air at that depth.

But I guess calling people names is a lot easier than actually reading what they are saying, and responding on topic to the thread.
denverd0n is offline
Old 02-06-2013
No more curry buffets

Join Date: Aug 2011
Location: Toronto
Posts: 414
Thanks: 3
Thanked 7 Times in 7 Posts
Rep Power: 6

Re: DIY - discussion on building a DIY hookah diving compressor

I cannot understand why you people keep debating this thread. It's like arguing which framing hammer is best to bash yourself in the head with.

Bashing about on Lake Ontario and Beyond
"Ariel" '79 Endeavour 32
Ritchard is offline
Old 02-12-2013
Junior Member

Join Date: Nov 2005
Location: Coumbia river, Oregon
Posts: 29
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0

Re: DIY - discussion on building a DIY hookah diving compressor

For those who know more than I, does hose labeled for "food use" qualify as acceptable for breathing hose?

We do not stop playing because we grow old; we grow old because we stop playing! Ben Franklin
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

SV Mariah's Child - Roberts 45 in steel
Yachts66 is offline
Old 02-12-2013
I don't discuss my member

Join Date: Feb 2003
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 2,419
Thanks: 13
Thanked 44 Times in 41 Posts
Rep Power: 15

Re: DIY - discussion on building a DIY hookah diving compressor

Quote:
Originally Posted by Yachts66 View Post
For those who know more than I, does hose labeled for "food use" qualify as acceptable for breathing hose?
Probably. What is it you intend to use?

Last edited by Fstbttms; 02-12-2013 at 08:44 AM.
Fstbttms is offline
Old 02-12-2013
No more curry buffets

Join Date: Aug 2011
Location: Toronto
Posts: 414
Thanks: 3
Thanked 7 Times in 7 Posts
Rep Power: 6

Re: DIY - discussion on building a DIY hookah diving compressor

Quote:
Originally Posted by Yachts66 View Post
For those who know more than I, does hose labeled for "food use" qualify as acceptable for breathing hose?
Is it going to be crush resistant at pressure?

Bashing about on Lake Ontario and Beyond
"Ariel" '79 Endeavour 32
Ritchard is offline

Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.

## Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.

User Name:
OR

## Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

 Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

 Similar Threads Thread Thread Starter Forum Replies Last Post gamayun Pacific Seacraft 5 12-13-2012 12:10 AM PDixon Boat Review and Purchase Forum 38 01-01-2010 10:55 AM j34035 Gear & Maintenance 19 10-01-2008 08:26 AM sherymia Cruising & Liveaboard Forum 5 12-21-2007 01:11 AM NewsReader News Feeds 0 09-14-2006 07:15 AM

 Posting Rules You may post new threads You may post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OnTrackbacks are On Pingbacks are On Refbacks are On Forum Rules