Compressed Air for Sterile application

                          Compressed air used in sterile pharmaceutical applications (e.g., for aseptic manufacturing, lyophilization, or sterile packaging) must meet stringent quality standards, as it may come into direct or indirect contact with sterile product, containers, or closures. To ensure this, regular testing and qualification of the compressed air system is mandatory.

🔍 Compressed Air Tests for Sterile Applications

  1. Non-Viable Particle Count (Particulate Monitoring)
  • Purpose: Ensure compressed air doesn’t introduce particulates into the sterile environment.
  • Test Method: ISO 8573-4 or equivalent; ISO 14644-1 (reference class limits).
  • Acceptance Criteria:
    • Typically equivalent to ISO Class 5 or Class 7, depending on usage point.
    • For ISO Class 5: ≤ 3,520 particles ≥0.5 µm per m³
  1. Viable Microbial Count (Microbiological Monitoring)
  • Purpose: Detect microbial contamination in compressed air.
  • Test Method: Use of impaction samplers (e.g., sieve samplers) with agar plates.
  • Frequency: Periodic—based on risk assessment and SOP.
  • Acceptance Criteria:
    • Aseptic area (Grade A): 0 CFU/m³ (ideally)
    • Grade B/C/D: As per EU GMP Annex 1 or WHO guidelines, 10, 100 & 200 CFU/m³ (respectively)
  1. Oil Vapor and Oil Aerosol Content
  • Purpose: Ensure no oil is carried over from compressors.
  • Test Method: ISO 8573-2 (oil vapor) and ISO 8573-5 (oil aerosol)
  • Acceptance Criteria:
    • Total Oil (vapor + aerosol): ≤ 0.01 mg/m³ (ISO 8573-1 Class 1)
  1. Moisture (Dew Point)
  • Purpose: Prevent microbial growth and corrosion inside air lines.
  • Test Method: ISO 8573-3
  • Acceptance Criteria:
    • Dew Point: Typically, ≤ –40°C pressure dew point (ISO Class 2 or better)
  1. Pressure and Flow Rate Verification
  • Purpose: Ensure system can deliver required pressure/volume at usage points.
  • Acceptance Criteria: Defined in the URS and equipment manuals.
  • Notes: Overpressure or pressure drops can disrupt critical operations (e.g., vial stoppering).
  1. Residual Gases / Contaminants
  • Tests May Include:
    • CO, CO₂, NOₓ, SO₂ (if air quality is at risk from intake location)
    • Odor or hydrocarbon detection (via GC or chemical indicators)

🧪 Test Methods & Standards

Test Parameter

Standard Reference
Particulate Matter ISO 8573-4, ISO 14644-1
Microbiological Count ISO 8573-7, EU GMP Annex 1
Oil Content ISO 8573-2 / -5
Dew Point (Moisture) ISO 8573-3
Total Air Quality ISO 8573-1 Classification

📅 Typical Testing Frequency

Test Type

Frequency
Particle & Microbial Quarterly to monthly
Oil & Dew Point Quarterly to semi-annually
Full Qualification Annually or after major maintenance

🧩 Best Practices

  • Use point-of-use filters with 0.22 µm retention.
  • Sample at the point-of-use, not just compressor outlet.
  • Maintain logs of compressor maintenance and filter changes.
  • Ensure compressors are oil-free or have effective downstream filtration.
  • Have effective moisture separation before it goes to Dry Air receiver

                        When we discuss the application in pharmaceuticals then there are several critical factors comes in to consideration and those parameters do get more stringent if the application is for Sterile areas. Most of the parameters followed under the ISO 8573 specifications. those are mentioned below.

ISO 8573 consists of the following parts, under the general title Compressed air: ⎯

  • Part 1: Contaminants and purity classes

  • Part 2: Test methods for oil aerosol content

  • Part 3: Test methods for measurement of humidity

  • Part 4: Test methods for solid particle content

  • Part 5: Test methods for oil vapour and organic solvent content

  • Part 6: Test methods for gaseous contaminant content

  • Part 7: Test method for viable microbiological contaminant content

  • Part 8: Test methods for solid particle content by mass concentration ⎯ Part 9: Test methods for liquid water content

LINKS

https://towcompressor.ir/wp-content/uploads/2019/09/ISO-8573-1.pdf

 

🔬 Key Tests and Limits for Clean Room Compressed Air
   
ParameterTypical LimitTest Method
Particulate MatterOil-free, filtered to meet ISO 8573-1 Class 1-2 (particle size & count)Particle counters, ISO 14644 compliant
Oil Content≤ 0.1 mg/m³ (ISO 8573-1 Class 1)Oil mist test (photoacoustic, gravimetric)
Water ContentDew point ≤ -40°C (Class 1 or 2)Dew point meter, chilled mirror method
Microbial Load< 100 CFU/m³ (if air contacts product/critical surfaces)Microbial air sampler, culture plates
PressureAs required by process, stable and controlledPressure gauges and controllers
PurityOil-free & particle-freeFilter integrity and air quality tests
   
🔑 Standards to Refer:
ISO 8573-1: Air quality classes for particulate, water, oil.
EU GMP Annex 1 (2022): Compressed air must be suitable for intended use.
Pharmacopeial standards (USP <797>, <1116>) on compressed gases.
FDA & ISPE guidelines emphasize air quality control.
   
🧪 Typical Testing Frequency:
Routine monitoring: Quarterly or per risk assessment.
After maintenance or system changes.