Question: Mr. Heyer, could you please explain the problem?
AH: “Combustion gases, like acetylene, propane and hydrogen form a highly explosive mixture when combined with oxygen and can create a situation where accidents can occur. Typical reasons include damaged nozzles, leaking screw connections, oxygen overpressure and a lack of gas. However there are a number of human errors, which can cause these accidents, and in most cases will be re-created if not rectified.”
Question: Can users identify the dangers in time?
AH: “In most cases no. Working responsibly means checking the equipment’s condition in advance. Listen for whistling noises that might indicate a leakage while working. The well-known backfire of the burner is a clear signal. Cut off the gas flow immediately in this case. If a flashback occurs, the accident is inevitable, as the fire moves towards the gas supply at twice the speed of sound and can cause an explosion, if no flashback arrestor has been installed. You’re lucky, if all that happens is that you get a broken hose or a fire in the pressure reducer. “
Question: What would you recommend?
AH: “It is highly recommendable to use a flashback arrestor, between the gas supply and the working equipment to provide reliable protection of single cylinders, outlet points (hoses and any equipment) or pipelines.These small safety devices can stop the gas flow in a split of a second and extinguish the flames before they reach critical components.”
Question: What should buyers be aware of?
AH: “Firstly, only purchase your flashback arrestors from brand manufacturers like WITT or their authorised distributors. An increasing number of pirate copies are now available in the market – a problem that has been noted by the VDMA (German Engineering Federation). I can advise fabricators that using such copies can be fatal, because when they fail, as they will, they offer no protection.
Question: In relation to technology – what makes a good flashback arrestor?
AH: “Better flashback arrestors feature a triple protection with a gas non-return valve, a flame arrestor and a thermal cut-off valve. These devices protect the user against backfeeding and reverse gas flow of potentially explosive gas mixtures. Any flames are immediately extinguished in the sintered fitting core. Importantly, the ISO 5175 standard applies internationally, whilst EN 730 also applies in Europe. In addition, WITT flashback arrestors are tested by the Federal Institute for Materials Research and Testing (BAM), which is not only technically a benefit but also helpful with regards to insurance issues.”
Question: Does the use of a flashback arrestor have any disadvantages?
AH: No. However, keep in mind that flashback arrestors are designed for a defined pressure range and volume flow rate that varies depending on the gas type and temperature and you cannot choose any FBA for any application. Witt offers a large range of products to suit all customers requirements.Furthermore, the integrated dirt filter should be serviced regularly by the user.
A key point to consider is that standard systems – even if equipped with a triple protection – stop the gas flow if there is an indication of danger. However, they release the gas flow automatically after, providing the temperature-controlled cut-off valve has not been triggered. Users will only note a short interruption to the gas flow at the most.
It is best, if users opt for a flashback arrestor with an additional pressure-activated cut-off valve, which stops the gas flow permanently. Making sure no incidents remain undetected. The user can then check for the cause, removes it and reactivates the flashback arrestor. This is an innovation designed by WITT, the company that invented the original dry flashback arrestor around 65 years ago.
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