Millipore Integritest Exacta, Operating And Maintenance Manual

Page: 207 / 284

Millipore System Documentation Set
208
Operating and Maintenance Manual Publication XITXSP121 P Rev.A
Gross Leak detection prior to sizing
Prior to sizing, the system detects gross leaks by comparing the measured pressure drop
against the pressure drop that would be expected if a leak flowrate is set at twice the filter
diffusion specification. The pressure drop at this flowrate can be computed using the standard
diffusion equation:
dP/dt
limit
= 2* Q
spec
*14.7 / V
However, since the actual volume is unknown, the table below lists the assumed volumes.
Table 25: Assumed Volume Used for Leak Detection
Filter Classification Q spec
(mL/min)
Assumed volume
(mls)
Hydrophilic > 500 3600
3 < Q <
500
1800
< 3 425
Hydrophobic > 500 NA
3 < Q <
500
1800
< 3 152
HydroCorr >0.4 150
<= 0.4 25
<0.1 25
Listed below is an example of how this criterion would be applied.
A Millipak would have a default Q
spec
of 3 mL/min. and an assumed volume of 425 mL. The
maximum change in pressure over time would be determined as follows:
dP/dt
limit
= [2 * (3 mL/min) * (14.7 psi)]/[425 mL]
Based on this example, any pressure drop exceeding 0.21 psi/min would prompt this
message.