Overview
The Dwyer A3150 is a Series 3000 Photohelic® pressure switch/gauge that combines a precision analog pressure display with optical switching technology. This hybrid instrument functions as both a pressure monitor and a pressure-controlled relay, making it suitable for facilities management, HVAC systems, and industrial automation where accurate pressure monitoring and automatic switching are required. The A3150 employs Dwyer’s proven Magnehelic® gage design with phototransistor-actuated switching for reliable performance.
Key Features
- Dual DPDT Relay Control: Two phototransistor-actuated relays enable independent low and high pressure set points for versatile control logic
- Optical Sensing Technology: Infrared light shutter mechanism triggered by helix-mounted pointer eliminates drift and mechanical wear associated with conventional snap switches
- Continuous Gage Reading: Analog pressure indicator operates independently of electrical supply, providing real-time pressure visibility even during power loss or relay operation
- Tight Deadband Control: Dead band less than 1% of full scale ensures chatter-free, precise switching with minimal hysteresis
- Polycarbonate Display: Clear front cover and robust mechanical linkage allow reliable operation across industrial temperature ranges
- Configurable Logic: Supports high-latching, low-latching, or combination high-low latching circuits for alarm signaling and sequential control
Technical Specifications
- Manufacturer: Dwyer Instruments
- Series: 3000 (A3000 current designation)
- Model Number: A3150
- Standard Pressure Rating: 25 psig (1.7 bar)
- Optional Ratings: 35 psig (2.4 bar) or 80 psig (5.5 bar)
- Applicable Media: Air and non-combustible, non-corrosive gases
- Relay Type: DPDT (Dual Pole Dual Throw), 2 units included
- Switch Repeatability: ±1%
- Gage Accuracy: ±2% of full scale
- Deadband: Less than 1% of full scale
- Set Point Adjustment: Knob-controlled indicators on gage face
- Housing: Plastic enclosure with printed circuit board electronics
- Power Supply Dependency: Gage reading independent of electrical power
Typical Applications
- HVAC filter pressure monitoring and fan damper control
- Compressed air system pressure regulation and alarm
- Pneumatic equipment startup/shutdown sequencing
- Industrial vacuum and positive pressure process monitoring
- Building automation pressure differential sensing
- Pump and blower discharge pressure protection
Compatibility & Replacements
Compatible With
- Standard relay transformer modules (Dwyer Part A-601 manual reset push button)
- HVAC control systems requiring 24 VAC or 115 VAC signal switching
- Pneumatic process control networks
- Air and gas distribution systems (non-combustible media)
- Building automation and BACnet systems via external relay interfaces
Replaces / Drop-In Replacement For
- Dwyer Series 3000 models (earlier non-“A” designation equivalents)
- Older mechanical pressure switches in low-hysteresis applications
- Note: Direct replacement compatibility varies by exact range and relay wiring configuration. Verify set point ranges and contact ratings with your system integrator before ordering.
Works With
- Dwyer Magnehelic® differential pressure indicators
- Standard HVAC building automation controls
- Pneumatic logic valve panels
- 24 VAC and 115 VAC relay-based switching circuits
- Latching and non-latching control schemes
