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Scrutinizing the theory of flow switches

A flow switch is a device that examines the flow of air, stream or liquid. It gives a “trip signal” to a different device in the system, such as pump. The trip signal will indicate to the pump to turn on or turn off. It is mandatory to offer damage protection and circuit cooling or adjust flow rate that can be too high or too low.

Flow switches perform their sensing function with an electrical contact output at a specified flow rate that has different varieties of flow switches. The varieties include paddle, thermal, piezo, and shuttle or piston.

Meaning of flow

Any physical movement or velocity of liquid, gas or steam in a pipe that prompts the switch to start up is a flow. A decrease in velocity or full stoppage means no flow. No flow makes the switch to return to its previous state.

Types of flow switches

Flow switches can be classified on the basis of flowing media or on the measurement type.

On the base of flowing media, flow switches are divided in following two types.

  • Gas flow:  They are actually used in HVAC applications. These switches are for media like air and stream.
  • Liquid flow: They are commonly used in many industrial applications. These switches are basically for media like water, lubricants, chemicals, and slurries.

On the basis of measurement, flow switches are divided in following two types.

  • Volumetric flow: These switches are helpful in measuring the flow of liquid or gases. The measurement done is entirely is based on volume per unit time that means cubic feet per minute.
  • Velocity flow: These switches provide assistance in measuring the flow rate of moving media. This measurement is based on velocity that means feet per minute.

Uses of flow switches

A liquid flow switch is used in the procedure of chlorination of a swimming pool, hot water heating, air conditioning, liquid transfer system, fire sprinkler systems and industrial laser cooling systems.

Flow switches are helpful in case of fire because at that time a flow switch can initiate an electrical fire alarm device to turn on. Water flow switches are useful in water sprinkler systems. While air flow switches are helpful in cleaning rooms, filtering systems, exhausting ventilation, and in air treatment systems.

Flow switches have other applications too. Such as:

  • Duct type heating
  • Additive or blending systems
  • Water treatment systems
  • Air supply systems

Functions of a flow switch

A flow switch performs many functions as per the requirements.

A flow switch can help in detecting if there is any flow in the piping and opens or closes an electrical contact. It is mainly used in heating, air conditioning, refrigeration, water treatment, additive pumping and process systems. With the help of a flow switch, one can control devices such as pumps, burners, compressors, refrigerators, and motorized valves. This assists in turning on the indicator and alarm devices as well as regulating equipments for dosing water additives.

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