Using a gas cutter which works with a mixture of oxygen and fuel gas It is possible to reverse gas and sparks. If a sudden drop in gas pressure occurs Will result in gas and sparks at the cutting or welding nozzles with higher gas pressure. flows back into the line of the gas cut-off unit, which is at lower pressure. and in the reverse flow of the gas If there is heat from a spark and sufficient gas mixture will explode
gas cutting kit
There are many reasons for the sudden drop in gas pressure, for example:
- There is scrap material from welding, cutting to cover the hole at the gas nozzle or rat milk, causing a blockage.
- The pressure may be reduced by bending of the gas line or being crushed by a car.
- Sparks from elsewhere landed on leaking gas lines. damage the cable
- When the oxygen tank is exhausted while in use before closing the valve on the handle Acetylene gas or LPG will flow back into the line and the oxygen gauge
- When the tank valve is closed Open the valve on the handle to expel oxygen and fuel gas. The lower pressure fuel gas flows out first, allowing the oxygen to flow back to the fuel gas line and gauge.
6.When both the oxygen and fuel gas valves are opened at the same time and then ignited to use (Adjust the two pressures to balance) if the oxygen flow rate is greater than the rate that the rat milk will be released. Oxygen will flow back through the fuel gas line and gauge.
How to prevent reverse power
This can be done by installing a check valve and flashback arrestor.
check valve
Acts to prevent backflow of gas. which causes the reverse light But the non-return valve can’t stop the reversing light. Therefore, the use of non-return valves alone Definitely not enough to prevent reverse fire.
flashback arrestor
reverse power protection Which is the cause of serious accidents, there are types that are installed at the gas cutting / welding head, installed at the line, and installed at the pressure regulator (Regulator)
Torch-mounted flashback arrestors
It is a reverse fire protection device for installation on the gas cutting/welding head. and stop gas reversing with a built-in anti-backlash valve system
Anti-reflection at the cutting head
The backfire protection device’s fire filter is made of sinter metal, where metal is braided into a filter and increases the temperature to near the melting point (about 90%), causing diffusion of the atomic structure at the point of contact. The structure has a strong, long service life. Can be reused and washed many times. But the filtering quality remains the same. Importantly, it can be used at high pressure and temperature.
Installing torch-mounted flashback arrestors is the reason for the voltage drop. and the gas flow rate decreases. Be sure to check the flow rate you want to use.
Hose-mounted flashback
Reverse power protection device Installed on the line There is a working system similar to the Torch-mounted flashback arrestors installed on the gas line near the cutting head.
Regulator-mounted flashback arrestors
Reverse power protection device Mounted type on pressure regulator It is installed at the gas outlet at the pressure regulator. both in the oxygen and fuel gas
Installing a reverse power protection device
We can prevent reverse fire. by installing a reverse power protection device At the gas cutting set, 4 points are as follows:
- Exit of Oxygen Regulator
- Outlet of Fuel Gas Regulator
- Torch welt on the side where the oxygen line is connected.
- Torch welt on the side connected to the fuel gas line.
Install 4 reverse lights
Buying a flashback arrestor flashback protection device
Please see details whether this device is fully functional or not. If this is not complete Confirm that the reverse light cannot be completely prevented.
flashback
- Gas Non-return Valve is a valve that allows gas to flow in one way. This will make the gas running backwards unable to pass through.
- Flame Arrestor When sparks run backwards, the flame arrestor device is made of dense and porous stainless steel. will cause the spark to reduce the temperature to lower Flash point temperature (Ignition Temperature) causing the fuel gas inside to be unable to ignite and therefore fire.
- thermal cut-off valve, cooker which automatically closes When the internal temperature rises, the Burnback exceeds the setpoint causing the internal gas to stop flowing. to prevent explosion (available only for some models)
which the installation of such equipment can definitely prevent danger
Flashback Arrestor Inspection
best way Probably using a device to check using a flashback detector.
If it’s a general check that there isn’t a tool. Check the external condition of the reverse fire protection device. It must not be damaged or deformed.
Threads or connectors must be in normal condition. Can be installed firmly, not loose
Anti-reflection device, clean, dry, no oil stains
Test the check valve with air pressure below 2 psi, blow it back. If air is able to pass through, the check valve of the backfire arrestor is no longer operational.
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