Compressed air validation

System Description

The air compressor unit shall deliver non lubricated compressed air sucked from atmosphere through its suction filter and should delivers at discharge end its various components, which is dried, stored, filtered and finally distributed to the service valves. The system consists of:

• Air suction and Filtration
• Water Cooled Heat Exchanger
• Compressor Motor
• Oil Pump
• Safety Valves
• Air Dryer
• Air Receiver Tank
• Mist Separator
• Odor Removable
• FRL Unit (Filter & Regulator)

Qualification Plan & Methodology

Testing and monitoring of compressed air at compressed air header and from critical user points that come into direct contact with products is vital to assuring the quality and safety of those products. Compressed air is a Critical Process Parameter (CPP) whose variability has an impact on the Critical Quality Attribute (CQA) and therefore shall be monitored or controlled to ensure the process produces the desired quality.

During Validation following test parameter shall be performed at compressed air header:

• Particle Count
• Carbon Dioxide
• Carbon Monoxide
• Sulphur Dioxide
• Nitric Oxide
• Nitrogen Dioxide
• Water Content
• Dew Point
• Oil Mist

During Validation following test parameter shall be performed from critical user points:

• Verification of Dew point.
• Verification of Water Vapor Content.
• Verification of Oil Mist Content.
• Non-Viable Particulate Count.

Total Viable Count from each identified location shall be monitored for continues three days

Verification of Dew Point

The test shall be carried out to determine the dew point at the outlet of each compressed air user point.

• Before the test, ensure air temperature between 0 to +40°C and relative humidity of air between 0 to 90%.
• Open the compressed air valve and let the air to be drained out for 1 minute.
• Connect the Compressed air outlet point to connection pipe of Dew Point Temperature Transmitter.
• Insert the Dew Point Temperature Transmitter in the connection pipe.
• Ensure that the probe of Transmitter is directly perpendicular to Compressed air flow.
• Ensure that there is no leakage in the connections as the penetration of humidity from the environment will affect the end results.
• Switch on the power supply of transmitter.
• Take the reading of dew point for each compressed air user point from transmitter once it is stabilized.

Acceptance Criteria: The Pressure dew point should be ≤ -40°C after Dryer.

Verification of Water Vapor Content

• The test shall be carried out to detect the absence or presence of water vapor in compressed air at the outlet of each compressed air user point. The procedure is outlined below:
• Install a reducer pressure with gauge and flow meter to compressed air line and adjust the flow meter to flow rate of 100 ml/min.
• Break the tips off a fresh detector tube in the tube tip breaker and insert the tube into tube holder. When breaking the tube ends, keep away from the eyes. Do not touch the broken glass tube, pieces and reagent with bare hands. (Measuring range: 30-80 mg/m3)
• Attach the rubber tube holder to the flow meter outlet. Make certain the tube arrow G> on the tube pointing in a down direction.
• Turn on the valve and set the flow meter to 100 ml/min. Record the flow rate with stopwatch.
• Pull handle all the way out until it locks on pump stroke (100 ml). Wait for 10 minutes. The sampling time represents the time necessary to draw the required air sample of 1000 ml through the tube. The tube must be positioned in the desired sampling area for the entire sampling time or until the flow finish indicator indicates the end of the sample.
• As soon as sampling time of 10 minutes has elapsed, turn off the valve and remove the tube from the tube holder and then read the color change in layer immediately.
• If water content present, yellow color changes to purple.
• The reaction principle is that water vapour reacts with chemical reagent to produce basic compound and indicate purple stain.

Acceptance Criteria: No color change should be observed in the detector tube and compressed air should be moisture free & should be NMT 0.1 mg/m3. 

Verification of Oil Mist Content

The test shall be carried out to determine the content of total oil mist in compressed air at the outlet of each compressed air user point. The procedure is outlined as following:

Attach a pressure reducer with gauge and flow meter to air line and adjust the flow meter to the required setting.

• Break the tips off a fresh detector tube tip breaker and insert the tube into a tube holder.
• Attach the rubber tube holder to the flow meter outlet. Make sure the tube arrow (G>) on the tube is pointing in the downward direction.
• Turn on the valve of air line and confirm the flow meter according to tube specifications.
• Time the flow rate with stopwatch.
• As soon as the sampling time has finished, turn off the valve of air line, and remove the tube from the tube holder and then read the colour-changed layer immediately.
• If the stain length reaches the maximum calibration mark during sampling stop pressure reducer operation and obtain the true value by following:

                                                                                            Tube reading X 20000

                                    Tube concentration (mg/m3) = --------------------------------------

                                                                                             Sampled volume (ml)

                  Acceptance Criteria: Total oil mist content should be less than 1 mg/m3.

Verification of Nitrogen Oxides (NO + NO2)

The test shall be carried out to determine the content of nitrogen Oxides in compressed air. The procedure is outlined as following:

• Break the tips off a fresh detector tube in the tube tip breaker and insert the tube into tube holder. When breaking the tube ends, keep away from the eyes. Do not touch the broken glass tube, pieces and reagent with bare hands. (Measuring range: 2-5 ppm)
• Insert the pump tube into the pump inlet with the arrow (G >) on the tube pointing toward the pump.
• Make certain pump handle all the way out until it locks at one pump stroke (100 ml). Wait for 2 minutes and confirm the completion of sampling. Repeat the above sampling procedure one more time.
• Read the concentration level at the interface where the stain reagent meets the unstained reagent.
• If necessary, multiply the readings by the correction factors of the pump strokes and atmospheric pressure respectively.

Acceptance Criteria: No color change should be observed in the detector tube and compressed air should be nitrogen Oxides free (NO + NO2) & should be NMT 2 ppm.

Verification of Carbon Monoxide

The test shall be carried out to determine the content of Carbon Mono Oxide in compressed air. The procedure is outlined as following:

• Break the tips off a fresh detector tube in the tube tip breaker and insert the tube into tube holder. When breaking the tube ends, keep away from the eyes. Do not touch the broken glass tube, pieces and reagent with bare hands. (Measuring range: 10-30 ppm)
• Insert the pump tube into the pump inlet with the arrow (G >) on the tube pointing toward the pump.
• Make certain pump handle all the way in. Align the guide marks on the pump body with the guide marks on the handle.
• Pull the handle all the way out until it locks at one pump stroke (100 ml). Wait for four minutes and confirm the completion of sampling.
• Read the concentration level at the interface where the stain reagent meets the unstained reagent.
• If necessary, multiply the readings by the correction factors of the pump strokes and atmospheric pressure respectively.

Acceptance Criteria: No color change should be observed in the detector tube and compressed air should be carbon mono oxide free & should be NMT 10 ppm.

Verification of Carbon Dioxide

The test shall be carried out to determine the content of Carbon Dioxide in compressed air. The procedure is outlined as following:

• Attach a pressure reducer with gauge and flow meter to air line and adjust the flow meter to the required setting.
• Break the tips off a fresh detector tube tip breaker and insert the tube into a tube holder.
• Attach the rubber tube holder to the flow meter outlet. Make sure the tube arrow (G>) on the tube is pointing in the downward direction.
• Turn on the valve of air line and confirm the flow meter according to tube specifications.
• Time the flow rate with stopwatch.
• As soon as the sampling time has finished, turn off the valve of air line, and remove the tube from the tube holder and then read the colour-changed layer immediately.
• If the stain length reaches the maximum calibration mark during sampling stop pressure reducer operation and obtain the true value by following:

                                                                                          Tube reading X 500

                                    Tube concentration (ppm) = --------------------------------------

                                                                                         Sampled volume (ml)

Acceptance Criteria: No color change should be observed in the detector tube and compressed air should be carbon Dioxide free & should be NMT 300 ppm.

Verification of Sulphur Dioxide

The test shall be carried out to determine the content of Sulphur Dioxide in compressed air. The procedure is outlined as following:

• Break the tips off a fresh detector tube in the tube tip breaker and insert the tube into tube holder. When breaking the tube ends, keep away from the eyes. Do not touch the broken glass tube, pieces and reagent with bare hands. (Measuring range: 0.2-5 ppm)
• Insert the pump tube into the pump inlet with the arrow (G >) on the tube pointing toward the pump.
• Make certain pump handle all the way out until it locks at one pump stroke (100 ml). Wait for one minute and confirm the completion of sampling. Repeat the above sampling procedure one more time.
• Read the concentration level at the interface where the stain reagent meets the unstained reagent.
• If necessary, multiply the readings by the correction factors of the pump strokes and atmospheric pressure respectively.

Acceptance Criteria: No color change should be observed in the detector tube and compressed air should be Sulphur Dioxide & should be NMT 5 ppm.

Non-Viable Particulate Count

The test shall be carried out to determine the total non-viable particulate count in the compressed air. The procedure is outlined below:

Connect the particle counter to compressed air user point with diffuser. Take one sample (one mtr3) of compressed air at each user point.

Record the number of particles per cubic meter of air for different particle size range.

Acceptance Criteria:

Particle size between 0.5 micro meter to 1.0-micro meter ranges should not be more than 90,000 in each cubic meter of compressed air.

Particle size between 1.0 micro meter to 5.0- micro meter ranges should not be more than 1000 in each cubic meter of compressed air.

Total Viable Count

The test shall be carried out to determine the total viable count in the compressed air. The procedure is outlined below:

• Take 300 ml of sterile water in glass bottle, plug with cotton and wrap it with aluminium foil. Sterilize the glass unit as per SOP of storage, preparation and sterilization of media.
• Keep all the sterile sampling bottles required for microbiological testing in a tray and carry the tray to the concerned area (compressed air user point) to conduct sampling as described below.
• Connect the compressed air point with silicon tube from which sample has to be withdrawn. Clean thoroughly the outer surface of the compressed air pipeline with 70 % IPA solution. Wait for 5 minutes.
• Take the pre-sterilized glass unit containing sterilized sterile water Remove the cotton plug from glass bottle and dip the cleaned silicon tube of compressed air supply in to sterile water.
• Open valve of the compressed air line gradually for 2 minutes so that the compressed air enters into the glass unit containing sterilized purified water. Ensure that the air bubbles generated into the glass bottle do not cause spillover of the sterile water.
• After 2 minutes, close the valve of compressed air line and also re-plug sterile glass bottle with cotton. Wrap the glass bottle with aluminium foil and bring it to microbiology lab for analysis.
• Transfer the above collected water sample containing compressed air from user point to a sterilized filtration funnel fitted with sterile membrane of nominal pore size equal to 0.45µ.
• Filter it and after filtration, put the membrane filter on the media plate of Soyabean Casein Digest Agar (SCDA). Incubate the sampling plate for 72 hours at 20 to 25°C for fungal count followed by 2 days at 30 to 35°C for bacterial count. Incubate a negative control which has been treated in a similar way as test except the sample i.e. compressed air.
• Perform the positive control as per SOP, Microbial monitoring of compressed air.

Acceptance Criteria: Total viable count should not be more than 10cfu/ml.

Requalification Criteria

Change in location of air compressed Air Unit

Modification in design of compressed Air Unit.

Major breakdown resulting in replacement of receiver, Air dryer Unit.

Continue failure to delivering desired quality of predefined air.

Any Other activity which impact quality of compressed air.