Compressed Air/Nitrogen Gas Testing or Validation

What is compressed air and its impact in Pharmaceutical Industries

Clean dry air is essential for many different types of industrial applications. This air is supplied by compressors which draw in large volumes of air from the surrounding atmosphere containing contaminants. Typically, drying and hydrocarbon removal systems are in place prior to filtration and then release to the compressed air line system of the plant. However, having these treatments in place is no guarantee of their efficacy. In some cases the air compressor itself can add contaminants.

Why compressed air testing is required?

Site specific air testing is the most assured way to produce valid, repeatable testing results that will reinforce your quality of air whether the product is in direct contact or in indirect contact. The air used in the manufacturing processes should be evaluated by a competent technical individual to determine the appropriate requirements to protect the safety of the employees and the integrity of the products.

The presence of water, Hydrocarbons (Oil mist) and solid contaminants in a compressed air system can affect compressed air quality (i.e. product sterility) and lead to rust, scaling, instruments clogging, valves sticking and process contamination.

The ISO 8573 standard test methods were developed to verify air quality in a compressed air system, and lay out a classification of purity levels, for the key parameters of: Particles, Water, Oil and Microbiological contaminants.

Following tests to be performed for Checking Compressed Air Quality

a) Dew Point Measurements Test :

What is Dew point?

The dew point is the temperature below which the water vapor in air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates. The condensed water is called dew when it forms on a solid surface.

Pressure Dew Point

The term “pressure dew point” refers to the dew point temperature of a gas at pressures higher than atmospheric pressure. When addressing dew point in pressurized compressed air, the correct terminology is actually “pressure dewpoint,” but this is often shortened to “dew point” in common usage.

Dew point is performed using a calibrated Dew Point Transmitter connected to the compressed air system – giving instantaneous results.

Why is dew point so important in pharmaceutical applications?

Compressed air may be used for a number of applications in the pharmaceutical industry, such as raw material transport, processing equipment, pneumatic power sources, and cleaning. The importance of knowing the dew point in a compressed air line may be critical for some applications but less relevant for others. For example, bulk solid and powder conveyers used for moving product rely on sufficiently dried and filtered air in order to perform their function properly and prevent product contamination. Continuous monitoring and control of dew point is often a requirement for instrument air, drying processes, packaging, and actuating process control valves. The risks associated with letting dew point levels go unchecked can include equipment failure, condensation in process lines and on finished product, and the potential for bacterial formation.

Why is dew point so important in laboratory environments?

Laboratory environments are often designed to maintain a controlled atmosphere in order to eliminate airborne contaminants and any sources of error that may interfere with testing. Dewpoint can be an important parameter to control. This is usually accomplished through the environmental control system and has little to do with compressed air. Some lab equipment, such as glove boxes, may require their feed gas to meet an established dewpoint level in order to maintain the inert atmosphere of the chamber.

Acceptance Criteria As per ISO 8573

Class Pressure Dewpoint ℃
0 As specified by the equipment user or supplier and more stringent than class 1
1 ≤ -70
2 ≤ -40
3 ≤ -20
4 ≤ +3
5 ≤ +7
6 ≤ +10

b) Non viable particle count test with Diffuser :

Non-viable particle counting is performed by connecting a Laser Particle Counter with High Pressure Diffuser to an access point on the compressed air system, with instantaneous differential counts being measured for each of the specified ranges of particle size

Acceptance Criteria as per ISO 8573

Maximum number of particles per cubic metre as a function of particle size, db
0,1 µm < d u 0,5 µm 0,5 µm < d u 1,0 µm 1,0 µm < d u 5,0 µm
0 As specified by the equipment user or supplier and more stringent than class 1
u 20 000 u 400 u 10
u 400 000 u 6 000 u 100
Not specified u 90 000 u 1 000
Not specified Not specified u 10 000
Not specified Not specified u 100 000

c) Viable organism testing (Will Delete or Not) :

Viable Organism testing is performed using a Slit to Agar sampler, where a high velocity of air through the sampler impacts upon a sterile agar plate allowing the air to deflect away from the plate while any particles remain in the collection plate. A 24-48 hour incubation period will then determine the presence, or otherwise, of any viable micro-organisms within the air system.

d) Remaining test with gas detector tube :

Compressed air, oxygen, nitrogen, and carbon dioxide are often used in pharmaceutical production environments and are subject to the Good Manufacturing Practices.

­­­­Analyzing gases within a production environment involves testing them upon receipt at the facility as well as subsequent tests when the system is operational and after any changes or intervention to the production systems are made. The aim is to verify the absence of any potentially hazardous or disruptive materials.

Creative consultancy provides advice, sampling, and GMP compliant analysis of media in a pharmaceutical environment based on the requirements of the pharmacopoeias (e.g. EP, BP and USP).

Following test to be performed as per BP and USP:-

Sr. no. Test Instrument to be used
Acceptance Criteria
EP 01/2009 : 1238 USP35-NF30
1 Water vapour Content With Specified air detector Tube
≤ 67 ppm No traces on
2 Traces of Oil With Specified air detector Tube
≤ 0.1 mg/m3 No traces on
3 Oxygen Content With Specified air detector
Tube /Digital analyzer
20.4 – 21.4% 19.5 – 23.5%
4 Carbon Dioxide With Specified air detector Tube
≤ 100 ppm ≤ 0.05%
5 Carbon Monoxide With Specified air detector
Tube /Digital analyzer
≤ 5 ppm ≤ 0.001%
6 Nitrous oxide or Nitrogen Dioxide With Specified air detector Tube
≤ 0.5 ppm ≤ 2.5 ppm
7 Sulfer Dioxide With Specified air detector Tube
≤ 0.5 ppm ≤ 5 ppm

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