Written By Car Bibles Staff
Published Aug. 22, 2019

We’ve finally moved on from the times where professionals simply guessed how A/C systems were operating. Micron gauges are the cost-affordable solution to measure the levels of degassing and dehydration in a system, so your equipment stays with you for years to come.

Fed up of guessing if the oil in your system is clean or not? We’ve assembled the top ten digital micron gauges on the market to ensure that your system has no potential leaks. Plus, purchasing one for yourself and going down the DIY route will save you a lot of money as a result. It’s a win-win solution for you and your bank balance!

The Best Micron Gauge

First on our list is Fieldpiece’s four port digital manifold with a Micron Gauge. The renowned set is one of the toughest advanced digital refrigerant manifolds on the block thanks to its water and impact resistance heavy-duty casing. Another great perk concerning the design is the strategically placed thermocouple ports that allow you to hook up from all angles.

Up to seven days of detailed data – that’s a whopping 168 continuous hours – can be logged into the wireless unit as well as a maximum of nine separate jobs. One indispensable feature that we love is the timer which tracks the duration of the test itself so ensure that false positives aren’t generated. It’s a strong and staunch solution to your leakage problems, what more could you want?

Key Features
  • Item is water resistant with an impact resistant screen
  • 168 continuous hours of data/seven days can be logged at once
  • Durability maintained thanks to heavy-duty casing and reinforced hook
  • Tightness test over duration of test clearly identifies leaks
  • Advanced digital refrigerant manifold allows for easy download via USB port
Specification
  • Brand Fieldpiece
  • Model SM480V
  • Weight 6.42 pounds

From the moment you turn on CPS’s Vacuum Gauge, their five-digit Digital LCD Display is a tell-tale sign that their product is as reliable as one can get. CPS’s model is calibrated to meet diligent NIST (National Institute of Standards and Technology) standards, so you’ll receive the most accurate reading possible. What’s more, this reading can be delivered in microns, torr, in/hg, or mBar – whatever unit of measurement you’re most comfortable using.

The field cleanable sensor can withstand up to 400 PSI of positive pressure with a burst pressure of 3000 PSIG. Manufactured in the USA, CPS’s vacuum gauge is of the highest quality possible – all you need to do to maintain its longevity is keep it snugly inside its compact case and clean it well from time to time. Just remember to isolate this vacuum gauge with a core removal value and you’ll be leak-free for years to come.

Key Features
  • Calibrated to adhere to diligent NIST (National Institute of Standards and Technology) standards to maintain accurate readings
  • Can withstand 400 PSI of positive pressure
  • Easy to use and read due to five-digit LCD display
  • Ensures systems are contaminant-free
  • Can select freely between units of measurements microns, torr, in/hg, and mBar
Specification
  • Brand CPS
  • Model VG200
  • Weight 10.6 ounces

Fieldpiece’s SMAN360 is a bigger and better replacement from the older SMAN3 sporting a rugged internal and external design that will blow your mind. The most wonderful difference between the old and new models is the fantastic interface display – with the target superheat mode down the middle being the only extra mode that you have to access off the main screen.

As well as the alarm that workers can set to a chosen micron level, the device is able to carry out a linear adjustment of pressure sensors too. Plus, as new features are added online, all you have to do is plug in and enjoy the luxury of owning an up-to-date model downloaded from the comfort of your own home.

Key Features
  • Instantly calculates target superheat to minimize need for manual calculations
  • Built-in micron gauge with resolution from 50 to 9,999 microns
  • Alarm sounds when vacuum reaches chosen micron level
  • Stopwatch and rate indicator keep worker informed
  • Interface is accessible and simple to operate
Specification
  • Brand Fieldpiece
  • Model SMAN360
  • Weight 4.9 pounds

What’s one of the only things better than owning your very own Testo manifold? Owning a whole kit. Included inside this kit is a service case and two removable temperature clamp probes. What’s more, the convenient app is great for delivering reports and invoices via email. Evidently, every feature of this kit is geared towards making your evacuation as stress-free as possible. With over sixty refrigerant profiles, the manifold is able to offer direct superheat and subcool readings.

Plus, thanks to Testo’s irresistible Bluetooth technology, the manifold communicates with the Bluetooth smart probes to facilitate monitoring, report generation, you name it! And as if it couldn’t get any better, the Testo 550 includes instant access to any measurement data directly on your smartphone and tablet. What’s not to love?

Key Features
  • Metal frame around display protects manifold from major collision
  • 60 refrigerant profiles and added functionality for leak tests maintain versatility
  • Measurement data can be viewed on smartphone and tablet
  • Report can be sent from job site thanks to Bluetooth/App integration
  • Temperatures clamp probes will give direct superheat/subcool readings
Specification
  • Brand Testo
  • Model 0563 01550
  • Weight 2.34 pounds

Are you more than tempted to purchase the Testo’s Digital Manifold Kit reviewed above yet don’t want to part with the cash for all the fancy features? Buying Testo’s Digital Manifold individually is the only gauge you’ll ever require. With sixty available refrigerant profiles at the tip of your fingers as well as the readable 2-line backlit display, you’re looking straight at a bargain.

The product will provide real-time superheat and subcooling with optional temperature probes as well as calibrating high/low side pressures and saturation/evaporation temperatures. Plus, satisfied customers confirm that the accuracy is within 2%. With three available connections at the ready, Testo’s Manifold both adaptable as well as accurate.  

Key Features
  • 60 available refrigerant profiles stored on-the-go
  • Product backed by five-year warranty
  • Delivers instant superheat and sub-cooling due to exact temperature probes
  • Two-line backlit display is accessible and easy to read
  • Detailed User's Manual keeps worker informed when concerning correct usage
Specification
  • Brand Testo
  • Model 549
  • Weight 2.34 pounds

It may not look like much, but Uniweld’s UVG Digital Vacuum Gauge and Adaptor is practically futuristic when it comes down to the features it has on offer. Measurements can be taken in Microns, Pascals, Millibars, and mmHg with resolution down to one micron.

Thanks to the self-calibration feature, no other equipment is needed for Uniweld’s creation to work seamlessly. And the device won’t be running out of charge anytime soon – the two included ‘AAA’ batteries will keep the gauge running for up to 1000 hours. Yet what we love the most about this model is the oil sensor that disregards false readings in real-time as well as flashing ‘OIL’ when the sensor needs rebooting. If in doubt, change it out!

Key Features
  • Units of measurement include Microns, Pascals, Millibar, and mmHg
  • Self-calibration feature disregards need for other equipment
  • UVG protected by durable, orange rubber gauge boot
  • Includes two 'AAA' batteries that allow device to be used up to 1000 hours
  • Large backlit LCD display is easy to read
  • Vacuum sensor can tolerate overpressure up to 500 PSI
Specification
  • Brand Uniweld
  • Model UVG
  • Weight 7.8 ounces

Proudly made right here in the USA, Fieldpiece’s Digital Vacuum Gauge works exactly as it should. The easy-to-read display makes the evacuation process easy due to the display reading ‘OL’ until the vacuum level drops below 10,000 microns. Plus, accompanied with the rate indicator, alarm, and timer, it’s as handy as having another worker on the job with you when assessing the vacuum level in an A/C system.

With a respectable 0-999-micron range to operate within, Fieldpiece takes SVG3’s durability seriously and have kitted it out with a rugged rubberized case and a hook that allows the gauge to be inserted at any angle. And if you’re confused about any part of the process, the user manual will keep you on the right track. No matter the situation, Fieldpiece always deliver – and their Vacuum Gauge isn’t an exception to the rule.

Key Features
  • Compact and rubber gauge is sturdy to maintain durability
  • Strap hook allows vacuum gauge to be suspended at any angle
  • Manufactured in the USA
  • Dual display with rate indicator, alarm, and timer is simple to use and keeps a worker on track
  • Features a generous 0-999-micron range
Specification
  • Brand Fieldpiece
  • Model SVG3
  • Weight 1.4 pounds

With a range of 0 to 0.39 PSI or 0 to 20,000 microns, Testo’s Micron Gauge will read all the way down to a complete vacuum in a flawless fashion. Made in the USA, the full H20 saturation display is featured to ensure that a full and proper evacuation has been carried out. What’s more, the compact design – featuring a nimble hook at the strap and a polymer case – can take a right beating and still work flawlessly.

Electronically speaking, the Bluetooth capacity will link automatically to your smart phone or device immediately. Plus, with the help of the free Testo SMART Probes app, your reading results will be documented in an accessible manner. All in all, the device is perfect for carrying out a perfect evacuation of air conditioning, refrigeration, and heat pump systems.

Key Features
  • Dual display with rate indicator is extremely well organized
  • Hook at strap allows for use in any position
  • Made in the United States of America
  • Display clearly reads OL until vacuum level drops below 10,000 microns
  • Wireless Bluetooth communication facilitates smooth transition of data
Specification
  • Brand Testo
  • Model 552 BT
  • Weight 1.59 pounds

If the bright-blue and orange aesthetic of Supco’s Vacuum Gauge doesn’t catch your eye first, then its wide array of features will attract your attention. In particular, we’re a huge fan of both the audible and visual alarms for high and low vacuums that alerts its user to when the limit has been attained. Concerning the design itself, we particularly admire the built-in handing apparatus for maneuverability.

With impressive resolution between 0.5 to 1000 micron as well as a 0-12,000-micron vacuum range, this top-of-the-range model is as accurate and precise as a DIYer can get.

Key Features
  • LCD Backlit display of 0-1200 microns is easy to read
  • Device can measure in seven international units
  • Thermistor sensor ensures accurate readings
  • Backed by a one-year limited warranty
  • Magnet holder part of innovative design
Specification
  • Brand Supco
  • Model VG64
  • Weight 4 ounces

As usual, we’ve decided to save one of the best products for last. Although TPI’s Digital camo-green Vacuum Gauge looks old-fashioned, the multitude of features on offer make it far from outdated. Able to read a vacuum in seven international units of measure, the digital vacuum gauge can successfully operate between 32 to 104 degrees Fahrenheit.

Still can’t make up your mind between this stellar gauge and hiring out a professional? The auto-power feature, meaning that power shuts off entirely when the vacuum is above 12,000 microns, will surely tempt you. And our personal favorite feature has to be the strong magnet mount – the no-hands feature allows us to unleash our inner laziness! All in all, TPI’s vacuum gauge is an inexpensive solution when working on a modern A/C or heat pump system.

Key Features
  • Auto-power ensures automatic turn-off when vacuum goes above 12,000 microns
  • Measurements can be taken in seven international units
  • Sensor is easily cleanable
  • Guarantees accuracy to within 10%
  • Contains wall hook and magnets for no-hand use
Specification
  • Brand TPI
  • Model 605
  • Weight 10.4 ounces

Best Micron Gauge Buying Guide & FAQ

Features to Consider When Buying a Micron Gauge

Like all professionals and DIYers out there, you want a trusty gauge to make sure you’re receiving the most accurate reading possible. Yet between the wide scope of options, you’re spoiled for choice. Ask yourself these three questions below to determine if the gauge you’ve got your eye on is the one for you.

  • Can your chosen micron gauge be cleaned easily?

As a general rule, dirt is never our friend. The smallest specs can enter into our micron gauges, causing their systems to break down and havoc to reign. To make sure that your micron gauge isn’t at risk of shutting down, clean it regularly with isopropyl rubbing alcohol by placing a small amount of liquid in the open port, shaking it gently, and then pouring it out. Likewise, the caps are there for a reason – make sure that you keep them on when the gauge is not in use.

  • Can your gauge be connected easily?

By connection here, we’re referring to both the gauge connections and the wireless connections on offer. Having the choice between a wide range of connection sizes is important for compatibility. Likewise, the fantastic Bluetooth feature that many micron gauges include allows invoices and accurate readings to be sent while on the job.

  • How durable is your micron gauge?

We recommend opting for a gauge that water-resistant and impact resistant – accidents happen, and you don’t want to lose your data if your device falls. Likewise, a reinforced hook and heavy-duty casting always goes a long way when durability is concerned.

Benefits of Micron Gauges

Designed to figure out the exact level of vacuum in an air conditioning system, micron gauges are handy to own. These nifty devices can be used to measure the level of dehydration and degassing in a unit to facilitate longevity. Yet what are some of the main benefits we should look out for?

  • Immediate Reading of Pressure Changes: If you possess a micron gauge that works in real-time, leaks will be found promptly – therefore reducing the amount of time you’re holding up your gauge and cramping your arm in the process!
  • Large LCD Screens: As Digital Micron Gauges have developed over the years, their touch-screens have developed alongside them. The very best models now possess impact and water resistant five-digit LDC screens so even the short-sighted among us can make the most out of their micron gauge.

Principle of Electronic Vacuum Measurement

During an evacuation, the longer atmosphere is removed for, the weaker the ability to transfer heat by conduction to surrounding air is. This process therefore allows vacuum to be accurately read with the aid of a few trusty thermocouple gauges. Consequently, the deeper the vacuum goes, the hotter the sensor becomes due to the lack of molecules to conduct away the high temperature. The change in temperature of the thermocouple therefore is analogous to the level of degassing and dehydration of piping and system components.

Difference Between Moisture and a System Leak

It’s the worst feeling when your leak rate doesn’t decrease and instead, keeps going up and up rapidly – how can you tell if it’s a leak or only moisture present in your system?

If the system has moisture – The moisture in your system will usually be trapped under the compressor oil. When this oil escapes, it will show up in the gauge as a higher reading.

Secondly, another mistake DIYers make when panicking that they’ve got a leak is by not removing the access valve cores before pulling on the high and low side of the system. This failure to do so creates a massive restriction and leads to a time-consuming evacuation time. Therefore, check for both these scenarios before you panic!

If the system has a leak – If you’ve checked over and over again that you’ve not made the above errors, you could have a leak on your hands. You’ll be aware if your system has a leak as the vacuum gauge will continue to rise quickly until it hits atmospheric pressure. In digital gauges, this ‘atmospheric pressure’ can be shown by a helpful alarm. To check for leaks properly, you must use copper tubing or metal hoses to obtain the most accurate results.

How to Use a Micron Gauge

Before we begin with explaining how to conduct a leak-proof test, let’s make sure you, our reader, are aware of two key terms: degassing and dehydration. Degassing, the removal of air and other non-condensibles, is combined with dehydration, the removal of moisture, to complete the process of evacuation.

  1. Set-up for success – Remove the core values and then connect large diameter vacuum rated hoses to the back of the core tools at both sides of the system. Then, connect the hoses to the vacuum pump with your handy manifold gauge.
  2. Pulling a Vacuum – Once all the valves are open, pull a vacuum. Isolating the gauge from the pump is imperative for ensuring that there is zero chance of gas permeation through the hoses. As soon as the sensor reads between 300 and 400 microns with compressor in the vacuum, close valves to the high and low side of the system with the micron gauge open.
  3. Install your chosen gauge and wait – Either using a copper line or brass connector – straight to the core on the suction line via a 1/4″ connector to see if your pump can reach a vacuum level of 1,500 slowly. Wait around five to twenty minutes to allow system pressure to equalize – at the end of this step, you should know how much moisture you have in the system.
  4. Change that oil! – Oil should be changed over after each job depending on the moisture level. Moreover, it must be replaced when it’s still warm – if not, the moisture separates from the oil and attaches to the metal of the pump. For this reason, we recommend keeping checking it with the micron gauge to ensure that the pump pools the proper vacuum to eradicate moisture from the system.
Related Post: Best Boost Gauge, Best Wideband Gauges and Best Tire Pressure Gauges

Our Top Pick

So, if we had to choose between all the trusty micron gauges compiled together in our buying guide, which one would we trust to work on our own A/C or vacuum pump system? We just can’t resist Fieldpiece’s SMAN’s Microfold Micron Gauge. The tightness test is what makes this device one of the front-runners on the market today: by recording the pressure in real-time, leaks are made obvious due to the ‘pdif’ function over the duration of your test. And storing data on your device has never been easier: the amount of percentage space available will flash up before you begin your logging for the day. Yet it’s not often that this situation would arise – after all, 168 continuous hours of data will keep most DIYers and professionals satisfied!

Sources:

  1. How Air Conditioners Work – HowStuffWorks

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