1. Series Platform
400V400 Vacuum Series (Diaphragm, max working pressure 350 psig)
400L400 Low Pressure Series (Diaphragm, max working pressure 870 psig)
400H400 High Pressure Series (Piston, max working pressure 5,000 psig)
Product page
NOSHOK
400 Series Heavy-Duty Mechanical SPDT Pressure Switch
The NOSHOK 400 Series Heavy-Duty Mechanical Pressure Switch delivers robust, reliable on/off interlocking and process control across demanding industrial fluid power systems. Built around a high-capacity SPDT snap-action micro switch with self-cleaning solid silver contacts, the 400 Series handles electrical switching loads up to 6A at 125/250 Vac or 6A at 12/24 Vdc. The series is divided into three specialized operational platforms: 400V for vacuum applications (-5 inHg to -28 inHg), 400L for low-to-medium positive pressure ranges (3 psig to 230 psig) utilizing an elastomeric NBR diaphragm, and 400H for high-pressure hydraulic service (145 psig to 4,600 psig) utilizing a heavy-duty stainless steel piston mechanism with NBR sealing. Housed in a rugged zinc die-cast body rated up to IP65 / IP67, the 400 Series features CE compliance with built-in suppression for RFI, EMI, and ESD. An external adjustment knob provides fast, secure setpoint calibration under operating pressure, making it ideal for mobile hydraulics, machine tool lubrication, power generation, pump skid control, and water management.
SPDT snap-action microswitch with self-cleaning solid silver contacts rated for 6A @ 125/250 Vac and 6A @ 12/24 Vdc
Switch adjustment ranges from vacuum (-5 to -28 inHg) up to 4,600 psig with proof pressures up to 5,000 psig
Dual sensing architecture: sensitive NBR diaphragm for ≤ 230 psig and stainless steel piston for ≥ 500 psig
Narrow switching hysteresis: 1% to 11% FS on diaphragm models and 2% to 8% FS on piston models
Ready for quotationShare your range, connection and case requirement.
Talk to ATHSwitch FunctionSPDT (Single Pole Double Throw) snap-action micro switch
Contact Rating6A @ 125/250 Vac; 6A @ 12/24 Vdc (Solid Silver, self-cleaning)
Repeatability±2% of full scale of adjustment range
HysteresisDiaphragm type: 1% to 11% of range; Piston type: 2% to 8% of range
Switching FrequencyMaximum 200 cycles/minute
Service Life> 1,000,000 mechanical load cycles
Pressure RangesVacuum (-5 to -28 inHg), Low pressure (3 to 230 psig), High pressure (145 to 4,600 psig)
Proof Pressure350 psig (Vacuum 400V), 870 psig (Low pressure 400L), 5,000 psig (High pressure 400H)
Measuring ElementNBR diaphragm (≤ 230 psig); Stainless Steel piston with NBR seal (≥ 500 psig)
Housing MaterialZinc die-cast body, zinc-plated steel process connection
Environmental RatingIP65 (DIN EN 175301-803 Form A); IP67 (M12 x 1 circular connector)
Temperature LimitsMedia & Ambient: -20 °C to 80 °C (-4 °F to 176 °F); Storage: -25 °C to 85 °C (-13 °F to 185 °F)
Electrical ConnectionsDIN EN 175301-803 Form A (std, cable, or LED indicator); M12 x 1 (4-pin)
Process Connections1/4" NPT male, G 1/4 B male, G 1/4 B female, 7/16-20 SAE-4 male
Technical data
Selection and ordering reference
Construct the complete 400 Series part number by selecting the series platform (Vacuum, Low Pressure, or High Pressure), switch function, process connection, adjustment range, electrical connection, and optional diaphragm or calibration features.
Switch FunctionSPDT Snap-Action Microswitch
Contact Rating6A @ 125/250 Vac, 6A @ 12/24 Vdc
Adjustment Range-5 inHg vac to 4,600 psig
Proof PressureUp to 5,000 psig
Repeatability±2% of adjustment range span
EnclosureZinc Die-Cast (IP65 / IP67)
2. Switch Function
3Single Pole Double Throw (SPDT) snap-action micro switch
3. Process Connection
21/4" NPT Male
10G 1/4 B Male (DIN EN 837)
19G 1/4 B Female
457/16-20 SAE Male, Non-Adjustable
4. Adjustment Ranges (Max Working Pressure)
5/28-vac400V Vacuum: -5 inHg to -28 inHg (-170 to -950 mbar) [350 psig]
3/30400L Low Pressure: 3 psig to 30 psig (0.2 to 2 bar) [870 psig]
7/120400L Low Pressure: 7 psig to 120 psig (0.5 to 8 bar) [870 psig]
15/230400L Low Pressure: 15 psig to 230 psig (1 to 16 bar) [870 psig]
145/435400H High Pressure: 145 psig to 435 psig (10 to 30 bar) [5,000 psig]
145/1160400H High Pressure: 145 psig to 1,160 psig (10 to 80 bar) [5,000 psig]
145/1750400H High Pressure: 145 psig to 1,750 psig (10 to 120 bar) [5,000 psig]
145/2320400H High Pressure: 145 psig to 2,320 psig (10 to 160 bar) [5,000 psig]
300/2900400H High Pressure: 300 psig to 2,900 psig (20 to 200 bar) [5,000 psig]
300/3600400H High Pressure: 300 psig to 3,600 psig (20 to 250 bar) [5,000 psig]
450/4600400H High Pressure: 450 psig to 4,600 psig (30 to 320 bar) [5,000 psig]
5. Electrical Connection
8DIN EN 175301-803 Form A Hirschmann Connector (IP65)
1DIN EN 175301-803 Form A with 36" (0.9 m) Attached Cable
46DIN EN 175301-803 Form A with Integrated LED Status Indicator
25M12 x 1 (4-Pin) Circular Connector (IP67, available up to 225 psig)
6. Options & Accessories
EPEPDM Diaphragm / Seal (-40 °F to 212 °F / -40 °C to 100 °C)
HNBRLow Temperature NBR Diaphragm (-40 °F to 176 °F / -40 °C to 80 °C)
VTFKM (Viton) Diaphragm / Seal (0 °F to 212 °F / -18 °C to 100 °C)
SPFactory Adjusted Switch Point (Customer specified rising/falling setting)
Model designation example
400H-3-2-300/2900-8-SP
400HSeriesHigh Pressure Piston Switch
3Switch FunctionSPDT Snap-Action
2Process Connection1/4" NPT Male
300/2900Adjustment Range300 to 2,900 psig span
8Electrical ConnectorDIN EN 175301-803 Form A
SPOptionFactory Preset Switch Point
Technical specifications
Switch TypeSPDT snap-action micro switch (Solid Silver contacts)
Contact Rating6A @ 125/250 Vac; 6A @ 12/24 Vdc
Repeatability±2% of full scale adjustment range
HysteresisDiaphragm: 1% to 11% FS; Piston: 2% to 8% FS
Max Cycle Rate200 cycles per minute
Mechanical Durability> 1,000,000 operations
Shock / VibrationShock: 30g (IEC 60068-2-27); Vibration: 10g (IEC 60068-2-6)
Approvals & ComplianceCE (EU 73/23/EWG RFI/EMI/ESD), RoHS compliant
Operating & Installation Notes
Setpoint adjustment: Rotate hex knob clockwise to increase setpoint, counterclockwise to decrease. Secure with center locking screw.
High pulsation hydraulic circuits should utilize optional NOSHOK piston or sintered snubbers to maximize contact service life.
M12 x 1 connector option (25) is rated IP67 and available on vacuum and low-pressure models up to 225 psig.
Precision Mechanical Snap-Action Architecture
The NOSHOK 400 Series combines rugged electromechanical engineering with fine setpoint stability. Its SPDT snap-action microswitch utilizes solid silver contacts that self-clean during each actuation cycle, preventing contact oxidation and ensuring consistent contact resistance over more than 1,000,000 operations.
The switch mechanism features high switching capacity (6A at 250 Vac / 24 Vdc), allowing direct actuation of motor contactors, solenoid valves, warning horns, and PLC digital inputs without requiring intermediate interposing relays.
Optimized Diaphragm & Piston Sensing Technologies
To achieve optimal sensitivity and overpressure safety across diverse process media, the 400 Series employs dual sensing technologies tailored to the working pressure envelope. For vacuum and low-pressure ranges up to 230 psig (Series 400V and 400L), an elastomeric NBR diaphragm delivers rapid response and low hysteresis (1% to 11% FS).
For demanding high-pressure hydraulic circuits up to 4,600 psig (Series 400H), a precision-machined stainless steel piston with NBR elastomeric seal absorbs intense hydraulic pressure surges, rapid pressure cycling (up to 200 cycles/min), and withstands maximum proof pressures up to 5,000 psig without calibration shift.
Industrial Electrical Interfacing & Interference Suppression
Operating in heavy industrial plants requires robust immunity against electrical noise. The 400 Series is CE compliant per EU Standard 73/23/EWG, providing integral suppression against Radio Frequency Interference (RFI), Electromagnetic Interference (EMI), and Electrostatic Discharge (ESD).
Electrical termination options include standard DIN EN 175301-803 Form A plugs (with optional 36-inch molded cable or built-in LED switching status indicators) and compact M12 x 1 (4-pin) industrial circular connectors rated IP67 for washdown and mobile machinery applications.
Key Industrial Applications
Industrial and mobile hydraulic systems, hydrostatic transmissions, and power steering skids
Pneumatic machinery, shop air monitoring, and automated pick-and-place assembly lines
Power generation turbine lubrication, coolant circulating systems, and fuel oil boost pumps
Pumps and air compressors: high/low cut-out, unloading valves, and pressure accumulator charging
Tank blanketing, vacuum hold verification, and fluid level hydrostatic head monitoring
Municipal water management, booster stations, irrigation manifolds, and filtration skid backwash
Calibration & Field Installation Guidelines
Switch point adjustment is executed via the external hex adjustment knob. Turning the knob clockwise compresses the internal range spring, increasing the switch setpoint. To lock the setting, tighten the central locking screw.
For aggressive media or extreme fluid temperatures (-40 °F to 212 °F), optional EPDM (EP), low-temperature NBR (HNBR), or FKM (VT) diaphragm materials can be specified. For pulsating hydraulic lines, install an optional piston-type or sintered-type pressure snubber to prevent premature microswitch fatigue.