Components

Regulators

In order to work with the gas in the high-pressure cylinders, you must reduce the pressure to a working pressure. This is accomplished by utilizing pressure regulators. The regulator will control the release of pressure and flow or volume of gas per hour.

The typical regulator will have two gauges: a high-pressure gauge to indicate the pressure in the bottle and a gauge to indicate the pressure and flow of gas. These will both read zero psig (pounds per square inch gauge) until the bottle is opened and the regulator is adjusted to the desired pressure. If the bottle valve is open and the cylinder pressure gauge still reads zero, this does not mean the cylinder is empty. The pressure in the cylinder is simply equal to the surrounding atmosphere. This means there are still gasses in the cylinder.

The two types of regulators are single-stage and double-stage regulators.

A single-stage regulator will reduce the pressure from the cylinder to the desired working pressure in a single step. The internal workings of the regulator are a nozzle for the gasses to pass through, a valve seat to close off the nozzle, a diaphragm, and a balancing spring. All this is contained in the housing of the regulator.

A fuel gas regulator and an oxygen regulator are almost exactly the same, but the fuel gas regulators are not designed to handle the extreme pressure from the oxygen bottle. Regulators should only be used for what the manufacturer designates them to be used for.

Oxygen enters the regulator and passes through a glass wool filter to remove dust and debris. To adjust the working pressure on the regulator, tune the adjusting screw clockwise, allowing oxygen to pass from the high-pressure chamber to the low-pressure chamber and out the hose to your torch. The more the adjusting screw is tightened or turned in the clockwise direction, the working pressure will increase. Backing the adjusting screw off or turning in the counterclockwise direction will reduce the working pressure. When lowering the pressure, you must open the oxygen valve on the torch to get a correct reading on the low pressure side of the regulator. The high-pressure regulator shown earlier in Figure 12.5 is graduated from 0 to 4000 psig and from 0 to 225 psig. The high-pressure graduation on these regulators will stay pretty consistent. The low-pressure or working-pressure side of the regulator will vary depending on the type of regulator used. Some could be graduated from as low as 0 to 80 psig, and others may be much higher 0 to 400 psig for heavy cutting requirements. They will all be calibrated to read correctly at 70 degrees Fahrenheit.

The challenge for single-stage regulators is maintaining consistent working pressure as the cylinder pressure drops. You may have to adjust the working pressure on the regulator because having a consistent pressure release from a cylinder that has 2200 to 5 psig in one step is not feasible. The double-stage regulator is designed to mitigate this problem. Not different from the single-stage regulator, the double-stage regulator simply reduces the pressure in two steps. The first stage is a predetermined pressure set by the manufacturer. This allows the second stage to reduce the pressure further to the desired working pressure, producing a more consistent flow.

Hoses and Hose Connections

The hoses you use will be color coordinated green for oxygen and red for fuel. These hoses can vary in size and length depending on the size of your torch system. If you are in a small shop, you will probably only need 25 ft of hose to get around the shop. If you are a ship, you might have a portable cart that has 150 ft of hose so you can go down three decks without bringing both cylinders with you. The conditions throughout the system will also have a safer feature other than the color of the hoses. The connections on the fuel hose will be left-hand threads making it impossible to connect to the oxygen. This will be denoted by a hash mark going around the nuts.

Flashback arrestors should always be used for safety to prevent flames from backfeeding into the cylinder. Here is a link to a video on flashback arrestor

Torch Body

These come in various sizes and can come in a variety of combinations. Some torches will come as a cutting torch, and some will have attachments you can change out for welding, heating, and cutting. There are two needle valves on the torch, one for oxygen and one for fuel, these should never be over-tightened. Over-tightening these needle valves can cause damage and limit your ability to adjust the flame settings.

All torches will have a variety of tip sizes depending on the thickness of the material you are cutting, welding, or heating. There is a common numbering system where the higher the number, the higher the heating capacity. A tip size 1 has less potential than a 2, and a 00 has less heating potential than a 0. Refer to the manufacturer’s guidelines for tip size, fuel, and oxygen pressures for the material thickness you are working with.

The torch brand you are using will have a tip chart that will tell you the size of the tip for the thickness of the material and the oxygen and fuel settings. An example tip chart is the Victor Acetylene Cutting Tip Chart at Eureka Oxygen Co.

Types of Flames

Knowing the types of flames involved in OFC is very important for operation. You will have three types of flame that you will want to get used to recognizing so you can make the proper adjustments.

carburizing flame is when you have an excessive amount of fuel compared to Oxygen. If you have a carburizing flame, you will be able to see a long feather cone in the middle of the flame, and the rest of the flame will be bright orange, giving off lots of smoke and soot .

neutral flame is the type of flame that you want. The inner cone will shrink to a small point at the tip of your torch. This is when you have a good balance of fuel and oxygen. There will be a distinct time when the inner cone stops shrinking. The inner cone will be a vibrant bright blue.

oxidizing flame means you have an excessive amount of oxygen. After the inner cone stops shrinking and you continue to add oxygen, the cones will get sharper and a little dimmer than the neutral flame. Learn to recognize this as you set up your torch. Reduce the amount of oxygen or add more fuel to bring it back to a neutral flame.

Setting up the System

Attaching regulators

First, inspect the opening on the cylinder valve and remove any debris that may be inside with a lint-free rag. On the oxygen cylinder, you will want to crack the valve open to blow out anything you may not have been able to get or see. When doing this, make sure the opening is facing away from you and anyone else. Attach the regulator, tighten it by hand, and then use a wrench to add a quarter turn. Do not over-tighten. Slowly open oxygen all the way. This is a double-seated valve.

Next, attach the acetylene regulator, which will have left-handed threads. Use your hands to tighten, then add a quarter turn using a wrench. Slowly open the acetylene cylinder a quarter turn or until you get a strong reading on the bottle pressure side of the regulator.

Once attached and open, you can check for leaks by spraying the fittings with soapy water. Look for bubbles in the soapy water, which will help you to see leaks. If you see a leak, slightly tighten the regulator with a wrench. If this does not work, shut off the valves, remove the regulator, and check for defects.

Turn the regulators clockwise to adjust the working pressure. Once this is reached, you can check all hose connections for leaks using soapy water.

Open needle valves to purge unwanted debris in hoses and check the regulators for actual working pressure. Close both needle valves using the tips of your fingers. Do not over-tighten the valves! This can cause damage to the small needle valves in the torch and lead to frustration later.

Light the Flame

Begin by opening the fuel valve on the torch. You just want to crack this, then using your friction igniter, light the torch. Add fuel until you have a strong feathery flame similar to the one the sailor has in Figure 12.11.

Achieve a Neutral Flame

Add oxygen until you get a neutral flame. Squeeze the lever on the torch to open the oxygen-cutting jet. Your preheat cones should not change as you do this. You can adjust the fuel and oxygen valves as your cutting jet is open to bring it to a neutral flame.

Inspect the flame for inconsistencies, this will indicate a dirty tip. If needed, shut down the torch and clean the tip. For this step, you only need to shut down the torch and not the complete system.

Once you achieve a neutral flame, you can begin your cutting. Be sure to follow safety guidelines and shut down your system properly when you have finished.

Shut Down

Turn off the fuel valve on the torch, then turn off the oxygen valve on the torch. Do not over-tighten. This will blow out and soot and keep your torch clean, reducing future issues.

If you have a sustained backfire in the torch (you can no longer see the flame, but the torch is making a noise), turn off the oxygen and then fuel. Remove the cutting tip and clean before lighting again.

• Once the torch is off, turn off both cylinder valves.
• Open both oxygen and fuel valves to bleed off the lines.
• Once both gauges on the regulator read zero, back off the regulators until they feel loose.
• Store the torch and horse neatly with wide loops to not kink the hoses.

Other Torch Attachments and Applications

• Welding tips have a single hole designed to focus the heat on your material. This can be used for welding and brazing. These come in various sizes.
• rose bud is an attachment that will create a large flame with multiple holes to spread the heat out. This is used to preheat material, or even heat straighten material. It is possible to anneal aluminum with this attachment by using a carburizing flame to put a layer of black soot on the aluminum then with a neutral flame to burn off the soot and then letting the aluminum air cool. The burning/disappearance of the soot gives you an indication that you have gotten the aluminum hot enough to anneal.

Attributions

1. Figure 12.5: Oxygen Regulator by Karl Fulton, for WA Open ProfTech, © SBCTC, CC BY 4.0
2. Figure 12.6: Acetylene Regulator by Karl Fulton, for WA Open ProfTech, © SBCTC, CC BY 4.0
3. Figure 12.7: Double-stage regulator by Naval Education and Training Professional Development and Technology Center in the Public Domain; United States government work
4. Figure 12.8: Nut with notches by Karl Fulton, for WA Open ProfTech, © SBCTC, CC BY 4.0
5. Figure 12.9: Types of gas torch head by Anthony Appleyard is released under CC0
6. Figure 12.10: Characteristics of the oxyacetylene flame by Naval Education and Training Professional Development and Technology Center in the Public Domain; United States government work
7. Figure 12.11: US Navy 111106-N-EZ913-299 Sailor ignites an acetylene torch aboard aircraft carrier USS John C. Stennis by Mass Communication Specialist 3rd Class Dugan Flynn in the Public Domain; United States government work