$50 Harbor Freight hookah system testing

[mr.jadkowski]

I made a few changes to my rig, mostly on the diver side. I replaced the snap hook hose attachment with a snap shackle with a long tag so it's easy to grab and release. I also started using a weight vest along with my belt so I can move weight up to my shoulders for better trim. I also added a D-ring to the weight vest so I can secure my airline to the vest instead of my belt.

I'm also running the compressor with the top off my enclosure and that seems to be adequate for cooling. I had a nice dive last week with a max depth of 26 feet, averaging around 20, and I had 30 minutes of downtime before the batteries ran out. It is still working great and I'm very happy with it.

I found my new favorite local dive spot; lots of fish and interesting stuff to see along an underwater ledge.

 

[mr.jadkowski]

I got another good dive in the other day, this time with a max depth of 29' and 33 minutes of dive time. No video this time; I brought my still camera rig and my strobe batteries were dead so the pictures were kind of ****. It was also much murkier than the last dive in the same spot. I need to make sure my air hose is straighened out before I dive; once I got to the bottom and started pulling the float with the hose I discovered I had a weird loop at my hook-in point that was pulling the regulator away from my mouth. You can see it in the picture below. It took a few tries to get it straightened out on the bottom. Luckily I had a dive buddy to hold my camera and laugh at me while I was swinging my regulator and hose around randomly trying to make it straight. It would have been much easier to do on the surface before I got in the water.

At this point I'm pretty satisfied that my hookah rig is capable of doing what I wanted it to do: supply air to one diver at 30 feet, last for at least 30 minutes, and be self-contained. If anyone else wants to build one, this is the list of parts that I used. There are a few small things that aren't on that list, like some string to tie the snap shackle to the airline, and the D-rings I sewed onto my weight belt and vest to hook the snap shackle on. It also doesn't include the stuff that I use to charge the tool batteries on my boat, since most of that is custom-made 3D printed parts that I hacked together with an RC charger. The total cost ended up being just under $500, but nothing is modified to the point where it can't be used for its intended purpose. You can still use the compressor to fill your car tires if you want (with a different hose), the float will still hold your beer cooler, and the 20V Harbor Freight batteries can be used in any Bauer 20V cordless tool. In the end there are only $150 worth of parts that are dedicated solely to the hookah.

The only thing I would change is to possibly buy a different, cheaper box for the compressor to sit in while it is on the float. Originally I wanted something weather tight, but since I'm now running it with the top off the box that doesn't really matter. Any basic plastic storage tote will do; it is just there to protect the compressor from light splashing from the side, and to store everything on the boat when it is not set up.

 

[John Doomernik]

@JanNL the Nemo is only rated to 10ft though and stopping and starting pumps like that isn't great. If I was trying to design an intermittent system I would set the second stage at say 80psi of regulated outlet pressure, then have the compressor "low" turn on point set to 85psi, that way as soon as the tank pressure gets close to the regulated pressure, the pump kicks back on and runs until the high pressure kicks it off. The lower the high setpoint is and the smaller the accumulator tank is, the more cycling you will have

Yes, I am thinking of designing a hookah compressor system, better than the rest of those on the market. I dont really like the Nemo either, the other China one's are worse! "Pressure/Volume," brought me here today. Volume, sufficient for two divers, pressure to suit the depth requirements. Diving 10-15' volume is the key factor. Runtime/cooling periods with pressure tank/on-off switches. Another main obstacle is "power consumption" it's easy to get a compressor that's over rated for the job, but Amp/Hr consumption is greater, bottom time/batteries becomes the issue. Perfectly matched, a compressor with 12ah draw and 135L/min, 2-3 bar. with what I can find so far. A made in China pump, grrrrr!! Quality ="unknown" My question, do you know a reasonably priced compressor of quality, up to do this job? btw, rebuild kits must be available. Thanks for you input.

 

[John Doomernik]

Does any one have experience with the compressors from Aliexpress?

Those are the one's I'm also looking at. many variations. be careful the one you choose. Also request a diaphragm rebuild kit, or 2. An un-rebuildable pump is time limited life = possible toxic fumes, and death of the pump and or user. . lol.

The 12v, 160W 136L/min 1.8 bar (one diver 25-30', or 2.3 bar maybe 2 divers 10-15' (req a "breathe easy" dive buddy)
Pressure switches/air tank, the 13Ah pump is a good fit for 12V 12Ah 144Wh Lithium ion Batteries. Approx 1hr/bottom time/battery.

It would be better if I trusted Ali-express ethics/shipping, with container ship problems. If FedX ships by air.. I'm in for that. Let me know your thoughts..

 

[tbone1004]

Yes, I am thinking of designing a hookah compressor system, better than the rest of those on the market. I dont really like the Nemo either, the other China one's are worse! "Pressure/Volume," brought me here today. Volume, sufficient for two divers, pressure to suit the depth requirements. Diving 10-15' volume is the key factor. Runtime/cooling periods with pressure tank/on-off switches. Another main obstacle is "power consumption" it's easy to get a compressor that's over rated for the job, but Amp/Hr consumption is greater, bottom time/batteries becomes the issue. Perfectly matched, a compressor with 12ah draw and 135L/min, 2-3 bar. with what I can find so far. A made in China pump, grrrrr!! Quality ="unknown" My question, do you know a reasonably priced compressor of quality, up to do this job? btw, rebuild kits must be available. Thanks for you input.

California Air Tools is probably the closest you'll get. They're not "cheap" but they're rebuildable and continuous duty rated.
Power consumption is directly proportional to pressure and volume though so you won't get any compressors that are appreciably more efficient than others. Variable speed will help because it can slow down to maintain a fixed pressure instead of using a regulator and cycling but it's not a magic bullet.
If you need a lower duty cycle then you need a compressor that is sized appropriately against your breathing rate and then an appropriately sized accumulator. I.e. if you need 1cfm and a 50% duty cycle, then you need a 2cfm pump and a large accumulator. Finding an adequately sized compressor that is continuous duty rated is better though.
You may want to just bite the bullet for the Brownies VS system. You won't be able to buy anything considerably cheaper than that.

 

[John Doomernik]

California Air Tools is probably the closest you'll get. They're not "cheap" but they're rebuildable and continuous duty rated.
Power consumption is directly proportional to pressure and volume though so you won't get any compressors that are appreciably more efficient than others. Variable speed will help because it can slow down to maintain a fixed pressure instead of using a regulator and cycling but it's not a magic bullet.
If you need a lower duty cycle then you need a compressor that is sized appropriately against your breathing rate and then an appropriately sized accumulator. I.e. if you need 1cfm and a 50% duty cycle, then you need a 2cfm pump and a large accumulator. Finding an adequately sized compressor that is continuous duty rated is better though.
You may want to just bite the bullet for the Brownies VS system. You won't be able to buy anything considerably cheaper than that.

Yes, I agree.. 100%duty cycle, with enough volume, combined with pressure to fill a tank, whereas the pump had adequate cooling cycles. I was looking and nearly pulled the trigger on the Air Zennith OB2, 4.2cfm, 200psi 100% duty cycle, with rebuildable parts kits. I had a Brownies gas power and sold it, because it was too restrictive to the locations I wanted to use it. Electric 12v, the AZ draws 35amps, which will create many situations of recharging batteries with a generator. Avoiding that as much as possible, I chose a 12v 13amp 2.3 bar, 136L/min, for two divers in the shallow's 10-15'. With underwater metal detecting becoming more and more popular, the Chinese thought to open a new market, for diving compressors, a crumby pump, barely any real accurate specs, or health/safety assurance, attach a yellow hose and reg..and yer off to the races!! Pumps over heating, PTFE discharge, no matter. a sale is a sale. buyer beware. You know what, the China pump I described, on Azn to get it here, $1,140.00 that's BS!!

I went to "California Air Tools" Model SP-9413 watched the video for the twin head ultra quiet, looked at the specs. If I seen that correctly, that an AC 8.5amp motor that will pull 1000+ watts from an Inverter from a 12V battery. Correct me if I'm wrong, 77AH draw from the battery, running continuously, Divide that to 50% run cycle, I'm right back at 35+ amps 12V, as is the AZ OB2. Please make me wrong. Thanks, looking forward to your input.. I forgot to mention, sorry, I plan to build a floating hookah system, that's quite portable.

 

[tbone1004]

@John Doomernik if the pump is rated for 100% duty cycle why does it need "adequate cooling cycles"? They are usually much happier to just stay running and not deal with temperature cycling. Let it heat soak and it won't get any hotter.

Earlier in this thread I outlined the CAT pump that I use and would recommend. The SP-9413 is not rated for 100% duty. For a hookah application the pump MUST be rated for 100% duty cycle for the duration of your planned dive. This is not negotiable. Compressor duty cycles are rated for minutes off to cool down, not seconds off. The higher end CAT compressor is rated for a 70/30 duty cycle with up to 60mins of continuous run-time. If you have 2 divers breathing on it then it is going to be running almost constantly for that duration and then it is supposed to sit for 30 mins to cool off. Running for 2mins then sitting for a minute is not an acceptable duty cycle and will put an insane amount of wear on the compressor and motor which is not designed for rapid start/stop.

2x divers at 1.5ata working is optimistically 0.9cfm*2 divers*1.5ata=2.7cfm which is the rated output of the pump you linked at about 60psi. It's rated 2.2@90, 3.1@40 so it depends on what outlet pressure you're giving the divers. That pump calls for 8.5a at 120vac, 1020w consumption. If running from an inverter it will consume ~1200w from the battery with the inverter losses. Ah can't be determined without knowing the battery chemistry you intend to use with it since their nominal voltages vary. I would use the more expensive pumps using the CAT-MP100LF which has an output of 4@40, 3@90 with a power consumption of 7.6a which is about 10% more efficient but also higher volume. In either instance, the pump is going to be running 100% while the divers are working so you can't count on any duty cycle for reduced power consumption.

If you plan to build a floating hookah then you need a pump that runs on DC and can be run directly from the battery because you don't want the losses associated with inversion and it will be impractical to seal the inverter. Practically you'll also need to use lithium batteries instead of AGM since they are both half as light and have twice the usable wh. I.e. a 100ah AGM battery should only be discharged to about 50% DoD, so 50-60ah usable and weighs 100lbs ish. A 100ah LiFePO4 battery weighs about 50lbs and has 90ah usable. They can also be charged faster. For consumption this high you'll also want a 24v or 48v system instead of 12v because the motors are smaller/lighter and the whole system is smaller because there is a lot less amperage moving around. By the time you do this properly you will rapidly be approaching the cost of the Brownies Sea Lion