And, yes, again, I realize that I am grossly over-thinking this. I am just curious what the real minimum requirements are, versus "stuff with these specifications are readily available, so why not just use them?".
ADDITIONAL:
Okay, so I went and did some looking. 50' of 1/4" ID hose will introduce a pressure drop of 1.6 psi. So, pretty insignificant.
...
On top of that, you probably need a couple more psi to overcome resistance in fittings and so forth, and then whatever your regulator requires as a minimum pressure.
You may note I personally find little wrong with overthinking a "problem."
This is not advice, just a “Thought Experiment” for you to consider…
Let us try and come at the solution set from both ends.
If we take the CFM required as ~ about ~ 2.0 at 90 psi [Seems to be the "metric]
The loss in a 50 ft hose as 1.6 psi {[Assume this loss rate be uniform through a range of pressures]
It would seem you maybe could use a compressor/pump that delivers 2.0 CFM @ 60psi. In the 50 feet of hose the loss would probably not be noticeable.
Not a recommendation – just a series of observations– borne out by the examples commercially available. I am not recommending any of these units. Just using them as an example of available Hookahas.
The “PowerDive” sold in Australia (I believe) operates:
Compressor: 2 cfm
Operating pressure: 18 psi
Another version (larger) of the PowerDive gives:
Compressor: 4 cfm
Operating pressure: 25 psi
Quote:
Originally Posted by transmitterdan
At what air flow delivery rate did you calculate 1.6psi drop for 50' of 0.25" hose? I think your calculations need a bit more work.
Breathing is not a constant air flow application. There will be high flow followed by periods of no flow. The industry uses the pressures they do because it works. Regulator design pressures were not generated by a random number machine. They are based on calculations and literally decades of testing.
Several (reluctant to say – many) Hookah rigs use a tank to accommodate the “inconstant/non-constant” flow requirements by offering additional volume, much like a low pressure scuba tank. Typically, they would require strength to meet max pressure of your pump -- plus a safety factor. A quick survey yields a steel tank rated for 125psi would have a safety factor of about 3:1. A plastic tank may be less dangerous if it blew - can't say.
Compressors you will note deliver a different CFM at various pressures. This chart if from the data available on the Thomas 1207PK80 that has been highly recommended. Note if you look to use 25 psi as you running pressure, you’d get around 3.3 CFM from the Thomas, and note the PowerDive gives 4 CFM. Now, find and setup a regulator - and, Bob's your Uncle!
Quote:
Originally Posted by transmitterdan
At what air flow delivery rate did you calculate 1.6psi drop for 50' of 0.25" hose? I think your calculations need a bit more work.
Note the graph was built from the Thomas data provided on their webpage. Intersting to note the relationship between CFM and PSI is linear. That could help in selecting alternative pumps.
I hope this thought experiment will be helpful, or at least offer a alternative look at selecting a pump. The specs needed include your choice of pump (CFM vs PSI) and Regulator pressure ranges, power source, quality of build and costs.
DISCLAIMER: Not associated with any manufacturer, just making interesting observations.
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 5,478
Re: Hookah ,diy
Quote:
Originally Posted by Laughing Buddha
Hookah rigs use a tank to accommodate the “inconstant/non-constant” flow requirements by offering additional volume, much like a low pressure scuba tank.
This not why some hookahs incorporate an accumulator tank. Most that have this arrangement do so because they are based on small jobsite compressors (typically used to run nailguns etc.) masquerading as purpose-built hookah compressors. Hookamax is a prime example.
Other rigs incorporate a tank to act as a safety feature, providing additional air in case of unwanted compressor shutdown or failure. A side benefit of this is that the compressor isn't running constantly, theoretically lengthening the compressor's lifespan.
I earn my living using a compressor that is sold in many high-end recreational/light commercial hookahs. It runs for hours on end without complaint. There is no accumulator tank in my system, nor is there any issue with lack of air flow. Air flow is constant and cool. Further, I cannot overbreathe the compressor. I consider accumulator tanks to be uneccessary. They add size, weight and plumbing to a system that does not need it.
This not why some hookahs incorporate an accumulator tank. Most that have this arrangement do so because they are based on small jobsite compressors (typically used to run nailguns etc.) masquerading as purpose-built hookah compressors. Hookamax is a prime example.
Other rigs incorporate a tank to act as a safety feature, providing additional air in case of unwanted compressor shutdown or failure. A side benefit of this is that the compressor isn't running constantly, theoretically lengthening the compressor's lifespan.
I earn my living using a compressor that is sold in many high-end recreational/light commercial hookahs. It runs for hours on end without complaint. There is no accumulator tank in my system, nor is there any issue with lack of air flow. Air flow is constant and cool. Further, I cannot overbreathe the compressor. I consider accumulator tanks to be uneccessary. They add size, weight and plumbing to a system that does not need it.
Excellent points and thanks for clarifying my misunderstanding RE: Acclumulators.
So, basically, we'd want to right-size the compressor, and thereby downsize the added weight and unnecessary gear.
Advantage for accumulator tank for a diy is the compressor can.also be used to run other gear on the boat. Like a ssmall air ratchet for other chores aboard. Or air to blow spaces and hoses out to clear dirt or dust.
An accumulator tank can allow a smaller compressor and therefore less energy consumption.
Without an accumulator the compressor has to be sized to deliver the CFM needed during an inhalation, if there is a tank, then all you need is a compressor that will deliver an average CFM a little higher than what you breathe.
Length of service wise, I'd have to think a constantly starting and stopping motor won't last as long as one run continuously, you see a lot of arcing the brushes on a brushed motor at start up, and I have to think a lot of these motors are brushed. Ideal would be a variable speed brushless, but I haven't seen one.
I think it was Cotemar that detailed to the smallest part every item you need to roll your own Hooka, for not much money, go that route?
I think if you have 25psi at the compressor end of a 50 foot 0.25" hose and try to take a breath from a regulator at 10 foot waterdepth you will be shocked how hard it is to suck air into your lungs. Such a rig will be a death trap IMO.
I think if you have 25psi at the compressor end of a 50 foot 0.25" hose and try to take a breath from a regulator at 10 foot waterdepth you will be shocked how hard it is to suck air into your lungs. Such a rig will be a death trap IMO.
Anyone that has run out of air in a tank has experienced it, you get just a little bit of air, it's like trying to breathe through a tiny straw, almost, but not enough air.
Way back when divingsteel 72's with J valves, before submersible pressure gauges, you would dive until tank pressure got too low to breathe, then you were supposed to reach back and flip the J valve, just like the reserve tank on old motorcycles and end the dive, and just like old motorcycles when you went to flip the valve that is when you find out that you never reset it, and instead of being low on air / gas, you were out and got to do a swimming ascent.
As long as you stay out of overhead environments with a Hooka you will be fine, just do a swimming ascent, and you should never do overhead environments without the equipment and training of course.
I think if you have 25psi at the compressor end of a 50 foot 0.25" hose and try to take a breath from a regulator at 10 foot water depth you will be shocked how hard it is to suck air into your lungs. Such a rig will be a death trap IMO.
And yet, if you use actual science, real numbers, and the empiric evidence of many existing users out there, you see that there is nothing even remotely "death trap" in what we are talking about. Up to you what you want to believe.
As for accumulator tanks, I would point out that the hose itself acts as a very small (or perhaps, not so small) accumulator tank. Breathing air hoses are all capable of withstanding many times the pressures that we are talking about. When the regulator closes, if the compressor continues to run, then the pressure will build within the hose, thereby increasing the volume of ambient pressure air that is available.
Not the same, by any means, as a 1 or 2 gallon accumulator tank, but still, probably enough to even out the inhaling/exhaling cycle.
Of course, if you do not have a continuous duty compressor, then an accumulator tank may be necessary to allow the compressor to rest from time to time.
Location: Under a boat, in a marina, in the San Francisco Bay
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Re: Hookah ,diy
Quote:
Originally Posted by transmitterdan
I think if you have 25psi at the compressor end of a 50 foot 0.25" hose and try to take a breath from a regulator at 10 foot water depth you will be shocked how hard it is to suck air into your lungs. Such a rig will be a death trap IMO.
My experience with a 110-volt compressor is that 75-80 psi is what is needed to breathe comfortably.
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Re: Hookah ,diy
*we were given a Sea breath hookah unit from the companies' owner. We haven't even had the chance to try it yet. I'm only posting as I thought something from their FAQ would be germane to this discussion about operating PSI:
What pressure does the system operate?
Sea Breathe incorporates a unique variable pressure system that allows the air pressure to increase as the diver descends. Thus if you are at shallow depths, i.e. cleaning your boathull, the pressure (and hence the current draw from the battery will be minimized., approximately 12-14 psi. When the diver descends to say 20 feet the pressure will automatically adjust to about 20 psi. This feature ensures that there is the minimal drain on the battery during the dive, which of course increases battery duration.
My experience with a 110-volt compressor is that 75-80 psi is what is needed to breathe comfortably.
Have you ever tried using a regulator that will operate at 30 or 40 psi?
I strongly suspect that, with the right regulator, and the right compressor, you would find that half that much pressure could provide all the air you would ever need.
I strongly suspect that, with the right regulator, and the right compressor, you would find that half that much pressure could provide all the air you would ever need.
You could of course design a reg that would operate at almost 0 pressure, even a CPAP will hold the same very low pressure with varying demands, however at least one problem is hose size, to get the same volume at lower pressures will require a larger hose.
My bet is almost all Hooka regs are actually Scuba regs with little if any modifications, and they are designed to operate at higher pressures. I adjusted one of my Dive rites to work fine at 90 PSI, but I'm sure it won't down to really low pressures as the orifice in the reg would have to be larger as well to get the same air flow at lower pressures.
Often an inexperienced person will panic if they start overbreathing their reg. I have never over breathed one myself and in truth don't see how you could, but so guess some can.
Too low a pressure will decrease flow and make over breathing easier
You could of course design a reg that would operate at almost 0 pressure, even a CPAP will hold the same very low pressure with varying demands, however at least one problem is hose size, to get the same volume at lower pressures will require a larger hose.
My bet is almost all Hooka regs are actually Scuba regs with little if any modifications, and they are designed to operate at higher pressures. I adjusted one of my Dive rites to work fine at 90 PSI, but I'm sure it won't down to really low pressures as the orifice in the reg would have to be larger as well to get the same air flow at lower pressures.
Often an inexperienced person will panic if they start overbreathing their reg. I have never over breathed one myself and in truth don't see how you could, but so guess some can.
Too low a pressure will decrease flow and make over breathing easier
Overbreathing is easy. That's how I can tell when my 12v battery has run out of juice up on the surface. I can no longer take in an easy deep breath, I suspect it would kinda be the same feeling. Shallower breaths.
Have you ever tried using a regulator that will operate at 30 or 40 psi?
I strongly suspect that, with the right regulator, and the right compressor, you would find that half that much pressure could provide all the air you would ever need.
Question: Have you tried it? If so, were you also doing work while down there like scrubbing or scraping the junk off a bottom which will cause you to take more frequent and deeper breaths?
Question: Have you tried it? If so, were you also doing work while down there like scrubbing or scraping the junk off a bottom which will cause you to take more frequent and deeper breaths?
You could not with a regular Scuba reg, but it could be done, for example my CPAP is set to 8 in of water which is I think about .3 PSI, and I can't over breathe it. I have tried out of curiosity.
We are talking only very shallow depths of course, or otherwise it would have to have a way to ramp up pressure with increasing depth
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