The Greystone Model ELPF1250PS Duct Low Pressure Transmitter (Economy Low Pressure Series), engineered and manufactured by Greystone Energy Systems Inc. in Moncton, New Brunswick, Canada, is an advanced, cost-effective, and highly reliable air differential pressure monitoring instrument designed for smart Building Automation Systems (BAS), commercial HVAC ductwork, and clean environmental facilities.

Model Number Configuration Breakdown (ELPF1250PS):
- ELP: Economy Low Pressure Transmitter Series.
- F: Heavy-duty grey polycarbonate enclosure featuring a hinged gasketed cover with a secure snap latch, supplied complete with an integrated 1/2" NPT to M16 thread adapter and a liquid-tight cable gland fitting.
- 1250P: Calibrated 1250 Pascal pressure span, field-selectable between Unidirectional (0 to 1250 Pa) and Bidirectional (±1250 Pa) operating ranges via on-board jumpers.
- S: Integrated rear-mounted duct static pressure probe for direct insertion into air distribution ductwork.

Key Engineering Features & Operational Advantages:
- High-Accuracy Piezoresistive Silicon Sensor: Utilizes a proven micro-machined piezoresistive silicon pressure transducer designed for clean dry air or non-corrosive inert gases. The sensor delivers an accuracy of ±1% of Full Scale Output (F.S.O.), a rapid 250 ms response time, annual stability under ±1% F.S.O., and thermal compensation spanning 0°C to 50°C.
- Integrated Duct Static Pressure Probe: The rear of the unit features a factory-fitted static pressure probe (serving as the internal High pressure port). Technicians simply drill a pilot hole into the duct wall, slide the probe through, and fasten the unit with two mounting screws. The lateral nylon barbed port (Low pressure port) remains accessible for differential reference tubing or ambient room sensing.
- Field-Selectable Multi-Signal Output: Features easy-to-configure jumpers allowing on-site selection between 4 to 20 mA current loop (2-wire connection) or 0 to 10 VDC voltage output (3-wire connection). This eliminates stock code proliferation and provides seamless compatibility with any commercial DDC controller or PLC platform (Honeywell, Johnson Controls, Siemens, Schneider Electric).
- Pushbutton Auto-Zero Functionality: Equipped with a momentary tactile pushbutton on the PCB. During commissioning or routine maintenance checks, technicians simply isolate both pressure ports to ambient atmosphere and depress the ZERO button for 3 seconds. The microprocessor recalibrates and locks in the new zero reference point without requiring potentiometer adjustments.
- Rugged IP65 / NEMA 4X Enclosure (F-Style): Molded from UL94-V0 flame-retardant grey polycarbonate that resists UV degradation and mechanical impacts. The hinged cover with integrated sealing gasket allows one-handed access without dropping screws. Supplied with a 1/2" NPT to M16 adapter and cable gland to ensure ingress protection against condensation, dust, and water spray.

Typical Industrial Applications:
- Supply and return air duct static pressure control for variable frequency drive (VFD) supply fan speed regulation.
- Air handling unit (AHU) and fan coil unit (FCU) differential filter pressure monitoring (pre-filter, bag filter, and HEPA filter loading status).
- Variable Air Volume (VAV) terminal box velocity pressure tracking.
- Positive and negative pressure containment in pharmaceutical cleanrooms, medical isolation rooms, surgical suites, and biological research labs.
- Stairwell pressurization monitoring for emergency smoke control in high-rise commercial structures.

• Manufacturer: Greystone Energy Systems Inc.
• Country of Origin: 100% Canada (Made in Canada)
• Product Line: ELP Series Economy Low Pressure Transmitters
• Model Designation: ELPF1250PS
• Sensing Technology: High-precision Piezoresistive Silicon Sensor
• Measured Media: Clean dry air or non-corrosive, non-ionic inert gases
• Pressure Ranges (Jumper Selectable):
  - Unidirectional: 0 to 1250 Pa
  - Bidirectional: ±1250 Pa (-1250 Pa to +1250 Pa)
• Mounting Style: Duct mount with integrated rear static pressure probe (Probe code: S)
• Accuracy: ±1% F.S.O. (Full Scale Output)
• Response Time: 250 milliseconds (250 ms)
• Long-Term Stability: < ±1% F.S.O. per year
• Thermal Effects: < ±3% over compensated temperature range
• Compensated Temperature Range: 0°C to 50°C (32°F to 122°F)
• Proof Pressure: 40” W.C. (~10 kPa)
• Burst Pressure: 120” W.C. (~30 kPa)
• Output Signal Types (Field Selectable):
  - Current Loop: 4-20 mA (2-wire configuration)
  - Voltage Output: 0-10 Vdc (3-wire configuration)
• Output Drive Capabilities:
  - Current Loop: 400 Ω maximum @ 24 Vdc
  - Voltage Output: 10 kΩ minimum
• Power Supply Requirements: 20 to 28 Vac/dc (non-isolated half-wave rectified)
• Current Consumption: Current mode: 20 mA maximum; Voltage mode: < 4 mA
• Protective Circuitry: Reverse voltage protected and output current limited
• Zero Calibration: Pushbutton auto-zero (depress and hold for 3 seconds)
• Pneumatic Connections:
  - High Pressure Port: Integrated rear static probe for duct insertion
  - Low Pressure Port: 6.35 mm (0.25") Nylon barb fitting for 3.175 mm to 4.762 mm (0.125" to 0.1875" ID) flexible tubing
• Electrical Wiring Termination: Screw terminal block accommodating 14 to 22 AWG wiring
• Conduit & Cable Entry: 1/2" NPT conduit connection with supplied 1/2" NPT to M16 adapter and liquid-tight cable gland
• Enclosure Construction: Grey Polycarbonate, UL94-V0 flame retardant, hinged cover with latch and sealing gasket
• Ingress Protection Rating: IP65 / NEMA 4X (dust-tight and protected against water jets)
• Operating Ambient Conditions: 0°C to 50°C (32°F to 122°F), 5% to 95% RH non-condensing
• Agency Approvals: CE marked, RoHS compliant, ISO 9001 certified manufacturing
• Net Instrument Weight: Approximately 250 g (8.8 oz).