Is HEPA filter integrity test performed for only supply filter?
HEPA filters are always installed at the air supply point only.
Sir It means this test will be done only for supply filter, not for return filter.
Yes, because there are no HEPA filters installed at the return air end. There are normal filters affixed at the return air end (10 /15 / 20 microns porosity)
Please notice that’s correct if we say HEPA filter “usually” installed at the supply air end but in some cases for example if you need to protect the Environment from potent API then at least 2 sets of HEPA filters ( EN 1822 classification of at least H13 or equivalent) have to be installed at exhaust end.
WHO; GUIDELINE TO THE INSPECTION OF HORMONE PRODUCT MANUFACTURING FACILITIES
9.3.7 Air should be exhausted to the outside through HEPA filters and not be recirculated except to the same area, and provided that further HEPA filtration is used (normally this condition would be met by routing the recirculated air through the normal supply HEPA filters for that area). Where HEPA filters are mentioned in this guideline, they refer to HEPA filters with a minimum rating of H12 according to EN 1822.
Yes, this is absolutely correct, HEPA filters are installed at air supply end and not at the exhaust end for all normal products / APIs manufacturing.
Only for specific potent products, the example you have explained which require HEPA filters at exhaust end also.