Flow switches are vital in regulating the flow in a controlled channel. In some cases, you use a flow switch to activate a response when the fluid level drops or rises beyond a marked point. An easy application of flow switches monitors the water in a water tank for residential or industrial uses.
However, there are regular switches and pressure switches. They look similar, but their uses make all the difference.
Pressure flow switches activate an alarm or response action when the pressure of fluid hits a certain level. Mainly, the response pressure is between 500PSI and 700 PSI. When the pressure gets to this level, the switch may switch on or off, activate the hot water burner, or any other action you intend to do with the flow switch.
From the above, you can see that a pressure flow switch is a tool you use to gauge the pressure of liquids and gases. The pressure indicates the force that you need to stop the fluid from expanding. A pressure switch serves the same purpose as a transducer. The pressure switch produces a signal as a sign of the pressure inflicted.
You can use pressure switches on many daily uses. It only depends on the type of application you have.
Pressure Measurement Types
You can class a pressure flow switch on the type of pressure test gauge, the pressure range, or heat levels. The following are the types of pressure you can use with a pressure-flow switch.
Absolute Pressure
The types of switches in these types of uses gauges a presumed perfect pressure. They are used in large industrial uses. They are best where constant referencing is needed. Some uses include industrial packaging, monitoring industrial pumps, industrial aviation control, aviation inspection, and liquid pressure gauging.
Vacuum pressure
The tool does not gauge pressure under a vacuum. Instead, it gauges the pressure below the absolute pressure. You can also use it to measure absolute pressure, similar to a vacuum.
Gauge Pressure
This is a switch that causes pressure relative to air pressure. One example of a gauge pressure switch is a tire pressure pump. When the readings are zero, it means the pressure within is equal to the ambient pressure. The gauge reading rises with the increase in pressure. Many gauge pressures can gauge up to 50 bar pressure.
Sealed Pressure
This tool is similar to gauge pressure. The only difference is that it gauges the pressure against static pressure.
Differential Pressure
This is a tool that gauges two different pressures at different points. The pressure change may be due to a change in cross-section area, a bend, or some changes in the fluid traits. You can use differential pressure flow switches to gauge pressure drop on flyers, flow rate, and fluid level. They are the most common pressure-flow switches in the market due to their demand.
Pneumatic Pressure Flow Control Valves
Pressure Sensing Technology
Pressure sensors are in two main classes. The first type is the force collector type. There are several subclasses under this type. The next category has no specific name. They are classified under “others.”
Force Collector pressure switches
These pressure switches gauge a strain through a force collector such as a piston, diaphragm, bellows, or bourdon tube. The strain is due to the pressure applied to an area. Piezoresistive force sensors use the piezoresistive effect to detect pressure. Also, it’s the most used type of sensing technology in use.
A capacitive sensor uses a diaphragm and pressure cavity to detect a strain. The pressure deforms the diaphragm causing the capacitance to decrease. You can use metal, silicon, or ceramic diaphragms.
Some materials like quartz need a unique sensor. Thus, you can use piezoelectric pressure sensors. The tech is helpful to gauge highly dynamic pressure. Note that you can not gauge any static pressure with this type of pressure-flow switch.
Electromagnetic pressure switches use the inductance to gauge pressure. Thus, you will need a magnet and a conductive fluid for the switch to function. The pressure readings increase with the increase in inductance.
Strain-gauge sensors use thin films to gauge the increase of strain due to pressure. It’s effective on low pressures due to the thin films. It can gauge the force that amounts to 15000 bar. They have electrical links that amplify the pressure signals, thus giving accurate gauge readings.
Optical sensing tech is useful in remote areas and areas under high heat levels. Also, the uses should be immune to magnetic fields. You use an optical fiber to detect the physical changes due to pressure.
Other Types
The other types include resonant switches and others. The resonant switch uses resonant frequency to sense the stress in an object.
You use the tech with a force collector. Also, you can use the switch directly with the media you are gauging. The frequency, in this case, will depend on the density of the fluid. The sensor can be a vibrating wire or cylinder, silicon MEMS, or quartz.
Thermal sensors depend on fluids’ voltage, while ionization sensors gauge the flow of charged gases through ions.
How To Select Pressure Flow Switches
There are a few features you should check when selecting pressure-flow switches. Below are the vital features.
Pressure
It would better if you had an idea of your maximum working pressure. Then select a flow switch that will work well with that pressure. Do not ignore the lowest pressure the switch can gauge.
Media
Some pressure-flow switches are helpful with both liquids and gases. But there are a few that are made for a specific media. You may limit your choices for the liquid media due to viscosity, density, and other fluid traits.
Heat Levels
Due to the material and sensing tech, heat levels are limiting factors to your flow switch choice. First, it’s due to the material of the switch. Sometimes, it may be due to the strength of the sensor.
Hysteresis
Every switch has a reset point and a switch point. Check the difference between the points before you make a choice. A large reset point makes the switch stay longer when it’s still on. Some people would prefer that kind of switch. But you may need a different hysteresis if you work with precision gauging.
Repeatability
First, the switch should be accurate. Then it should produce a repeatable, precise gauge reading for a long time. It should maintain precise gauging until the next calibration.
Applications
Pressure flow switches have a wide range of uses. They include:
- Water pumps in homes, farms, and commercial uses. They ensure there’s enough water pressure to push the water around the whole area of distribution.
- Well-pump pressure switches are for pumping water from a well. The water is useful for domestic, commercial, or irrigation uses.
- Vacuum pressure switches to check negative pressure in a system. You’ll find them in air compressors, boilers, electrical heaters, and transmission systems.
- Furnace pressure switches work with safety tools in commercial and residential buildings.
- Oil pressure switches check the pressure drop of the oil in an engine or hydraulic system.
- Generally, pressure flow switches check the pressure in a system’s air pressure.
Conclusion
Pressure Water flow switches play vital roles in several areas. They are great for setting pressure as well as cutting leakage and losses. You can use the proper selection criteria so that the tool is practical for your uses. Some knowledge of your firm’s needs will guide you to choosing the right tool.
