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.
[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.
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.
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.