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Bubblers & Tanks

The process of Electrolyzing water has a minimum of two by-products, hydrogen and oxygen gases. As the gases are made, they rise to the top of the water - in the form of bubbles. The bubbling action on the surface can be quite turbulent. The turbulence can cause foam. The foam can collect on the waters surface and get carried or sucked into the engine. Is that a good thing or a bad thing? Well, a bubble is a gas trapped inside of a membrane. In our case, it is a water membrane. If you jump into a lake, you come out wet - right? Well the gases come out of the hydrogen generator wet. They are trapped inside a thin membrane of water. Some of the bubbles are big; some are small; some are in the form of mist; and under certain conditions, they are sometimes  in the form of steam (steam is not a bubble).

As long as the water is pure, the bubbles are not much of a problem for gasoline engines. Gasoline engines are always burning fuel mixed with water vapor in the air. They will even run while you pour water down their throat. Diesel engines are not like that. Water will not compress into vapor, inside the combustion chamber, thus it will lockup the piston and damage the engine. Water vapor however will compress so it is ok. Diesel engines burn water vapor all of the time; it comes from the air.

One by-product of burning gasoline and diesel fuel is also water. Both fuels are hydrocarbons. Some by-products of burning carbon are Carbon Dioxide and Carbon Monoxide. The only by-product of burning hydrogen is water. So while your engine does not burn water, it sure makes a lot of it, in the form of steam.

If our engines can handle water vapor, then what is the big deal about having a bubbler? For the most part, the problem is the other contents of the water. We add Electrolytes to the water - to increase gas production. Water is a very poor conductor of electricity - and the electrolytes change that for us, Chemically. It is the chemicals in the water that can be destructive to our engines. As the gases rise to the surface of the electrolyzer, they get trapped inside a water membrane. The membrane contains the chemicals that are in the water. The bubbles, and the mist contain traces of the chemicals, That contaminated moisture has the potential to cause harm to aluminum parts in our engines.

The bubbler's job, in most cases, is to get rid of any foam. It can also be used to rinse or wash the gases; in other words, get rid of the chemicals. A bubbler that contains electrolytes can not wash out or remove electrolytes. To do this, you will need a second bubbler which does not contain any electrolytes. I will cover this more, later.

Sometimes a bubbler is used as a Flash Arrestor; but not reliably. I have witnessed engine backfires that passed from the intake manifold, to the bubbler, through the water (from bubble to bubble) and out of the bubbler to the electrolyzer. The closer the bubbles are together, the better the chances for a flashback to make it through the water. HHO is an explosive gas. The explosion travels faster than a speeding bullet; over 3,000 feet per second. Don't trust a bubbler to stop a flashback.


Wet Cell - Water Bath Systems

Hydrogen generators that do not have sealed off water compartments, between each set of electrode plates or tubes, are considered water bath systems. In other words, water can flow or touch all parts of the plates; the bottoms, the tops, the sides. My tube cell is a prime example; or Joe Cell design as some want to call it, My tubes are submerged in a container of water. Water fills the tubes from the bottom and from the top (if I keep the water level up). I allow 4 to 5 inches of freeboard above the top of the tubes; freeboard is waterless head space. I use this area to dissipate the foam. By doing this, I do not need a bubbler; it is built in.

This is an excellent design for cold weather. If and when the water freezes, the generator can not produce hydrogen and oxygen. As soon as the water starts to thaw, the generator is safe to use. I only have one hose on the generator; it is at the top of the water free space, above the frozen water.

I could use a Bubbler as a Scrubber to wash or filter electrolytes from the gasses. But by doing so, I would risk the safety of a frozen generator. I do not have a problem with foam, so I choose not to use a bubbler.

If you use a stainless steel container with tubes, for your water bath system, you will not have to worry about your system breaking or cracking when it freezes. At most, it will just push the hose off of the lid. A tube stainless steel water bath system is by far the safest hydrogen generator. It is also the most expensive to build.


Dry Cell Systems

Hydrogen generators that have sealed off water compartments, between each set of electrode plates or tubes, are considered dry cell systems. In other words, water can not flow or touch all parts of the plates. The bottoms, the tops, the sides are all sealed off so that water can not get past them. Each set of plates forms a water tight compartment.

There is very little head space, if any. A lot of foam is produced and it has no place to accumulate, so it gets pushed or pulled out of the generator.

This system is going to need a Bubbler. The bubbler can also be used to re-supply water to the Dry Cell. That would make it both a bubbler and a tank. By installing the bubbler/tank above the Dry Cell, water will circulate and help cool the generator.

Another option would be to use a separate Tank to refill the Dry Cell, and use a Bubbler to wash/scrub the gases. If you do this, you loose the cooling circulation. If you want the circulation, then you will have to use a pump to keep the water circulating between the Tank and the generator. In order to use the Bubbler as a washer, the hose from the generator to the Bubbler needs to be- above the water line. It can then be extended below the surface of the water. If you connect that hose at the bottom of the bubbler, the water in the bubbler will mix with the water in the generator. The water in the generator contains electrolytes. The water in the bubbler does not.

A Dry Cell is disadvantaged when it comes to winter driving. The main reason is the Bubbler. If the water in the bubbler freezes, the water lines also freeze. The cell can not be operated safely until ALL of the lines thaw. If the generator thaws out before the water lines thaw, and you turn it on, the gases will build up pressure. If they can not find an escape rout, they can self ignite under pressure.

A Dry Cell System is the most efficient electrolyzer design. It is most popular built using flat plates, but it can be built using tubes.


Caution Tips

  • Never assume the Lid on the Bubbler is sealed. Imperfections may exist with the Tank, the Gasket, or the Lid. Give it a Blow Test. It is simple. Tighten the Lid, stop-up all of the hose fittings - but one; blow constant pressure into the tank via the one hose fitting. If there is a leak, you will know it. That is, unless you blow like a blond (no pun intended women). Do it like you are trying to blow up a balloon, not blowing out a candle.
  • Perform the Blow Test on the complete system; from the cell exit hose, all the way to the engine input. If it will not hold pressure, there is a leak. Hydrogen will find the slightest leak.
  • Always test for HHO output where it enters the engine. Remove the hose from the engine input and place it in a container of water. Bubbles should be present when the HHO generator is operating.



  US Plastics

  Flambeau Fluid Systems will custom make products for you - if you order in quantities.


More Tanks

Tanks with 12v and 24v Pumps

Flambeau Fluid Systems will custom make products for you - if you order in quantities.

  Pump tanks

  Just Pumps




  US Plastics Caps - Un-vented, Heavy Duty

  Flambeau Caps



Misc. Parts

  US Plastics

  Many types available at Flambeau Fluid Systems

  McMaster-Carr Tube Fittings    

Heavy Duty Bubbler / Scrubber / with Flash Port

* 19 inches Tall
*  4 inches Wide
*  3/8 inch Barbs



Available from GreenFuelH2O

 Flash Port


Available from GreenFuelH2O



Screen Strainers

   468941A - 1-5/8 Inch Removable Neck Strainer Removable Neck Strainers; available in 2 sizes


Water Level Sensors

   Level Sensors




Masterkeeper Clear PVC Tubing (thick)



   US Plastics Tubing

Excellent physical and electrical properties. Wide range of working temp. -100°F to 400°F. Fluorinated ethylene propylene (FEP) is a chemically inert thermoplastic. Transparent tubing is excellent for acids (all concentrations), aliphatic alcohols, aldehydes, bases, esters, hydrocarbons (aliphatic, aromatic and halogenated), ketones and strong oxidizing agents. Can be rigorously cleaned in boiling nitric acid for high-purity analysis.


  Tygon® Inert Tubing SE - 200

Tygon® Inert Tubing can handle many applications where flexible tubing of the past could not be used. It’s FEP inner inert, meaning it will not extract or contaminate fluids being transferred, liner provides the ultimate in chemical resistance and can handle a wide variety of fluids from corrosives to MEK-based solvents. The fluid path will not impart odor or taste, making it well-suited for food and beverage use. It meets FDA criteria for food and beverage applications, as well as USP Class VI criteria for biocompatibility. Use single barb insert fittings. Max working temp 170°F.

   Clear Reinforced Tubing. Comes in 3/8 inch I.D and larger.

Available at Lowe's home supply stores.







Page Last Edited - 04/03/2022

    Copyright © 2003   All rights reserved.   Revised: 04/03/22.                                             Web Author, David Biggs
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