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Regulatory Requirements HEPA Filters

Citations are being issued to companies that do not have documented justifications for their dirty HEPA filter (change filter) pressure points.
Have you calculate your compensated filter change pressure? Do you have a written justification?

Alex Kennedy

pressure diffrential across HEPA is the most important parameter from which expiry of HEPA Filters can be determined.
daily logs of Pressure Differential Across HEPA for each supply is to be maintained.
Limit ==12 pascals…

Prasad

[quote=alexkennedy]Citations are being issued to companies that do not have documented justifications for their dirty HEPA filter (change filter) pressure points.
Have you calculate your compensated filter change pressure? Do you have a written justification?

Alex Kennedy


[/quote]

Differential pressure should be less than 2.2 inches of watere, the differential pressure will increase then HEPA must be replaced.

[quote=alexkennedy]Citations are being issued to companies that do not have documented justifications for their dirty HEPA filter (change filter) pressure points.
Have you calculate your compensated filter change pressure? Do you have a written justification?

Alex Kennedy


[/quote]

How much is the pressure differential which necessiates to change the HEPA located in LAF cabinate,LAF located in dynamic passbox,LAf located in sterilizing tunnel?

Same acceptance criteria, NMT 2.2 inches of water

I asked this question to provoke some thought and hence discussion into filter pressure drops. Unfortunately no one has answered correctly.

Every HEPA filter has a flow rating and at this flow it will produce a known pressure drop across the filter.

Your filter certificate will indicate that at a flow of X cubic meters per second a pressure drop of Y pa will be generated across the filter. And when this pressure increases to Y + Z, the filter requires to be changed. Z, being the working range of the filter.

X, Y and Z are all design variables, and filters are made too many differing combinations.

This is where the problem begins because the chances of having a flow that matches the filter standard flow, exactly – are remote.

So you have to measure the flow you actually have, and work out what percentage of the maker’s standard flow it is. Then using the makers filter performance charts (in which the filter differential pressure is plotted against the flow rate. i.e. reduce the flow you obviously reduce the pressure drop). Use this chart to obtain the clean filter differential pressure, for the actual flow you have.

You can now placard the system with the pressure differential that will be shown with a clean filter – add Z (the working range of the filter) and you can placard the system with the Change Filter At – pressure.

Without carrying out this calculation you cannot say whether a high indication is due to a high flow or a blocked filter. The regulators ask to see your written justification for this.

Alex Kennedy