Door Grilles/Pressure relief grilles in hospital rooms

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Hello,
Are door grilles/pressure relief grilles recommended in hospital spaces. Specifically, rooms that have negative or positive pressure requirements.
I'm wondering about the provision of door grilles in hospitals. I can imagine that they would not be allowed in critical environment rooms such as isolation rooms and operation theaters as it wouldn't be possible to achieve the recommended pressure difference if air is continuously leaking in or out and the idea is to isolate these areas, However, how can I be sure that these spaces won't become excessively over pressurized (or under pressurized) and cause my fans to be choked off or cause problems with doors opening. All fans are constant drive based on the request of the client.
 
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I'm less familiar with hospitals, but I do a lot of lab and GMP manufacturing work...

I wouldn't say "not allowed", but yes, due to the large airflow through the grille/louver it is harder to achieve the desired pressurization. And it isn't just the total airflow that is a problem, but the variation is large too. Typically if you are trying to achieve a specific pressure*, you would provide a supply and return, and start with an assumed differential airflow needed across the door (frame) and any other leakage sources. Then the balancer will adjust the return to achieve the exact pressurization value desired. Smaller gaps mean less total transfer airflow and less adjustment to "dial-in" the pressurization you are looking for.

Conversely, if you have automatic control and a very "tight" room, it could have trouble making fine enough adjustments to maintain the pressure. I wouldn't expect hospitals to be too tight, though.

And again, I'm not sure of the regulations for hospitals; for some less critical applications, you just keep a certain differential airflow and don't worry so much about the exact pressure. That's common in labs. For GMP you need the pressure to be exact.
 
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russ_watters said:
I'm less familiar with hospitals, but I do a lot of lab and GMP manufacturing work...

I wouldn't say "not allowed", but yes, due to the large airflow through the grille/louver it is harder to achieve the desired pressurization. And it isn't just the total airflow that is a problem, but the variation is large too. Typically if you are trying to achieve a specific pressure*, you would provide a supply and return, and start with an assumed differential airflow needed across the door (frame) and any other leakage sources. Then the balancer will adjust the return to achieve the exact pressurization value desired. Smaller gaps mean less total transfer airflow and less adjustment to "dial-in" the pressurization you are looking for.

Conversely, if you have automatic control and a very "tight" room, it could have trouble making fine enough adjustments to maintain the pressure. I wouldn't expect hospitals to be too tight, though.

And again, I'm not sure of the regulations for hospitals; for some less critical applications, you just keep a certain differential airflow and don't worry so much about the exact pressure. That's common in labs. For GMP you need the pressure to be exact.
Thank you , I've been reading up on isolation rooms and the general consensus is that they must be kept tight for the obvious reason of contamination prevention. Operation rooms and isolation rooms require a specified minimum pressure difference 2.5 Pa. I'm thinking about encouraging the architectural team to design these critical spaces specifically tight and placing pressure relief dampers ,as Lnewqban implied, in case of excessive negative or positive pressure.
 
tj00343 said:
I like it, if I'm getting you right, you're suggesting that the rooms be designed tight and utilizing pressure relief dampers in case of excessive pressure.
Please, take it only as an option to be considered, as I don't know what the code and regulations regarding ventilation and air balance in hospitals of your area is.

That is a common way to prevent excessive force to be applied to open or close doors of emergency-pressurized stairways in high-rise buildings.
Upon activation of the smoke alarm system, the shaft is pressurized by emergency fans, so people have fresh air in it while escaping the building.

The doors to get in and out of that shaft should be able to be opened by a elderly person, so the actual pulling or pushing force is measured during tests and is adjusted via balancing-weight manipulation of the gravity dampers.