Dwyer Series ADPS Differential Pressure Switch: HVAC Filter & Fan Status Monitoring
Posted on: 27/07/2026
What Can a Differential Pressure Switch Do That a Gauge Cannot?
In Building Management Systems (BMS) and HVAC/AHU/PAU applications, engineers frequently evaluate whether to install a Differential Pressure Gauge or a Differential Pressure Switch.
The distinction is clear: A gauge delivers a VISUAL NUMBER on-site, whereas a switch outputs an AUTOMATED CONTROL SIGNAL.
The Dwyer Series ADPS (USA) is an adjustable differential pressure switch designed for air and non-combustible gases. When the differential pressure exceeds the dual-scaled preset setpoint, an internal silicone diaphragm actuates a Single Pole Double Throw (SPDT) snap switch. This electrical signal is immediately transmitted to the control cabinet or BMS to sound alarms, illuminate warning lights, or interlock HVAC equipment. As a result, the system achieves 24/7 automated monitoring without requiring manual gauge inspection.
Three Essential HVAC Applications
1. Air Filter Clogging Monitoring: Tap ports upstream and downstream of air filters (G4, F7, HEPA). As dust accumulates, pressure drop increases. Upon reaching the setpoint, the switch signals maintenance teams to clean or replace filters, preventing energy waste and fan strain.
2. Fan Status Verification: Measures differential pressure across the fan. Detecting active pressure difference proves airflow presence — far superior to monitoring electric contactors, which report 'running' even if fan belts break or blades fracture.
3. Safety Interlock Protection: Interlocked with duct electric heaters, humidifiers, or UV lamps. Ensures auxiliary components operate only when active airflow is verified, preventing severe overheating and fire hazards.
Technical Specifications :
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Service
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Air and non-combustible, compatible gases
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Wetted Materials
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Silicone diaphragm, Polycarbonate / Noryl housing
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Temperature Limits
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Ambient & Process: -4 to 185°F (-20 to 85°C)
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Max Operating Pressure
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10 kPa (100 mbar / 40 in w.c.) for all ranges
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Switch Type
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SPDT (Single-Pole Double-Throw) snap switch
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Electrical Rating
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Max 1.5 A @ 250 VAC (50/60 Hz); Min 10 mA @ 24 VAC/VDC
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Electrical Connections
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Screw terminals; M16x1.5 conduit or 1/2" NPS adapter
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Process Connections
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2 x 1/8" / 3/16" ID flexible tubing (4 mm / 6 mm ID)
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Enclosure Rating
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IP54 / NEMA 13
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Set Point Tolerance
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±15% full scale
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Mounting Orientation
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Vertical position recommended (dial calibrated vertically)
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Standard Model Selection Chart:
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Model
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Set Point Range
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Switching Differential (Deadband)
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ADPS-08-2-N
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20 – 200 Pa (0.08 – 0.8 in w.c.)
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10 Pa (low end) – 15 Pa (high end)
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ADPS-04-2-N
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30 – 400 Pa (0.12 – 1.6 in w.c.)
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15 Pa – 22 Pa
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ADPS-03-2-N
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50 – 500 Pa (0.20 – 2.0 in w.c.)
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20 Pa – 28 Pa
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ADPS-05-2-N
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200 – 1000 Pa (0.80 – 4.0 in w.c.)
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45 Pa – 60 Pa
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ADPS-06-2-N
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500 – 2500 Pa (2.0 – 10.0 in w.c.)
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85 Pa – 125 Pa
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ADPS-07-2-N
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1000 – 4000 Pa (4.0 – 16.0 in w.c.)
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130 Pa – 250 Pa
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Important Installation & Setting Notes
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Setpoint Determination: Measure actual pressure drop across clean filters and set threshold between clean and dirty filter levels (typically 2-3x initial clean pressure drop).
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Process Connections: Connect High port (P1/+) to upstream higher pressure and Low port (P2/-) to downstream lower pressure. Use 4 mm or 6 mm ID flexible tubing.
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Mounting Position: Always mount vertically with pressure taps facing downward. Non-vertical mounting causes setpoint shift by approx. 20 Pa due to diaphragm weight.
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Environmental Protection: Secure IP54 cover and conduit fittings when operating in harsh or outdoor environments.
👉 View Product & Request Quote: Dwyer Series ADPS Differential Pressure Switch at DLK
Contact DLK for Consultation & Quotation
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24/7 Hotline: 0937972339
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Sales Department: 0783683479
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Email: info@dlk.com.vn
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Address: 111/7, Vuon Lai Street, Phu Tho Hoa Ward, Tan Phu District, Ho Chi Minh City