Friday, 10 March 2023

Differential Pressure Transmitters (DPT) VS Differential Pressure Switches (DPS) Instrument devices used in HVAC Field !!

 


The key differences between Differential Pressure Switches (DPS) and Differential Pressure Transmitters (DPT) in HVAC applications are:



1. Function:

 - DPS: Provides a binary, on/off signal based on a preset pressure differential setpoint.

 - DPT: Provides a continuous, proportional electrical output (4-20 mA or 0-10 VDC) that corresponds to the measured pressure difference.


2. Applications:

 - DPS:

 - Filter status monitoring - Triggers an alarm when the filter becomes clogged and the pressure drop across it exceeds the setpoint.

 - Airflow monitoring - Detects loss of airflow in ducts or air handlers.

 - Proof of operation - Verifies that a fan or blower is running by detecting the pressure difference it creates.


 - DPT:

 - Variable Air Volume (VAV) systems - Provides feedback to the control system to modulate dampers and maintain desired airflow.

 - Building pressure control - Monitors and maintains the desired pressure differential between indoor and outdoor environments.

 - Air balancing - Provides data for adjusting dampers and registers to achieve the desired airflow distribution.

 - Filter monitoring - Tracks the gradual increase in pressure drop across filters to schedule maintenance.


3. Precision and Range:

 - DPS: Typically have a fixed setpoint and a limited adjustability range.

 - DPT: Offer a wider measurement range and better precision, allowing for more accurate monitoring and control.


4. Output:

 - DPS: Provides a simple on/off signal, suitable for basic monitoring and alarm applications.

 - DPT: Provides a continuous, proportional output signal that can be integrated into more advanced control systems.


In summary, DPS devices are better suited for basic monitoring and switch-based control, while DPT devices are preferred for more sophisticated pressure-based control, monitoring, and optimization applications in HVAC systems.

Prepared by M.Ajmal Khan

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