$50 Harbor Freight hookah system testing

[mr.jadkowski]

I'm going to jump into the discussion to document my own DIY hookah build.

I'm primarily a shallow-water, fresh water freediver, but it's hard to find dive buddies where I live and even when I do the visibility is so bad that below 15 feet you can't see another diver from the surface. I would like to build something with similar capability to the Blu3 NOMAD or the AirBuddy, just with less cost. Harbor Freight now sells a brushless, cordless compressor that, on paper, should have the capability for one diver at 1ATM. As far as I know it hasn't been used in a hookah system, except for one dude on YouTube who used it in his pool, so I bought one to test.

To get to the point where I can use this to dive from a dock or my boat, to test the capabilities of the compressor, I ordered:
Cheapo regulator and breathing hose
.3 micron filter

I've read through this thread a couple of times and have seen all the warnings about rust in the tank, teflon particulate from oilless piston pumps, residual oil in hoses from manufacturing, securing the air line to a weight belt or harness, and all the standard safety precautions for compressed air diving. I still have yet to completely tear down the compressor, but from what I can see it looks like a teflon-lined, oilless piston pump and the tank is definitely steel. In order to mitigate some of the risks from using this non-ideal compressor setup, this is what I have done and plan to do:

• 30 minute compressor break-in (as recommended in the manual) - done
• Washed the inside of the compressor tank with 13:1 hot water:simple green - done
• Rinsed the inside of the compressor tank with hot water 2x - done
• Flush the breathing hose and regulator hose with 13:1 hot water:simple green
• Rinse the breathing and regulator hoses with hot water 2x
• Install .3 micron coalescing filter between the compressor and breathing hose
• Set the outlet air pressure to the lowest pressure I can tune the regulator to
• Do some incremental testing with increasing depth and dive times with a commercial diver buddy
• Not dive any deeper or longer than I can safely do a free-swimming ascent without a safety stop
• Drain the tank after every dive and leave the drain valve open to prevent moisture build-up
• Stop diving with the compressor once the tank starts to rust

What am I missing? It seems very possible that the compressor isn't going to live up to my hopes for depth (30 feet) or run-time (30 minutes), but it seems relatively safe for me to test it to those limits using the setup I've planned and a gradual testing approach. The simple green wash should take care of any residual contamination in the tank or hoses from manufacturing, and the .3 micron filter should filter out any nasty stuff that may be coming out of the compressor.

If this thing actually works like I hope it will, I plan on putting it in a floating enclosure with a snorkel intake so I can dive away from the boat. I did a quick test running the compressor continuously with the maximum amount of flow that it could handle and still maintain the tank at 40 PSI, and one battery lasted 13 minutes. It doesn't seem totally unreasonable that two batteries could last 30 minutes if the compressor isn't running at maximum flow all the time.

 

[mr.jadkowski]

Quick update: I tore down the compressor to check out and clean the inside. It is indeed a piston compressor with a teflon-lined cylinder. There was a ton of teflon particulate on the cylinder walls and in the cylinder head, I'm guessing largely from the break-in process. Anyways, you definitely wouldn't want to breath from one of these without a filter!

There is a cooling fan on the brushless motor and another cooling fan on the crankcase side of the compressor. Neither seemed to have much residual heat after running continuously for 13 minutes, but it was also only compressing to 40 PSI. If I end up mounting this in an enclosure I'll take off the whole plastic shroud so there is a little more airflow. The motor control electronics are potted, but not well, and the battery interfaces are not, so it will require some waterproofing to protect those circuits.'

 

[tbone1004]

that is not the compressor design that I would want on a breathing compressor... I'll stick to the diaphragm pumps...

 

[mr.jadkowski]

that is not the compressor design that I would want on a breathing compressor... I'll stick to the diaphragm pumps...

Just to be sure that I understand your reasoning, your primary concern with these piston-style oilless compressors is carcinogenic Teflon particulate contamination from overheating the Teflon sleeve in the cylinder?

Also, thanks for all of your input on this thread. It is very helpful!

 

[tbone1004]

Just to be sure that I understand your reasoning, your primary concern with these piston-style oilless compressors is carcinogenic Teflon particulate contamination from overheating the Teflon sleeve in the cylinder?

Also, thanks for all of your input on this thread. It is very helpful!

correct, I would much rather deal with the extra weight of the diaphragm compressors. I know the battery packs are nice and if they used DeWalt packs with a diaphragm pump I'd be in, but for something like this I would rather deal with extension cords or a generator and not try to filter those particles out. The extra heat from the super high RPM of the compressor also makes knocking the water out and that's where the particles are going to be knocked out.

 

[mr.jadkowski]

correct, I would much rather deal with the extra weight of the diaphragm compressors. I know the battery packs are nice and if they used DeWalt packs with a diaphragm pump I'd be in, but for something like this I would rather deal with extension cords or a generator and not try to filter those particles out. The extra heat from the super high RPM of the compressor also makes knocking the water out and that's where the particles are going to be knocked out.

Got it, thank you. Just trying to do some informed risk mitigation.

Actually, one more question: The Puma pumps used in the Hookahmax and Gator Gill setups look to be piston-style as well. Do you know if that is true?

 

[tbone1004]

Got it, thank you. Just trying to do some informed risk mitigation.

Actually, one more question: The Puma pumps used in the Hookahmax and Gator Gill setups look to be piston-style as well. Do you know if that is true?

never heard of them before. The 12v from Hookamax looks to be piston, but the 110v is a diaphragm pump, unsure about the gas one since I can't really see it. The Gator Gill pumps also appear to be high rpm piston pumps.

 

[mr.jadkowski]

I've been doing some more research on the potential hazards of the teflon piston pump configuration and this is what I've found:

• A whole bunch of the off-the-shelf hookah dive systems use oilless (teflon) piston pumps, including Hookahmax, Gator Gill, Brownies, and Keene. For what it's worth, those companies don't think it's too dangerous to sell oilless piston pumps to consumers.
• Overheated teflon is problematic, in that above 300C it will start to offgas and can cause something called "Teflon Flu". I found one reference that said above 450C the outgasses change and can cause acute lung injury. I always thought overheated teflon caused cancer as well, but I can't find any evidence of that. There is also a link to PFOA (sometimes used in PTFE production) ingestion, which has some research suggesting that can cause hormonal imbalance, but the general consensus of the research I read is that there isn't any demonstrable link between PTFE use and PFOA ingestion because the residual levels of PFOA are so low.
• I ran an entire battery through my pump again running it at 120 PSI while monitoring the temperature of the PTFE cylinder sleeve with an IR heat gun. It never got above 95C, and that was the highest temp I saw anywhere on the whole pump assembly. I can believe the inside of the cylinder is hotter than the outside, but not 200+C hotter after running for 15 minutes. When I tore the pump down that PTFE cylinder appeared to be solid plastic, so I doubt it would survive heating to 300C anyways.
• After tearing my pump down it's pretty obvious that a particulate filter is absolutely necessary with a piston pump, as there was plenty of teflon particulate on the cylinder walls and the cylinder head after the break-in run.

After everything that I read, using a .3 micron filter on the outlet to catch any particulate coming out of the pump, and actually testing the pump to make sure it's not getting anywhere near "teflon flu" levels of heat, I feel comfortable using it to breath. I'm not saying that it's 100% safe, but after everything I've read I'm not seeing any red flags. We'll see if it can actually supply enough air to do any meaningful diving, but it is "rated" to almost double the capacity of the compressor that was originally tested in this thread so I'm optimistic. The rest of my parts (2nd stage and breathing hose) should be here tomorrow.

 

[mr.jadkowski]

Initial results with that compressor are pretty promising. I got everything cleaned out and hooked up, and I just sat here breathing on it for 39 minutes on one 5 aH battery (it can run on two in parallel). The duty cycle was somewhere around 34% (averaging around 40 seconds on, 1:15 off). I realize that I can cut that time in half at 30 feet, and then subtract some more for swimming, but it's still a bit better than I expected. 30 minutes of dive time seems doable if I'm taking it easy, freediving style. The air tastes and smells clean and there isn't any visible particulate accumulating in the filter after two runs.

 

[mr.jadkowski]

I had a good first dive with my setup yesterday, mostly just screwing around under my sailboat between the surface and 7 feet practicing some basic skills. I got 25 minutes of dive time out of one battery, and the compressor was running ~50% of the time. I was happy enough with it that I picked up a second battery on my way home. The compressor can use two batteries in parallel, so that should double the run time and cut the amp draw per battery in half. Leaving everything on the boat and just bringing the tool batteries home to charge is very convenient. I'm going to try to design and 3D-print a charging adapter so I can charge the batteries onboard from my house battery using an RC charger. These Bauer batteries have no internal BMS (it's all done in the charger and the tool) and break out every cell group in the pack so I should be able to do a proper balance charge with the RC charger.

The cheap chinese 2nd stage can be adjusted to very very low pressures, but I think the pressure regulator on the compressor is pretty restrictive. I had it adjusted to 35 PSI to start, but I found that if I didn't wait long enough between breaths it took more effort to inhale. It's not a compressor capacity issue, because it happens all the time even when the tank is fully charged to 135 PSI and the pump isn't running. I can see the pressure dropping ~20 PSI on the outlet side of the pressure regulator when I take a breath and then coming back up to the set pressure, and not particularly fast. I came back to the boat and set the pressure to 50 PSI and it was a little better, but on the next dive I'm gonna set it to 100 for comparison. My thinking is that if the filter and hose is charged to a higher pressure, a smaller volume of higher-pressure air has to flow through the pressure regulator for each breath and the pressure drop should be lower and the recovery faster. Even if that isn't the case, it still works fine as is and I'm happy with it so far.