Overview
The Dwyer 3000-00 Photohelic pressure switch/gage combines the functions of a precision analog gage with a highly repeatable pressure switch. Using infrared LED and phototransistor sensing technology, the 3000-00 measures and controls positive, negative, or differential pressures of air and non-combustible compatible gases. This dual-function instrument reduces installation complexity by eliminating the need for separate pressure measurement and switching devices.
Key Features
- Dual phototransistor-actuated DPDT (Form C) relays for independent low/high limit switching
- Large 4-inch dial face with dual-scale markings (psi and bar) for easy operator reference
- Adjustable set points via external knobs on gage face; no disassembly required
- Repeatability of ±1% of full scale; deadband less than 1% full scale for tight process control
- Patented infrared sensing design eliminates mechanical switching chatter and chattering
- Gage reading continuous and unaffected by switch operation or power loss
Technical Specifications
| Parameter | Value |
| Model | 3000-00 |
| Accuracy | ±4% of full scale |
| Pressure Range | -20″ Hg to 25 psig (-0.677 to 1.72 bar) |
| Temperature Operating Range | 20°F to 120°F (-6.67°C to 48.9°C) |
| Process Connection | 1/8″ female NPT |
| Dial Face Diameter | 4 inches (101.6 mm) |
| Overall Diameter | 5 inches (127 mm) |
| Depth | 8.25 inches (209.55 mm) |
| Weight | 4 lbs (1.81 kg) |
| Relay Type | 2 x DPDT (Form C); 10A @ 28 VDC; 10A @ 120/240 VAC |
| Electrical Connections | Screw terminals |
| Service | Air and non-combustible compatible gases |
| Repeatability | ±1% of full scale |
Typical Applications
- HVAC Systems: Filter pressure monitoring, ductwork static pressure control, and damper actuation
- Clean Rooms & Laboratories: Room pressure differential monitoring for containment assurance
- Fume Exhaust Systems: Stack pressure and exhaust duct status indication with alarm capability
- Process Equipment: Pneumatic pressure control for fans, compressors, and pressure vessels
- Industrial Compressed Air: Low/high pressure cutout and system pressure monitoring
Compatibility & Replacements
Compatible With
- Allen-Bradley and Rockwell Automation control systems via relay input modules
- Siemens S7-1200, S7-1500 PLCs (via digital input cards for relay contacts)
- Standard HVAC and pneumatic control systems requiring 120 or 240 VAC power
- Building Automation Systems (BAS) with dry-contact input capability
- Pneumatic pressure networks operating up to 25 psig standard or 80 psig with HP option
Replaces / Drop-In Replacement For
- Earlier Series 3000 legacy models (when pressure range matches application)
- Mechanical pressure switches requiring phototransistor-based solid-state reliability
- Standalone gage + switch combinations where space and cost are concerns
Works With
- 120 VAC / 240 VAC / 24 VAC power supplies (power via screw terminals)
- Dry-contact switching circuits for latching, alarm, and monitoring applications
- Manual reset push buttons (e.g., Dwyer Part A-601) for latching circuits
- Stainless steel wetted materials available (consult Dwyer for compatibility)
- Dwyer weatherproof enclosures and mounting brackets (flat aluminum bracket available for Series 3000MR compatibility reference)
