Room Pressurization within the pharmaceutical industry

[Essences]

Could anyone assist me with the following problem. Although I have a control systems background I am unfamiliar with HVAC systems. The brief is as follows-

During the commissioning of a new air system within a Front Line Pharma Manufacturing Type facility, in which rooms require the maintenance of a constant pressure, it is observed that pressures cannot be maintained. The design principle is for room pressures to be maintained by a static balance of supply and extraction systems, with fans maintaining a constant system supply pressure regardless of filter conditions. What aspects of the system would you check to resolve this problem (i.e. that pressures cannot be maintained)?

Can anyone offer any suggestions? VAV systems?

 

[itsmoked]

It's a tough subject!
You need control of the air into a room and out of the room.
The problems are many. The system/actuators that throttle air in can be too slow. Doors opening are sudden huge 'leaks'. The exit restrictions are important. Then you overlay this whole thing over multiple rooms, with interaction between them, and you can easily have, "pressures cannot be maintained".

Sort of a house of cards thing. It'd be very useful to have a technician that has experience in this stuff to assist since it is a bit of an art to get it all balanced.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[BulldogUK]

HI, I was just passing and thought I would answer
The VAV's and Balancing the system will not change the pressure in the room. The pressure transducer (sensor) in the supply fan duct will be faulty or the Inverter controlling the speed of the fan is in hand on the inverter or incorrectly programed inverter or faulty software controling the set up.
Example: your require 350kpa in the supply duct or room which ever. The controls system you have reads the Pressure transducer and modulates the inverter, usually 0-10v dc signal to ramp the fan speed up or down. The system then holds the fan at the correct speed to maintain pressure. SO the fan will be constantly changing speed on a VAV system. As VAV's close and open so the pressure rises and falls.
I hope this helps.
Check pressure Tranducer in the duct, check inverter is in Auto and Modulating (speeding up and slowing down)
Then look at your software.

Cheers John