Differential Pressure between Clean Rooms Classes
Differential Pressure between Clean Rooms Classes
(OP)
WHat is the PHYSICAL reason for the 0.05"wg ? (Sometimes acceptable 0.04 to 0.06) value for DP? WHy not smaller of larger
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Differential Pressure between Clean Rooms Classes
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RE: Differential Pressure between Clean Rooms Classes
4.13.11* Door Opening Force. The maximum force for pushing or pulling open a door shall be as follows:
(2) Other doors.
(b) interior hinged doors: 5 lbf (22.2N)
RE: Differential Pressure between Clean Rooms Classes
According to the given codes, for a 3 x 7 hinged door P = 5 lbf / 21 sqft = 0.238 lbf/sqft which is exactly 0.05 in wg. PERFECT!
This means that the Differential Pressure could turn dependent on the door size, eg, Bigger doors less Delta P.
Smaller doors higher Delta P. Is that correct?
Interesting point is that Clean room Standards do not consider door size on their recommendations for Delta P.
Neither Pressure nor size change modifies the codes for reasoning this concept.
RE: Differential Pressure between Clean Rooms Classes
RE: Differential Pressure between Clean Rooms Classes
RE: Differential Pressure between Clean Rooms Classes
This is absolutely dependant on the door size and cracks and can be calculated using ASHRAE 2013 Fundamentals Equation 16.36
knowledge is power
RE: Differential Pressure between Clean Rooms Classes
RE: Differential Pressure between Clean Rooms Classes
I wouldn't trust calculations as much as having a balancing damper and flow control. I've seen differential flows from anywhere between 60 CFM and up to 200 CFM depending on the leakiness. If you are on the high end, it might be time to get the silicon caulk out. Specifying good door hardware is important. The Phoenix valve web site may still have good tutorials for this.
No need to maintain 0.05 IWC under open door scenario, as long as positive volumetric flow is verified (smoke the door). If contaminants or viral/bacterial agent could swim against the flow, it would be a moot point.