Practical answers on choosing, fitting and looking after the spare parts for a powered air welding helmet system.
When should I change the filters on a powered air helmet?
Change them as the maker's instructions say, and sooner if a filter is damaged, visibly contaminated or breathing becomes harder. The HSE says filters for powered respirators, marked TH or TM, should be changed as the manufacturer instructs. Maker manuals add that used filters cannot be cleaned or reused, and that cleaning with compressed air or water can damage them.
Many systems have a filter alarm. When it sounds, leave the work area and change the pre-filter. If the gaps between alarms keep getting shorter, replacing the main filter as well is usually recommended. Fit only the filter type the maker lists for your system.
What should I check before each use of a powered air helmet?
Follow the maker's pre-use check every time. A typical routine is to make sure the spark protector, pre-filter and main filter are fitted and the cover clicks shut, check the air hose and connections for holes, cuts or cracks, switch on and watch the start-up self-test, then test the low airflow alarm by blocking the end of the hose with a clean palm until it sounds.
If the alarm does not sound, or you find damage, do not use the unit until it is put right. HSE guidance says never to keep working if the fan stops or the flow rate falls; leave the work area.
Does a powered respirator need regular examination and records?
Yes. The HSE says respiratory protective equipment must be correctly maintained, examined and tested, and that records must be kept. Its guidance on reusable equipment describes thorough examination at suitable intervals, which it gives as monthly, or every three months if used less often, with records kept for at least five years.
A competent person should do this following the maker's instructions. For powered equipment, key tasks include changing filters, cleaning, and checking the battery charge and flow rate. Your risk assessment and the maker's manual decide the details for your system.
What do the battery and filter alarms mean, and what should I do?
Maker manuals describe a low battery alarm and an airflow or filter alarm, usually a red light and an audible signal. If either sounds, the instruction is to leave the danger area at once. After that, charge or replace the battery, or replace the filter.
HSE guidance says never to keep working if the fan stops or the flow rate falls. A powered air unit with particle filters does not protect against gases, so leaving promptly matters. Do not take the helmet off until you are clear of the contaminated area, and follow your manual and risk assessment.
What do the TH2 and TH3 markings on a powered respirator mean?
TH marks equipment for use with a fan-assisted powered respirator. HSE guidance lists powered respirators with helmets or hoods as classes TH1, TH2 and TH3, with protection factors of 10, 20 and 40, and says they are tested to a European standard. HSE also says arc welders should have a protection factor of at least 20.
The class applies to the complete combination of blower, filter and helmet, and maker manuals show it can differ by helmet type or when a hard hat is fitted. Check the marking and manual, and only mix parts the maker lists together.
Which parts of a powered air helmet system wear out?
Maker parts lists show the replaceable items: the main filter, pre-filter, spark protector, filter cover, battery, face seal, air hose and the protective cover for the hose. Seals, including the one between the filter and the blower, are replaced when worn or damaged.
The hose cover loses its flame-retardant effect with ultraviolet and infrared exposure, so replace it when it fades or bleaches and at the maker's interval. Manuals say not to use the system until worn or damaged parts are replaced. Heavy grinding and spatter shorten the life of filters and protectors.