Flashback arrestors are safety devices used in gas welding to prevent a flame from traveling back into the equipment and causing a potentially dangerous situation, such as an explosion or fire. There are two main types of flashback arrestors: resettable and non-resettable. Here's how they differ in function and operation:
Resettable Flashback Arrestors:
Function: These devices are designed to stop a flashback and then can be manually reset to resume operation. They typically have a mechanism that can be reset by the user after they have been activated.
How They Work: When a flashback occurs, the arrestor automatically shuts off the gas flow and extinguishes the flame. The user can then inspect the equipment for safety, clear any blockages, and manually reset the arrestor to its original state, allowing gas flow to resume. This reset mechanism often involves a button or switch on the device.
Non-Resettable Flashback Arrestors:
Function: These are designed to be a one-time use safety device. Once they activate to stop a flashback, they cannot be reset and must be replaced.
How They Work: Similar to the resettable type, they stop the flashback by cutting off the gas flow and extinguishing the flame. However, once activated, the internal mechanism permanently alters, rendering the device unusable. This permanent change ensures that a potentially damaged or compromised arrestor is not inadvertently used again, which could lead to safety risks.
In both types, the primary components typically include a flame barrier, check valve, and thermal cut-off. The flame barrier stops the flame from traveling back into the equipment, the check valve prevents reverse gas flow, and the thermal cut-off shuts down the gas flow if a certain temperature is exceeded.
Reset Capability: Resettable arrestors can be reused after activation following a safety check and reset, while non-resettable ones must be replaced after a single use.
Maintenance and Cost: Resettable arrestors may require more maintenance and inspection to ensure they are functioning correctly after being reset. Non-resettable arrestors, while potentially more costly due to the need for replacement, offer a higher assurance of safety as they eliminate the risk of improper resetting.
In choosing between the two, considerations include the frequency of use, the specific welding environment, safety protocols, and cost factors. In high-risk environments or where welders may not be trained to properly reset arrestors, non-resettable types might be preferred for their fail-safe nature.
