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A pressure switch is usually noticed only when something goes wrong: a pump does not cut off, a compressor keeps running, a boiler safety circuit trips, or a hydraulic unit gives unstable operation. In many factories, the mistake is not that a pressure switch was used. The mistake is that the wrong pressure range, reset type, differential, enclosure rating, or process connection was selected.

The Danfoss RT Series Pressure Switch is used in industrial and marine applications where pressure needs to trigger an electrical switching action. The RT range includes pressure switches, differential pressure switches, neutral-zone regulation switches, and safety pressure switches for specific boiler plant applications. Danfoss describes RT pressure switches as pressure-controlled, single-pole changeover switches where contact position depends on pressure at the connection port and the set value.

This guide focuses on commonly used RT pressure switch models available for industrial selection: Danfoss RT 5, RT 110, RT 112, RT 116, RT 121, and RT 200.

Below details are based on the available information. Final specification should be confirmed from the official datasheet before purchase.

What is a Danfoss RT Series Pressure Switch?

A Danfoss RT pressure switch is an electromechanical pressure switch used to make or break an electrical circuit when pressure reaches a set point. In simple words, it converts pressure condition into a switching command.

Typical use cases include:

• Pump ON/OFF control
• Compressor cut-in / cut-out control
• Hydraulic power pack protection
• Lubrication oil pressure monitoring
• Boiler and burner safety interlock
• Vacuum or suction pressure monitoring
• Alarm signalling to control panels
• Marine and industrial equipment protection

Most RT pressure switch models use SPDT contact function, which means the switch can be wired as normally open or normally closed depending on the control logic. For many control panels, this is useful because the same switch can be adapted for alarm, trip, interlock, or start-stop logic.

Why RT Series Selection Matters in Actual Plant Conditions

A pressure switch is not selected only by pressure range. The real selection depends on how the switch will behave when the system pressure rises or falls.

For example, a pump protection application may need automatic reset after pressure normalizes. A high-pressure safety application may require manual reset so the system does not restart without operator checking. A vacuum application needs a negative pressure range, while a compressor application needs a range that covers cut-in and cut-out points with the correct differential.

This is where many buyers make a mistake. They ask for “Danfoss RT pressure switch” but do not confirm:

• Required pressure range
• Cut-in and cut-out pressure
• Adjustable or fixed differential
• Auto reset or manual reset
• Process media
• Process connection
• Enclosure rating
• Electrical load
• Panel wiring logic
• Whether the switch is for control, alarm, or safety

A purchase team may compare price, but the maintenance team will face the result if the switch trips incorrectly or does not reset as expected.

Danfoss RT Series Models Covered

Danfoss RT 5

Danfoss RT 5 is useful when the application requires pressure switching in a higher range compared to low-pressure models. It is often considered where pressure rise must be monitored and a manual maximum reset is preferred so the system does not restart without operator attention.

Technical points to note:

• Regulation range: 4–17 bar
• Differential: 1.2 bar
• Contact function: SPDT
• Reset function: Manual Max
• Pressure connection: G 3/8 male
• Enclosure rating: IP54
• Maximum working pressure: 22 bar
• Confirm exact code and variant before ordering

Where it is commonly used:

• Air compressor systems
• Hydraulic power packs
• Pump discharge pressure monitoring
• Industrial machinery protection
• Utility pressure panels
• High-pressure alarm circuits

Danfoss RT 110

Danfoss RT 110 is suitable for low-pressure applications where the system must not resume operation automatically after pressure drops below a set point. This is useful in protection logic where low pressure indicates a fault condition.

Technical points to note:

• Regulation range: 0.2–3 bar
• Differential: 0.08 bar
• Contact function: SPDT
• Reset function: Manual Min
• Pressure connection: G 3/8 male
• Enclosure rating: IP54
• Maximum working pressure: 7 bar
• Useful where low-pressure fault must be manually acknowledged

Where it is commonly used:

• Lubrication oil pressure protection
• Low-pressure pump circuits
• Burner or boiler auxiliary systems
• Compressor auxiliary pressure monitoring
• Industrial safety interlocks
• Control panel alarm circuits

Danfoss RT 112

Danfoss RT 112 is better suited when the pressure range is low and automatic reset is acceptable. It is practical for low-pressure control or alarm applications where the switch should return to normal after pressure recovers.

Technical points to note:

• Regulation range: 0.1–1.1 bar
• Differential: 0.07–0.16 bar
• Contact function: SPDT
• Reset function: Auto
• Pressure connection: G 3/8 male
• Enclosure rating: IP66
• Maximum working pressure: 7 bar
• Better suited where pressure recovery can automatically restore the contact condition

Where it is commonly used:

• Low-pressure pump systems
• Air or water pressure monitoring
• Utility pressure alarms
• HVAC auxiliary pressure monitoring
• Industrial process panels
• Low-pressure control circuits

Danfoss RT 116

Danfoss RT 116 is a practical medium-pressure switch for applications where the operating set point falls within the 1–10 bar range. It is useful for pump control, compressor auxiliary control, and general industrial pressure monitoring.

Technical points to note:

• Regulation range: 1–10 bar
• Differential: 0.33–1.3 bar
• Contact function: SPDT
• Reset function: Auto
• Pressure connection: G 3/8 male
• Enclosure rating: IP66
• Maximum working pressure: 22 bar
• Suitable for common industrial pressure bands

Where it is commonly used:

• Pump pressure control
• Compressor pressure monitoring
• Hydraulic auxiliary circuits
• Industrial water systems
• Utility pressure panels
• Process equipment pressure alarms

Danfoss RT 121

Danfoss RT 121 is used when the process condition is below atmospheric pressure. This makes it suitable for vacuum or suction-side monitoring where normal positive-pressure switches are not suitable.

Technical points to note:

• Regulation range: -1 to 0 bar
• Differential: 0.09–0.4 bar
• Contact function: SPDT
• Reset function: Auto
• Pressure connection: G 3/8 male
• Enclosure rating: IP66
• Maximum working pressure: 7 bar
• Selected specifically for vacuum / negative pressure conditions

Where it is commonly used:

• Vacuum systems
• Pump suction monitoring
• Filter blockage indication
• Process suction lines
• Packaging machinery vacuum circuits
• Industrial utility vacuum panels

Danfoss RT 200

Danfoss RT 200 is a general-purpose pressure switch for lower-to-medium pressure applications where the range is around 0.2–6 bar. It is commonly considered for pump, air, water, and utility pressure switching.

Technical points to note:

• Regulation range: 0.2–6 bar
• Differential: 0.25–1.2 bar
• Contact function: SPDT
• Reset function: Auto on one common variant
• Pressure connection: G 3/8 male
• Enclosure rating: IP66
• Maximum working pressure: 22 bar
• Confirm exact code, because reset function may vary by product variant

Where it is commonly used:

• Pump control systems
• Water pressure monitoring
• Compressor auxiliary circuits
• Industrial utility panels
• Air pressure control
• Process pressure alarms

Key Selection Factors for Danfoss RT Pressure Switches

1. Pressure Range

The selected pressure switch range should comfortably cover the actual operating set point. Do not select a switch where the set point is at the extreme edge of the scale.

2. Differential

Differential is the gap between switching point and reset point. Too small a differential may cause frequent switching. Too large a differential may delay response.

3. Reset Type

Auto reset is useful for normal control. Manual reset is better for safety or fault conditions where operator inspection is required.

4. Contact Function

Most models listed here use SPDT contact logic, useful for panel wiring as NO or NC depending on alarm or control requirement.

5. Enclosure Rating

IP66 is better for harsh, dusty, humid, or outdoor-type locations than IP54, but exact site conditions should always be checked.

6. Process Connection

The listed models commonly use G 3/8 male connection, but confirm whether your installation needs an adapter, isolation valve, siphon, snubber, or gauge cock.

7. Media Compatibility

Confirm whether the switch is being used with air, water, oil, steam, refrigerant, or another process media. Media temperature and compatibility must match the datasheet.

8. Electrical Load

Check whether the switch is switching a relay/contactor coil, PLC digital input, alarm circuit, or direct load. Use interposing relays where needed.

Common Applications

Danfoss RT Series pressure switches are commonly used in:

• Air compressors
• Industrial pumps
• Hydraulic power packs
• Boiler and burner systems
• Marine machinery
• HVAC and utility systems
• Lubrication oil pressure monitoring
• Water treatment systems
• Process pressure alarms
• OEM machine panels
• Control and safety interlock panels

Common Mistakes to Avoid

Do This, Not That

Quick Selection Checklist

1. Confirm whether the application is pressure, vacuum, or differential pressure.
2. Note the normal operating pressure, alarm point, cut-in, and cut-out pressure.
3. Select the correct pressure range with margin.
4. Confirm required differential.
5. Decide whether auto reset or manual reset is required.
6. Check SPDT wiring logic for PLC, relay, contactor, or alarm panel.
7. Verify process connection and adapter requirement.
8. Confirm IP rating and installation environment.
9. Check media compatibility and temperature condition.
10. Confirm exact Danfoss product code and datasheet before ordering.

Specifications to Confirm Before Purchase

Before buying any Danfoss RT Series pressure switch, confirm:

• Exact model and product code
• Pressure regulation range
• Differential range
• Reset function: auto, manual minimum, or manual maximum
• Contact function and contact rating
• Process connection size and type
• Maximum working pressure
• Maximum test pressure
• Enclosure rating
• Ambient temperature range
• Media temperature range
• Media compatibility
• Electrical cable entry
• Mounting arrangement
• Required approval or certification
• Compatibility with PLC, relay, contactor, alarm, or safety circuit

Why Buy from Radical TechMart?

At Radical TechMart, the focus is not only to supply the product, but to help customers select the right instrument for the right application.

For Danfoss RT Series pressure switches, correct selection matters because the same product family includes different pressure ranges, reset types, enclosure ratings, and application roles. A buyer may ask for Danfoss RT 116 or RT 200, but the final choice should depend on actual process pressure, switching logic, installation environment, and maintenance requirement.

Radical TechMart can support OEMs, factories, system integrators, panel builders, EPC contractors, MRO teams, and process industries with product selection, pricing, availability, datasheet support, and technical inquiry guidance.

Final Thoughts

The Danfoss RT Series is a strong choice for industrial pressure switching, but the right model must be selected by application logic. RT 5, RT 110, RT 112, RT 116, RT 121, and RT 200 are not interchangeable just because they belong to the same series. Each model fits a different pressure band, reset requirement, and control purpose.

In industrial applications, the right pressure switch is not selected only by price or model number. It is selected by understanding the process, the pressure range, the switching logic, the environment, and the final control requirement.

FAQs

1. What is the use of Danfoss RT Series pressure switch?

Danfoss RT Series pressure switches are used to switch an electrical contact when pressure reaches a set value. They are commonly used in pumps, compressors, hydraulic systems, boiler plants, marine systems, and industrial control panels.

2. What is the difference between Danfoss RT 116 and RT 200?

RT 116 is commonly selected for 1–10 bar applications, while RT 200 is commonly selected for 0.2–6 bar applications. Final selection should be based on set pressure, differential, reset type, and exact product code.

3. Which Danfoss RT model is suitable for vacuum applications?

Danfoss RT 121 is suitable for vacuum or negative pressure applications because it has a regulation range of -1 to 0 bar.

4. Can Danfoss RT pressure switches connect to PLC panels?

Yes, RT pressure switches with SPDT contacts can be wired into PLC digital inputs, relay circuits, alarm panels, or contactor control circuits, provided the wiring and electrical rating are suitable for the application.

5. What does manual reset mean in a pressure switch?

Manual reset means the switch will not automatically return to normal after pressure recovers. Operator action is required. This is useful in safety or fault conditions where automatic restart may not be desirable.

6. Is Danfoss RT 5 suitable for high-pressure applications?

RT 5 has a 4–17 bar regulation range and 22 bar maximum working pressure in the listed Danfoss data, making it suitable for higher pressure applications within its rating. Confirm the final datasheet and exact product code before purchase.

7. What should be checked before buying a Danfoss RT pressure switch?

Check pressure range, differential, reset type, contact rating, process connection, IP rating, media compatibility, working pressure, electrical wiring, mounting, and exact product code.

Buy Danfoss Products here
A pressure switch usually gets attention only when a machine stops, a compressor trips, a pump fails to cut off, or a pressure alarm does not operate at the right time.

In many plants, the purchase team searches for a replacement pressure switch by matching only the model number. But in actual plant conditions, that is not enough. The pressure range, differential, reset function, enclosure protection, pressure connection, contact rating, media compatibility, vibration level, and installation location all decide whether the switch will work reliably.

This is where the Danfoss KPS pressure switch range becomes important for industrial applications. The KPS Series is commonly selected for pressure monitoring, alarm, and control duties in compressors, pumps, hydraulic systems, boilers, marine systems, diesel plants, power plants, and factory utilities. Danfoss describes the KPS range as suitable for indoor and outdoor applications, while its industrial pressure switch family is used in alarm and regulation systems across factories, diesel plants, compressors, power stations, and ships.

This guide explains how to choose between Danfoss KPS 43, Danfoss KPS 45, and Danfoss KPS 47 based on actual pressure range and application need.

What is a Danfoss KPS Pressure Switch?

A Danfoss KPS pressure switch is an electromechanical pressure control device used to open or close an electrical contact when system pressure reaches a set point.

In simple words, it converts pressure change into an electrical switching action.

It can be used for:

• Pressure alarm
• Compressor start/stop control
• Pump protection
• Hydraulic pressure monitoring
• Boiler pressure alarm
• Marine pressure control
• Process pressure safety interlock
• Control panel relay logic

Unlike a pressure transmitter, a pressure switch does not continuously send a 4–20 mA or digital pressure signal. Instead, it gives a switching output when pressure crosses the set value. That makes it useful where the requirement is alarm, trip, interlock, or ON/OFF control rather than continuous pressure indication.

Why KPS Pressure Switch Selection Matters in Actual Plant Conditions

A wrong pressure switch can create problems that are not visible during purchase but become serious during commissioning or maintenance.

For example, if a compressor needs switching around 35 bar but the selected pressure switch has a low range, it may not operate correctly. If the differential is too narrow, the compressor may cycle too frequently. If the differential is too wide, the system pressure may fall too much before restart. If the enclosure is not suitable for dusty, wet, or outdoor conditions, the switch may fail early.

The Danfoss KPS 43, KPS 45, and KPS 47 look similar as a product family, but they are not interchangeable for every pressure condition. The major selection difference is the operating pressure range and differential band.

How Does a KPS Pressure Switch Work?

A pressure switch senses pressure through its pressure connection. When the pressure rises above the set value, the internal mechanism changes the electrical contact position. When the pressure falls by the selected differential value, the contact returns to its original state.

For KPS pressure switches other than KPS 31, contacts 1–4 make and contacts 1–2 break when pressure rises above the set range value; the switch changes back when pressure falls to the range value minus the differential.

This makes the switch useful for practical control logic such as:

• High pressure alarm
• Compressor cut-out
• Pump stop at upper pressure
• Hydraulic system pressure supervision
• Boiler pressure safety alarm
• Pressure interlock in control panels

The important point is that the set pressure and differential must be selected according to the actual process requirement, not only by the maximum pressure rating.

Danfoss KPS Series Product Selection

Danfoss KPS 43 Pressure Switch

The Danfoss KPS 43 is suitable when the system pressure falls in the lower-to-medium industrial pressure range. It is useful for applications where the control or alarm point is within a 1 to 10 bar range.

Technical points to note:

The above KPS 43 details are listed by Danfoss for model 060-410566 / KPS43, including 1–10 bar regulation range, 0.7–2.8 bar differential, G 1/4 connection, IP67 enclosure rating, and 120 bar maximum working pressure.

Where it is commonly used:

• Pump pressure control
• Air pressure monitoring
• Utility pressure alarm
• Low-to-medium pressure compressor systems
• Water treatment pressure lines
• OEM machine pressure interlocks

Danfoss KPS 45 Pressure Switch

The Danfoss KPS 45 is suitable when the pressure requirement is higher than the KPS 43 range. It is a good fit for medium-to-high pressure industrial systems where the set point falls between 4 and 40 bar.

Technical points to note:

Danfoss lists the KPS45 with 4–40 bar regulation range, 2.2–11 bar differential, auto reset, G 1/4 pressure connection, IP67 enclosure rating, and 120 bar maximum working pressure.

Where it is commonly used:

• Compressor pressure control
• Hydraulic system pressure monitoring
• Pump discharge pressure control
• Industrial process pressure alarm
• Power plant auxiliary systems
• Marine and diesel plant applications

Danfoss KPS 47 Pressure Switch

The Danfoss KPS 47 is suitable for higher pressure industrial applications where the set point is between 6 and 60 bar. It is better suited when the pressure level is beyond the comfort zone of KPS 43 and KPS 45.

Technical points to note:

Danfoss lists the KPS47 with 6–60 bar regulation range, 3.5–17 bar differential, auto reset, G 1/4 pressure connection, IP67 enclosure rating, and 120 bar maximum working pressure.

Where it is commonly used:

• High-pressure compressor protection
• Hydraulic power packs
• Power plant pressure systems
• Marine pressure applications
• Industrial safety interlock panels
• Heavy-duty pump and pressure systems

Quick Comparison: Danfoss KPS 43 vs KPS 45 vs KPS 47

Key Selection Factors for Danfoss KPS Pressure Switches

1. Pressure Range

First confirm the actual working pressure, alarm pressure, cut-in pressure, and cut-out pressure. Do not select the switch only by maximum pressure. The set point should fall comfortably inside the regulation range.

2. Differential

Differential is the gap between switching point and reset point. If differential is too small, the switch may chatter or cycle frequently. If it is too large, the system may operate over an undesirable pressure band.

3. Media Compatibility

Confirm whether the switch will be used with air, gas, oil, water, hydraulic fluid, or another process medium. Always check media compatibility with the official datasheet before purchase.

4. Pressure Connection

The listed models use G 1/4 pressure connection in the Danfoss store data. Confirm whether your installation needs G 1/4, adapter fitting, manifold connection, or a different thread standard before ordering.

5. IP Rating and Installation Area

The listed models show IP67 enclosure rating, which is useful for dusty, wet, or outdoor-like industrial environments. Still, confirm actual installation exposure, cable gland sealing, and panel location before final selection.

6. Contact Rating and Control Circuit

Check whether the pressure switch will directly switch a load, relay, contactor coil, alarm circuit, or PLC digital input. For PLC input use, contact type and wetting current should be confirmed.

7. Vibration and Pulsation

Compressors, pumps, hydraulic systems, and diesel systems may create pulsation. Use proper mounting, snubber, siphon, or isolation accessories if needed.

8. Replacement Fitment

For replacement jobs, match the old model number, pressure range, differential, connection, cable entry, and mounting arrangement. Do not assume all KPS models are direct replacements.

Common Applications

Danfoss KPS Series pressure switches are commonly used in:

• Air compressors
• Hydraulic power packs
• Pump control panels
• Boiler pressure alarm systems
• Marine engine room systems
• Diesel plant utilities
• Power plant auxiliary systems
• Process pressure alarm panels
• Water treatment pressure lines
• OEM machine safety interlocks
• Industrial automation panels
• Factory utility systems

Common Mistakes to Avoid

Do This, Not That

Quick Selection Checklist

Before selecting Danfoss KPS 43, KPS 45, or KPS 47, confirm:

1. Required pressure range
2. Cut-in and cut-out pressure
3. Required differential
4. Media type
5. Maximum working pressure
6. Pressure connection size and thread
7. Electrical contact requirement
8. Cable entry and wiring method
9. Installation environment and IP requirement
10. Datasheet, pricing, availability, and replacement compatibility

Specifications to Confirm Before Purchase

Below details should be confirmed from the official datasheet before final selection:

• Regulation range
• Differential range
• Reset function
• Pressure connection
• Contact function
• Contact rating
• Max. working pressure
• Burst pressure
• Enclosure rating
• Ambient temperature
• Media compatibility
• Cable entry
• Mounting arrangement
• Accessories such as snubber, siphon, adapter, or isolation valve
• Suitability for compressor, pump, hydraulic, boiler, marine, or process application

Specifications may vary depending on exact code and variant. Please confirm the datasheet before final selection.

Why Buy Danfoss KPS Pressure Switches from Radical TechMart?

At Radical TechMart, the focus is not only to supply the product, but to help customers select the right pressure switch for the right application.

For a pressure switch, wrong selection can affect compressor cycling, pump control, alarm reliability, hydraulic safety, and plant uptime. Radical TechMart can support buyers with model comparison, range selection, datasheet support, pricing, availability, and application guidance for industrial pressure control products.

This is especially useful for:

• Maintenance replacement
• OEM panel building
• Compressor panel projects
• Pump automation
• Hydraulic power pack systems
• EPC procurement
• Industrial MRO purchase
• Factory utility upgrades

Final Thoughts

The Danfoss KPS pressure switch should not be selected only by brand or model number. The real selection depends on the pressure range, differential, connection, environment, switching logic, and application.

For lower-to-medium pressure applications, KPS 43 is often the practical choice. For medium-to-high pressure compressor and hydraulic applications, KPS 45 fits better. For higher pressure systems, KPS 47 gives the wider range needed for demanding industrial duty.

In industrial applications, the right pressure switch is selected by understanding the process, the set point, the reset point, the environment, and the final control requirement.

FAQs

1. What is the use of a Danfoss KPS pressure switch?

A Danfoss KPS pressure switch is used for pressure alarm, pressure control, compressor cut-in/cut-out, pump protection, hydraulic pressure monitoring, and industrial safety interlock applications.

2. What is the difference between Danfoss KPS 43, KPS 45, and KPS 47?

The main difference is pressure range. KPS 43 covers 1–10 bar, KPS 45 covers 4–40 bar, and KPS 47 covers 6–60 bar. The differential range also increases from KPS 43 to KPS 47.

3. Which Danfoss KPS pressure switch is suitable for high pressure applications?

For higher pressure applications, Danfoss KPS 47 is usually the model to evaluate because it has a 6–60 bar regulation range and 3.5–17 bar differential range.

4. Can Danfoss KPS pressure switches be used in compressor systems?

Yes, KPS pressure switches are commonly used in compressor pressure control and pressure alarm applications. The correct model depends on compressor operating pressure and required differential.

5. What is differential in a pressure switch?

Differential is the pressure gap between switching action and reset action. It prevents rapid ON/OFF cycling and helps maintain stable pressure control.

6. Is Danfoss KPS suitable for outdoor or dusty industrial areas?

The listed KPS 43, KPS 45, and KPS 47 models show IP67 enclosure rating in Danfoss product data, which supports use in demanding environments. Final suitability should still be checked against the actual installation condition.

7. What should I check before buying a Danfoss KPS pressure switch?

Check pressure range, differential, reset function, pressure connection, media compatibility, contact rating, IP rating, cable entry, and exact datasheet code before purchase.