Air conditioning

[shameem]

Hi
In a pharmaceutical project we install 500X500 HEPA filter(For 750CFM).After installation this filter air flow rate of this room is decrease then previous .Can any one tell me what is actual static pressure require for this filter.And how to calculate it.

[Brian_UK]

You need to get that information from the filter manufacturer.

It is part of their design data.

[Magoo]

Hepa air filters will remove fine particulates to a standard as specified by the supplier. As Brian_UK suggested refer back to filter suppliers for specifications.
Hepa filters will reduce airflow by the fact that they filter the air.
The loses should have been built into system design and fan total static selection.

[hamidpia]

Pressure drop across Hepa filters is highest among the all the filters,which are used in HVAC, this pressure drop across filter varies with thickness of filter, Flow rate and dirt build up.e.g. 12in thickness filter should show a pressure drop between 0.7 to 1.00 in of water, again depends on manufacturer data as has been suggested by Brian. If your blower is not strong enough you may experience reduced air flow, as is happening in your case. Generally when using HEPA filter you AHU Fan must be capable of developing ESP (External Static Pressure) 3.00 to 4.00 in of water, taking into consideration wire mesh,Panel, bag filters that are going to be used with HEPA Filter and again depends TEL (Total Equivqlent of your Ducts) .If you want short answer 3.50 in of water ESP of AHU should suffice. Let me know if you have further query.
Best regards
Hamid