Room differential pressure limits in pharmaceutical production areas

Regarding monitoring differential pressure between rooms in production areas in pharmaceutical industry:

Is it required to set 3 levels of limits , i.e. Alert limit then Action limit then Acceptance limit

or it is required to set only 2 levels of limits, i.e.
1- Alert limit
2- Action limit (which is equivalent to Acceptance limit)

(My little understanding of “WHO Technical Report Series, No. 961, Annex 5 (pages 256 & 241)” and "WHO Working document QAS/15.639/Rev.1 May 2016 (pages 67 & 54) " is that only 2 levels of limits are required (Alert and Action limits only) not 3 levels of limits)

Thanks a lot

The following pictures are Snapshots from "WHO Working document QAS/15.639/Rev.1 May 2016 (pages 67 & 54) "


Generally, two levels alert and action limits are being used. But someone may also have acceptance limit for better understanding.

I didn’t get the second part of the response

Do you mean that for this “someone” he will set Action limit that is different from Acceptance limit or both are equivalent as understood from WHO Annex 5 ??

Do you mean that for this “someone” he will set Action limit that is different from Acceptance limit or both are equivalent ??

Dear sir,

this is nice information about differential pressure , but can you give values of alert limit and acceptance limit in MM HG of water .

A 5 - 20 pa range I think is a very safe acceptance range between areas of the same grade (e.g grade d) since this range is mentioned in WHO Annex 5 and ISO 14644-4

there is no unit called mm Hg water

either mm water or mm Hg

note that some gauges their unit is mm water column X 10 (i.e. cm Water column)

the following links are for converting pressure units

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What action to be taken if dp s are below the limit

“At least” stop work in this room and ensure that this door remains well closed

Hello Sir,
I need some answer on the following query that I require in workplace practically-

  1. is the air flow of a dynamic pass box laminar? if laminar, what’s the air flow velocity range?
  2. what’s the requirement of minimum pressure difference of the adjacent area connected via dynamic pass box?
  3. what’s the mechanism of dust blowing and exhaust?
  4. is the air is a recirculated one?
  5. what’ll be the minimum gap to place a material to be passed through the pass box and the air return grill of that box?
    Thanks a lot

dear sir
velocity of air in dispensing area or room …?

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Dear Sir, I am B.Seshavardhana Reddy I completed in Mechanical engineering, can u please give me suggestion about Job opportunity and it’s future plz sir, Thank u

In Pharmacy Company Sir

thank u for reply mr awad sir

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Frequency of monitioring differetial pressure shall be increased.
Say, if you were monitoring the DP for 8 Hours during normal limit, now you should monitor for every 4 hour.