Question

Bourdon gauges are used for measurement of pressures

• A. Local atmospheric pressures
• B. Local absolute pressures
• C. Low range vacuum pressures
• D. Large range gauge pressures

Hint:

Bourdon gauges measure gauge pressure over a wide range, from small vacuums to high pressures, making them versatile for industrial applications.

Answer 1

The Correct Option is D

Step 1: Understand the Bourdon gauge.
A Bourdon gauge is a mechanical pressure-measuring device that uses a curved, hollow tube (Bourdon tube) that straightens under pressure. The movement of the tube is mechanically linked to a pointer on a dial to indicate pressure. It is commonly used in industrial applications. Step 2: Analyze the pressure types and ranges.
Gauge pressure: Pressure relative to atmospheric pressure (\( P_{\text{gauge}} = P_{\text{absolute}} - P_{\text{atm}} \)). Bourdon gauges typically measure gauge pressure.
Absolute pressure: Pressure relative to a perfect vacuum (\( P_{\text{absolute}} = P_{\text{gauge}} + P_{\text{atm}} \)).
Vacuum pressure: Negative gauge pressure (below atmospheric pressure).
Range: Bourdon gauges are effective for a wide range of pressures, typically from slightly below atmospheric (small vacuum) to high pressures (e.g., 0 to 1000 bar or more), depending on the design.
Bourdon gauges are most commonly used to measure gauge pressures over a large range, from slightly below atmospheric to very high pressures. They are not typically used for precise measurement of low vacuum pressures (e.g., 10\(^{-3}\) Torr), where devices like Pirani or McLeod gauges are more suitable. Step 3: Evaluate the options.
(1) Local atmospheric pressures: Incorrect, as Bourdon gauges measure gauge pressure (relative to atmospheric), not atmospheric pressure itself. A barometer would be used for atmospheric pressure. Incorrect.
(2) Local absolute pressures: Incorrect, as Bourdon gauges measure gauge pressure, not absolute pressure, unless modified with a vacuum reference. Incorrect.
(3) Low range vacuum pressures: Incorrect, as Bourdon gauges are not sensitive enough for low vacuum pressures (e.g., 10\(^{-3}\) Torr); they can measure small vacuums (e.g., -1 bar gauge) but not low-range vacuums. Incorrect.
(4) Large range gauge pressures: Correct, as Bourdon gauges are designed to measure gauge pressures over a wide range, from small vacuums to high pressures (e.g., 0 to 1000 bar). Correct.
Step 4: Select the correct answer.
Bourdon gauges are used for the measurement of large range gauge pressures, matching option (4).