Pressure Sensor Specifications

Selecting a pressure sensor or pressure transmitter in an industrial plant is not just about pressure range.
A wrong selection can lead to:

• Frequent failures
• Wrong readings
• Process trips
• Safety risks
• Increased maintenance cost

This article explains all important pressure sensor specifications in simple language, with practical industry meaning, so you can select the right instrument the first time.

1. Pressure Range (LRV & URV)

This is the first and most basic specification.

• LRV (Lower Range Value) → Minimum pressure
• URV (Upper Range Value) → Maximum pressure

Example:

• Pressure range: 0 to 10 bar
• 0 bar → 4 mA
• 10 bar → 20 mA

Practical Tip:

✔ Never select a transmitter with URV equal to normal operating pressure
✔ Keep 20–30% margin above maximum operating pressure

This protects the sensor from overpressure and increases life.

2. Type of Pressure Measured

• Pressure sensors are classified based on reference pressure.

  a) Gauge Pressure

  • Measures pressure relative to atmosphere

  • Used for pumps, tanks, pipelines

  Example:    5 bar(g) means 5 bar above atmospheric pressure.

b) Absolute Pressure

• • Measured relative to perfect vacuum
  • Used in vacuum systems, condensers

Example: 0 bar(abs) = perfect vacuum

c) Differential Pressure (DP)

• • Measures difference between two pressures

• • Used for:

    • • Level measurement
      • Flow measurement
      • Filter monitoring

Always select the correct type, or readings will be meaningless.

3. Accuracy

Accuracy tells you how close the measurement is to the true value.

Typical Accuracy Values:

• • ±0.5% → General purpose
  • ±0.25% → Process control
  • ±0.1% → Critical measurement

Example:   If accuracy is ±0.5% and range is 0–100 bar:

• • Possible error = ±0.5 bar

Practical Tip: Higher accuracy = higher cost
Do not over-specify unless process demands it.

4. Output Signal

Most industrial transmitters use:

✔ 4–20 mA (Industry Standard)

• • Noise immune
  • Long cable distance
  • Fault detection

Other outputs:

• • 0–10 V (short distance only)
  • HART (4–20 mA + digital)
  • Modbus / Fieldbus (digital)

Practical Tip:  For harsh industrial environments → always prefer 4–20 mA.

5. Power Supply Requirement

Check how the transmitter is powered:

a) 2-Wire (Loop Powered)

• • Powered by 4–20 mA loop
  • Most common
  • Simple wiring

b) 3-Wire / 4-Wire

• • Separate power supply
  • Used for high accuracy or fast response

Practical Tip:  If unsure → choose 2-wire transmitter.

6. Process Connection

This defines how the sensor is mounted on the process.

Common connections:

• • ½” NPT (most common)
  • ¼” NPT
  • Flanged (chemical, high pressure)
  • Sanitary clamp (pharma, food)

Practical Tip:  Match the existing tapping on the pipeline or vessel.
                                 Adapters increase leakage risk.

7. Wetted Parts Material

Wetted parts are materials in contact with process fluid.

Common materials:

• • SS 316 → general industrial use
  • Hastelloy → corrosive media
  • Monel → marine / chemical

Practical Tip:  Wrong material = corrosion + sensor failure
Always check process fluid compatibility.

” Pressure Transmitter Troubleshooting – Practical Video Demonstration ”

The following video demonstrates real troubleshooting scenarios such as zero shift, span error, loop current issues, and process connection problems commonly faced in the field.

Click Below – 

https://youtu.be/ij1e3zASdxs?si=BqYIeIySzndiEV8I

8. Operating Temperature

Pressure sensors have:

• • Process temperature limit
  • Ambient temperature limit

Example:

• • Process temp: −20 to 120°C
  • Ambient temp: −10 to 60°C

Practical Tip:  High temperature reduces sensor life
Use remote diaphragm seal if process temperature is high.

9. Overpressure & Burst Pressure

This defines how much extra pressure the sensor can tolerate.

• • Overpressure: Temporary pressure without damage
  • Burst pressure: Pressure at which sensor fails

Practical Tip:  Select sensor with overpressure rating ≥ 2× URV. This protects against pressure spikes.

10. Response Time

Response time is how fast the sensor reacts to pressure changes.

• • Fast response → control applications
  • Slow response → stable readings

Typical Range: 100 ms to 1 second

Practical Tip: Fast response is not always good — it can increase noise.

11. Environmental Protection (IP Rating)

IP rating defines protection against dust and water.

• • IP65 → Dust tight, water jets
  • IP67 → Temporary immersion
  • IP68 → Continuous immersion

Practical Tip: Outdoor installation → minimum IP67

12. Certification & Safety

For hazardous areas:

• • ATEX
  • IECEx
  • Explosion Proof
  • Intrinsically Safe

Practical Tip: Never ignore area classification.
Wrong selection can cause serious safety incidents.

13. Calibration & Adjustability

Check if the transmitter allows:

• • Zero adjustment
  • Span adjustment
  • Field calibration

Practical Tip: Local zero/span buttons save time during commissioning.

14. Mounting Orientation

Some sensors are sensitive to:

• • Position
  • Mounting direction
  • Vibration

Practical Tip: Follow manufacturer mounting guidelines to avoid zero shift.

15. Cost vs Reliability (Final Decision Factor)

Do not select based on price alone.

Consider:
✔ Process criticality
✔ Maintenance access
✔ Spare availability
✔ Brand support

A cheap sensor failing repeatedly costs more in the long run.

Final Thoughts

Selecting the right pressure sensor is a balance between:

• • Technical requirements
  • Process conditions
  • Safety
  • Long-term reliability

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If you understand these specifications clearly, you can confidently select the right transmitter for any industrial application.

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