7 Key Factors to Consider When Selecting a Pressure Switch

Selecting the right pressure switch is a critical engineering decision that directly affects the safety and uninterrupted operation of an industrial system. An incorrectly selected pressure switch can lead to premature failures, inaccurate switching, and even serious safety risks. In many field applications, a significant proportion of equipment failures are not caused by the product itself, but by choosing a model that is unsuitable for the application. In this article, we examine seven essential factors to consider when selecting the right pressure switch, supported by practical examples.

1. Switching Range and Operating Pressure

Every pressure switch is designed to operate within a specified pressure range, and this range should comfortably cover the actual operating pressure of the system. Continuously operating a switch close to its minimum or maximum limits can reduce switching accuracy while shortening its mechanical service life.

Although products such as the MT Series, with operating ranges from 5 bar to 600 bar, are suitable for a broad range of applications, pressure fluctuations within the system should always be taken into account during product selection.

In applications such as pump discharge lines or hydraulic cylinders, where sudden pressure surges are common, selecting a switch with an adequate safety margin above the normal operating pressure helps prevent unexpected failures. For this reason, both the average operating pressure and the maximum peak pressure of the system should be considered.

2. Switching Differential

The switching differential refers to the difference between the pressure at which the switch activates and the pressure at which it resets. If the differential is too narrow, excessive switching may occur; if it is too wide, the responsiveness of the system may be reduced.

Selecting either a fixed or adjustable differential according to the application’s sensitivity requirements is essential for maintaining stable system performance.

For example, a narrow differential may be appropriate for compressor shut-off applications, whereas a wider differential is often preferable in hydraulic systems operating under continuously varying loads, as it extends contact life and reduces unnecessary wear.

Pressure switches with adjustable differentials offer greater flexibility during commissioning, making them particularly suitable for prototype installations or pilot production lines.

3. Connection Type and Thread Size

Connection options such as side-entry block connections, bottom-entry block connections, or G1/4″ threaded fittings should be selected according to the physical installation requirements and the connection standards used within the existing system.

Choosing an incorrect connection type may require additional adaptors, increasing both installation costs and the number of potential leak points. Existing piping specifications should always be reviewed before selecting a connection configuration.

Side-entry connections are generally preferred where installation space is limited, while bottom-entry connections provide a practical solution for vertical installations. Union-type connections simplify maintenance where frequent removal and reinstallation are required.

It is equally important to ensure that thread specifications, sealing washers, and gasket types are fully compatible with the existing installation.

4. Contact Configuration and Electrical Characteristics

Electrical interface options—including NO/NC contact arrangements, Faston terminals, or DIN 43650A connectors—must be compatible with the control system being used.

The pressure switch’s rated voltage and current should also meet the electrical requirements of the connected control circuit. Electrical incompatibilities are among the most common issues discovered only after installation, often resulting in costly modifications.

For PLC-based automation systems, pressure switches designed for low-current digital inputs are generally preferred. In applications involving direct contactor control or other higher-current circuits, the contact rating must always be carefully verified.

Selecting an unsuitable contact configuration can eventually lead to contact welding or sticking, significantly reducing overall system reliability.

5. Environmental Conditions and Protection Rating

Environmental factors such as humidity, dust, vibration, and exposure to chemical vapours make selecting the appropriate IP protection rating essential.

Pressure switches installed outdoors or in production environments subject to frequent wash-down procedures require higher levels of protection than those operating in clean, controlled indoor environments.

Ignoring environmental conditions can cause equipment to fail much earlier than expected.

In food and beverage processing plants, for example, frequent high-pressure cleaning procedures make high-IP-rated products almost essential.

Similarly, in applications close to compressors or electric motors where vibration levels are high, mounting accessories and vibration-damping components should also be carefully considered.

6. Material Compatibility and Corrosion Resistance

The wetted parts of the pressure switch must be chemically compatible with the process fluid.

Where aggressive chemicals, saline environments, or hygienic applications such as food processing and pharmaceuticals are involved, stainless steel or specially coated housings should be selected.

Material incompatibility may eventually result in seal degradation, leakage, and inaccurate switching performance.

In coastal facilities or installations near cooling towers where humidity levels are consistently high, stainless steel pressure switches generally offer significantly lower long-term maintenance costs than standard steel alternatives.

Selecting a pressure switch before fully understanding the chemical properties of the process medium may lead to costly operational problems later.

7. Certification and Documentation

For facilities operating within regulated industries, complete CE documentation and supporting technical documentation are not optional—they are essential.

Always request operating manuals, technical data sheets, and CE Declarations of Conformity from your supplier. These documents simplify inspection procedures while providing confidence that the product meets its declared performance specifications.

Comprehensive technical documentation is valuable not only for regulatory compliance but also for clarifying warranty responsibilities and liability should equipment failure occur.

Although uncertified products may appear more economical initially, they often introduce significantly greater long-term risks.

Frequently Asked Questions

One of the most common questions concerns whether replacing an existing pressure switch with a different product series requires additional installation work.

Provided the connection type and electrical interface remain compatible, replacement can usually be completed without additional adaptors. Where different connection standards are involved, suitable adaptor kits and sealing components generally allow straightforward installation.

Another frequently asked question is whether more than one pressure switch should be installed on the same system.

In safety-critical applications, using two independent pressure switches for redundant monitoring is a well-established engineering practice that helps maintain system safety should one switch fail.

The Importance of Working with the Right Supplier

Selecting the correct technical specifications is only part of the process. Working with a reliable supplier is equally important for achieving long-term performance.

A manufacturer capable of providing technical consultancy, application-specific recommendations based on field experience, and responsive after-sales support can significantly reduce selection errors while minimising downtime should issues arise.

At PNOTOL, we are committed to supporting our customers throughout every stage of their project—from product selection and system design through to commissioning and ongoing technical support.

Conclusion: The Right Selection Delivers Long-Term Reliability

Selecting a pressure switch involves far more than choosing a single technical specification. Switching range, connection type, environmental conditions, material compatibility, and certification requirements should all be evaluated together to achieve the most reliable solution.

Making the right product selection reduces operating costs, improves system safety, and enhances long-term reliability. Equally important is receiving expert technical guidance throughout the selection process.

With our MT and GT Series Pressure Switches, PNOTOL provides reliable pressure switching solutions backed by professional technical support for a wide variety of industrial applications.