Protocol: Compressed Air and Process Gas Qualification

This is a ready-to-use qualification protocol for compressed air and process gases that contact product, primary containers, or the product environment. There is no rinse after a nitrogen purge, so whatever the gas carries lands on or in the product. The protocol tests at the point of use, after the final filter, against the right standard, ISO 8573 purity classes for engineering quality, and the pharmacopeial monograph where the gas is itself a defined substance. Replace every <<FILL: ...>> placeholder, read numeric limits off the current standards, and route it through your validation lifecycle. A filled specimen follows. Confirm each cited standard and monograph against the current source before you rely on it.

Approval page

1. Objective

Demonstrate that the gas system delivers, at every product-contact point of use, gas that meets its defined quality: the ISO 8573 purity classes for oil, water (dew point), and particles, plus microbial control, and, where the gas is a pharmacopeial substance, the identity and purity of its monograph. Prove that point-of-use sterilizing filters are integrity-testable and that the system holds dew point and pressure across the demand range.

2. Scope

Covers the generation and treatment train, distribution, and the product-contact points of use in Attachment A for <<FILL: gas>>. Black-utility uses of the same gas (for example valve actuation) are out of scope and are commissioned only. State which regime applies:

• Gas contacts product as a defined gaseous substance (for example pharmaceutical-grade nitrogen) -> pharmacopeial monograph plus a microbial/particle/oil control regime appropriate to the contact.
• Gas contacts product surfaces or environment but is not itself a monograph substance -> ISO 8573 purity classes plus microbial control.

3. System description

<<FILL: describe the compressor type (oil-free, or oil-lubricated with coalescing/carbon filtration), dryers (desiccant/refrigerant) and target dew point, point-of-use sterilizing filters (for example 0.22 micron hydrophobic membrane, integrity-testable housing), sample ports, and instrumentation (dew point transmitters, pressure).>>

4. Prerequisites

• URS and risk assessment approved; the applicable quality regime (ISO 8573 classes and/or monograph) defined.
• Commissioning complete; filters installed.
• Instruments calibrated and traceable (dew point, particle counter, pressure; gas analysis methods available and validated).

5. Acceptance criteria (system level)

Every product-contact point of use meets the acceptance table in section 7 across the sampling study; point-of-use filters are integrity-testable and pass; the system holds dew point and pressure across the demand range; all deviations closed.

6. IQ / OQ highlights

7. PQ sampling study and acceptance table

Sample at the worst-case point of use (farthest from treatment or highest demand), after the final filter, in the actual fitting. Run an intensive phase, then routine monitoring at a justified frequency; dew point is usually monitored continuously, oil and microbial periodically.

Cite a gas quality as the ISO triplet, for example “ISO 8573-1:2010 Class 1.2.1” (oil Class 1, water Class 2, particles Class 1). Take each class threshold from the current ISO 8573-1 table.

8. Deviation handling

Record each discrepancy as a numbered deviation, assess impact, resolve, and re-test. QA approves each deviation and the final disposition.

9. Summary and conclusion

10. References

ISO 8573-1 (purity classes) and the companion parts: ISO 8573-2 and -4 (oil aerosol and particles), -5 (oil vapor), -7 (viable microbial contaminant). USP / Ph. Eur. monographs for the relevant gas (for example Nitrogen, Oxygen, Carbon Dioxide). EU GMP Annex 1 (2022); 21 CFR 211.46, 211.63, 211.67. Related reading: clean utilities qualification, bioburden and endotoxin testing.

Confirm the current version and clause numbers of each reference before issue.

11. Revision history

Filled specimen

The following shows a completed PQ acceptance table for an example nitrogen used to overlay open product, so you can see how the two-regime approach reads. The values are illustrative; take real limits from the current standards.

In this example the nitrogen was held to both its pharmacopeial monograph (identity and purity, because it is a defined gaseous substance in contact with product) and the ISO 8573 purity classes plus microbial control. A common failed protocol tests oil aerosol but not oil vapor, or assumes dry gas is sterile and omits the ISO 8573-7 microbial sample. Testing total oil and running a microbial sample at the point of use is what closes those gaps.

Common inspection findings this protocol prevents

• Point-of-use sterilizing filter changed on a schedule but never integrity tested.
• Pressure dew point set above the line temperature, so water condenses and organisms grow.
• Oil-lubricated compressor feeding product-contact gas with only aerosol oil tested, not vapor.
• The wrong standard cited (a monograph where ISO 8573 was needed, or vice versa).
• Sampling at the receiver instead of the point of use after the final filter.

How to adapt this protocol

1. Set your protocol number, gas, and contact type on the approval page, and state which quality regime applies.
2. Read the ISO 8573 class thresholds and monograph limits off the current standards; do not carry remembered numbers.
3. List the real product-contact points of use and the worst-case selection in Attachment A.
4. Include the point-of-use filter integrity test and its schedule.
5. Confirm every standard and monograph against the current published version before issue.