Pressure Hold Testing
Processing Steps

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Pressure Hold Testing

In beverage applications, pressure hold testing is the method used by most automated integrity test systems. The pressure hold test, also known as pressure decay or pressure drop test, is a variation of the diffusion test.

In pressure hold testing, a highly accurate gauge is used to monitor upstream pressure changes due to gas diffusion through the filter. Since there is no need to measure gas flow downstream of the filter, any risk to downstream sterility is eliminated.

How to Define the Pressure Hold Value
The pressure hold value is dependent on the diffusion flow and upstream volume. You can calculate the pressure hold value using the following equation:

where:
D = Diffusion rate (mL/min)
T = Time (minutes)
Pa = Atmosphere pressure (1 Atm)
Vh = Upstream volume of apparatus (mL)
∆P= Pressure Drop (bar or psig)

Your filters and housing are integral if pressure hold measured is equal to or lower ∆P.



Pressure hold testing is performed using much the same procedure as the diffusion test, except for step 4: a highly accurate gauge is used to monitor upstream pressure changes due to gas diffusion through the filter.