Pressure Switches and Pressure Transmitters

Pressure Switches and Pressure Transmitters two common devices used in process control and automation.

thought this comparison would be useful, especially for those working with DCS/PLC systems or new to instrumentation.

Pressure Switch

1. Works like a simple ON/OFF switch.

2. Provides a digital signal (either ON or OFF).

3. Activates or deactivates an electrical contact when the pressure crosses a pre-set limit.

4. Used for basic control applications (e.g., turning pumps or compressors ON/OFF).

5. Suitable where only a threshold action is required, not continuous monitoring.

Pressure Transmitter

1. A more advanced pressure-measuring device.

2. Continuously measures the actual pressure value.

3. Provides a continuous analog output signal (typically 4-20 mA or 0-10 V).

4. Used in process control systems like DCS, PLC, or SCADA.

5. Essential for applications needing accurate, real-time pressure data.

In Short

Pressure Switch Only indicates if pressure is too high or too low (ON/OFF).

Pressure Transmitter Continuously tells you the exact pressure value. Pressure Switches and Pressure Transmitters-two common devices used in process control and automation.

Comments

Type of Heat Exchanger

There are several types of heat exchangers used in HVAC systems, including: 1. Coil Type: - Chilled water coils - Hot water coils - DX (direct expansion) coils - Evaporator coils - Condenser coils 2. Shell and Tube Type: - U-tube heat exchangers - Straight tube heat exchangers 3. Plate Type: - Plate and frame heat exchangers - Plate and shell heat exchangers 4. Finned Tube Type: - Finned tube heat exchangers 5. Spiral Type: - Spiral heat exchangers 6. Regenerative Type: - Regenerative heat exchangers 7. Adiabatic Type: - Adiabatic wheel heat exchangers 8. Run-Around Coil Type: - Run-around coil heat exchangers These heat exchangers are used in various applications, including: - Air conditioning - Heating - Ventilation - Refrigeration - Heat recovery - Industrial processes Each type of hea...

HVAC common unit converter chart

Here's a comprehensive HVAC unit converter chart: Volume Flow Rate 1.CFM (Cubic Feet per Minute) to CMH (Cubic Meters per Hour): 1 CFM ≈ 1.699 CMH 2.CFM to m³/s (Cubic Meters per Second): 1 CFM ≈ 0.000472 m³/s Airflow Velocity 1.FPM (Feet per Minute) to m/s (Meters per Second): 1 FPM ≈ 0.00508 m/s 2.m/s to FPM: 1 m/s ≈ 196.85 FPM Energy and Power 1.BTU/h (British Thermal Units per Hour) to kW (Kilowatts): 1 BTU/h ≈ 0.000293 kW 2.Tons of Refrigeration to kW: 1 Ton ≈ 3.517 kW Pressure 1.Inches of Water Gauge (in wg) to Pascals (Pa): 1 in wg ≈ 249.08 Pa 2.PSI (Pounds per Square Inch) to kPa (Kilopascals): 1 PSI ≈ 6.895 kPa Temperature 1.°F (Fahrenheit) to °C (Celsius): °C = (°F - 32) × 5/9 2.°C to °F: °F = °C × 9/5 + 32 Additional Conversions Length 1.Inches to Millimeters: 1 inch = 25.4 mm 2.Feet to Meters: 1 foot = 0.3048 meters Area Square Feet to Square Meters: 1 sq ft = 0.0929 sq m Volume Gallons to L...

VALVES USED IN A CHILLER SYSTEM AND THE TYPICAL VALVE PACKAGE

VALVES USED IN A CHILLER SYSTEM AND THE TYPICAL VALVE PACKAGE 1.Chilled Water Side Valves ⇒Isolation valve (manual/electric actuated). ⇒ Installed on CHW supply and return lines. ⇒ Used to isolate chiller for maintenance. 2. Balancing Valve (Manual or Automatic) ⇒ Ensures correct flow rate to/from chiller. ⇒ Helps maintain Delta T and proper flow distribution. ⇒ Located after evaporator outlet (return line). 3. Differential Pressure Bypass Valve (if 2-way valves in system) ⇒ Prevents excess pressure build-up when terminals shut. ⇒ Maintains flow through chiller. 4. Flow Switch ⇒ Senses chilled water flow across evaporator. ⇒ Safety interlock: trips chiller if flow is lost. ⇒ Usually paddle type or electronic. 5. Air Vent Valve (Manual or Automatic) ⇒ Removes air pockets. ⇒ Placed at high points of piping and chiller headers. 6. Drain Valve ⇒ For flushing, cleaning, and maintenance. ⇒ Located at low poin...

HVAC engineers

Search This Blog