What Information Do You Need Before Ordering a Pressure Switch?

Last updated: August 3, 2026

TL;DR

Do not order a pressure switch based only on its appearance or pressure rating. Collect the manufacturer, complete part number, application, system requirements, connection information, electrical characteristics, operating environment, and required approvals. Final selection should follow the equipment manufacturer’s documentation, approved plans, and guidance from the qualified professional responsible for the system.

Why pressure-switch identification matters

Pressure switches are used in many different systems, including pumps, compressors, HVAC equipment, industrial machinery, process systems, and fire-protection equipment. Although two switches may look similar, they may have different functions, materials, electrical ratings, pressure ranges, connections, approvals, and environmental limitations.

Manufacturers use several criteria to identify an appropriate pressure switch. Danfoss, for example, asks users to identify the system, enclosure, reset function, connection size, and setting range in its industrial pressure-switch selector.

That does not mean customers should determine technical settings themselves. The safest approach is to collect the existing system information and have the final selection confirmed against manufacturer documentation and project requirements.

Pressure-switch ordering checklist

1. Identify the system and application

Start by describing what the switch is part of:

• Pump or water system
• Air compressor
• HVAC or refrigeration equipment
• Boiler or burner
• Hydraulic or pneumatic machinery
• Industrial process equipment
• Fire-sprinkler or fire-alarm system
• Alarm, shutdown, control, or supervisory system

This distinction matters. A switch designed for one application should not be assumed suitable for another.

For example, Potter’s PS15 and PS25 products are designed primarily to supervise pressure in automatic fire-sprinkler dry-pipe and preaction systems. They should not be treated as general replacements for HVAC, pump, compressor, or industrial controls. See Potter’s official information for the PS15 supervisory pressure switch and PS25 supervisory pressure switch.

2. Record the complete manufacturer and part number

The most useful information is usually found on the existing device label, equipment nameplate, approved plans, parts list, or manufacturer manual.

Record:

• Manufacturer
• Complete model or catalog number
• Series
• Revision or suffix
• Equipment model in which the switch is installed
• Any replacement or supersession information supplied by the manufacturer

Small differences in a part number can indicate different electrical contacts, pressure ranges, enclosures, materials, or approvals. Do not leave off letters or suffixes.

If a label is readable without opening equipment or entering a restricted area, take a clear photograph of the entire label.

3. Confirm the required pressure information

Provide the pressure range and operating requirements shown in the approved system documentation or equipment manufacturer’s instructions.

This may include:

• Pressure range
• Required operating point
• Reset requirements
• Differential or deadband
• Normal system pressure
• Maximum allowable pressure

Do not estimate these values from the existing dial position, a similar installation, or an online article. The system designer, equipment manufacturer, or qualified service professional should confirm them.

4. Identify what the switch is supposed to do

Pressure switches can serve different purposes. Determine whether the switch is intended to:

• Start or stop equipment
• Provide an alarm
• Initiate a shutdown
• Monitor high pressure
• Monitor low pressure
• Provide a supervisory signal
• Monitor pressure between two points

A control switch and a supervisory switch may respond to pressure but perform very different jobs.

5. Record the electrical information

Copy the electrical characteristics directly from the existing label, wiring diagram, approved plans, or manufacturer documentation.

Useful information may include:

• Supply or circuit voltage
• Contact rating
• Contact arrangement
• Number of switching circuits
• Electrical connection or conduit entry
• Required control signal or output
• Required certifications or approvals

Do not open electrical compartments to obtain this information unless you are qualified and authorized to do so. Electrical testing and wiring should be performed by qualified personnel.

6. Identify the pressure connection

Record the connection information shown in the documentation or on the existing device:

• Connection size
• Thread or connection type
• Male or female connection
• Mounting arrangement
• Any required adapter or accessory

A switch with the correct pressure range but the wrong connection may not be an acceptable substitute. Adapters should not be assumed appropriate without checking the equipment and manufacturer requirements.

7. Identify the material being monitored

The switch must be suitable for the material that contacts its pressure-sensing components. Examples may include:

• Air
• Water
• Steam
• Oil
• Refrigerant
• Hydraulic fluid
• Process chemicals
• Fire-suppression system air, nitrogen, or water

Material compatibility involves the switch’s wetted components, seals, diaphragm, pressure connection, and operating-temperature limits. Provide the exact medium and consult the manufacturer when compatibility is uncertain.

8. Document the operating environment

Tell the supplier where and how the device will be used:

• Indoors or outdoors
• Dry, damp, or wet area
• Dusty or dirty environment
• Washdown area
• Corrosive environment
• High- or low-temperature location
• High-vibration equipment
• Hazardous or classified location

Do not assume that any weather-resistant enclosure is suitable for every outdoor, corrosive, washdown, or hazardous application. Copy the exact enclosure and approval requirements from the equipment documentation, specifications, or approved plans.

9. Confirm required listings and approvals

Listings and approvals depend on the application. A general industrial control, fire-protection device, hazardous-location switch, and potable-water component may require different certifications.

Provide any requirements identified by:

• Equipment manufacturer
• Project engineer
• Approved plans
• Project specifications
• Local Authority Having Jurisdiction
• Fire-alarm or sprinkler-system documentation
• Facility safety or maintenance standards

A UL mark alone does not establish suitability for every system. The product must be listed or approved for its intended use.

10. Explain whether this is a direct replacement or a new application

Tell the supplier whether you are:

• Replacing an existing switch with the same part
• Replacing a discontinued product
• Repairing original equipment
• Changing the system’s operation
• Designing a new installation
• Working from an engineer’s or manufacturer’s specification

A direct replacement may still require confirmation if the original part has been discontinued or replaced by a newer model. New applications and system changes should be evaluated by the responsible designer or qualified professional.

What photographs should you provide?

Useful photographs may include:

• Complete exterior of the device
• Full product label
• Equipment nameplate
• Existing part number
• Accessible connection area
• Manufacturer wiring diagram supplied with the equipment
• Approved plan or parts-list reference

Do not remove guards, open energized equipment, reach into machinery, or access restricted components just to take a photograph.

Common ordering mistakes

Avoid these common problems:

• Ordering based only on appearance
• Matching only the pressure range
• Leaving suffixes off the part number
• Assuming all pressure switches perform the same function
• Substituting a general-purpose switch for a fire-protection device
• Ignoring the monitored medium
• Assuming an enclosure rating covers every environment
• Overlooking contact ratings or connection differences
• Selecting setpoints without approved system information
• Treating a manufacturer’s suggested replacement as automatically suitable

Special warning for fire-protection systems

Fire-sprinkler and fire-alarm pressure switches are specialized life-safety components. Their selection, settings, installation, testing, and connection to other systems must follow the approved design, manufacturer instructions, applicable standards, and local requirements.

Use the exact product specified or obtain approval for any substitution from the responsible fire-protection professional and Authority Having Jurisdiction.

What should you bring to Revco?

Before contacting Revco, gather:

• Manufacturer and complete part number
• Application and equipment type
• Equipment model number
• Photographs of accessible labels
• Required pressure information from approved documentation
• Electrical characteristics
• Pressure-connection information
• Monitored medium
• Environmental requirements
• Required listings or approvals
• Quantity and required date
• Name of the professional confirming the selection

Having this information available can help Revco identify possible products or obtain manufacturer documentation. Final approval remains with the equipment manufacturer, system designer, contractor, engineer, fire-protection professional, or other qualified person responsible for the system.

Call your preferred Revco branch before visiting to confirm availability.

About Revco Lighting & Electrical Supply

Revco Lighting & Electrical Supply has served Long Island since 1978. Revco operates six Suffolk County branches in Southampton, East Hampton, Southold, Riverhead, Bohemia, and Rocky Point. Each location has an electrical supply counter supporting contractors, facility teams, builders, and other customers with lighting and electrical products.

Find a Revco location or call 631-283-3600 for assistance.

Disclaimer

This article is a product-information checklist, not a system-design, selection, wiring, installation, testing, or calibration guide. Follow the equipment manufacturer’s instructions, approved plans, applicable codes, and the direction of the qualified professional responsible for the system.