The air and compressed gas quality control is not always carried out, despite its importance. Often in direct contact with the finished product or its semi-finished materials, ISO 8573-7:2003 is the most recent standard that regulates its specifications, testing procedures, and certain quality thresholds. All industries using compressed air or gas are concerned! You use them compressed gases, but ISO 8573-7 is still unclear? We’ll tell you everything!
Creating control windows on the manufacturing process of your products through compressed air pipelines: this is the idea. Your partners, or auditors, can advise you on setting alert and action limits, as well as a specific sampling plan for your activity. But the standard itself indicates the sampling procedure to be implemented, as well as the best practices to get interpretable routine results. The challenge lies in accurately measuring a repeatable volume of air that allows the identification of the microbiological load present in compressed gas or compressed air. These samples are recommended every 3 to 6 months. So why invest in a dedicated device? Something adaptable will allow you to quickly make it profitable. One of the most versatile, practical, and efficient solution is the air sampler, coupled with a gas adapter. It’s a simple accessory to attach to your standard air sampler!
What about the results: if several bacteria pass through the same grid hole, is there only one CFU (Colony Forming Unit)? Thanks to Mr. Macher, the question no longer arises! We explain why the use of the Results Conversion Grid is important 👉here👈
ISO 8573-7 imposes two conditions in its sampling procedure:
– Two blinds: one plate before sampling and one after. No gas will be impacted on these plates, which will validate that no external contamination (environment or technician) will seep into your sampling. Beware: the risk of contamination due to lack of good practices is high, costly in terms of time and money, and yet easily avoidable.
– A sterility test plate: although not named in the ISO, it is described as follows: “Using the same means of transport, ‘geographically’ trace a Petri dish the entire distance from the manufacturer who filled the Petri dishes with agar, to the place of sampling and the laboratory, in order that it can be inspected for unintended after-contamination. The dish shall not subsequently show growth.” The mercyless destiny of this control plate is to follow the same path as your sampling plate but without being opened a single time, until the final analysis.
These two types of control must ultimately show a count <1 CFU/box to be “validated” according to ISO 8573-7. These are the only thresholds given by the standard.
An AIRWEL gas adapter consists of a sterilizable tube that carries air from your pipeline to the bio-collector’s aspiration head. Compressed air passes through a calibrated valve at 100L/min, ensuring this flow as long as the original flow rate is sufficient. Once the original flow rate is verified and the pipeline is connected to the adapter, on which the bio-collector with the Petri dish is placed, the aspiration chamber valve can be opened. AIRWEL is programmed directly in volume, so select the desired volume. It will take you 10 minutes to impact 1000 liters of air.
Once finished, the air sampler will sound, simply close the valve and aseptically remove the Petri dish or contact plate. Then label it and send it to the laboratory for analysis. While the use is relatively simple, the real challenge lies in adhering to good practices to reduce the risk of cross-contamination and obtain valid and representative results.
They apply to the entire sampling environment and significantly and simply reduce the risk of contamination of blank plates and the sample itself.
Let’s guess the perfect technician’s dress code:
As you may have guessed, the perfect dress code is the one on the right! A safety cap, protective glasses, a clean lab coat, and new and cleaned fitted gloves (using ethanol or 70% alcohol) are the best friends of laboratory technicians and the worst enemies of bacteria!
Sampling should be done in a clean and dust-free area. Clean and disinfect the area before taking your sample.
The lid should always be facing downwards, so no dust will land on the inside surface, because it can carry microorganisms. Most dishes come with their sterile bag for return to the laboratory. Feel free to place the lids facing down in the sterile bag, ensuring your gloves are clean.
Only one opened dish at a time. This reduces the opening time and potential contamination.
The Petri dish should be sealed. If the dish has a closing system, make sure to secure it properly. You can also wrap it in plastic film or seal it with adhesive tape to prevent the lid from falling off and to preserve humidity.
These good practices ultimately protect the sample from its environment and from the technician, while also saving the technician time!
Your report should include several criteria:
◉ The blank plates should be considered positive or negative, with a final growth of <1 CFU/plate.
◉ The sterility test plates should be considered positive or negative, with a final growth of <1 CFU/plate.
◉The gas sampling should comply with the limits and specifications of the sampling plan. However, always keep in mind the measurement uncertainty mentioned on the calibration certificate of your air sampler (according to ISO 17025).
Indeed, all organizations that provide calibration services must include on their certificate the tolerance corresponding to the measurement uncertainty of the various instruments involved in the metrology chain. Ideally, consider it as a variable in the analysis of results before determining a compliant or non-compliant outcome.
