How Many Microns Is A Good Vacuum? The Vacuum Micron Levels

Have you installed your air conditioning system? If you have, then it is most likely that its system has air and moisture. The atmosphere and humidity will make your AC not function well. Therefore you must have proper evacuation. The evacuation will help remove the air and water from your system.

Proper evacuation depends on the correct practices and assembling of tools. You will need a high-quality pump, large diameter hoses, and a vacuum gauge to have a successful evacuation process. The problem comes when you want to choose the best vacuum pump to use.

How good a vacuum pump is, depends on its micron levels. A vacuum with a lower amount of microns is better than those with a high amount of microns. Therefore how many microns should your vacuum be for it to be good?

How Many Microns Is A Good Vacuum?

How good a vacuum is, depends on many factors. The micron levels of a vacuum can tell if it is good or not. A good vacuum should have at least 500 microns and below. However, it is best if it reaches 50-100 microns.

To ensure you get the accurate micron levels, you need to use the correct hose. The hose’s conductivity determines how well the micron levels get measured. Therefore ensure you use a large diameter hose with high conductivity.

Testing Your Vacuum Pump

Testing your vacuum pump will determine the vacuum in your pump, thus knowing your vacuum pump’s micron levels. To test your vacuum pump, you will first attach the micron gauge to the vacuum pump using a ¼” connection. You will then confirm if your pump can achieve a micron level of 100 or less. A high-quality vacuum pump can achieve even below 50 microns with ease.

To minimize the chances of gas permeation through the hoses, ensure you isolate the pump and the hose using core tools. If your pump fails to reach 100 microns or below, you should consider changing your oil. You should ensure you use high-quality, low vapor pressure oil like Appion Tezom.

The purpose of changing your oil is to remove a significant amount of moisture from a wet pump. If your vacuum pump still does not reach a deep vacuum, you should consider a replacement. If you want your vacuum pump to have lower microns, you can follow the following steps.

1st Standing Test

The first step involves the 1st standing test. What do you do in the 1st standing test? The first thing is to pull the vacuum until it reaches the micron level of 1000. You can achieve this level faster if you use a hose with a larger diameter. It might take you fifteen minutes or less.

You will then isolate the vacuum with the core tools while the pump is still running. After five minutes of stabilization, you will record the leak rate on the vacuum gauge. Leak rate is the rate derived from the drop of vacuum over a unit of time. If the pressure rises after the five-minute stabilization period, moisture is still present in the system. It can also be that there is a small system leak.

2nd Standing Test

The 2nd standing test is the next step you will follow. You will open the core tools and continue the evacuation process until the vacuum level is 500 microns or less. You will then determine if there is any decrease in the leak rate. When the second leak rate is less than the first one, the dehydration job is progressing.

Finishing Vacuum

The last step is the finishing vacuum. Once you finish the 2nd standing test, you will let your vacuum pump run until it is below 200 microns. A good pump can attain 50-100 microns without any problems. Once your pump achieves the required microns, you will isolate the vacuum rig with the core tools.

You will then let the system stand for fifteen to thirty minutes. When you notice that the micron levels do not rise above the 500 microns, it indicates that the evacuation is complete. However, if there is a rise of micron levels above the 500 microns, open the core tools and let evacuation continue.

After the evacuation completion, keep the pump isolated and crack the suction line open. When you open the suction line, allow a small refrigerant amount into the system. The refrigerant will bring the system slowly into a positive pressure. It would be best to be cautious that you do not break the micron gauge by over-pressurization.

You will then open the liquid service valve to reinstall the valve cored and removing the vacuum gauge and core tools. After doing this, you will purge your manifold hoses and install gauges to complete the system commissioning.

The Evacuation Process Using A Vacuum Pump

AC and Refrigeration systems have a design that operates with oil and refrigerant flowing through them. Therefore, air and moisture and detrimental to the system operation. When a typical system gets installed and serviced, air and humidity will enter the system. Therefore you will need to remove the air, other non-condensable, and moistures in a process called evacuation. The method of removing air and non-condensable materials is degassing, while that of water is dehydration.

The evacuation process starts by removing the valve cores and connecting large diameter vacuum hoses. You will join the hoses to the back of the core tool at both of the system’s high and low sides. By doing this, you will ensure that both sides get pulled down at the same time.

The recommended diameter of your hose should be ½” and not ¼”. The reason is that the ½” hose will reduce the required time for evacuation by 16 times over the ¼” diameter hose. Therefore, a larger diameter hose will save on time and cost.

You will then connect the hose to the vacuum pump with a vacuum-rated manifold with o-ring seals. You should ensure that you keep the connection to a minimum point while the point of access is at the maximum. Next is to install a high-quality vacuum gauge directly to the core installed on the suction line using a copper line.  It will allow complete isolation of the evacuation rigs from the system during the “standing pressure test.” the vacuum quality will get measured during the “standing pressure test.”

The Gas Ballast Equipped In Some Vacuum Pump

Opening the ballast introduces free air into the pump during the discharge stroke, thus keeping the moisture in equilibrium. On the other hand, when it is closed, the water vapor will get condensed, and the humidity will drop ot in the oil. What will cause this to happen is the pressure created in the discharge stroke.

It would be best to leave the ballast open during the initial pull-down of a wet system. It is because the open ballast will help prevent condensation within the pump. You should ensure you keep it open until you are at 15000-10000 microns.

After reaching 15000-10000 microns, ensure you close the ballast since it prevents the pump from getting its ultimate micron level. It would be best only to use the ballast during the roughing period and when the system has moisture.

The ballast is only adequate when there is a small amount of moisture in the system. Therefore, if the system is very wet, try using the alternative option of frequent oil changes.

How Does A Hose Affect The Micron Level?

There are many factors you should look at when determining how good a vacuum is. One of the factors is the micron level. Most people consider a good vacuum to have low microns; the lower the microns, the better.

Hoses affect the micron levels by the time it will take to reach a certain micron level. The evacuation process can either be slow or fast, depending on the size of the hose. A large diameter will reduce friction and thus increasing the conductance speed. Therefore the micron levels will get reached faster.

What Is A Micron?

When measuring a vacuum of a vacuum pump, it gets measured in microns. In the micron vacuum scale, the starting point is at 760,000 microns at sea-level atmospheric pressure. It then works down towards a perfect vacuum of zero microns. It is the reason why a vacuum pump with lower microns gets considered to be a better pump.

Are 500 Microns Enough For Your Vacuum Pump?

The pump capacitance is responsible for determining the vacuum effectiveness. When selecting the vacuum pump to use, you should ensure you measure its micron levels. The pump that can calculate a low amount of microns is the better choice. Most high-quality pumps have microns of 500 and below.

If you are using your vacuum pump for general purposes, the 500 microns is good enough. However, it might not be enough for an intense worker vacuum.


Now that you know the need for the evacuation process ensure you do it every time you install your AC/refrigerator system. to have a successful evacuation process ou will need a good vacuum pump. To know the best vacuum to use, you will calculate its micron levels. If the vacuum has lower microns, then the vacuum is suitable for use. The vacuum with 50-100 microns is the best.

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David Huner
David Huner
David Huner is a tech lover. After completing his graduation from the University Of Phoenix, he started gather his knowledge mostly on latest technologies that keeps his life smart and cool. Now he wants to spread his knowledge with people who loves technologies.

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