Pressure Washer Gauge

Figure 1: A pressure gauge attached to a pressure washer pump

Figure 1: A pressure gauge attached to a pressure washer pump

A pressure washer is a mechanical device that uses a pump to generate high-pressure water for cleaning surfaces containing dust, mud, mold, paint, oil, and dirt. There are two types of pressure washers: The first is a hot water pressure washer, which is popular in industrial applications for cleaning oils and grease from a surface. The second is a cold water pressure washer typically used by homeowners because of the lower operating temperature (below 60°C / 140°F), making it safer to operate. Pressure washers are powered by air, gas, or electricity.

A pressure washer gauge is used to measure the water pressure generated by a pressure washer pump. These gauges can have a pressure scale of over 2,000 bar (29,007 PSI). Pressure washers are rated by the maximum amount of pressure that the pump can deliver. Most pressure washers have a fixed volume of flow through the nozzle determined by the pump. However, the pressure can be varied using an unloader valve.

Pressure washer gauges are usually installed at the pump outlet to measure the outlet pressure, which is the pressure in the hose. They can also be installed at the suction of the pump to measure the inlet pressure. However, the type of pressure gauge at the inlet has a lower measuring scale and range than the outlet type, which is the main focus of this article.

Operating principle

The pressure washer gauge is installed at the discharge of the pressure washer pump. The gauge can be attached to the pump or installed at the beginning of the hose. By installing the gauge at the closest point to the pump discharge, the pressure measurement is independent of the length of the hose and the pressure drop in the hose.

Pressure washer gauges mostly use the Bourdon tube principle to measure the pressure in a pipe. The Bourdon tube principle is based on the straightening effect when a flattened or circular tube is pressurized. A detailed description of how pressure gauges work can be read here.

Due to the pressure washer gauge operating conditions, the Bourdon tube pressure gauge is modified as follows: The pressure gauge is filled with a liquid, usually glycerine with the addition of a snubber installed before the pressure gauge pressure inlet. The purpose of the liquid is to:

  • Stabilize vibrations from the pump and the motion of the hose that can damage the gauge.
  • Reduce wear and tear by reducing the frequency of motion of the gears and links.
  • Prevent condensation of the glass as the environment will be wet.
  • Achieve consistent performance in all conditions.
  • Protect against icing in winter conditions.
  • Reduce motion of indicator needle due to liquid resistance. It increases the ease of reading the measurement and doesn’t create a false max reading from pulsations if the gauge has a maximum reading pointer.

Learn more about liquid filled pressure gauges by reading our dedicated article. You can also learn more about pressure gauges in our pressure gauge article, while our articles on diaphragm and bellows pressure gauges offer gauge specific information. 

Functions of pressure washer gauge

Figure 3: A glycerin pressure gauge for pressure washers

Figure 2: A glycerin pressure gauge for pressure washers

Pressure gauges are an important instrument when operating a pressure washer. The following are some of the functions of a gauge on a pressure washer:

  • The primary function of a pressure washer gauge is to measure the pressure levels of the pump.
  • The gauge can show an indication of damage to the pump internal components.
  • The pressure gauge is used in calibrating the pressure washer pump operation.
  • It serves as a visual confirmation when the pressure level is changed.
  • When installed at the suction side of the pump, the pressure gauge can help indicate the onset of cavitation.
  • They are used in troubleshooting the pressure washer when a fault is observed.
  • Indicates potential leakages in the hose or the housing of the pump.

Watch the below Youtube video for more information:


Selection criteria

  • Measuring range: Pressure washers operate at relatively high pressure compared to conventional applications. It is typical to have pressure gauges from 50 up to 2,000 bar (725-29,007 PSI). Allow about 10 % higher range than the expected maximum pressure of the pressure washer to avoid damage. Always choose the narrowest measuring range whenever possible for higher accuracy.
  • Connection size and type: Pressure washer gauges come in different connection sizes. It is common to use an inline adapter to connect the pressure gauge between the pump and the hose. The most common connection type is threaded.
  • Connection material: Pressure washer gauges can come with different connection materials such as brass, copper alloy, etc. Ensure the selected material is compatible with the pump discharge material or hose. Please check out Tamesons material compatibility chart before you decide.
  • Maximum operating temperature: Most pressure washer gauges for residential and commercial applications work within a 60° – 80° C (140°-176°F) maximum temperature range. There are special pressure washer gauges for high-temperature industrial applications.
  • Unit of measurement: For gauge pressure measurement, it is quite common to have both bar and psi.

You can learn much more about what choices to make when choosing a pressure gauge in our pressure gauge selection tips.

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