UK standards as follows:-In accordance with the requirements of the British Compressed Gases Association Code of Practice 7 – Flashback arrestors should have all threads examined for damage or contaminants as well as the joints being tested at working pressure for leak tightness. They should also be tested annually to ensure they are still operating as designed by checking for leak tightness, non return and flow cut off function. Code of Practice 7 “Guidance on Maintenance” recommends that Flashback Arrestors are replaced after 5 years in service US standards as follows:OSHA and ANSI Z49.1 2012* require that each and every flashback arrestor and check valve be tested and maintained according to the manufacturer's instructions. Testing is usually required once per year, or more often in heavy duty or abusive applications. Failure to perform testing can result personal injury accidents, equipment damage, and heavy OSHA violations and fines.

In any case, are you sure it was a flashback arrester, or a non-return valve? !