1. Introduction
The Dwyer Photohelic Series A3000 Pressure Switch/Gauge is a versatile instrument that combines the functions of a precise pressure gauge with highly repeatable pressure switches. Utilizing the proven Magnehelic gauge design, this device accurately measures and controls positive, negative, or differential pressures of air and compatible gases.
It features two phototransistor-actuated, DPDT relays for low/high limit control, allowing for precise system management. Set points are easily adjustable via knobs located on the gauge face. The continuous gauge reading remains unaffected by switch operation, even during power loss, ensuring reliable monitoring.
2. Features
- Combined Functionality: Operates as both a pressure gauge and a pressure switch.
- Precise Measurement: Employs the Magnehelic gauge design for accurate pressure readings.
- Dual Control Relays: Includes two phototransistor-actuated DPDT relays for low/high limit control.
- Adjustable Set Points: Easy-to-adjust set point indicators via front-mounted knobs.
- Continuous Reading: Gauge reading is continuous and independent of switch operation or power status.
- Optical Limit Switches: Utilizes optical limit switches for enhanced reliability and extended service life.
- Variable Deadband: Set points can be interlocked to provide a variable deadband, suitable for fan or damper control.
- Robust Construction: Features a clear polycarbonate plastic cover and a light shield to protect internal components and ensure clear visibility.
3. Setup and Installation
Proper installation is crucial for the accurate and reliable operation of your Photohelic Switch/Gauge. Refer to the detailed wiring diagrams and mounting instructions provided with your specific model for complete guidance.
3.1 Mounting
The unit is designed for vertical position calibration. Ensure the mounting surface is stable and free from excessive vibration. Secure the gauge using appropriate fasteners through the designated mounting holes.
3.2 Pressure Connections
Connect pressure lines to the appropriate ports on the gauge. Ensure all connections are sealed properly to prevent leaks, which can affect measurement accuracy. The gauge is suitable for air and compatible gases.
3.3 Electrical Connections
Connect the power supply and control circuits to the DPDT relays as per the electrical schematic. Ensure all wiring complies with local electrical codes and safety standards. The optical limit switches are designed for reliability and precise switching accuracy.
Figure 1: Dwyer Photohelic Series A3000 Pressure Switch/Gauge. This image displays the device with its clear polycarbonate cover, revealing the internal circuitry, the pressure gauge face calibrated for vertical position, and the two set point adjustment knobs labeled "ZERO". The gauge face indicates a maximum pressure of 25 PSIG.
4. Operation
4.1 Power On
Once installed and wired, apply power to the unit. The gauge pointer will indicate the current pressure.
4.2 Zero Adjustment
Before operation, ensure the gauge reads zero when no pressure is applied. Use the "ZERO" adjustment screw (typically located on the front cover or near the bottom of the gauge face) to calibrate the pointer to zero.
4.3 Setting Control Points
- Identify the two set point knobs on the front of the gauge. These control the low and high limit switches.
- Rotate the desired knob to move its corresponding red set point indicator to the required pressure value on the gauge face.
- When the actual pressure (indicated by the main pointer) crosses a set point indicator, the associated DPDT relay will actuate, triggering the connected control circuit.
- The individual set point deadband is approximately one pointer width, which is less than 1% of the full scale.
- For applications requiring a variable deadband, the set points can be interlocked according to specific wiring diagrams.
4.4 Reading the Gauge
The gauge provides a continuous visual indication of the measured pressure. The scale is typically in inches of water column (WC) or pounds per square inch (PSIG), depending on the model. For example, the gauge face shown in Figure 1 indicates a range up to 0.50 inches of water, with markings at .20, .30, .40, and .50.
5. Maintenance
The Dwyer Photohelic Switch/Gauge is designed for long-term, reliable operation with minimal maintenance. However, periodic checks are recommended.
- Cleaning: Keep the exterior of the gauge clean. Use a soft, damp cloth to wipe the clear cover. Avoid abrasive cleaners or solvents.
- Calibration Check: Periodically verify the zero point and accuracy of the gauge using a known pressure source. Recalibrate if necessary.
- Connection Integrity: Inspect all pressure and electrical connections for tightness and signs of wear or corrosion.
- Environmental Conditions: Ensure the operating environment remains within the specified temperature and humidity ranges to prevent damage to internal components.
6. Troubleshooting
If you encounter issues with your Photohelic Switch/Gauge, consider the following common troubleshooting steps:
- No Gauge Reading:
- Check pressure connections for leaks or blockages.
- Verify that pressure is being applied to the correct ports.
- Incorrect Gauge Reading:
- Perform a zero adjustment.
- Check for proper calibration against a known standard.
- Ensure the gauge is mounted in a vertical position as calibrated.
- Switches Not Actuating:
- Verify electrical power to the unit.
- Check wiring to the DPDT relays.
- Ensure set points are correctly positioned relative to the current pressure.
- Inspect optical limit switches for any obstructions or damage.
- Intermittent Operation:
- Check for loose electrical connections.
- Ensure stable power supply.
- Verify environmental conditions are stable and within operating limits.
If problems persist, contact Dwyer technical support for assistance.
7. Specifications
| Parameter | Value |
|---|---|
| Model Number | A3001AV (Specific model example) |
| Pressure Ranges | Various, from 0-.25" WC up to 30 psi (21 bar); single positive pressure to 6000 psig (413 bar) |
| Max. Operating Pressure | Standard models: 25 psig (1.7 bar); Options: 35 (2.4) or 80 (5.5 bar) psig; 36000S models: 6000 psig (413 bar) |
| Switch Type | Two phototransistor actuated, DPDT relays |
| Set Point Deadband | Less than 1% of full scale (one pointer width) |
| Media Compatibility | Air and compatible gases |
| Material | Plastic (cover) |
| Item Weight | 4.7 Pounds (approx.) |
| Manufacturer | Dwyer Instruments |
8. Warranty and Support
For warranty information, technical support, or service inquiries, please contact Dwyer Instruments directly. Refer to the official Dwyer website or your purchase documentation for the most current contact details and warranty terms.
Dwyer Instruments, Inc.
www.dwyer-inst.com
