During HVAC requalification if HEPA filter fails during DOP test then what should be best method.
- Change filter & retest.
- Calculate leak area if acceptable put sealant & retest.
Please share your opinion about this.
I believe you are right. First try to put sealant. If the leak area is big, then it will be better to change it.
Dear Biswajit
pls refer ISO 14644-3
Thanks for ur rply…
ISO 14644-3 only mentioned that leak should be repaired by agreement between customer & supplier. But acceptable % of leak not mentioned. Do you have any reference does mention about acceptable percentage of leak.
If the DOP leak test fails ie. greater that 0.01%, means that there is a possibility that the HEPA filter is allowing particles to pass through. In order to ensure that the room is within the required classification, the particle count must be done. This will provide data that although there is a leak in the filter, the particle count is sufficiently low to meet the room classification. This also provides an evaluation of the effect of the non-conformance since the last DOP. If the particle counmt is OOS, then a detailed investigation will be required.
Dear Biswajit,
There are two aspects related to your question.
1st is to repair the filter by a suitable material like (silicone) but the area which is repaired should not be more than 5% of total area.
If the patch(repaired area) is more than 5% then you need to replace the filter
Testing has to be done to assure that repairs is fine & no leakage present.
2nd is to go back & check the previous batches manufactured under this leaked filter (Failed) . Investigate the reason & impact on safety & purity of products manufactured before you came to know about the filter leakage.
Pradeep281001
There are two aspects related to your question.
1st is to repair the filter by a suitable material like (silicone) but the area which is repaired should not be more than 5% of total area.
If the patch(repaired area) is more than 5% then you need to replace the filter
Testing has to be done to assure that repairs is fine & no leakage present.
2nd is to go back & check the previous batches manufactured under this leaked filter (Failed) . Investigate the reason & impact on safety & purity of products manufactured before you came to know about the filter leakage.
Can you please share the available guideline for your statements.
[quote=Pradeep281001]Dear Biswajit,
There are two aspects related to your question.
1st is to repair the filter by a suitable material like (silicone) but the area which is repaired should not be more than 5% of total area.
If the patch(repaired area) is more than 5% then you need to replace the filter
Testing has to be done to assure that repairs is fine & no leakage present.
2nd is to go back & check the previous batches manufactured under this leaked filter (Failed) . Investigate the reason & impact on safety & purity of products manufactured before you came to know about the filter leakage.[/quote]
please name the guideline or share regarding 5 % criteria…
Yes sir i was just asking the same kindly share that particular guideline
Dear all,
I follow BS EN 1822-4 Standard.
" NOTE: All repairs together (including those made by the filter manufacturer) shall not block or restrict more than 0,5% of the filter face area (not including the frame) and the maximum length of each single repair shall not exceed 3,0 cm. Alternative repair criteria may be otherwise agreed between buyer and seller.
[quote=Kiatpornsiri]Dear all,
I follow BS EN 1822-4 Standard.
" NOTE: All repairs together (including those made by the filter manufacturer) shall not block or restrict more than 0,5% of the filter face area (not including the frame) and the maximum length of each single repair shall not exceed 3,0 cm. Alternative repair criteria may be otherwise agreed between buyer and seller.[/quote]
Dear Sir,
I have been searching for this reference for a long time. Thank you for kind sharing.
If failis we need to investigateif the exact cause is due to hepa damage then replacement is the only option.
now a days sealing are not allowed as early
regards