Flow Switch: Different Options for Different Uses

A flow switch isn’t something that you have to think about every day but they are an essential component for most types of pumps, cooling systems and even flow monitoring systems. If they aren't working properly the pump doesn't engage or disengage at the correct time, leading to a variety of problems depending on the system usage. Switches with alarms are also essential in many types of industrial applications to alert if pressure rises or falls too low within a specific system. Having the right options for replacement parts is essential to keep the pump operating at peak performance.

One of the biggest concerns when selecting a replacement switch is to make sure that it is correctly designed for the specific flow rate within the pump. A flow switch should not be used that are incorrectly calibrated for the flow rate as this can lead to incorrect functioning of the device. All switches are rated in gallons per minute or GPM. The term is fairly easy to understand, the switch operates at the given GPM which can range from as little as 0.1 GPM to up to 48 GPM. Additional higher volume types of switches are typically only used in specialized industrial types of applications such as oil and gas pipeline monitoring.

Besides the gallon per minute rating, these switches can also be rated on the operating velocity range which is measured in FPM or feet per minute. These are often seen in booster pumps and flow protector types of options that will automatically shut down if the flow of the liquid, usually water, drops below a specific volume. This is perfect for protecting pumps against trying to run it dry or if there is not enough water in the system to allow the pump to operate without causing damage to the mechanism. These switches, which can also measure air flow, range in rating from 0-300 fpm to up to 1610 fpm.

Another key consideration in choosing a flow switch is the material of construction. There are a huge number of options with many switches having several different materials depending on the specific part of the switch. In general there are brass and stainless steel switches that are commonly used for measuring the flow of liquids. Polypropylene materials are also used for liquids, typically potable water, and are excellent in heaters, water purifiers, water chlorinators, evaporators, filters and reverse osmosis units. Since they are very lightweight and completely corrosive resistant they are an excellent option for a switch in all types of drinking water systems.

A rotor type flow switch is typically made of a variety of materials. They can include brass, ceramic, PPS composite, polysulfone and Vitron. Typically the body itself is brass, with ceramic and polysulfone exterior. These rotor types of switches are commonly used in highly specialized pumps and systems including semiconductor processing, high-power tubes, robotic welding equipment and even in laser and specialized medical equipment. These types of switches also include filtration of up to 150 microns, ideal for the highly sensitive equipment they are used in.

Choosing the right type of flow switch is essential to the proper operation of the system or systems. As with all replacement parts, it is critical to stay to the pump manufacturers specs and to avoid substituting a part that is not recommended for that specific system. You will also need to carefully check out the operating temperature and rating for the switch, especially if it is used in specialized equipment as opposed to a water filtration or heating system.