Understanding what is a pressure switch and how does a pressure switch work

Sandy Zhang

Vice President Of DeepMaterial For Epoxy Adhesive,UV Adhesive,Pur Adhesive

Published Nov 19, 2020

Understanding The Basics of Pressure Switches

There is no doubting the fact that pressure switches have become far more popular than they were in the past. There are lots of applications using them (both domestic and industrial) to ensure better functionalities. This has made experts to predict that in the nearest future, most products will include pressure switches in one way or another. The problem is that most people are yet to understand how these switches work. Without this knowledge, you will be taking shots in the dark. In other words, you will guessing about its functionalities and features.

Are you trying to find out how pressure switches have been built to function? Do you know that without proper understanding of such switches, it will be very difficult to make the most of them? There is no need to rack your brains as you have definitely come to the right place. The major aim of this post is to help you understand everything about pressure switches. The details you will discover below can help you make a decision about whether to include pressure switches in your project or not. There are lots of hidden facts about these switches and you will soon discover them below.

What is a pressure switch?

There have been lots of misconceptions about pressure switches amongst people. For instance, there are those who believe that these switches are the same as conventional switches. This is not correct in any way as you will soon find out. Pressure switches are used in breaking or making electrical circuit once a particular pressure has been reached. Its primary use of is to carry out detection of fluid pressure (presence). In other words, any pressure switch you find will always have a sensing element that helps in the process of detecting whether the set amount of pressure has been reached or not.

In simple terms, pressure switches are devices used in detection of changes in the amount of pressure. There is always a predetermined level the pressure is expected to reach before being detected. This is known as set point. At such stage, the electricity can either flow or stop. It is a situation when the contacts can either be open or closed. The use of pressure switches in industrial settings is to ensure safety amongst workers. For instances, most industries have machines that regulate automatically. That is to say, they can go off or start working on their own without being operated manually by anyone.

The process of such machines working and stopping automatically is made possible through the presence of pressure switches. They detect when a particular pressure has been reached. Such is the point when the machine can either start functioning or be interrupted. A typical example is a company which uses a machine that requires cooling off after some time. It is with the aid of a pressure switch that the time for such cooling off can be determined. In this case, it detects when there is a change in pressure to either allow circuit breakage or flow of electricity thereby making such application to continue working.

Advantages/benefits of pressure switches

Just as mentioned above, the use of pressure switches is becoming more rampant as compared to previous years. Companies are starting to see reasons why they cannot do without these switches based on what they can achieve when included in applications. Are you doubting the potentials of pressure switches? Below are some of the advantages you can experience once it is used today.

Easy installation

This is one of the reasons why pressure switches are becoming very popular as companies seem to be exploring their options in recent times. They can be easily installed as compared to traditional switches which monitor changes. It means you do not need any special skill or knowledge to understand how they can be installed for usage in any application. Even when it seems a little bit complicated, you only need to take out time in order to understand such type of pressure switch. This will help you know how it can be easily installed without any problem.

Generally, pressure switches have been built in such a way that you can get a grasp of how they work without having to rack your brains. For instance, you need to understand its various components like knob (lever), terminals, contacts, diaphragm, relief valve, and adjustment springs. Once you can understand how these parts have been designed to function in a pressure switch, the process of installation will be much easier than you thought. Also, you can easily have the components dismantled and re-installed.

High level of Accuracy

Before the advent of pressure switches, there were the conventional detecting or sensing switches which checked whether changes had occurred in applications or not. However, these were not accurate as compared to what pressures switches offered. Such brought about a situation whereby companies were still vulnerable to problems that can arise due to their machines being under or over pressure. This simply means they are likely to suffer losses due to the high level of uncertainty caused by inaccurate devices used in monitoring pressure levels.

This is one problem that pressure switches have been created to help companies solve. They have detecting devices that ensure machines will either start or stop working once the setpoint has been reached. They have very high level of accuracy in carrying out such detection process. Companies therefore, do not have to worry anymore about their applications breaking down due to too much pressure. Through this, work activities will definitely not be interrupted in any way. Simply, pressure switches do not give room for the occurrence of parallax error.

Automatic functioning

A pressure switch brings about automation in the way an application works. For instance, have you seen how an air conditioner functions? Did you notice that it stops working after some time? This is because the setpoint has been reached. It is the duty of its pressure switch to detect whether such has been reached or not. Through its presence, you will not have to bother about going to get such application turned off since detection will be automatic.

Therefore, it can be said that the presence of a pressure switch helps to ensure that applications are automated with regards to how they work. It is the same even in pumping machines used in producing water for homes and other environments. The presence of pressure switches ensure that such machines can stop once water has been pumped up to a certain level. In this case, there will be interruption or breakage of circuit.

High level Safety

One of the reasons why companies prefer the idea of using pressure switches in their applications is to ensure safety practices within the work environment. When machines start experiencing overheating, there is the risk of breakdown issues occurring. The worst part is that the safety of workers is likely to be endangered. This is probably why pressure switches have gained popularity. They help to detect changes in pressure in order to avoid any danger that may want to arise.

In case you have been thinking about how to ensure the safety of your workers while they operate a machine, the use of pressure switch makes such possible. It will detect the changes that pressure is changing and regulate how such machine works over a given period of time. This simply means you do not have to bother about problems on machines experiencing overheat. A device such as this can save you lots of money in the long run. For instance, it plays the role of a safety valve thereby venting out pressure once it has exceeded its setpoint.

What are the types of pressure switches?

Now that you have known what pressure switches are including the benefits they can offer when used, there is no doubt that you must be eager to purchase one from the market today. Although this is good, there is a right and wrong way to about it. The first and most important thing you need to understand about these switches is the fact that they are of different types. Therefore, it is very crucial to know the various types in order to identify the one that can meet your needs today when used in an application. Below are the different types of pressure switches you will likely come across.

Electromechanical Pressure Switches

These types of pressure switches are very popular amongst people. There are two components present in them – snap action and sensing element. It is the sensing element or sensor which has the role of detecting whether pressure change has occurred in relation to the setpoint or not. In other words, it can check whether the maximum or minimum amount of pressure in an application has been exceeded or not.

The snap action is the lever or knob component. It is the part responsible for determining whether the switch will maintain a close or open contact state once changes in pressure has been detected. Please note that all of these will happen automatically when the switch has been installed.

Differential pressure switches

These switches are a little bit different from what has been explained above. For instance, they are characterized by the presence of two ports. While one is for high pressure, the other is for low pressure. There is a sensing element which tends to control both the high and low pressure fluids. In a situation whereby the pressure is maintaining an equilibrium state, it can be said that both sides have the same amount of surface areas.

Once there is an increased amount of pressure on the high side, the amount of pressure on the low side will automatically decrease. The piston is going to move upwards thereby having the snap action activated. It should be noted that there are different types of sensor technology in pressure switches. As a matter of fact, this is what defines how they carry out their functions.

Categories of switches you should know

Switches are of different categories. Understanding how they are grouped will help you make the most of a pressure switch.

Diaphragm Switches

These are switches which have been made with metal diaphragm (weld-sealed). A snap-action is what the diaphragm actually acts on. Some of its characteristics will be listed below:

• Low rate of cycle (not up to 25 cycles per minute)

• It has a repeatability of ±1%

• The pressure is up to around 10.43

Tube Switches

These switches have been made with bourdon tube (weld-sealed). It is responsible for having the snap-action switch actuated. Its characteristics are:

• Pressure between 3.45 and 1241.06 bar

• Repeatability of around ±1%

• Cycle rates that are very low. They are not up to 25 cycles for every minute

Diaphragm Piston

This diaphragm is elastomeric and tends to act on a piston in order to get the snap action switch actuated.

• The vacuum pressure is around 110.32 psi

• Its repeatability is around ±2%

• It has around 2.5million cycles

Once you can understand the categories of switches, your decision about which pressure switch to make use of will become much easier.

Solid-State Pressure Switches

These types of pressure switches came into existence in the year 1980 after being introduced by Barksdale. It has developed in recent times into something with multiple switch points, analog, and digital displays outputs. They are also characterized by full programmability. The functions or roles of these switches have gone beyond what people know them for over the years. This is because they can also be used to switch open-loop controllers.

They can ensure the circuits in pressure switches are closed or opened. Furthermore, they can provide digital or analog output signal that will facilitate the operation of an application or machine. It is possible for the analog signal to interface with computers, distributed control systems (DCSs), and Programmable Logic Controls (PLCs). It should be noted that the major advantage can be traced to their life cycles. For instance, solid-state switches have been known to have higher level of durability as compared to others above. They cycle are around 100million. This represents their operational life.

Advantages of solid-state switches

As compared to electromechanical switches, solid-state switches have some advantages/benefits. This is why they are used in most appliances. Some of them are:

Longer life

This is one of the most notable advantages of solid state switches. They have very long life cycle to ensure you do not need to bother about when to have them replaced. For instance, their operational cycle is around 100million.

Improved accuracy

There is no better way to check the level of pressure change like using solid-state switches. This is due to the high level of accuracy they are known for. In other words, they accurately detect situations which require open or close contact.

Highly resistant to vibration and shock

Solid-state switches ensure much higher level of safety in different environments where machines are used. If you have a company and want to ensure everyone is safe, these switches are perfect. This is because of how they have been built to be vibration and shock resistant. The safety of such environment or surrounding is guaranteed.

Durability

Solid-state switches have been designed to work for the long term. This is what makes them highly reliable for most applications, machines or systems.

Electronic pressure switch

Although the solid-state switches have been very popular over the years, technology seems to be advancing on a regular basis. This has led to the innovation of electronic pressure switches. It is a game-changer that will aim to revolutionalize how pressure switches function when used in machines and applications given its impressive features.

Electronic pressure switches are proving to more effective than the other types of switches mentioned above. For instance, they are perfect for both indoor and outdoor usage. Also, they are highly flexible with regards to how outputs are displayed. The bottom line is that these pressure switches takes how change in pressure is measured to a whole new level which otherwise would not have been possible.

How does a pressure switch work?

Just as explained above, pressure switches are existing to sense or detect changes in pressure levels. However, most people usually find it very confusing when it comes to the aspect of how pressure switches work. Below are some of the details to help know more about these switches.

For a much better illustration, well pumps will be used. It is important to note that every pressure switch can either be operated as NO (normally open) or NC (normally closed). Their major use is to provide response to change in fluid pressure. In other words, as fluid pressure tends to be changing, that is how they will be making adjustments automatically.

In the case of oil pumps, pressure switches play the role of regulating how machines will work over a given period of time. This is done through having to monitor whether pressure has reached its setpoint or not.

Normally open and normally closed

Every pressure switch you will come across is either normally closed or normally open. These are contacts that determine when a machine or application will start or stop working once the adjusted setpoint has been reached. Another system which uses pressure switch is pumping machine for producing water that you make use of for various purposes outside and within your home. You will notice that these machines are operated automatically.

The reason for this is that they can detect when water level has gone down and needs to be pumped. On the other hand, they can also detect when water level has reached its highest point thereby pumping process needs to be suspended or interrupted temporarily.

The maximum or minimum amount of water level is known as the set point. It is that stage whereby the pumping machine will either start or stop pumping water for usage. When the water level is at minimum, the pressure switch will be at normally closed thereby allowing water to be pumped through the flow of electricity. On the other hand, there is a situation of circuit breakage when there will not be flow of electricity thereby making the pumping machine to stop working.

At this point, you have to understand that water pressure is strongly relied upon for the job to be done as expected. You will notice that based on this explanation, these switches are designed to check how pressure will be changing in such application from one period of time to another.

Another instance

Air conditioners also make use of pressure switch. This is to ensure that the system is properly monitored to avoid any kind of damage to their compressors. Air conditioners have been designed to stop working automatically after some time. This is the role carried out by pressure switches as they detect when the setpoint has been reached. For instance, an AC can have room temperature cooled up to a particular degree after which it will then switch off.

You will notice that it starts working after some time when the minimum setpoint has been reached. In these cases, there is usually a change of contacts. In the first case when the AC stops working due to the room becoming too cold, it has reached its maximum setpoint. The normally open is going to be activated. Once this happens, the AC will stop working.

In the second instance whereby minimum setpoint is reached, the pressure switch normally closed contacts will be activated thereby making the AC to start working again. It will continue like this over and over again. There will not be any need of having the AC turned on/off as it is regulated by the presence of a pressure switch. The same way that pressure switches function in air conditioners, that is how they work in heating systems.

The bottom line is that whenever a pressure switch stops working, know that its normally open contacts have been activated. On the other hand, when it is working, the normally closed contacts are activated.

What are the different uses of pressure switch?

The use of pressure switch is becoming more popular than ever before. As a matter of fact, engineers have discovered that they can be used in lots of ways as compared to the past when they were limited to a few applications. In case you have been trying to find out about how pressure switches are put to use, ensure to check out the details below. They will help you understand the different scenarios that these switches can be of help.

Water heaters

This is another important use of pressure switches which most people are not used to. Sometimes you are forced to think that pressure switches are only used in industrial appliances. This is not true in any way as they can also be used in household appliances with water heaters being one of such. Without pressure switches in these appliances, water will heat continuously until there is explosion or some other danger that can lead to injury.

The role of pressure switch in them is to ensure water is heated to a particular point whereby it will be turned off automatically. The point where it gets turned off is where the normally open contacts are activated. In other words, it is the point where electricity flow is interrupted thereby ensuring the heater stops working.

At this point, heat will be released up to a certain degree before the normally closed contacts will become activated. This will then make the heater to start working. With the advent of pressure switches in water heaters, it has helped to avoid the danger of people being exposed to water that is excessively hot.

Safety device

Do you know that pressure switches can also be used in safety devices? Are you aware that without it, your riding lawn mower becomes unsafe to make use of? Once your weight is heavy enough to have its seat pressed down up to the extent of depressing the button which is beneath, such mower is going to crank as the key is turned on. This will make the engine start running.

On the other hand, once you get up from its seat, the button is not going to be depressed again. This means the engine will stop working. In this case, the mower is going to be automatically shut off. It is a process that does not require you to do anything else apart from having to sit on the mower for the engine to function.

You will be wondering how pressure switch can ensure your safety in riding lawn mowers. It is simple to understand as you will be protected from getting injured once you ever fall off from such mower. It means you will not suffer any injury as a result of the engine running continuously since it has been stopped automatically due to you getting up from the seat.

If you happen to be using such device in an environment where there are children, it will help your mind to be at rest knowing that the engine cannot be started at will. This is because there is a particular amount of pressure which needs to be generated before the engine can start. If the child does not have the required weight, its engine will not start.

Well pump machines

These machines are used in pumping water for various purposes. Most people are not aware of the fact that these applications make use of pressure switches more than any other. Have you ever noticed that they can stop working after pumping water for some period of time? If you observe closely, you will see that they are always stopping and starting after some time. This function could not have been possible without the help of a pressure switch.

It has the role of detecting when water has been pumped to its highest or lowest point. Pressure switch in this case can help ensure avoidance of a situation whereby the pumping machine is prone to excessive pressure. For instance, without such switch being installed, there is every chance that a pumping machine will work continuously without stopping. This puts it in a danger of breaking down at any time. In order to avoid such scenario, the use of pressure switches to determine the chance of water pressure has become very important.

Uses in automobiles

Do you know that without the presence of pressure switch it will be difficult for your car to function as expected? As a matter of fact, these switches are used in ensuring that you do not have to visit a professional mechanic every now and then looking for how to repair your engine. For instance, if your vehicle does not have enough or adequate oil pressure, there could be problem later on. This means your engine may knock down thereby leading to disappointment and spending of more money in the long run.

The most crucial component in the engine of every car is oil. Without its presence, your engine will get damaged. Apart from oil shortage, there is also likely to be problem when too much oil is in your car. This can affect the engine. Through the presence of a pressure switch, these problems can be addressed properly. It senses the pressure level of oil and provides output signal to help ensure your engine is running smoothly.

Pressure cookers

One of the reasons why pressure switches are included in household items is to ensure safety. Have you ever imagined what can happen when a pressure cooker works without any interruption? It simply means apart from your food getting burnt, there could be explosion in your home thereby leading to injuries. This is one of the reasons why pressure switches are included in pressure cookers.

With a pressure switch installed, pressure cookers will regulate the rate at which they work through open or closed contact. For instance, they can work up to a point and stop until after some time before starting again. They will help in checking or detecting the level of pressure changes in such device.

Pressure switch problems you should know

The problems affecting pressure switches can take various forms depending on the application it is being used in. There are some times when the problem may even appear to be connected with such pressure switch. However, in the real sense it is not. This section will be looking at some of the problems of pressure switches in water pumps and air compressors.

When the application or machine does not turn off

Have you ever noticed that your appliance or machine which used to regulate automatically, is working continuously? This is a clear sign that your pressure switch is faulty. It is common in pumping machines and can lead to such system overworking thereby breaking down eventually. For instance, pressure switches are built to detect changes in pressure levels as explained above. In a pumping machine, it is expected to detect whether the setpoint has been reached in order to stop or start working at regular intervals.

This means there will be times when normally closed contacts or normally opened contacts will be activated. However, due to one fault or another, such may not be possible as the machine will refuse to switch off automatically. A problem like this exposes such machine to experiencing damage.

In a pressure cooker, the role of such switch is to ensure whatever is being cooked is regulated. In other words, it reaches a point and switches off automatically without the aid of anyone. This to avoid a situation of burnt food or even explosion. When the pressure switch is faulty, it becomes difficult for the process of switching off and on at regular intervals to occur.

Wear and tear

This is common in the case of air compressors since they make use of air pressure to function effectively. One of the major causes of this problem is that such switch must have depreciated. In other words, the wear and tear factor has set in. It does not really matter as every pressure switch will stop working at some point in time.

At such point, the best solution is to have it replaced by an expert. Even if it is installed in your pumping machine, you still need to find a way of replacing it. In this case, there are some problems that can be experienced. These could be such pump not turning on/off the setpoint pressure, low water pressure despite the pump running and more.

Replacing such pressure switch is the best solution to address any problem related to wear and tear. Sometimes, the components can be replaced to help it function well again. Although this will save you some money, it is only a short term fix.

Failure of machine to start

Pressure switch has a crucial role to play when it comes to determining whether machines or applications will start or not. For instance, in a compressor, the appliance may not start once the pressure switch is faulty. This is one symptom of faulty pressure switches that most people are yet to understand in recent times. In this case, the pressure goes below the setpoint and the machine or compressor is expected to start.

However, it fails to start. In this case, there is every chance to suspect a depreciated pressure switch. It also could be that the components have not been connected properly. This problem is likely to be experienced in situations when your machine is repaired. There is every chance that its components have not been properly fixed with pressure switch being one of such.

Loose electrical connections

As simple as this may sound, it is responsible for over 50% of cases related to pressure switch failure. This is why you need to ensure your pressure switch has been connected by a professional. Most of the time, the process may seem more technical than imagined. In such case, you need an expert who understands how to put together all the components of such machine without any guesswork.

When the connections are loose, two things will likely happen in most cases to your application or machine. These are either they will not work at all as expected or you will notice they are stopping and starting abruptly. It is very important to check the connections whenever there is an issue of pressure switch not working. This will save you the stress of replacing parts or components that are functioning properly.

Troubleshooting for pressure switch

Once you have noticed that your machine or appliance is not working as expected, the next step will be to find out what has actually gone wrong. The steps below will be of great help in lots of regards when it comes to detecting the fault in a pressure switch.

Switching off the device

This is the first step you have to take while trying to find out what must have gone wrong with a device. The reason for this is safety since you are prone to electric shock. This is even more important when it has to do with a water pumping machine.

Checking for leakages

This is for water pumps. There is a higher chance of your pressure switch not working well once there are leakages. Even when it does work, there is every possibility that it will not start and stop at the setpoint.

Check the switches

This is usually for a device such as riding lawn explained above. The engine is usually triggered by pressure switch. This is why you need to check whether the switch is in a great condition. For instance, if the switch contacts are not making physical contact whenever necessary, it will not work as expected.

Conclusion

The above details are a pointer that there are lots of facts you need to understand about pressure switches before making a decision to purchase them. The facts will ensure that you end up making a reasonable decision about which pressure switch to install in your machine.

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