How to change the Caustic Tank O-Ring on a Hydrogen Torch


Hey Folks, today on the bench I have a single torch water welder that is not performing properly. I’ve attempted to start the unit and fire up the torch. In the process, I noticed there is no air pressure coming from the torch and I’m unable to light it. I’ve inspected and replaced the check valve, booster seals, hoses and booster cap for leaks, and they are all working fine. The next thing to do is check the O-Ring on the caustic tank. If the seal is damaged or worn, the gases can escape and you will lose pressure from the tank, causing low pressure and preventing the check valve from opening. So I’ve decided to replace the caustic tank O-ring to rectify the issue.

Even though it is a simple O-ring, it can be a bit of a process to access it. Also, I’m going to include some good cleaning tips for the caustic tank to help it run even better as an added bonus.

So let’s begin with the tools and parts you are going to need to perform this operation.

The process for a duel and single torch Hydrogen welder is the same, except the tools might be a little different.

Tools and Parts Needed

Caustic Tank O-Ring- for single torch (H20CAUSTK250), and for duel torch (H20COR350)

One gallon of distilled water for tank rinse and cleaning

Phillips head screwdriver to remove the cover screws

Brass Cleaning brush (MG851) for caustic tank rust and debris removal

7mm open end wrench or socket

10mm open end wrench or socket

13mm open end wrench or socket

Now that we have all the tools and parts, let’s begin the steps needed to perform the repair.

  1. For safety, make sure the unit is turned off and unplugged.
  2. Remove the booster tank from the booster block by unscrewing the handle from the tank.
  3. Remove the caustic tank safety cap and drain the caustic solution from the tank. Then remove the rubber grommet seal from around the tank receptacle.
  4. With a phillips head screwdriver; remove all the screws for the water welder cover.
  5. Use a 10mm open end wrench or adjustable wrench to unscrew the hose fitting nut from atop of the caustic tank. Then disconnect the hose.
    WW.Hose disconnect
  6. Now use the 7mm wrench to remove the nut for the ground wire and copper conductors from the caustic tank. (be sure to save the hardware careful and not lose the pieces)
    Ground Wire Removal
  7. Next take the 10mm wrench to loosen the nut for the (max.) and (min.) sensors and carefully remove the hardware and wires from the sensor threads.
  8. Now with a 13mm wrench loosen and remove the four nuts securing the caustic tank lid.
  9. Now carefully remove the tank lid, the four insulators should be removed with the lid as well. This will expose the old caustic O-Ring.
  10. Now that you have the tank cover off, you can remove the old caustic O-ring. This is also a good time to clean the tank by scrubbing it with a brass wire brush to loosen up any rust and debris. Finish by rinsing it out with distilled water a few times until the rinse water is clear.
  11. Place the O-ring atop the tank by carefully aligning it into the designated groove.
  12. Take the cover and carefully realign it into the same position as before, double check to see if the O-ring didn’t shift in the process.
  13. Next, use the wrench to tighten down the cover with the four nuts. Be sure to alternate the tightening in an (x) pattern to avoid uneven pinching and shifting of the O-ring. Do this until the cover is nice and snug with the tank.
  14. Take the 10mm wrench to tighten the nuts and hardware for the (max.) and (min.)
  15. Now use the 7mm wrench to remount the grounding wire and copper conductors to the tank.
  16. Reattach the hose and secure it into place by tightening the fitting nut with the wrench.
  17. Now reattach the cover into place with the screws and screwdriver. Then, insert the rubber grommet seal inside the welder opening.
  18. Lastly, Fill the caustic and booster tanks and test the unit to see if it is working properly.

Now that the O-ring is replaced and the caustic tank is clean you’re ready to get to work on whatever brazing project at hand. If you have any questions or would like to share your experiences with us, feel free to comment below. Good Luck and have fun!


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