Pulling A Vacuum Without A Micron Gauge! (Do’s & Don’ts)

By - Ron Singh

Updated -

It is essential to do a vacuum pull on a system to make the system run correctly and effectively, and it also helps to guarantee that the system lasts longer.

However, most technicians never get enough training to pull a vacuum properly. 

Many believe that pulling a vacuum to 500 microns is sufficient; nevertheless, you must do more work to get the system to 500 microns or lower and maintain that level. So, how do you pull a vacuum without a micron gauge?

The positioning of the gauge, and the dimension of the hoses, are all critical considerations. To exemplify, a tiny pump that has larger hoses attached to it will complete the task at hand much more quickly than a massive pump that only has relatively tiny hoses.

What Is a Micron Gauge Used For?

Pulling a Vacuum Without a Micron Gauge

A Micron gauge is a device used for determining the degree to which a system is evacuated or subjected to a vacuum.

In addition, it analyzes the degree to which various appliances, such as air conditioners, refrigerators, and cooling systems, have dehydrated and refluxed the air within them. 

Specific individuals also use this instrument to measure vacuum in automobile engines. One of the processes of determining the level of absolute vacuum is mercury.

Microns are a unit of measurement used to express the vacuum level; roughly one millimeter of mercury is equivalent to one thousand microns.

Its primary function is to determine the amount of vacuum inside a system or unit, and the instrument can also be known as a vacuum gauge.

Can I Pull My Vacuum Without a Micron Gauge?

No, you can’t pull a vacuum without a micron gauge. When comparing the reading on the vacuum gauge with the actual vacuum level, it is essential to draw a clear separation between the two.

Pulling below 500 microns and having a micron count less than 500 are two distinct things.

Overpowering dehydration may cause a decent vacuum apparatus paired with a massive pump, which can draw below five hundred. Still, it cannot remove the moisture entirely since doing so takes time.

You will not be able to identify the maximum amount of vacuum until the vacuum is separated.

Therefore, when determining the absolute vacuum level in a system, it is necessary to use core tools to detach the vacuum pump and rig from the environment.

Is a Micron Gauge Necessary to Complete An Evacuation?

Yes, a micron gauge is mandatory to complete an evacuation. However, it essentially depends on so many factors.

Modern-day evacuation methods remove non-condensable and moisture from a system, ensuring that these pollutants will not harm the gas or the refrigerant oil in the mechanism.

When water mixes with oil, it creates sludge; when it mixes with refrigerant, it creates hydrofluoric and hydrochloric acids. Therefore, they can potentially harm the refrigeration system.

How long an evacuation will take is determined by a variety of elements, ranging from but not limited to the following: the system’s capacity, pollution levels, suction tubing size and length, the existence of Schrader cores in the service valves, lubricant dryness, and the vacuum pump’s capacity. 

Knowing when an evacuation is over is more vital than how long it will take. It’s simple to remove air, but moisture removal is far more complex and takes a lot more time.

Molecular interactions between moisture and the surfaces it adheres to are solid, making it difficult to remove them.

As a result, breaking the bindings using heat and time, the pump must operate in a deep vacuum to remove the moisture from the system.

Preparing the copper tubing for evacuation should always precede all other considerations.

If you can avoid using an assembled evacuation procedure to clean the system, you’ll save a lot of time by ensuring it stays clean, dry, and leak-free throughout the assembly process.

Since the repercussions are far more severe than the time wasted in the process of evacuating, there is no way to hurry or cut corners throughout the procedure.

Therefore, cleanliness is vital for preparation and evacuation. It implies that you should maintain cleanliness in the system pipes, your vacuum rig, the oil, and the operations you follow.

I cannot emphasize this point enough when attempting to cut down on the amount of time necessary to finish the procedure accurately.

Micron Gauge Vs. Vacuum Gauge: Which Is Better?

You have a fundamental comprehension of micron and vacuum gauges’ capabilities. However, there is still some further information that you need.

For example, you’ll learn which option is superior and the many ways in which they differ from one another with greater specificity.

#1. Gauge Rank

This rank is the total number of microns that the component can measure. If the gauge has higher micron readings, you may anticipate that it will be more accurate or more helpful to use.

However, a micro-gauge is not superior to a vacuum gauge. We can declare with absolute certainty that an upgraded digital micron gauge will most likely reach nine thousand up to twelve thousand microns in the case of the most advanced devices.

This level is sufficient to assure accuracy and provide the possible use for any endeavor.

An analog vacuum gauge will not be able to provide accurate readings to this level. However, they often remain between one thousand and four thousand microns in size.

Therefore, if you desire a little more measuring capacity, you can have difficulty finding a vacuum gauge that suits your needs.

#2. Cost

Discussing these two gauge kinds would be impossible without addressing their financial viability. In this scenario, you will discover that vacuum gauges are undoubtedly the most cost-effective option.

The fact that they employ older designs and construction methods, don’t have as many features, and don’t deliver digital readings explains why they are so much lower when priced.

A vacuum gauge is your best option if you want something relatively inexpensive.

#3. Accuracy

The accuracy is not due to the digital capability; instead, it primarily depends on the fact that it is newer and better.

However, using a micron vacuum gauge instead of a vacuum model will provide more accurate readings.

This action occurs because the layout and general structure of the sensor work together to prevent air from entering the sensor.

Indeed, this eliminates the possibility of any reading influenced by the surrounding air. Aside from that, they provide a wide variety of designs that are less complicated to implement.

These make it easier to set them up and ensure they remain securely connected, eliminating the possibility of any pressure lost when measuring the vacuum.

It is not always the case that the analog alternative or vacuum gauge provides erroneous readings.

However, when measured, the somewhat retro design may let some pressure escape while allowing air to enter. Because of this, You may impact the accuracy of the readings.

Similarly, facilitated structures are not simple attachments. So even while it won’t be challenging to set them up for a reading, the process will be somewhat more complex than with micron models.

And it may most definitely have a slight impact on the accuracy.

#4. Leaking Stability

What are the best models for preventing leaks? Micron gauges are more reliable in this situation as well.

Because micron gauges are from using the most advanced technology, this results in a more accurate reading.

Thus, even a micron gauge with the weakest performance will not let you down. In addition, they simplify the process of connecting the gauge to the line.

Vacuum pressure gauges don’t allow air to enter since they don’t leak all the pressure.

However, due to its conventional structure, it may be a little more challenging to install. Consequently, minor pressure leaks may be the result of this process.

How Many Microns Should a Vacuum Pump Pull?

A vacuum pump should pull 100 microns. This procedure is sufficient to guarantee all the moisture that may have been present in the components of your air conditioning system, for example, has been eliminated.

Putting a micron gauge on your vacuum pump will allow you to confirm this information for yourself. There will be times when you need your pump to draw even 50 microns.

In addition, a vacuum of 1000 microns is adequate; nevertheless, you should concentrate on achieving a vacuum of 500 microns. 

The 500-micron filter is an excellent choice for both newly installed systems and those in operation for a significant amount of time.

For example, if you let your vacuum run for no more than half an hour at a time, you should be able to obtain this perfect measurement.

Types Of Vacuum Gauges, their Upsides, and Downsides

Bourdon gaugeSimple and very cheapMeasures vacuum only up to one Torr
Thermocouple gaugeVery effective and sensitiveCannot measure high vacuum
Pirani gaugeVery effective and sensitiveCannot measure high vacuum
Hot cathode ionization gaugeIt can measure small vacuumIt requires frequent maintenance


Always remember that vacuum travels in waves and seeks its level, much as pressure found above the level of the atmosphere does.

Low pressure in a system causes a wave. However, it’s not as noticeable as with more significant pressure, and the lowest pressure in a system during evacuation occurs at the pump.

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