VR3200 / VR3201 Series Pneumatic-Electric Relay

Brand: SOLH by Richge Technology 

Product Positioning

     SOLH VR3200/3201 series are classic pneumatic-electric relays, also known as air pressure signal switches. They convert pneumatic pressure signals into electrical switching dry contacts, widely used for pressure monitoring, fault alarming, safety interlock and digital signal input to PLC in automated production lines, serving as the standard signal conversion interface between pneumatic pipelines and electrical control systems.

Model Classification & Core Differences

     -- VR3200-01: Open frame type, weight 130g, exposed terminal block, for dry, dust-free indoor cabinet environments

     -- VR3201-01: IP44 drip-proof sealed housing, weight 260g, fully enclosed construction, suitable for humid, dusty workshops and production equipment

     -- VR3202-01: IP44 drip-proof with dedicated grounding terminal, CE certified, ideal for heavy electromagnetic interference and export machinery

     -- Port code: 01 = standard Rc1/8 internal thread; NPT1/8 thread optional

Universal Technical Specifications

  1. Adjustable Operating Pressure Range: 0.1 ~ 1.0 MPa (factory preset trigger pressure ≈ 0.15MPa)

  2. Ambient Temperature: -5℃ ~ +60℃ (no icing)

  3. Contact Form: 1AB (1 Normally Open + 1 Normally Closed + Common COM)

  4. Micro Switch Contact Ratings (Resistive / Inductive Load):

     -- AC125V: 15A resistive, 3A inductive

     -- AC250V: 15A resistive, 2.5A inductive

     -- DC30V: 6A resistive, 1.5A inductive

  5. Interface Layout: Air inlet Rc1/8; electrical screw terminals (VR3201 equipped with Pg13.5 cable gland for sealed wiring)

  6. Material Composition: Brass valve body, POM piston, stainless steel return spring, NBR sealing ring

Working Principle

  1. Compressed air enters port IN and pushes the piston to compress the spring, mechanically triggering the built-in micro switch once pressure exceeds preset threshold.

  2. Contact switching logic:

     -- Pressure ≥ set value: NO closed, NC open

     -- Pressure ＜ set value: NO open, NC closed

  3. Fully mechanical structure, no external power supply required. Intrinsically safe and stable for explosion-prone and non-electrical hazardous zones.

Quick Selection Guidelines

     -- VR3200-01: Low cost, dry indoor cabinet installation

     -- VR3201-01: Humid/dusty machine tools, assembly lines, semi-outdoor equipment

     -- VR3202-01: CE certification + grounding protection, heavy EMC interference, export complete machines

     -- Pressure adjustment: Factory default trigger pressure 0.15MPa, fine tune via top adjustment screw

Typical Application Scenarios

     -- Cylinder stroke & clamping pressure detection: workpiece clamping confirmation, overload alarm

     -- Vacuum chuck negative pressure feedback: adsorption & workpiece falling loss detection

     -- Main air source low pressure warning: air compressor failure and pipeline leakage monitoring

     -- Open/close state feedback of pneumatic ball valves and butterfly valves

     -- Pneumatic signal conversion for explosion-proof workshops without electronic sensors

SOLH Interchange Advantage

     SOLH VR3200/3201 series are fully drop-in compatible with SMC equivalent models in overall dimension, port thread, contact parameters and adjustable pressure range. Competitive pricing and short lead time help customers cut mass production costs.

Terminal Wiring Definition

     -- COM：Common public terminal

     -- NO：Normally Open, conducts when air pressure reaches preset value

     -- NC：Normally Closed, conducts when air pressure below preset threshold

One Sentence Summary

     SOLH VR3200/3201 power-free mechanical pneumatic-electric relay converts air pressure signals into 1NO+1NC dry contact signals with adjustable 0.1~1.0MPa trigger pressure, available in open frame, IP44 drip-proof and CE grounded versions for PLC interlock, vacuum monitoring and air source alarm automation control.