What does a Flow Switch do?

Q: What Causes a Flow Switch to Fail?

Flow rate does not meet the standard: The most common reason for the flow switch not to operate is that the flow rate is too small and does not reach the threshold for the switch to start. You can confirm whether the switch start requirements are met by measuring the water flow rate. Water flow pipe blockage : Dust, impurities or scale accumulated in the water flow pipe will affect the smooth water flow and cause the flow switch to fail. The pipe needs to be cleaned to ensure smooth water flow. Valve problem : The valve in the pipe system may not be opened, resulting in water not flowing normally. Check whether the relevant valves are open. If they are open, further check other parts. Water pump problem : The failure of the water pump to get stuck, not turn or not be powered on will affect the water flow and cause the flow switch to fail. You need to check the status of the water pump and replace it if necessary. Water flow switch or motherboard failure : If there are no problems with the above checks, it may be that the water flow switch or motherboard is faulty. You can try to short-circuit the water flow switch protection interface. If the fault disappears, replace the water flow switch, otherwise, it may be a motherboard problem.

May 28, 2025

The function of a flow switch is to measure and control the flow of a pipeline. By monitoring the medium in the pipeline, different thresholds are set. When the medium flow rate is higher or lower than the threshold, the corresponding on/off operation instructions are issued, and the entire system is finally turned on/off. It protects the safe operation of the entire system.

What does a Flow Switch do on a Boiler?

How does a flow switch play its role in different types of boilers?

Power plant boilers

Power plant boilers usually need to process large amounts of water and fuel to generate enough steam to support power generation. Flow switches are used to monitor and control the flow of water. It can prevent problems such as pipeline blockage promptly. In power plant boilers, they are generally required to detect pipeline flow at different locations. It ensures the stable operation of the entire boiler system.

Industrial Heating Boilers

Industrial heating boilers are mainly used to provide heat for industrial equipment. Industrial heating boilers usually need to use multiple flow switches to ensure that the water flow just meets the heating needs. It monitors the smoothness of the pipeline. Industrial heating boilers need to operate stably for a long time throughout the year. Many flow switches are used to detect and control the flow of each pipeline. It avoids problems such as pump failure.

Chemical Boilers

Chemical boilers need to handle a large amount of water and chemicals to ensure the stability of the production process. Chemical boilers need to use more flow switches to monitor and control the flow of chemicals to avoid water pollution problems. Because chemical components may accumulate inside the boiler, causing equipment failure or pollution of the production environment. Many flow switches are used to ensure the stable flow of water. Flow switches can shoot trouble in time.

In short, flow switches play a vital role in various boilers. They can monitor and control the flow of pipelines to ensure that the water flow meets the design requirements and prevent pipeline blockages in time. Different types of boilers have different requirements for flow switches, depending on the design requirements and actual production needs of the boiler.

What is a Boiler?

The main purpose of a boiler is to provide steam, hot water or organic heat carriers through heat energy conversion. It is widely used in industries, electricity, building heating and daily life. The core functions of a boiler include power generation, process heating, district heating and domestic hot water supply.

Boiler energy conversion principle: A boiler converts the chemical energy of fuel (coal, gas, electricity, etc.) into thermal energy. Then it is transferred to the terminal equipment through water or organic media. This process involves two major systems: combustion in the furnace (chemical energy-thermal energy) and heat absorption in the pot (thermal energy-working fluid energy).

Sino-Inst supports customization. Here is an example of our customized case:

It is used for micro flow and high-temperature media

Flow rate: 0.1 to 1L/min

Media: heavy oil, slurry

Media temperature: up to 270 ℃

Media pressure: 1 – 10bar

Wire size: 1 inch

Wire material: SS316

Output: dry contact

Sino-Inst’s products are not only flow switches. We also have instruments for measuring pressure, liquid level and temperature. You can buy them from us. Sino-Inst is a supplier from China. Please feel free to contact us. Our professional engineers will provide you with the most correct solution.

What does a Flow Switch do on a Hot Tub?

The switch design of a bathtub is to provide users with a convenient and comfortable bathing experience.

Filling switch

The filling switch is one of the common switches for bathtubs. It is usually located on the side or bottom of the bathtub to control the inflow of water. When the water filling switch is turned on, water will flow into the bathtub through the pipe. When the preset water level is reached, the water filling switch automatically closes and stops adding water.

Drain switch

The drain switch is used to control the drainage of the bathtub. This switch is usually located at the bottom of the bathtub, near the drain. When the drain switch is turned on, the water in the bathtub will flow out through the drain. Some bathtubs are designed with the function of adjusting the water flow size, and the drainage speed can be adjusted as needed.

Massage spray switch

For bathtubs with massage functions, there are usually massage spray switches. These switches are usually located on the edge of the bathtub or on the control panel, which can control the water flow of the water jet. By adjusting these switches, different water flow patterns and intensities can be achieved, providing users with a comfortable massage experience.

Water temperature control switch

The water temperature control switch is used to adjust the water temperature in the bathtub. These switches are usually connected to the hot and cold water pipes, and the preset water temperature is achieved by adjusting the mixing ratio. This switch ensures that users can enjoy bathing at a comfortable water temperature.

If the flow rate is too low, the hot tub flow switch can also protect the pump components in spas, whirlpools and hot tubs from overheating. If there is a water flow failure or cavitation in the pump, the switch will open to prevent the pump or heating element from melting.

What does a Flow Switch do on a Pool?

The flow switch prevents the pool pump from continuing to operate under low-flow/no no-flow conditions. This can cause serious damage to the components.

The type of water flow switch commonly used in swimming pool heat pumps is mainly the flapper flow switch.

The flapper flow switch is a velocity-type flow switch. It relies on the flow rate of water to impact the flapper. The greater the flow rate of water, the greater the force acting on the flapper. The force acting on the flapper causes the flapper to move and trigger the control signal.

At present, the flapper flow switch can design the flapper according to the size of the water flow, reduce the water resistance generated by the water flow through the flow switch, and reduce the head loss of the water system.

What is the Function of the Air Flow Switch?

The main functions of the air switch can be summarized as follows:

Overload protection: When the current in the circuit exceeds the rated value, the air switch can cut off the circuit in time to prevent electrical equipment from being damaged due to overload. Overload may be caused by the use of high-power electrical appliances or improper circuit design.
Short circuit protection: Short circuit is a serious fault phenomenon that may cause a sudden surge in current in the circuit. The air switch will quickly cut off the circuit to prevent fire or equipment damage caused by short circuit.
Under-voltage protection: Some air switches also have undervoltage protection. When the circuit voltage is too low, the air switch automatically trips to prevent electrical equipment from working under low voltage and being damaged.
Isolation function: When the circuit is repaired, the air switch can manually disconnect the circuit to provide a safe isolation for maintenance personnel to operate.
Control function: The air switch can also be used as a switch controller for the circuit to easily realize the on and off operation of the circuit.

What are the Real Life Applications of Flow Switches?

Flow switches are also very common in life. It is used in boilers, hot tubs, air conditioning systems, central heating systems and swimming pool pumps.

What Causes a Flow Switch to Fail?

‌Flow rate does not meet the standard‌: The most common reason for the flow switch not to operate is that the flow rate is too small and does not reach the threshold for the switch to start. You can confirm whether the switch start requirements are met by measuring the water flow rate.

‌Water flow pipe blockage‌: Dust, impurities or scale accumulated in the water flow pipe will affect the smooth water flow and cause the flow switch to fail. The pipe needs to be cleaned to ensure smooth water flow.

‌Valve problem‌: The valve in the pipe system may not be opened, resulting in water not flowing normally. Check whether the relevant valves are open. If they are open, further check other parts.

‌Water pump problem‌: The failure of the water pump to get stuck, not turn or not be powered on will affect the water flow and cause the flow switch to fail. You need to check the status of the water pump and replace it if necessary.

‌Water flow switch or motherboard failure‌: If there are no problems with the above checks, it may be that the water flow switch or motherboard is faulty. You can try to short-circuit the water flow switch protection interface. If the fault disappears, replace the water flow switch, otherwise, it may be a motherboard problem.

The flow switch is small, but it has a big effect. They can be seen everywhere in life. Therefore, it is necessary to understand flow switches. If you need to buy a flow switch. Sino-Inst will provide you with the best quality flow switches and the most professional services. Sino-Inst is your best partner for instrument measurement. Our products have a one-year warranty and support international express delivery. You can contact us at any time.