كيفية تجنب الكائنات الحية الدقيقة في الهواء المضغوط

Hygiene-sensitive applications used in food and beverage companies are trying to reduce the risk of microbial growth in the final product, thus eliminating potential contamination sources from utilities such as compressed air. Food companies today are rightfully concerned about food safety. 

To prevent the growth of microorganisms, it is necessary to eliminate the conditions that allow the organisms to reproduce. All microorganisms require the following five factors to remain viable and reproduce. 

• Nutrients
• Proper pH
• غازات
• Proper temperature
• Moisture Nutrients

Proper pH and gasses are not affected by air during compression, provided an oil-free compressor with an aftercooler is used. The last two, adequate temperature and humidity, can be directly related to or affected by the compressed atmospheric air.

Suitable temperature

High temperatures are deadly to microbes, but each species has its heat tolerance. Fungi and mesophilic bacteria prefer moderate temperatures, between 25 and 40°C. Thermophilic or heat-loving microorganisms grow at temperatures between 45 and 90°C. During thermal destruction, such as pasteurization, the destruction rate is logarithmic, as is the growth rate. This means that bacteria exposed to heat are killed at a rate proportional to the number of organisms present. The destruction process depends on the temperature and the time required. High temperatures (>180°C) in oil-free compression elements are sufficient to reduce existing microorganisms significantly. Although this temperature does not last long enough, it cannot be considered sterilization.

رُطُوبَة

It depends on how much water a particular type of bacteria or fungus needs to grow. However, they all require some form of water to reproduce. Generally, they require a relative humidity (RH) of 75% or higher. Some can survive and reproduce in 50% to 75% relative humidity. Relative humidity below 50% generally does not support microbial growth. In other words, lowering temperature and humidity (RH) reduces the likelihood of creating a hospitable environment for microbes.

Pressure dew point (PDP)

The dew point is the temperature at which air must cool to reach saturation. This means a given water vapor concentration in the air will form dew. It is simply a measure of the moisture in the air. The dew point is expressed as a temperature on a °C or °F scale. It can be considered the maximum water content in grams or ounces of a standard air volume at a given temperature. When discussing compressed air, the term is designated as pressure dew point or PDP. This is critical because changing the pressure of a gas also changes its dew point. 

PDP is the maximum water content of compressed air under pressurized conditions. If the air comes into contact with the product after expansion (which is the case in most cases), the dew point or moisture content will decrease significantly. In this case, the atmospheric dew point or ADP is more relevant. Different technologies can be used for low dew point requirements, such as a heatless double-tower adsorption dryer, thermal compression twin tower, thermal regeneration blower dryer, thermal compression drum, refrigeration dryer, etc. 

Some drying technologies are designed for a fixed and very low dew point and can consume 10% to 20% of the power of their connected compressor. The annual energy costs required for these drying technologies can be as high as EUR 13.000 per 100kW of installed compressor power. In most cases, a maximum of 10% to 20% relative humidity is low enough to avoid the growth of organisms. Using relative moisture in compressed air codes instead of PDP on temperature scales helps achieve hygienically safe and energy-efficient installations.

The danger of microorganisms and bacteria in the compressed air

Microorganisms and bacteria present a unique set of dangers. Bacteria, viruses, and bacteriophages are microorganisms that can contaminate an air compressor. Bacteria are the main problem because viruses need a host to reproduce. Viruses are not likely to survive long in an air compressor system, but bacteria will, given the right conditions.

Ingesting certain microbes through food, medicines, or the air can cause serious problems. Foodborne bacteria such as E. coli can disrupt the digestive system and, in extreme cases, cause death. Toxins in the air can cause allergy-like symptoms and long-term respiratory problems.

Go through narrow spaces

Microorganisms are tiny- small enough to pass through many filters. Bacteria can be 1 to 3 microns, small enough to penetrate a basic filtration system easily. By comparison, bacteria are smaller than many “tiny” things, including a grain of sand, salt, and red blood cells. Bacteria can only be seen with a light microscope or a scanning electron microscope for the smallest bacteria.

Because of their size, they can be challenging to catch. They can live in small, hard-to-reach spaces, hidden from sight. That is why taking preemptive measures to limit their spread even more is so important.

Multiply from within the system 

Because they are living things, microbes reproduce under the right conditions. Although they are individually microscopic, they can accumulate and become increasingly dangerous over time. They tend to thrive in high humidity and warm environments — moist, warm environments that allow microbes to multiply quickly.

Certain pollutants, especially oils, serve as food for microbes and encourage their reproduction. Cleaning oil, water, and other substances from the air compressor will reduce the chances of bacteria surviving.

Spread disease and toxins

If certain bacteria come into contact with food or drugs, they can cause illness or death. This is especially true for Salmonella, Shigella, E. coli, and coliforms. Ingestion of these microbes can cause a range of unpleasant symptoms, including vomiting, severe stomach cramps, diarrhea, and fever. These symptoms can last for many days and lead to death. E. coli kills about 100 people a year in the United States. The eradication of these microbes is crucial for human health and well-being.

Plus, mold and bacteria contribute to air pollution—they can produce toxins and cause harm to anyone breathing the air. Some people are more sensitive than others to breathing mold, especially those with asthma, lung disease, or immunosuppression. Inhaling mold can cause allergy-like symptoms. Fungal infections can cause wheezing, coughing, and upper respiratory problems in otherwise healthy people.

Even if contaminated compressed air is unlikely to enter food or pharmaceuticals, limiting the spread of these microorganisms is still essential. They reduce air quality and cause short- and long-term symptoms in people who breathe the air.

Environmental factors causing microorganisms in air compressors

As organisms, microorganisms can only survive in specific environments. They thrive in warm, moist environments, especially in the presence of other substances, such as oils. All bacteria and fungi need some amount of water to survive, but the level of humidity required depends on the species. Microorganisms will reproduce and multiply by:

Water

While different types of microorganisms require different water levels, they all need a certain amount of water to survive. The air your air compressor draws should be dry, and you should use tools like a liquid drainer and an aftercooler.

Warmth

For the same reasons you put leftovers in the refrigerator, you should keep your air compressor in a cool setting. Bacteria need warm temperatures to grow.

Food

When we think of bacteria, we might not think of them as living organisms that need to eat, but they are! Bacteria need nutrients like all other living things. Different kinds of microorganisms require additional nutrients. Some perform photosynthesis, some eat organic compounds such as sugar and fat, while others eat inorganic compounds such as carbon dioxide. Limit potential microbial food sources in your facility.

To decrease the growth of microorganisms in your compressed air system, create an environment that is not conducive to their survival. Make sure your air compressor and its components are in a dry, cool area, and take precautions regularly.

Once you have your air compressor in place, address any leaks in the system. Remember that leaks allow foreign matter to enter and contaminate the system. When a leak occurs, the system becomes vulnerable to water droplets, oil, and microbes, which can collect and accumulate over time.

You should always check your compressed air system for leaks. Addressing leaks will help limit contamination and improve system efficiency, saving time and money. When there is a leak, the air compressor draws more power than it needs while running.

Prevent microbial growth with environmental factors

Because microbes are so tiny, they can be challenging to find and address. Preventing them from building up in the first place is the most vital thing you can do. Create an optimized environment to reduce microbial growth. To prevent microbial growth, you should:

Fixing leaks in your air compressor system

You can detect leaks by listening for a hissing sound or by using an ultrasonic frequency reader. You can also apply soapy water to the suspected leak — if there is a leak, air bubbles will form.

Install multiple filters

Implement multiple filters in your system, including particulate and absorber models. It’s essential to purchase air compressor filters and install them where the air enters the system, you should also have filters on the pipes.

Clean and replace the filter regularly

You should clean and replace the filter regularly, especially if the filter becomes wet. Clean the filter by blowing away dust, dirt, and debris. Regularly replace old or damaged filters.

Make sure the ambient air is dry and cool

If the air entering your air compressor is warm or humid, microbes can thrive. Put your air compressor in the proper environment.

Test your compressed air frequently

Perform routine air quality tests to check the contaminants.

How to identify bacteria in an air compressor

What microorganisms are in compressed air?

Various microorganisms, including bacteria, mold, and yeast, can live in compressed air systems. These organisms thrive in moist, dark places like your air compressor coil or compressed air piping, and they can grow anywhere the conditions are right.

To check for the presence of bacteria, you need to perform regular air quality tests. Certain areas in your compressed air system are most likely to harbor microorganisms. These areas are most susceptible to condensation buildup and foreign particle buildup. It would help if you planned to sample and test these areas at predetermined intervals. The most common places where microbes are found include:

• Dead end
• Compressed air coils
• Drains
• Leaks
• Filters

Decide when and where to sample your compressed air system

Collect samples close to high-risk points to detect microorganisms such as bacteria, mold, and yeast. When deciding where to sample, you can use a percentage-based system. For example, if you have 24 points to sample, choose eight different points to test each year—after three years, you’ll have sampled all of them. It is wise to select sampling locations along the compressed air system to see if the air quality drops as it passes through. This way, you can identify problem areas.

Regarding frequency, you can choose to test annually, semi-annually, or quarterly. Check the standard requirements in your industry – food processing, medical and pharmaceutical facilities often have to test for microbial life more frequently than other facilities. In addition to scheduled testing, you should perform testing before and after making changes to the system. Test the system after cleaning any components, including filters, valves, or piping.

When you perform these tests, you must look for any potential contaminants. These include rust, dirt, water vapor, condensation, oil vapor, and liquid oil. Check for microbial contamination using a sample test kit.

How to take a sample using a compressed air microbiological testing device

When using a compressed air microbiological testing unit (CAMTU), the sampling and testing process is as follows:

• Wear gloves and a mask to keep you safe and limit exposure to microbes.
• Connect the inlet tubing with the sample port.
• Now open the compressed air valve to the sample port.
• Open the shutoff valve.
• Purge the sample port.
• Close the shutoff valve.
• Connect the inlet tubing to the test unit.
• Now place the petri dish inside the test unit.
• Then close the test unit.
• Open the shutoff valve and let it run for 20 seconds.
• Close the lid, remove and incubate the petri dish.
• After completing these important steps, microbial organisms will become visible over time.

How to remove contaminants from an air compressor

If you find microbes in your air compressor, take steps to remove them and prevent them from growing again. Modern air compressor technology minimizes pollutants. Several tools will help reduce the chance of microbial buildup and remove microbes from your air compressor system. Learn what these sections do and your role in keeping them effective. Follow the steps below to remove contamination.

Use filters and change them often

Install multiple filters in your compressed air system and keep them fresh. A visual inspection of your filters may not indicate that you need to replace them. After all, microbes are invisible to the naked eye. In addition to looking at filters, monitor differential pressure—a significant drop can alert you to a problem. Check these gauges frequently and replace the filter if there is a problem.

It would help if you also planned to change filters at predetermined intervals, whether they are effective or not. Replace filters at least once a year or more often, depending on how often you use them.

Use an aftercooler to reduce the water content

Compressing air generates heat. Keeping the system temperature down is essential since warmer temperatures help microbes thrive. You can achieve this with an aftercooler placed directly after the compressor. It captures the condensate that flows through the system.

Use a mist eliminator filter

Using a mist eliminator with a large capacity tank and built-in differential pressure gauge will make a big difference in removing microbial contamination. Such filters remove oil, water, and other particles from compressed air. While it won’t wipe out the tiniest microbial life, it will limit the water and oil microbes needed to survive and reproduce.

Use zero-loss liquid drain with electronic controls

Compressed air system lines can accumulate condensation. Since microorganisms need water to survive, draining condensation from the system is crucial. Some air compressors have a manual valve to release the condensate, which allows the compressed air to escape and go to waste. Internal floating drains that open when water builds up can become stuck to remove air or become stuck and fail to release water.

Your best bet is a zero-loss, electronically controlled drain. These drains will sense the condensate level and open the valve when needed. Before any compressed air is wasted, the valve closes. One of these zero-loss drains may be even more expensive than manual or internal floating drains, but they are more efficient.

Properly dispose of condensate

Always dispose of condensate properly – never pour it down the drain. It is considered hazardous waste due to its potential oil and contaminant content. Use a condensate cleaning unit. This device separates the oil from the water so you can dispose of the oil as hazardous waste.