20/40 vs 30/50 Pressure Switch [How To Choose The Right One For Your Application]

Pressure switches are one of the most common and important components used in pneumatic and hydraulic systems across various industrial applications. They are used to control and regulate compressed air and fluid power systems by activating or deactivating pumps, valves, and other devices when preset pressure levels are reached.

There are two common types of pressure switches categorized by their pressure settings – 20/40 and 30/50. As the names imply, 20/40 pressure switches turn on at 20 psi and off at 40 psi, while 30/50 switches turn on at 30 psi and off at 50 psi. Both have their specific advantages and limitations depending on the application requirements.

Choosing the right pressure switch for an application is crucial for optimal performance and efficiency. This article will compare 20/40 and 30/50 pressure switches, their key differences, pros and cons, typical applications, and tips for selecting the right pressure switch for your needs.

Here is an updated in-depth comparison table for 20/40 vs 30/50 pressure switches:

What is a Pressure Switch?

Before diving into the comparison between 20/40 and 30/50 pressure switches, let’s first understand what a pressure switch is and how it works.

How a Pressure Switch Works

A pressure switch is an electromechanical device that operates an electric circuit in response to a change in pressure. It contains a flexible diaphragm or bellows and a snap-acting switch.

When the pressure rises to a preset limit, the diaphragm expands activating the electric switch contacts. This completes the circuit, sending a signal to turn “on” a pump, valve, alarm or other device.

When the pressure drops below a preset limit, the diaphragm contracts, deactivating the switch contacts, breaking the circuit, and turning the device “off”. This main function of turning devices on and off based on preset pressure levels provides automatic regulation and control of pneumatic and fluid power systems.

Types of Pressure Switches

There are several types of pressure switches that work on this same principle but have different pressure settings, construction, performance specifications, and applications. The main types include:

• Electromechanical Pressure Switches – The most common type, uses the expandable diaphragm mechanism. Provide on/off control at preset high and low pressures. Used across industrial applications.
• Electronic Pressure Switches – Use a piezoresistive sensor and solid-state switch instead of mechanical contacts. Allow tighter pressure control and computer interface. Used for precise control systems.
• Explosion Proof Pressure Switches – Built with enclosures that prevent ignition of flammable environments in chemical, oil and gas applications.
• High Pressure Switches – Constructed with high strength materials allowing higher max pressure up to 6000 psi. Used in hydraulic systems.
• Vacuum Switches – Activated by drops in negative pressure below a preset vacuum level. Used for vacuum packaging machines.

20/40 vs 30/50 Pressure Switches

Now that we have covered the basics of how a pressure switch works, let’s compare the specific differences between the two most common types – 20/40 and 30/50 pressure switches.

20/40 Pressure Switches

• Turn on at 20 psi, turn off at 40 psi
• Differential pressure range is 20 psi
• Withstand system pressure up to 250 psi max
• Typically used in applications with operating pressures up to 175 psi
• Provide the best energy efficiency for applications in their pressure range
• Used for control of air compressors, process control, and spray painting systems

30/50 Pressure Switches

• Turn on at 30 psi, turn off at 50 psi
• Differential pressure range is 20 psi
• Withstand system pressures up to 300 psi max
• Best used in applications with operating pressures between 175-300 psi
• Preferred for higher pressure hydraulic systems and larger air compressors
• Used in high pressure washer systems, hydraulic power units, and industrial automation.

Key Differences

The main differences between 20/40 and 30/50 pressure switches are:

• Operating pressure range: 20/40 are designed for lower pressure pneumatic systems up to 175 psi. 30/50 are built for higher pressure between 175-300 psi.
• Maximum system pressure: 20/40 max out at 250 psi. 30/50 can withstand up to 300 psi.
• Energy efficiency: 20/40 operate more efficiently in their intended lower pressure range.
• Cost: 20/40 pressure switches tend to be less expensive than 30/50 models.
• Applications: 20/40 for lower pressure control applications. 30/50 for higher pressure hydraulic systems.

Choosing Between 20/40 and 30/50

To select the right pressure switch, you need to evaluate your application requirements, operating costs, and installation factors. Here are some tips on choosing between 20/40 vs 30/50 pressure switches:

Application Requirements

The operating pressure range and maximum system pressure rating are the primary factors.

• For applications using less than 175 psi, a 20/40 switch is likely optimal. This includes air compressor control, paint spraying, process control systems, etc.
• For hydraulic systems and equipment operating at 175-300 psi, a 30/50 switch is required to handle the higher pressures.
• Verify the pressure switch maximum rating exceeds the system maximum pressure with a safety factor. An undersized switch can fail prematurely.

Cost Considerations

In general, 20/40 pressure switches will be less expensive than 30/50 models with the same features and specs. However, it is wise to compare pricing for specific models. Less expensive may not always mean the best value.

Evaluate costs over the long term accounting for:

• Energy efficiency – 20/40 operate more efficiently in lower pressure range
• Expected lifespan – quality components may cost more but last longer
• Maintenance needs – look for durable, simple construction with minimal maintenance

Installation Factors

Installation requirements may dictate one type over the other.

• Available space – 20/40 switches tend to have a more compact footprint
• Accessibility for wiring, inspection, service – ease of installation
• Exposure to vibration, shock, temperature extremes – robustness and ratings

Also ensure the pressure switch is suitable for the fluid media in the system – air, water, oil, chemicals, etc. Media compatibility must be verified.

This covers the key factors in determining whether a 20/40 or 30/50 pressure switch is right for an application. Properly sizing and selecting these devices is crucial for optimal operation and safety. Consult pressure switch manufacturers for recommendations and always verify ratings against your specific operating conditions.

Pros and Cons of Each Type

To further understand the differences between 20/40 and 30/50 pressure switches, let’s examine the unique pros and cons of each type.

20/40 Pressure Switch Pros and Cons

Pros:

• Lower differential pressure provides more precision control in lower range pneumatic systems
• Energy efficient performance in intended operating range up to 175 psi
• Compact size takes up less space
• Lower costs than 30/50 models
• Work well in dirty or wet environments
• Easy installation and maintenance

Cons:

• Not suitable for pressures over 175 psi
• Shorter lifespan compared to heavier duty 30/50 models
• Low maximum pressure rating provides less safety margin in overpressure conditions

30/50 Pressure Switch Pros and Cons

Pros:

• Withstand higher system pressures up to 300 psi
• More heavy duty and robust construction
• Tighter pressure tolerance and repeatability
• External access to set point adjustment
• Some models offer additional features like pressure gauges and status lights
• Longer lifespan suitable for continuous duty

Cons:

• More expensive than 20/40 models
• Larger size and footprint
• Not energy efficient when operating below 175 psi
• Overkill for low pressure pneumatic systems below 175 psi

As you can see, both types have their advantages and disadvantages. Choosing the right one depends on matching the pressure switch capabilities to the application requirements.

Typical Applications

Here are some examples of typical applications suited for 20/40 and 30/50 pressure switches:

When to Use 20/40

• Air compressor control
• Process control systems
• Conveying and packaging equipment
• Spray painting systems
• Pneumatic tool control
• Air powered pumps and equipment
• Opening and closing pilot operated valves
• Operating pneumatic cylinders
• Low pressure wash-down systems
• Vacuum packaging machinery

When to Use 30/50

• Hydraulic power units
• High pressure machine automation
• Clamping systems
• Molding press operation
• Lifting equipment like jack lifts
• Pressure washer and cleaners
• Test stand regulation
• Air compressor control above 175 psi
• High pressure pneumatic systems
• Hydrostatic transmission and braking systems
• Hydraulic cylinder control

These examples demonstrate when it is advantageous to use a 20/40 switch for lower pressure control applications vs a 30/50 switch for higher pressure hydraulic systems.

The specific pressure settings required and the maximum system pressures will determine which type of switch is the proper selection. Additionally, consulting pressure switch manufacturers for product recommendations based on your operating conditions is advised.

In the final part of this article, we will provide a summary and conclusion of the key takeaways when deciding between 20/40 and 30/50 pressure switches.

FAQs

What is the main difference between a 20/40 and 30/50 pressure switch?

The main difference is their operating pressure range. 20/40 switches are designed for lower pressure pneumatic systems up to 175 psi. 30/50 switches are built for higher pressures from 175-300 psi typical of hydraulic systems.

When should I use a 20/40 pressure switch?

Use a 20/40 switch for applications using less than 175 psi of pressure. They provide optimal performance and energy efficiency for lower pressure pneumatic systems while being compact and cost effective.

When should I use a 30/50 pressure switch?

Use a 30/50 pressure switch for applications operating in the 175-300 psi range. Their heavy duty construction allows them to withstand higher system pressures typical of hydraulic equipment.

Can a 30/50 switch be used for low pressure applications?

Yes, a 30/50 pressure switch can operate at lower pressures. However, they are less energy efficient when operating below 175 psi and the higher costs may not justify the benefits.

What happens if I undersize the maximum pressure rating?

Undersizing the pressure switch rating can lead to premature failure or malfunction. It is critical to choose a switch with a maximum rating well above the actual system pressure to provide a safety margin.

How do I determine the required pressure settings?

Analyze the application to determine the pump or compressor on and off pressures needed for proper operation and control. Consult pressure switch suppliers and equipment manufacturers for recommendations based on your system.

Conclusion

Deciding whether a 20/40 or 30/50 pressure switch is best suited for an application depends on several key factors we have covered in this article.

Properly sizing and applying either 20/40 or 30/50 pressure switches ensures optimal pressure control and efficient operation. Matching the capabilities to your requirements while accounting for all factors will provide the best value and return on investment.

With this overview of how they differ and guidelines for selection, you should now be able to choose the right pressure switch for your specific needs. Reach out to suppliers to discuss your application requirements and operating conditions to determine the recommended models. Investing in properly installed, quality pressure switches will provide effective pressure control and protection for your pneumatic or hydraulic system.