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.
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:
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.
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:
Watch the below Youtube video for more information:
You can learn much more about what choices to make when choosing a pressure gauge in our pressure gauge selection tips.