Danfoss RT Pressure Switch | RT 5, RT 110, RT 112, RT 116, RT 121, RT 200
Danfoss RT Pressure Switch | RT 5, RT 110, RT 112, RT 116, RT 121, RT 200
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
| Model | Typical Selection Meaning |
|---|---|
| Danfoss RT 5 | Higher pressure control applications where manual maximum reset may be required |
| Danfoss RT 110 | Low-pressure monitoring where manual minimum reset is needed |
| Danfoss RT 112 | Low-pressure automatic reset applications |
| Danfoss RT 116 | Medium-pressure automatic reset applications |
| Danfoss RT 121 | Vacuum / negative pressure applications |
| Danfoss RT 200 | General 0.2–6 bar pressure control applications |
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
| Mistake | Why It Creates Problems |
|---|---|
| Selecting only by model number | Old installation may have used a variant that is not ideal for the current application |
| Ignoring reset type | Auto reset and manual reset behave differently in safety circuits |
| Not checking differential | Wrong differential can cause short cycling or delayed switching |
| Choosing the wrong pressure range | Accuracy and switching behavior may suffer near scale extremes |
| Ignoring IP rating | Dust, humidity, and outdoor exposure can reduce switch life |
| Not checking process connection | Installation may require adapter or isolation accessory |
| Using switch output like transmitter output | Pressure switches give relay/contact action, not continuous 4–20 mA pressure signal |
| Not confirming datasheet | Product codes and variants can change selection details |
Do This, Not That
| Do This | Not This |
|---|---|
| Select the model based on actual set point and differential | Select only by “RT Series” name |
| Confirm auto reset or manual reset requirement | Assume every pressure switch resets automatically |
| Use RT 121 for vacuum range applications | Use a positive pressure switch for suction/vacuum service |
| Confirm enclosure rating and installation area | Install IP54 model in a wet or harsh area without checking |
| Check wiring with PLC, relay, or contactor logic | Assume contact rating and wiring are always suitable |
| Confirm exact Danfoss code before purchase | Order only from partial model name |
Quick Selection Checklist
- Confirm whether the application is pressure, vacuum, or differential pressure.
- Note the normal operating pressure, alarm point, cut-in, and cut-out pressure.
- Select the correct pressure range with margin.
- Confirm required differential.
- Decide whether auto reset or manual reset is required.
- Check SPDT wiring logic for PLC, relay, contactor, or alarm panel.
- Verify process connection and adapter requirement.
- Confirm IP rating and installation environment.
- Check media compatibility and temperature condition.
- 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.
