What is a Pressure Gauge and How Does It Work?

Posted by
John Woodard on December 21, 2023

Pressure gauges can help you improve your water treatment system by giving you an indicator of the system’s performance. While pressure gauges are a simple tool, there are multiple types available to purchase and various ways to use them. In this article, you can learn answers to common questions about pressure gauges and their uses.

What is a pressure gauge? 

pressure gauge is a device that helps monitor pressure within a system. Water systems and storage tanks function because of the pressure that the water and air inside is placed under. A pressure gauge measures the force of the pressure in the water or air so that you can determine whether you have any errors in your tanks or systems. If pressure inside a system significantly differs from the norm, then you must take action to correct a fault in the system.

What is a pressure gauge used for?

Pressure gauges are used for a variety of things. They can be used to gauge household pressure to see if the pressure regulator on the house is still working. They can also be used on a storage tank for a well system to make sure the pump is turning on and off properly. Water treatment equipment or systems like reverse osmosis use pressure gauges to ensure the pressure is allowing the system to function optimally. In some cases, even a simple tire gauge can help you test pressure on a storage tank. 

Types of pressure gauges

Pressure gauges come in a variety of forms, but the two most common types of pressure gauges used in the water treatment industry are manometer (U-tube) and bourdon tube gauges. 

Manometer (U-tube) 

Manometer pressure gauges contain a little U-shaped tube with liquid inside. When pressure is applied to either side of the gauge, the water in the tube rises one way or the other. You can determine the pressure inside a system by reading the markings indicated by the levels of liquid in the tube.

Bourdon tube 

The bourdon pressure gauge is most common type used in the water industry because it is very easy to use. It has a readable dial with a needle that points right to the operating pressure. Bourdon pressure gauges can be used on storage tanks for well systems to let you know if your pump is working properly. They can also be used on a filter setup to gauge how much pressure is entering or exiting the filter. 

Bourdon tube gauges contain a small sealed tube on the inside. When pressurized liquid or air enters the gauge, this tube straightens like a balloon being filled with air. As the tube straightens, it interacts with the gears on the inside to move the needle. These gauges are preset to measure a certain range of pressures, so you should not try to calibrate them yourself. 

What is pressure differential? 

Pressure differential is the variance, or the delta, between two pressures. In any given filter application, a certain pressure comes in, and another goes out. The difference between those two pressures is the differential. The higher the variance, the more pressure drop you will experience across that filter. 

How to read a pressure gauge

You can read a pressure gauge by simply matching the needle to the number on the dial. Digital pressure gauges will read the exact PSI, while an air pressure gauge, like a tire gauge, will shoot out a little stick marked with measurements of PSI. The stick will line up with the end of the gauge so you can read the pressure. 

Pressure gauges come in a variety of calibrations. They can range 0 to 15 pounds per square inch (PSI), all the way up to a range of 0 to 1,000 PSI. Make sure the gauge you are using is compatible with the scale of the application you are using it in. You can determine whether the pressure is too high or too low based on what parameters you are looking to operate under. 

What if the pressure is too low?

Pressure gauges provide information that allows you to monitor equipment. If you see pressure reading too high or low, it could be an indication that you need to fix something in our tank or filtration system. For example, if you monitor pressure differential across the inside of a filter and the outside, or the effluent side, of that filter, and the pressure is dropping too low, it may mean that the filter is clogged and needs to be changed. In this case, the water will eventually stop flowing into your house or through your equipment if the filter is not changed.  

What if the pressure is too high?

If the pressure on your gauge reads too high, you may also have to take action. Extra-high pressure could result in a catastrophic failure. Fittings or tubing could burst, or housings could come apart. If this happens, you will begin to experience leaks that could result in flooding and potential danger to your home or office. 

How install a pressure gauge 

Pressure gauges typically come with a threaded mount that you either put into a pipe fitting or into a manifold. The location of these threads determine where and how you install your pressure gauge. Some of the gauges come with threads on the very bottom. The gauge is typically mounted to the top of a filter housing or some type of plumbing configuration. Other gauges that come with threads on the back would need to be mounted on a panel or system that is configured to face you. 

When to calibrate a pressure gauge

Pressure gauges sometimes must be calibrated on a periodic basis. This ultimately depends on the type of gauge and the application it is used for. For example, if you are treating water in an application where a very specific pressure must be met, it is very important that your meter, or gauge, is calibrated correctly. These gauges come in different accuracy classifications. In the water treatment industry, typically for residential or light commercial use, calibration is not quite as necessary, or as frequently needed, as something that requires ultimate accuracy. 

How to calibrate a pressure gauge

To calibrate a pressure gauge, you must use some form of calibration tool, such as a pressure hand pump. Follow these steps to calibrate your pressure gauge:

  1. Connect the calibrator to the pressure gauge.
  2. Set the desired pressure on the calibrator.
  3. Pump the calibrator until the pressure is reached.
  4. Note the reading of the pressure gauge. If it differs from the calibrator, you must adjust the gauge’s calibration.
  5. If you must change the calibration of your gauge, consult your gauge’s instructions.
  6. Once changes have been made, repeat steps 1 through 5 until the calibration is successful.

What does negative pressure on a pressure gauge mean?

A pressure gauge that reads a negative pressure possesses some type of problem. Typically, pressure gauges range from zero up to any positive number. If your gauge is showing a negative number, either the gauge is malfunctioning, or it is working on a vacuum that is pulling the bourdon tube into a further curve, which would make the needle go down. It could be that the meter is calibrated poorly or needs calibration. 

Pressure gauges are great tools for measuring the pressure of your water treatment systems. They enable us to look at how our equipment is operating, and how our filters are performing. A pressure gauge is not going to create a problem, but it will certainly tell you if you have a problem with any of your water filtration equipment or systems.


If you have any additional questions, please do not hesitate to contact us.

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