<h2>Overview</h2>
<p>The <strong>Dwyer Series 3000 Model 3020 Photohelic pressure switch/gauge</strong> combines the functions of two versatile, highly repeatable differential pressure switches with a time-proven Magnehelic analog pressure gauge. Using solid-state phototransistor technology, this instrument provides independent gauge operation unaffected by switch activity, making it ideal for HVAC systems, clean rooms, filtration monitoring, and industrial process control applications requiring low-pressure measurement and automated switching.</p>
<h2>Key Features</h2>
<ul>
<li><strong>Dual DPDT Relays:</strong> <cite index=”1-7″>External knobs are used to adjust the two DPDT switch set points</cite></li>
<li><strong>Magnehelic Gauge:</strong> <cite index=”4-1″>Uses solid state technology combined with the durable, time-proven Magnehelic gauge design</cite></li>
<li><strong>Independent Gauge Operation:</strong> <cite index=”2-8″>Functions normally even if power is interrupted to electrical elements of the control</cite></li>
<li><strong>Optical Limit Switches:</strong> <cite index=”7-7,7-8″>Optical limit switches are used for reliability and long service life, individually aligned to assure precise switching accuracy</cite></li>
<li><strong>Clear Set Point Visibility:</strong> <cite index=”1-8″>Switch set points (indicated by red pointers) and system pressure are fully visible at all times</cite></li>
</ul>
<h2>Technical Specifications</h2>
<ul>
<li><strong>Model:</strong> Series 3000 Model 3020 (range variations available)</li>
<li><strong>Measurement Type:</strong> Differential pressure, positive, or negative</li>
<li><strong>Gauge Dial Size:</strong> <cite index=”8-13″>4″ (101.6 mm) dial face, 5″ (127 mm) O.D.</cite></li>
<li><strong>Accuracy:</strong> <cite index=”6-2″>±2% of FS</cite></li>
<li><strong>Pressure Range:</strong> <cite index=”1-9″>0″ to 0.25″ W.C. up to 10″ W.C. full scale</cite> (0-20″ W.C. common)</li>
<li><strong>Pressure Limit:</strong> <cite index=”6-12″>-20″ Hg to 25 psig (-0.677 bar to 1.72 bar)</cite></li>
<li><strong>Power Supply:</strong> <cite index=”6-2″>24 VDC, regulated ±10%</cite></li>
<li><strong>Switch Type:</strong> <cite index=”8-16″>Each setpoint has 2 Form C relays (DPDT)</cite></li>
<li><strong>Repeatability:</strong> <cite index=”8-17″>±1% of full scale</cite></li>
<li><strong>Operating Temperature:</strong> <cite index=”6-1″>20 to 120°F (-6.67 to 48.9°C)</cite></li>
<li><strong>Media:</strong> <cite index=”8-2″>Air and non-combustible, compatible gases</cite></li>
<li><strong>Process Connection:</strong> <cite index=”8-12″>1/8″ female NPT</cite></li>
<li><strong>Electrical Connection:</strong> <cite index=”6-11″>18″ cable assembly with 6 conductors</cite></li>
<li><strong>Weight:</strong> <cite index=”8-15″>4 lb (1.81 kg)</cite></li>
</ul>
<h2>Typical Applications</h2>
<ul>
<li>HVAC filtration and air pressure monitoring</li>
<li>Clean room differential pressure control</li>
<li>Low-pressure gas switching and alarm circuits</li>
<li>Duct static pressure control</li>
<li>Building automation and pneumatic process control</li>
<li>Industrial equipment pressure verification and protection</li>
</ul>
<h2>Compatibility & Replacements</h2>
<h3>Compatible With</h3>
<ul>
<li>Pneumatic and HVAC control systems requiring differential pressure switching</li>
<li>24 VDC powered automation and building management systems</li>
<li>Clean dry air and inert gas applications</li>
<li>Remote mounting enclosures for panel-mount installations</li>
</ul>
<h3>Replaces / Drop-In Replacement For</h3>
<ul>
<li>Dwyer Series 3000 pressure switch/gauge variants with same range and electrical specs</li>
<li>Verify exact replacement compatibility by confirming pressure range (0-20″ W.C. typical) and relay configuration with your system documentation</li>
</ul>
<h3>Works With</h3>
<ul>
<li>Form C (DPDT) relay circuits for high/low latching applications</li>
<li>Pneumatic control logic and sequencing circuits</li>
<li>24 VDC industrial control and automation platforms</li>
<li>Dwyer accessory enclosures (weatherproof ABS housing available)</li>
</ul>
