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|Overview

Differential Pressure Sensor (DPS) extends the sensor capabilities of 75F controllers. Its use opens an array of additional applications from flow sensing in variable air volume (VAV) boxes to monitoring filter performance in air handling units (AHU). The compact profile and rugged construction of DPS allow it to be mounted on the sides of VAV boxes, hard supports, or rafters.  

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The DP sensor connects to the 75F controllers like the Smart Node's sensor bus and works seamlessly 'out of the box' with the Facilisight suite of applications. Thoughtful design touches include, large cutouts making it easy to install when wearing gloves.

Powered by the 75F sensor bus, the DP sensor uses a 3 core molex connector for power and communication. The differential pressure pickup ports work with both 4mm and 1/4" tubing via an adapter. 

|Precautions

  • Failure to wire devices with the correct polarity when using a shared transformer may result in damage to any device powered.
  • Do not mount the tubing so that the inside or the outside tube ends are in direct line of a breeze or draft.
  • Turn off the power before wiring, never connect or disconnect the wiring with the power turned on.
  • Do not allow live wires to touch the circuit boards.

|Features

The DP sensors dramatically cuts down the time to install and commission applications such as.

  • Measuring flow for Variable Air Volume (VAV) based on ASHRAE GPC-36.
  • Advanced sequences for Demand control ventilation (IAQ) compatible with ASHRAE 90.1 and ASHRAE 62.1 2018. 
  • Filter performance and alerting based on ASHRAE GPC -36.

|Assembly

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Assembled PCB

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|Mounting

Mounting of DPS

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  • Mount the Differential Pressure Sensor using two #8-1.5 inch self-tapping screws as shown above The transmitter is factory-calibrated and must be installed vertically with the air inlet nozzles pointing perpendicular to the ground. To adjust the zero, both pressure ports must be open to the atmosphere

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Mounting of Air pick-up pipe

  • Mount the air pick-up pipe to the air inlet nozzles provided on the DPS. To fix the pipe, push one end of the flexible pipe till the edge butts out to the back of the nozzle and the other end to the crossflow tubes or pitots installed.

|Wiring

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  • Turn off the power. Connect one end of the 75F cable to one end of the RTS port on the Smart Node and the other end to the IN port of the DPS.
  • Power to the DPS is provided through this cable; no external power wiring is required. If an additional RTH sensor needs to be connected, connect the other 75F cable to one end of the OUT port of the DPS and the other end to the RTH sensor. 

Enable RTH Sensor Communication

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To enable RTH sensor communication, the Daisy Chain switch must be set to Yes. When there is no requirement for additional sensors to be connected to the OUT port of the DPS, the Daisy Chain switch must be set to No.

On the DPS, connect the static tube to “-“ and the total pressure pipe to “+”. This helps the sensor calculate the differential pressure in the duct.  

 

 

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