PST6/21N-K1/K PSP6/21N-K1/K DUPLOMATIC Pressure Switch 650 bar

Product Overview

The PS/PST series piston-type pressure switches are electro-hydraulic piston-type pressure switches engineered by DUPLOMATIC (Italy) for industrial hydraulic and mobile machinery applications. When system pressure reaches the set value, line pressure acts on the piston, overcoming spring force to actuate a microswitch and switch the electrical contact.

The PS/PST series covers multiple models including PSP2, PST2, PSP4, PST4, PSP6, and PST6, offering 4 pressure adjustment ranges (35 / 140 / 350 / 630 bar) with subplate mounting or 1/4″ BSP threaded connections. Standard configuration includes adjustment knob with pressure scale. Seal material options include NBR (code N) or FPM (code V).

Our complete range of DUPLOMATIC pressure switches strictly adheres to OEM technical standards, achieving 100% direct interchangeability with original components. Every unit undergoes 100% simulated operating condition bench testing prior to shipment, ensuring performance parameters are fully consistent with genuine DUPLOMATIC products. Direct replacement significantly reduces equipment downtime and maintenance costs.

⚠️ Brand and Model Attribution Note:

• PSP2/21N-K1/K, PSP4/21N-K1/K, PSP6/21N-K1/K belong to the DUPLOMATIC PSP series piston-type pressure switches (subplate mounting)

• PST2/21N-K1/K, PST4/21N-K1/K, PST6/21N-K1/K belong to the DUPLOMATIC PST series piston-type pressure switches (1/4″ BSP threaded port)

⚠️ Model Code Decoding:

• PSP / PST = Piston-type Pressure Switch

• 2 / 4 / 6 / 8 = Pressure adjustment range code (2 = 3–35 bar; 4 = 6–140 bar; 6 = 10–350 bar; 8 = 20–630 bar)

• 21 = Design series (Series 21)

• N = Seal material (N = NBR; V = FPM)

• K1/K = DIN 43650 electrical connection and contact configuration

Technical Specifications 

PS/PST Series General Specifications

• Product Series: DUPLOMATIC PS/PST series piston-type pressure switch

• Product Type: Electro-hydraulic piston-type pressure switch

• Brand: DUPLOMATIC

• Design Series: Series 21

• Maximum Operating Pressure: 650 bar

• Pressure Adjustment Ranges:

  • PS*2: 3 – 35 bar

  • PS*4: 6 – 140 bar

  • PS*6: 10 – 350 bar

  • PS*8: 20 – 630 bar

• Repeatability: < ±1% of set pressure

• Mounting Type: PSP = Subplate mounting; PST = 1/4″ BSP threaded port

• Seal Type: NBR (N) or FPM (V)

• Compatible Hydraulic Fluids: ISO 6743-4 HL/HM mineral oil

• Ambient Temperature Range: -20°C to +80°C

• Fluid Temperature Range: -20°C to +70°C

• Electrical Connection: DIN 43650 square connector

• Ingress Protection: IP65

• Mass: Approx. 0.67 kg

• Subplate Codes: 1950611 (A/B port connection), 1950621 (P port connection)

Model Specifications Overview

• PSP2/21N-K1/K: Subplate mounting, 3–35 bar adjustment range, 350 bar max pressure

• PST2/21N-K1/K: 1/4″ BSP threaded port, 3–35 bar adjustment range, 350 bar max pressure

• PSP4/21N-K1/K: Subplate mounting, 6–140 bar adjustment range, 350 bar max pressure

• PST4/21N-K1/K: 1/4″ BSP threaded port, 6–140 bar adjustment range, 350 bar max pressure

• PSP6/21N-K1/K: Subplate mounting, 10–350 bar adjustment range, 650 bar max pressure

• PST6/21N-K1/K: 1/4″ BSP threaded port, 10–350 bar adjustment range, 650 bar max pressure

Key Technical Advantages

1. Piston-Type Mechanical Structure for High Reliability and EMI Immunity
The PS/PST series features a piston-type mechanical structure where system pressure acts directly on the piston, overcoming spring load to actuate the microswitch. The purely mechanical structure does not require external power for pressure detection and contact switching, delivering exceptional reliability and immunity to electromagnetic interference—ideal for industrial environments with stringent EMC requirements.

2. 4-Stage Wide-Range Pressure Adjustment for Flexible Adaptation
Offers 4 pressure adjustment ranges (3–35 bar / 6–140 bar / 10–350 bar / 20–630 bar), covering complete application needs from low to ultra-high pressure. Precise set-point adjustment via rotary knob with integrated pressure scale—standard configuration includes adjustment knob and pressure scale, no additional tools required for on-site setting.

3. Ultra-High Pressure Resistance and Two Mounting Options
Maximum operating pressure up to 650 bar, compatible with the vast majority of high-pressure hydraulic systems. Supports both subplate mounting (PSP series) and 1/4″ BSP threaded connections (PST series) . PSP series can be stacked on ISO 4401-03 (CETOP 03) standard subplates with codes 1950611 and 1950621 available.

4. High Repeatability and Long Service Life
Repeatability < ±1% of set pressure ensures accurate pressure detection and consistent performance across multiple cycles. Both mechanical and electrical components are manufactured from high-quality materials for long-term reliable operation. Seal material options include NBR or FPM, compatible with ISO 6743-4 HL/HM mineral oils and HFD-R phosphate ester fluids.

5. 100% Direct Interchangeability and Simulated Condition Testing
All models strictly adhere to DUPLOMATIC original mounting dimensions and interface standards (ISO 4401-03 / CETOP 03), enabling direct drop-in replacement of original pressure switches without piping modification or system adjustment. Every unit undergoes 100% simulated operating condition bench testing prior to shipment, ensuring consistent, stable performance at rated pressure.

Application Areas

• Hydraulic System Pressure Monitoring & Control: System pressure detection and alarm for hydraulic power units

• Construction Machinery: Pressure protection for excavators, wheel loaders, cranes

• Injection Molding Machinery: Pressure control for injection molding and die-casting machines

• Mobile Machinery: Pressure monitoring and safety protection for mobile equipment hydraulic systems

• Industrial Process Control: Process pressure monitoring in chemical and metallurgical industries

• Machine Tools & Clamping Systems: Pressure control and safety protection for hydraulic clamping circuits

Expert Maintenance Tips

1. Verify Model and Range Compatibility Prior to Installation
The PS/PST series offers 4 pressure adjustment ranges (3–35 / 6–140 / 10–350 / 20–630 bar). Confirm that the numeric code (2/4/6/8) in the model corresponds to a pressure range that covers the system operating pressure. For example, PSP2/21N-K1/K has a maximum adjustment pressure of 35 bar and cannot be used in systems exceeding 35 bar.

2. Mounting Type Selection

• PSP Series (Subplate Mounting) : Can be stacked on ISO 4401-03 (CETOP 03) standard subplates. Subplate code 1950611 enables connection to ports A and/or B; subplate code 1950621 enables connection to port P.

• PST Series (Threaded Connection) : Features 1/4″ BSP thread interface. Use PTFE tape or thread sealant—apply sparingly to prevent sealant material from entering the valve body.

3. Pressure Setting
Set the switching pressure via the rotary knob with integrated pressure scale. Rotate the knob slowly while monitoring a pressure gauge to confirm the switching point. Never exceed the maximum operating pressure for the specific model (PS*2/PS*4: 350 bar; PS*6/PS*8: 650 bar).

4. Mounting Orientation and Sealing
The pressure switch can be mounted in any orientation without affecting normal operation. For PSP subplate mounting, ensure the mounting surface flatness and roughness meet the specified tolerances to prevent leakage. Seal material selection: NBR (code N) for HL/HM mineral oils; FPM (code V) for HFD-R phosphate ester fluids.

5. Fluid Temperature and Cleanliness Management
Operating temperatures above 80°C will accelerate degradation of hydraulic fluid and seals. Maintain fluid temperature within -20°C to +70°C. Recommended system cleanliness: NAS 1638 Class 10 or higher.

6. Electrical Connection
Features DIN 43650 square connector standard electrical connection. Verify supply voltage and contact capacity match prior to wiring. Ingress protection rating is IP65.

7. Periodic Functional Checks
Perform functional checks every 2,000 operating hours or annually to verify switching point accuracy and contact reliability. If set-point drift or poor contact is observed, arrange for servicing or replacement.