What is the difference between a normally open and normally closed hydraulic solenoid coil?

Hey there! As a supplier of hydraulic solenoid coils, I often get asked about the difference between normally open and normally closed hydraulic solenoid coils. So, I thought I'd write this blog to break it down for you in a simple and easy - to - understand way.

First off, let's talk about what a hydraulic solenoid coil is. A hydraulic solenoid coil is a crucial component in many hydraulic systems. It's used to control the flow of hydraulic fluid by activating a solenoid valve. When an electrical current is applied to the coil, it creates a magnetic field that moves a plunger inside the valve, which in turn controls the fluid flow. You can learn more about Hydraulic Solenoid Coil on our website.

Normally Open Hydraulic Solenoid Coils

A normally open (NO) hydraulic solenoid coil is designed in such a way that the valve is open when there is no electrical current flowing through the coil. In other words, the path for the hydraulic fluid is unobstructed under normal, non - energized conditions.

Let's say you've got a hydraulic system that's part of a piece of construction equipment. When the machine is turned off and there's no power to the solenoid coil, the valve remains open. This means that hydraulic fluid can flow freely through the system. It's kind of like a door that's always propped open until someone closes it.

One of the main advantages of using a normally open solenoid coil is in safety - critical applications. For example, in some emergency shutdown systems, having a normally open valve ensures that in case of a power failure, the hydraulic fluid can still flow to perform essential functions like releasing pressure or moving a component to a safe position.

Another scenario where normally open coils are useful is in systems where you want the fluid to flow continuously unless you specifically need to stop it. For instance, in a simple hydraulic circuit that powers a conveyor belt, a normally open valve allows the belt to keep moving until you apply power to the coil to close the valve and stop the fluid flow.

However, there are also some drawbacks. If there's an unexpected power surge or electrical interference, the coil might get energized and close the valve when you don't want it to. This could disrupt the normal operation of the hydraulic system and potentially cause damage.

Normally Closed Hydraulic Solenoid Coils

On the flip side, a normally closed (NC) hydraulic solenoid coil has a valve that is closed when there's no electrical current. So, the flow of hydraulic fluid is blocked under normal, non - energized conditions.

Think of it as a locked door. The valve stays shut until you apply power to the coil, which then creates a magnetic field that opens the valve and allows the fluid to flow.

Normally closed solenoid coils are commonly used in applications where you want to control the start and stop of fluid flow precisely. For example, in a milking machine, a Milking Machine Solenoid Valve Coil is often a normally closed type. The valve remains closed until it's time to start the milking process. When power is applied to the coil, the valve opens, and the hydraulic fluid can operate the milking mechanism.

In industrial automation, normally closed solenoid valves are used to control the flow of coolant or lubricant in machinery. The valve stays closed until the machine needs the fluid, at which point the coil is energized, and the fluid starts flowing.

One of the benefits of using a normally closed coil is that it provides better control over the fluid flow. You can start and stop the flow at will, which is great for systems that require precise timing and regulation. But, just like with normally open coils, there are some downsides. If there's a power failure, the valve will remain closed, and the hydraulic system won't be able to function as intended. This could be a problem in systems where continuous fluid flow is necessary for normal operation.

Key Differences

Now, let's summarize the key differences between normally open and normally closed hydraulic solenoid coils:

1. Default State

• Normally open: The valve is open when there's no power, allowing fluid to flow freely.
• Normally closed: The valve is closed when there's no power, blocking the fluid flow.

2. Application Scenarios

• Normally open: Ideal for safety - critical applications and systems that require continuous fluid flow unless stopped.
• Normally closed: Best for applications that need precise control over the start and stop of fluid flow.

3. Response to Power Failure

• Normally open: The valve remains open, which can be beneficial in some safety - related situations but may cause issues if continuous flow isn't desired.
• Normally closed: The valve remains closed, which can disrupt normal operation if continuous fluid flow is necessary.

Choosing the Right Type

When it comes to choosing between a normally open and a normally closed hydraulic solenoid coil, you need to consider the specific requirements of your hydraulic system.

First, think about the function of the system. If it's a system that needs to keep running unless you actively stop it, a normally open coil might be the way to go. On the other hand, if you need to control the start and stop of fluid flow precisely, a normally closed coil is probably a better choice.

You also need to consider safety. In systems where a power failure could lead to dangerous situations, you need to choose a coil type that will ensure the system can still operate safely. For example, in a hydraulic braking system, you might want to use a normally open coil to ensure that in case of a power failure, the brakes can still be released.

Another factor is the cost. While the price difference between normally open and normally closed coils isn't usually huge, it's still something to keep in mind. Sometimes, the cost of the associated control circuitry and power supply can also vary depending on the coil type.

Our Range of Solenoid Coils

As a supplier, we offer a wide range of Solenoid Control Valve Coil options, including both normally open and normally closed hydraulic solenoid coils. Our coils are designed to meet the highest quality standards and are suitable for a variety of applications.

We understand that every hydraulic system is unique, and that's why we work closely with our customers to provide the right solutions. Whether you're in the construction, agriculture, or manufacturing industry, we've got the expertise to help you choose the perfect solenoid coil for your needs.

Contact Us for Your Hydraulic Solenoid Coil Needs

If you're looking to purchase hydraulic solenoid coils or have any questions about the difference between normally open and normally closed types, don't hesitate to get in touch. We're here to assist you with all your hydraulic solenoid coil requirements. Just reach out, and we'll start a conversation about how we can meet your specific needs.

References

• Fluid Power Handbook, various editions
• Industrial Hydraulic Systems: Design and Application by John C. Fitch