Integrity testing is a critical operation, especially for sterilizing grade filters used in biopharmaceutical processing. When performed correctly, an integrity test is a fast, definitive, non-destructive way to assure filter retention performance. Fortunately, there are few ways a non-integral filter will pass the integrity test, eliminating the possibility a non-retentive filter is used undetected. Unfortunately, there are a lot of ways an integral filter can fail the integrity test, resulting in retests, lost time, productivity and potentially lost product. In this webinar you will: - Gain confidence in your integrity testing results - Provide justification for retests - Understand specific challenges and eliminate them to assure the integrity test can be performed correctly the first time

1. NOT FOR U.S. AND CANADA AUDIENCE
Randy Wilkins
Principal Technical Consultant

2. 2
• “Retesting is just a routine part of the process”
- The best option for troubleshooting is to not have to do it in
the first place
- Webinar: Filter Integrity Testing Best Practices
http://bit.ly/2jEKlEm
• “Filters always fail because they are not wet properly”
- Poor wetting is a reason, but far from the only reason
- Ignoring other potential failure modes result in lost time,
product and frustration
Integrity Testing Myths

3. 3
• “Retesting is just a routine part of the process”
- The best option for troubleshooting is to not have to do it in
the first place
- Webinar: Filter Integrity Testing Best Practices
http://bit.ly/2jEKlEm
• “Filters always fail because they are not wet properly”
- Poor wetting is a reason, but far from the only reason
- Ignoring other potential failure modes result in lost time,
product and frustration
• “You are only allowed to re-test the filter twice”
- You can’t simply retest until you get the answer you want
- Why impose a limit?
- If the reason for a failed/invalid test is clear and
documented, why limit the option for a re-test?
Integrity Testing Myths

4. 4
Demystifying Integrity Test Filters
Understanding the possible causes of IT failures
Being able to apply a logical step-by-step re-test procedure to distinguish between a
false failure and a real failure
Developing internal trouble shooting SOP to establish the root cause of IT failures
After today’s session you will be able to improve your internal IT process by:

5. 5
Integrity Test Review
Integrity tests are based on capillary forces that hold liquid in the pores of wet membranes. Liquid in the
pores of the membrane are a barrier to bulk gas flow. The smaller the pores, the stronger the capillary
forces.
4 . k .  . cos 
BP = -----------------
d
• k = shape correction factor
• = surface tension
• = contact angle
• d = pore diameter
Bubble Point Test
K . (P1 - P2) . A . 
Diffusion = --------------------
L
K = Diffusivity / Solubility coefficient
P1, P2 = Pressure difference
across the system
= Membrane porosity
L = Effective path length
A = Membrane area
Diffusion Test
5

6. Integrity Test Review – Diffusion
 Liquid is held in the pores of a fully wetted membrane filter by
capillary forces
 A pressure differential will give a gas concentration gradient across
the filter.
 Results in diffusive gas flow from upstream to downstream.
Wet membrane
Apply pressure
from validated
specification
Hold pressure
6

7. 7
Integrity Test Review - Diffusion
Gas flow rate within specification indicates flow is solely
from diffusion, which indicates the absence of defects or
over sized pores.
Out of specification
GasFlow
Within
specification
Pressure
Bad filter
Good
filter
Measure the
gas flow rate

8. Integrity Test Review – Bubble Point
8
Out of
specification
Within
specification
GasFlow
Pressure
Durapore®
CVGL:
50psid
Good
filter
Bad filter
Wet Membrane
 Water is held in the pores by
capillary force
Gradually raise
pressure
 Sufficient pressure will
overcome capillary forces and
push liquid from the filter
Determine pressure
were onset of bulk
flow is observed
 The smaller the pores, the
higher the bubble point
pressure

9. Integrity Test Review – Automated Testing
9
All else being constant, the change in pressure
can be used to determine the gas flow rate
1
During integrity testing gas molecules flow
through the filter and leave the system
2
Fewer gas molecules upstream result in lower
pressure
3
Upstream Pressurized
Compressed gas
Gas flow

10. Potential Results – General Categories
• What are potential results?
10-inch Durapore® filter specifications
Bubble point ≥50 psi
Diffusion ≤ 13.3 cc/min at 40 psi
GasFlow
Pressure
Diffusion spec
Bubble Point spec.
10

11. Potential Results – General Categories
GasFlow
Pressure
Diffusion spec
Bubble Point spec.
PASS
• What are potential results?
10-inch Durapore® filter specifications
Bubble point ≥50 psi
Diffusion ≤ 13.3 cc/min at 40 psi
Example 1 - PASS
BP = 55 psi
Diffusion = 10 cc/min
11

12. Potential Results – General Categories
• What are potential results?
10-inch Durapore® filter specifications
Bubble point ≥50 psi
Diffusion ≤ 13.3 cc/min at 40 psi
Example 1 - PASS
BP = 55 psi
Diffusion = 10 cc/min
Example 2 – Marginal Failure
BP = 48 psi
Diffusion = 20 cc/min
GasFlow
Pressure
Diffusion spec
Bubble Point spec.
PASS
Marginal failure
12

13. Potential Results – General Categories
• What are potential results?
10-inch Durapore® filter specifications
Bubble point ≥50 psi
Diffusion ≤ 13.3 cc/min at 40 psi
Example 1 - PASS
BP = 55 psi
Diffusion = 10 cc/min
Example 2 – Marginal Failure
BP = 48 psi
Diffusion = 20 cc/min
Example 3 - Gross Failure
BP < 5psi
GasFlow
Pressure
Diffusion spec
Bubble Point spec
PASS
Marginal failureGross failure
13

14. Potential Results – General Categories
• What are potential results?
10-inch Durapore® filter specifications
Bubble point ≥50 psi
Diffusion ≤ 13.3 cc/min at 40 psi
Example 1 - PASS
BP = 55 psi
Diffusion = 10 cc/min
Example 2 – Marginal Failure
BP = 48 psi
Diffusion = 20 cc/min
Example 3 - Gross Failure
BP < 5psi
Example 4 - Invalid Test
BP > 75 psi
Diffusion = 0 cc/min
GasFlow
Pressure
Diffusion spec
Bubble Point spec.
PASS
Marginal failureGross failure
Invalid
14

15. A Good Troubleshooting SOP is Essential
A well written, properly executed
troubleshooting SOP should answer two
questions:
1. Is the filter integral or not?
2. Why did the test fail in the first place?
15

16. SOP Development – What can go wrong?
Flow and Pressure Wetting Limits
0
10
20
30
40
50
60
0 0.2 0.4 0.6 0.8 1
Flow Rate (lpm/ft^2)
Pressure(psi)
INTEGRITY TEST PASS ZONE
INTEGRITY TEST
FALSE FAILURE ZONE
Recommended
Wetting
Conditions
16
1. Poor wetting

17. SOP Development – What can go wrong?
17
1.
2.
Poor wetting
Wrong test program

18. SOP Development – What can go wrong?
18
1.
2.
3.
Poor wetting
Wrong test program
Wrong filter used

19. SOP Development – What can go wrong?
19
1.
2.
3.
4.
Poor wetting
Wrong test program
Wrong filter used
Improper seals

20. SOP Development – What can go wrong?
20
1.
2.
3.
4.
5.
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter

21. SOP Development – What can go wrong?
21
1.
2.
3.
4.
5.
6.
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
4 . k .  . cos 
BP = -------------------------
d
• k = shape correction factor
• = surface tension
• = contact angle
• d = pore diameter
Bubble Point Test

22. SOP Development – What can go wrong?
22
1.
2.
3.
4.
5.
6.
7.
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Wrong test gas
K . (P1 - P2) . A . 
Diffusion = ---------------------
L
K = Diffusivity / Solubility coefficient
P1, P2 = Pressure difference
across the system
= Membrane porosity
L = Effective path length
A = Membrane area
Diffusion Test

23. SOP Development – What can go wrong?
23
z
1.
2.
3.
4.
5.
6.
7.
8.
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Leaks (housing, tubing, integrity tester)
Wrong test gas

24. SOP Development – What can go wrong?
24
z
1.
2.
3.
4.
5.
6.
7.
8.
9.
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Leaks (housing, tubing, integrity tester)
Wrong test gas
Temperature change

25. Stable Temperature Environment
Manufacturers specifications are typically established at ambient
temperature (~23°C)
If operating outside of ambient temperature, a ratio should be
established during validation and applied to test specification
- e.g., Cold room operation or heat jacketed housing
Effect of Tem perature on Diffusional Flow rate
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
5 10 15 20 25 30 35 40 45 50 55 60 65 70
Tem perature (C)
CorrectionFactor(Relative
to23C)
There is no significant impact on diffusive flow or BP
over normal ambient temperature range
1
2
25

26. Stable Temperature Environment
Within
Specification
Out of
Specification
AirFlow
ml/min
Time min
Test has to be repeated per retest SOP after
establishing stable test conditions
Apparent Gas Flow
Trained operator can identify the temperature effect by
reviewing the flow curve
Common reasons for temperature changes
 Inadequate stabilization after steaming or wetting
with hot WFI
 Environmental changes during testing near
autoclave, HVAC outlets, cold room door, near a
window, etc.
 When using Automatic Testers, temperature changes
during a test leads to additional upstream pressure
gain or loss – Test Error
 Idea Gas Law – PV=nRT
 As Temperature increases, Pressure increases
 As Temperature decreases, Pressure decreases
 Even a change of 1 C DURING the test can lead
to false failure because the pressure change
WILL NOT be solely due to gas flow
26
Flow at
unstable temp
False failure
Flow at stable
temp

27. SOP Development – What can go wrong?
z
1.
2.
3.
4.
5.
6.
7.
8.
9.
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Leaks (housing, tubing, integrity tester)
Wrong test gas
Temperature change
Surface tension suppression
27
Common causes for surface tension
suppression:
Residual Product: Develop product based on
integrity test specification and post-use flush
procedure
Application Note
AN1505EN00

28. SOP Development – What can go wrong?
28
z
1.
2.
3.
4.
5.
6.
7.
8.
9.
10
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Leaks (housing, tubing, integrity tester)
Wrong test gas
Temperature change
Surface tension suppression
Common causes for surface tension
suppression:
• Contaminants: New silicone tubing, residual
cleaning agent, etc.
- Identify and eliminate
Freon residue - silicone rubber Millidisk minus body oil
Silicone oil
100020003000
cm-¹

29. SOP Development – What can go wrong?
29
z
1.
2.
3.
4.
5.
6.
7.
8.
9.
10
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Leaks (housing, tubing, integrity tester)
Wrong test gas
Temperature change
Surface tension suppression
Common causes for surface tension
suppression:
• Contaminants: New silicone tubing, residual
cleaning agent, etc.
- Identify and eliminate
Impact of tubing material on the failure of product-specific bubble points of
sterilizing grade-filters Meyer and Vargas, PDA Journal of Parenteral
Science, Vol 60 n°4 2006

30. SOP Development – What can go wrong?
30
z
1.
2.
3.
4.
5.
6.
7.
8.
9.
10
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Leaks (housing, tubing, integrity tester)
Wrong test gas
Temperature change
Surface tension suppression
11. Damaged O-rings

31. SOP Development – What can go wrong?
31
z
1.
2.
3.
4.
5.
6.
7.
8.
9.
10
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Leaks (housing, tubing, integrity tester)
Wrong test gas
Temperature change
Surface tension suppression
11.
12.
Damaged O-rings
Instrument calibration

32. SOP Development – What can go wrong?
32
z
1.
2.
3.
4.
5.
6.
7.
8.
9.
10
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Leaks (housing, tubing, integrity tester)
Wrong test gas
Temperature change
Surface tension suppression
11.
12.
13.
Damaged O-rings
Instrument calibration
Air lock

33. SOP Development – What can go wrong?
33
z
1.
2.
3.
4.
5.
6.
7.
8.
9.
10
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Leaks (housing, tubing, integrity tester)
Wrong test gas
Temperature change
Surface tension suppression
11.
12.
13.
Damaged O-rings
Instrument calibration
Air lock
NOTE: This is not an exhaustive list.
Consider developing a site-specific list by
conducting a brainstorming session with the
people routinely performing the integrity
test.

34. SOP Development – What can go wrong?
34
Pass
Fail
Initial Test
Wet at 1 LPM/0.1 m2 filter area

35. SOP Development
35
z
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Leaks (housing, tubing, integrity tester)
Wrong test gas
Temperature change
Surface tension suppression
11.
12.
13.
Damaged O-rings
Instrument calibration
Air lock
Evaluate test results
Verify system set-up and test
parameters

36. Evaluate Test Results
36
36
Stable flow
Clear BP
Good test
Stable flow
Shifted up
Possible leak
Non-stable flow
Likely temp
change

37. Troubleshooting Flow Chart Development
37
Pass
Set up or
Execution
problem
identified
and
corrected
Fail
Initial Test
Wet at 1 LPM/0.1 m2 filter
area
Check test
set-up and
execution
Test set-up
and
execution
verified
correct

38. SOP Development
38
z
1.
2.
3.
4.
5.
6.
7.
8.
9.
10
Poor wetting
Wrong test program
Wrong filter used
Improper seals
Damaged filter
Wrong wetting fluid
Leaks (housing, tubing, integrity tester)
Wrong test gas
Temperature change
Surface tension suppression
11.
12.
13.
Damaged O-rings
Instrument calibration
Air lock
Remaining potential
failure modes require
re-test.

39. Rewet Options
Wetting Option Ease of Implementation Failure Modes Addressed Failure Modes Not Addressed
Longer Time Easy
Poor wetting, non-adsorbed
surface active residuals
Damage, Air Lock, adsorbed
surface active contaminants
Warm Water Flush Easy if facilities are available
Poor wetting, non-adsorbed
water soluble surface active
residuals
Damage, Air lock, adsorbed
surface active residuals
Higher Flow Rate
Easy depending on system
capabilities
Poor wetting, non-adsorbed
surface active residuals
Damage, Air Lock, adsorbed
surface active contaminants
Higher System Pressure Easy
Poor Wetting, non-adsorbed
surface active residuals,
Damage, Air lock, adsorbed
surface active residuals
Alcohol
Complex when alcohol
contamination in the process is a
risk
Poor wetting, non-adsorbed
surface active residuals,
adsorbed surface active
residuals,
Damage, severe air lock
39

40. Pressure Wetting
Standard Wetting
inlet
0
outlet
2
For 0.22 m Durapore® filter devices at 1 lpm/0.1 m2
Inlet pressure = 2 psi/0.14 bar
Outlet pressure = 0 psi/0 bar
p = 2 psi/0.14 bar
High Pressure Wetting
inlet
38
outlet
40
High Pressure Wetting at 1 lpm/0.1 m2
Inlet pressure = 40 psi/2.7 bar
Outlet pressure = 38 psi/2.6 bar
p = 2 psi/0.14 bar
40

41. Rewet Options
Wetting Option Ease of Implementation Failure Modes Addressed Failure Modes Not Addressed
Longer Time Easy
Poor wetting, non-adsorbed
surface active residuals
Damage, Air Lock, adsorbed
surface active contaminants
Warm Water Flush Easy if facilities are available
Poor wetting, non-adsorbed
water soluble surface active
residuals
Damage, Air lock, adsorbed
surface active residuals
Higher Flow Rate
Easy depending on system
capabilities
Poor wetting, non-adsorbed
surface active residuals
Damage, Air Lock, adsorbed
surface active contaminants
Higher System Pressure Easy
Poor Wetting, non-adsorbed
surface active residuals,
Damage, Air lock, adsorbed
surface active residuals
Alcohol
Complex when alcohol
contamination in the process is a
risk
Poor wetting, non-adsorbed
surface active residuals,
adsorbed surface active
residuals,
Damage, severe air lock
41

42. First Retest – High Pressure Wet
inlet
38
outlet
40
42
Pass
Consider poor wetting
as cause of initial test
failure
Fail
First Re-test
Wet at 1 LPM/0.1 m2 filter area with
back pressure

43. Second Retest – Alcohol Wet
43
Pass
Consider presence of
surface active
compounds as the
cause of initial test
failure
Fail
Second Re-test
Wet and test with 70/30 IPA
43

44. Third Retest – Dry and Re-wet with water
4444
Pass
Initial failures likely due
to air lock
Fail
Dry with dynamic air flow or
oven drying at 80 C for 8 hrs
Wet and test with water
Contact filter vendor for
confirmation and defect analysis

45. Summary
• When failing integrity test results occur,
consider all the potential failure causes
- Many are common, some may be site
specific
• Develop a troubleshooting flowchart based
on understanding of failure modes and
remedies
• Conclusions about failure modes may not
be definitive
- A logical approach will yield the best
assessment of failure mode
- Best assessment will yield justification for
re-tests and direction for corrective
actions
45

46. Additional TroubleshootingAdditional Troubleshooting - PDA 26
46
The 2008 revision includes an excellent trouble-shooting flowchart

47. Thank You.
Questions?
47