The Pentair R172086 is a 1/2-inch control valve replacement for the Pentair Rainbow automatic chlorine/bromine pool and spa inline feeder models 320, 322, and others. It is also known as a metering valve for soft washing proportioner.

A metering valve in the context of soft washing refers to a device used to regulate and control the flow of cleaning chemicals or detergents in a soft washing system. Soft washing is a low-pressure method used to clean surfaces, particularly exterior surfaces like roofs, siding, and other delicate surfaces, using specialized cleaning solutions and lower water pressure to prevent damage.

The metering valve allows the operator to accurately measure and adjust the amount of cleaning chemical or detergent being mixed with water, ensuring the proper dilution and concentration for effective cleaning without causing harm to the surface being cleaned. It helps maintain consistency and control in the application of the cleaning solution, optimizing the cleaning process.

The valve typically has settings or controls that allow the user to adjust the ratio of cleaning chemical to water, enabling them to tailor the mixture to suit the specific cleaning needs for different surfaces and types of dirt or grime. This level of control is essential for achieving efficient and safe soft washing results.