Printable PDF Tip & Tricks booklet.
Connecting Multiple Tanks to a Torch Manifold System
With the following instructions and illustrations, you will be able to set up a single torch or a multiple torch manifold system, using two oxygen tanks and two propane tanks that will automatically switch to the second tank when the first tank is empty. Although this will give you twice as much oxygen and propane to work with, the big advantage of this setup is that when one tank becomes empty, the second tank automatically takes over without any interruption to the operation of the connected torches. While the second tank is continuously supplying the torches, the empty tank can be changed. Even with a lot of large torches running, there will not have to be a panicked hurry to change the empty tank, because you will have as much time to do so as the second tank will last. With the following procedure, all torches connected to a torch manifold can be operated indefinitely without interruption.
The following diagrams show two tanks connected by a hose. Both tanks must be of the same gas. In other words, both oxygen or both propane. The diagrams show how only one of the gasses is setup. The other gas is setup identically, but independently from the other. The diagrams show that each tank has a pressure regulator connected. If operating more than six torches, especially large torches, you should use a larger pressure regulator than is industry standard for one or a few torches. A two stage pressure regulator is not necessary or even recommended. Connected to each pressure regulator is a flashback arrestor. The key part that makes this system work, as described above, is the check valve that each flashback arrestor has built within it. You can substitute with quick connects, which also have check valves built in, or with just check valves, but the flashback arrestors give the added safety benefit of stopping a flashback, should one ever occur. Connected to the flashback arrestor on the left tank of the first diagram is a T-Splitter. You can use a Y-Splitter instead. Connected to one of the two open ports of the splitter is a 3/8" diameter hose, appropriate for the gas being used. The other end of the hose is connected to the flashback arrestor on the other pressure regulator shown in the first diagram. A good length for this hose is 6'. Shorter restricts placement of the tanks. Longer is usually in the way. Connected to the one remaining open port of the splitter is a 3/8" diameter hose, appropriate for the gas being used, that leads to a connected manifold. This hose is typically 12½' in length. A 25' hose will allow the tanks to be placed further from the torches. The actual length of both hoses should be what best works with your situation. The torch manifold is usually placed centrally to the location of the connected torches. If the studio layout calls for two manifolds, simply add another T or Y-Splitter to the output side of the flashback arrestor on the tank on the right, as is shown in the second diagram, and connect as before. The second manifold will operate from the same gas source simultaneously. The diagrams show manifolds capable of connecting six torches each, but you can use a manifold with any number of connecting ports within practical limits. Be sure to apply all safety procedures when setting up this system as you would normally do for a single tank setup. For example, do not remove the cap to an oxygen tank before it is firmly secured in a safe location. Make sure regulators, hoses and all other components are properly connected and tightened. All manifold ports not being used are capped or have quick connects connected. Never allow oil or grease to come in contact with oxygen, which can cause an explosion. Check for leaks.
Follow normal procedures for opening tanks. Make sure that all connections are properly secured. Turn all torch valves off. Back off the pressure setting handle on each pressure regulator. Leaving the pressure set on a regulator when opening the tank's valve may cause damage to the regulator. Open both tank valves slowly for the first turn. Open oxygen tank valves fully and firmly. Check for leaks. Open propane tank valves two full turns. Check for leaks. Set the pressure on either one of the oxygen pressure regulators to 30 to 40 pounds. Do not set the pressure on the other oxygen pressure regulator yet. Set the pressure on either one of the propane pressure regulators to 15 to 20 pounds. Do not set the pressure on the other propane pressure regulator yet. Light at least one torch, using both gasses. Now go to the second pressure regulator of the oxygen. Turn the pressure setting handle slowly, just until you begin to hear the sound of gas going through it. Then back off the setting just enough to stop the sound and therefore the gas flow. The pressure set on this pressure regulator is now set slightly lower than on the other pressure regulator. Repeat this procedure on the second pressure regulator of the propane setup. You are now setup and ready to use all connected torches.
Using these higher pressure settings will buffer out pressure surges to each torch when one torch is turned on or off. Pressure regulators also perform better and have a longer life when they are set to higher pressures. Some propane pressure regulators have a red danger zone on the delivery pressure gauge. This only applies when the pressure regulator is used with acetylene. You can disregard it when using propane. Many torches give suggested pressure settings that are lower than what is stated here. These pressures are actually what the torch works best at, at a minimum. Supplying higher a pressure does not affect your ability to adjust the flame size nor does it increase gas consumption.
The way the system will now work is as follows: The tank with the pressure regulator that has the higher pressure setting will be consumed first. When this tank's pressure drops to what the other tank's pressure regulator is set to, the other tank will then come online and it will then be consumed. Without interrupting the operating torches, the first tank can be disconnected and a full one can then replace it. Do this by first backing off the pressure setting on the pressure regulator connected to the empty tank. Then turn off the empty tank's valve. Disconnect pressure regulator from empty tank and connect it to a full tank. The check valve in the flashback arrestor will not allow gas from the other tank to pass through and out the pressure regulator while it is disconnected. As before, open the tank valve slowly for the first turn, then fully and firmly for the oxygen tank or two full turns for the propane tank. Set the pressure regulator pressure, as described above, to just slightly below the other. If you set the pressure as described here, you will notice that after several tank changes, the pressure setting will be a little lower than when you first stared. This is because each time you change a tank, the new one is set to a lower pressure than the one running. Make adjustments as necessary.
A 20 pound propane tank (often referred to as a 5 gallon tank, but actually holds approximately 4½ gallons) will last about as long as 4½ K (240 cubic feet) or KH (282 cubic feet) size oxygen tanks. Because of this, and because if an emergency occurred where you would need to quickly turn off the propane tank(s), you might consider only turning on one of the propane tanks. Turn on the second one after you notice a change in the flame that indicates the propane is running low. The second tank is already setup. You will be able to quickly turn it on without any significant interruption.
Kits are available for each gas containing two larger pressure regulators, two flashback arrestors, one T-Splitter, one 6' hose, one 12½' hose. Substitutions on hose lengths can be made. Add to the kit the size torch manifold you will need to connect the number of torches you plan on using. If you are an instructor and travel a lot with this setup, consider using a combination flashback arrestor and quick connect at each pressure regulator and quick connects at the torch manifolds.
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