Flow Switch- A Complete Guide

 

Instruthinkhas been a reputable company manufacturing and supplying various instruments, including flow meters, transmitters, valves, flow-switches, and much more, since 1990. All the tools follow the international quality standards and delivering them at a competitive price. Instruthinkis always ready to offer outstanding products and the best services to all the customers in UK and worldwide.

Following are the answers to the queries about the flow switch:

What is the flow switch?

 

The flow switch is also known as the flow sensor and indicator that helps monitor the flow and liquid rate throughout the channel and system. The flow switch is the sensor that keeps checking the flow for a particular time to adjust and manage the total momentum of the flow continuously. The flowmeter helps indicate the proper flow of the flow switch for the registered device, displaying the registration along with the information.  The water flow keeps detecting mounting performance in the particular area where the room is servicing the machine. The able trigger action can start or stop the component anywhere in the system. The rate of adjustment and pressure is according to the levels of the programming. For example, suppose the flow switch gives the sign of wearing and tearing leakage of the function. Replace the flow switch instantly with the professional contractor of the sprinkler.

What is the main difference between flow switch and flowmeter?

 

Flow switch:  basically, the flow switch is a mechanical kind of instrument that helps in controlling the flow of air, liquid, or steam. The flow switch works by sending trip signals to the other device existing in the system. Flow switch also informs about turning on or shutting off, which helps protect the damage and protects the circuit by cooling it down. The flow switch keeps determining if the flow is above or below some specific rate that you can it as the set point. You can fix or adjust the set point that is dependent on the specifications of the particular instrument. When reaching the set point, the response is primarily the actuation of the electrical circuit. After tripping for once, the flow switch remains in the new state unless the fall falls under the setpoint.

Flowmeter: the flowmeters are those devices in the fluid systems for measuring the linear, non-linear, mass, or volumetric rate of the flow of the gas or liquid. They have various applications, and you can fit the flowmeter and the integration of the flow controlling valve to control the output flow. While selecting the flowmeter, you need to consider some factors like being familiar with the plant’s personnel, having experience with the calibration, maintenance, availability of the spare parts, and estimation time between the failure on the site. Unfortunately, there is no particular standard of off the self-flowmeter that is applicable for all applications.

The actual difference between the flow switch and flowmeter is their functionalities. The purpose of the flowmeter is to keep monitoring the flow rate, and the user has to check it themselves. On the other hand, the flow switch helps detect the flow’s existence at the specific set point, gives alerts to the user, and keeps performing the required action.

What is the working principle of flow switch?

 

The working principle of the flow switch depends on the freely floating magnetic piston that responds only to the movement of the fluids existing in the line, not to the static or pressures of the system. Within the presence of the liquid, the controlling movement of the piston is actuating an external hermetically sealed reed switch. This switch is helpful for the actuation of audible or visual alarms and relays or the other controls. There is a paddle or some magnetic trigger whose connection is with the circuit. Its placement is in the channel from where the gas or liquid is passing. The transducer takes the signal and passes it to the transmitter for readability. The transmitter shows the reading against the already defined set of parameters. It also keeps performing the actions according to the requirement for adjusting the behavior of the components and mechanisms. The flow switch can monitor, control, and report the liquid or gas flow rate within the particular part or whole system through this methodology. The flow switch also assures that the flow remains within the pre=defined set of parameters.

What are the specifications of the flow switch?

 

Product	Flow switch
Maximum pressure of the fluid	150 PSIG ( 1034 kPa)
Minimum temperature of the fluid	-29 degrees Celsius to 0 degrees Celsius
Maximum temperature of the fluid	121 degrees Celsius
Wiring connections	· Screw type of terminals · Solid conductor leading with the wires and 178 mm long
Weight of the flow switch	1.3 kg (2.8 lb)
Conduit connection	One 7/8 inch. 22mm hole for ½ inch. Conduit with 1-1/8 inch. 29mm knockout ring for ¾ inch. Conduit (F61KD)

What are the troubleshooting issues in flow switch and their problems?

 

Troubleshooting issues	Solution
Water condensation in the enclosure	It would help if you used the model of the NEMA 3R enclosure. But, the inspection of the grommet is essential in the conduit fitting. Replace the control if there is any defect in the grommet.
The fluid is leaking from the tank inside the enclosure due to the failure of the bellows.	There is a need to replace the flow switch.
The flow switch is not activating because some dirt particles exist in the mechanism of the flow switch.	Clear all the dirt, and it’s remaining in the working of the flow switch. You must test the operations of the flow switch multiple times so it works properly.
The flow switch fails and returning to the no-flow position.	Must set the flow switch lower than the settings of the factory. You can increase the environment. On the vertical pipes, make sure that the direction of the flow in the line is in an upward movement. The arrow in the flow switch must be pointing in the direction of the flow (up)
No changing of control when the flow increases	Check the broken paddle. The replacement of the control is essential where you find any crack in the paddle.

 

What are the functions of the flow switch?

 

The performance of the flow switch and its functionalities are dependent on the set of requirements. The flow switch can stop the motor when there is no flow and also triggers the engine whenever the fluid starts flowing in the same motor. The flow switch also alerts whenever the flow stops, and the notice gets off when the liquid reaches a suitable level. Since the flow switch is significant in the industries, the flow rate measurement needs to be accurate by calculating the velocity and differential pressure that force the liquid to flow in the pipe. You must know the cross-sectional area of the line, and velocity indicates the flow rate. Calculation of the flow rate is by setting the flow switch to the pre-determining the close functionality.

Which applications use flow switches?

 

• Water treatment systems
• Mixing or addictive systems
• Heating the water systems
• Pumping systems
• Equipment for cooling down the water
• Methods for transferring the liquids
• Fire extinguishing systems
• Systems for laser cooling in the industries
• Plans for filters and cleaning room
• Exhaust for ventilation
• Ways to handle the air

The flow switch also serves the purpose of an alarm if the ventilation fan stops working in hazardous areas and there is no flow of air. The flow switch is helpful in the following applications:

• Protecting the pump
• Monitoring the nozzle of safety spray
• Testing of the oil well system
• The flow of the drainage line
• Monitoring of the relief valve

How to test and install the flow switch?

 

Since there are different flow switches, there is also a vast range of installation methodologies and techniques to install the flow switch. For the installation process, you need to know the flow switch you are using and its purpose. There are some basic rules for installing the flow switch that is applicable on all kinds of flow switch that are as follows:

• Always install the flow switch on the straight section of the pipe
• Make sure that the length of the straight line is good enough from the front and back of the flow switch. Ideally, it should be ten times the diameter of the tube.
• Never fit or wire the flow switch near the valves, drains, or narrow/more comprehensive pipe sections. Or any other feature that may cause any fluctuations in the flow rate throughout this particular area.

For testing the flow switch, you need to know the purpose of trying it. In most cases, you can confirm the working of the flow switch simply by observing and checking the accurate response are triggering whenever the fluid stops flowing. In other scenarios, you may require an ohmmeter to measure the resistance of the electronics of the flow switch. It shows confirmation when there is completion and registration of the circuit whenever the flow switch activates. If you cannot receive correct results according to the requirements, it is better to repair or change the flow switch. When the flow switch gets attached to the safety equipment like fire sprinklers in the commercial areas, it is necessary to test the flow switch regularly.

What are the sizes and voltages of the flow switch?  

Along with identifying the proper type of flow switch for positioning and application, it is also essential to choose the accurate size and voltage of the flow switch to work correctly in the system you will install. Below are some basic sizes and their corresponding voltages of flow switch:

• 1-inch flow switch: of all types are helpful for the pipes of 1-inch diameter
• 2-inch flow switch: of all kinds are for the tubes of 2 inches diameter
• 4-inch flow switch: is primarily suitable for the lines of 2 inches diameter
• 24-volt flow switch: is very common, and you can find it across a vast range of types and sizes of the flow switch. It includes rotatory, paddle, or electromagnetic flow switches that are useful in liquid and gas applications.

What are the types of flow switches for air and gas?

 

The airflow switch is helpful for filtering and supplying the air in the systems, duct heating, and venting the exhaust. Following are the types of the flow switch for gas and air:

• Paddle airflow switch: You can also name this flow switch as a vane-type switch. It is the mechanical sensor that is partially protruding into the duct for monitoring. The gases and air pass through the vent and physically keep moving the paddle place directly in the airflow channel. It triggers the action whenever the flow increases or decreases beyond the required rate.
• Air Flow Switches for boilers: primarily, the airflow switch in the boiler keeps monitoring the venting of the waste gases from the systems by the fans. The expelling of the gases has to be safe before the boiler fires up. The boiler airflow switch is mostly riggers to allow ignition after recognizing that the fans are spinning already at a particular speed. The airflow switch can detect if the fan is not working correctly and won’t permit the boiler to fire unless the issue is resolved.
• Paddle type flow switch: this type of flow switch is a mechanical one that gets activated by the pressure of the medium. Mostly the medium is liquid that passes through the channel where there is an insertion of a flow switch. The paddle is a small strip of steel or metal hanging in the pipe and attaching to the spring or the chain of magnets. In the resting position of the paddle-type flow switch, its opening or closing is dependent on the functionality of the flow switch, and any medium passing from the duct along the vital force moves the paddle of the flow switch. Finally, the flow switch proceeds to the second position for completing the circuit and triggers an action or the alarm.
• Thermal dispersion flow switch: This flow switch is the equipment in solid-state which means that there are no moving parts in it. A probe in the thermal flow switch gets inserted in the center of the flow in the pipeline. This probe heats up continuously by the input of an electrical wattage. The principle of thermal expansion permits the flow of gas and liquid to calculate how fast the heat is carried away by the flowing molecules. The amount of wattage is sent to the probe to maintain the constant temperature that gives value to calculate the flow rate accurately. The thermal flow switch is valuable due to its flexibility in measuring high and low flow rates and is easy to insert into the system.
• Oil flow switch: The working of the oil flow switch is similar to other types of liquid flow switches and is available in various configurations. The purpose of designing an oil flow switch is to use the oil and fuel and a less aggressive medium. Therefore, the oil flow switch mainly works at high temperatures and more robust sealing and housing.
• Ultrasonic flow switch: This is the famous type of non-intrusive flow switch that means you don’t need to penetrate this flow switch in the pipe to monitor the flow rate. Instead, you can clamp the ultrasonic flow switch outside the channel for reading the flow rate by pinging the signals back and forth from the sensors. The movements reflect and are refracted by the bubbles present in the steam before going back to the sensor. You can calculate the rate of the flow with the help of the doppler effect. The ultrasonic flow switch is mainly found in monitoring the waster water and another dirty medium.
• Mechanical flow switch: This kind of flow switch has more than one moving part triggers by the physical contact with the monitoring medium. Primarily, the mechanical flow switch works by the movement of the components, which completes the circuit and activates an action. A typical example of an automatic flow switch is a paddle-type flow switch. You have to test and maintain the mechanical flow switch regularly as the continuous movement of the parts can cause wearing and tearing that affects the working of the flow switch.
• PVC flow switch: The PVC flow switch is favorable where there is a need for quick confirmation regarding the status of the flow in visual form. This flow switch is economical to install and generally rugging in construction. The main reason for designing the PVC flow switch is to clean and maintain easily. In addition, it has good compatibility with the chemical and is anti-corrosive.
• Industrial flow switch: The industrial flow switch is more significant than other types of flow switches. They can handle the higher pressure, flow rates, and volumes. The design of the industrial flow switch is so that it can easily manage the highly aggressive and hazardous materials. In addition, the industrial flow switch prevents magnetic parts from working correctly with the water that might contain rust or other metal particles.
• Calorimetric flow switch: The working of the calorimetric flow switch is quite simple if you have the grips and the functions of relating with the equivalenting the thermal dispersion. There are two temperature sensors that the industrial flow switch. One is used for heating, and the other is for monitoring the suitable temperature of the medium existing in the channel. It would help if you calculated the flow rate while comparing the readings of both temperatures. There is a more negligible difference in the faster flowing medium because heat carries away from the hot sensor under faster flow rates.
• Pneumatic flow switch: The pneumatic flow switch helps control the passage of the air through the valves whenever the flow starts or stops. The air valve is essential for draining the pressure if the flow rate falls below the required level. The pneumatic flow switch is suitable for those applications where the differential pressure is significant between various ducting areas.
• Adjustable flow switch: Any device helps the user calibrate the flow setting without reassembling the unit. This task is usually done by the screw-driver with the flat head for opening/closing and adjusting the sensitivity of the paddle whose location is inside the housing of the flow switch.
• Rotatory flow switch: basically, the functionality of the rotatory flow switch is similar to the turbine in the form of multiple blades mounting entirely in the stream of the duct on the freely-spinning bearing. The rotatory flow switch registers the flow rate as the liquid passing through it.

Final thoughts:

The flow switch helps monitor the flow of the medium for a particular period or setting up for the total flow continuously. You can order a flow switch and fix it in your application as the flow switch has multi-purposes, so it also serves as an alarm for indicating flow and its rate. Instruthinkis manufacturing and supplying the flow switch to several industries according to their requirements. Instruthinkis the famous supplier of high-quality flow switches in UK and across the globe. So, no need to wait and think. Just contact us on your number or even fill an online for a quick quotation.