Danfoss KPS Pressure Switch | KPS 43, KPS 45, KPS 47 Guide
Danfoss KPS Pressure Switch | KPS 43, KPS 45, KPS 47 Guide
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:
| Parameter | Danfoss KPS 43 |
|---|---|
| Regulation range | 1–10 bar |
| Differential | 0.7–2.8 bar |
| Reset function | Auto |
| Pressure connection | G 1/4 |
| Enclosure rating | IP67 |
| Max. working pressure | 120 bar |
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:
| Parameter | Danfoss KPS 45 |
|---|---|
| Regulation range | 4–40 bar |
| Differential | 2.2–11 bar |
| Reset function | Auto |
| Pressure connection | G 1/4 |
| Enclosure rating | IP67 |
| Max. working pressure | 120 bar |
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:
| Parameter | Danfoss KPS 47 |
|---|---|
| Regulation range | 6–60 bar |
| Differential | 3.5–17 bar |
| Reset function | Auto |
| Pressure connection | G 1/4 |
| Enclosure rating | IP67 |
| Max. working pressure | 120 bar |
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
| Model | Regulation Range | Differential | Best-Fit Use |
|---|---|---|---|
| Danfoss KPS 43 | 1–10 bar | 0.7–2.8 bar | Lower-to-medium pressure pumps, utilities, air systems |
| Danfoss KPS 45 | 4–40 bar | 2.2–11 bar | Compressors, hydraulic systems, industrial pumps |
| Danfoss KPS 47 | 6–60 bar | 3.5–17 bar | High-pressure compressor, hydraulic, marine, power systems |
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
| Mistake | Why It Creates Problems |
|---|---|
| Selecting only by model number | Old model may not match current pressure requirement or connection need |
| Selecting the highest range by default | High range may reduce practical setting resolution for low-pressure systems |
| Ignoring differential | Can cause frequent cycling, delayed reset, or unstable control |
| Not checking pressure connection | Installation may need adapter or rework |
| Ignoring media compatibility | Seal or sensing element may not suit the application |
| Not checking IP rating and cable entry | Outdoor or wet installations may fail early |
| Directly switching high loads without checking contact rating | Can damage contacts or create unreliable switching |
| Not confirming datasheet before purchase | Wrong selection can delay commissioning |
Do This, Not That
| Do This | Not This |
|---|---|
| Select KPS model based on actual set pressure and reset pressure | Select only by price |
| Confirm differential requirement before ordering | Assume differential is not important |
| Match pressure connection and thread type | Leave fitting decision for installation day |
| Use relay or contactor logic where required | Overload the switch contact directly |
| Confirm media and temperature compatibility | Assume every pressure switch works with every fluid |
| Check datasheet before final purchase | Depend only on visual similarity |
Quick Selection Checklist
Before selecting Danfoss KPS 43, KPS 45, or KPS 47, confirm:
- Required pressure range
- Cut-in and cut-out pressure
- Required differential
- Media type
- Maximum working pressure
- Pressure connection size and thread
- Electrical contact requirement
- Cable entry and wiring method
- Installation environment and IP requirement
- 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.
