Question

Which is the most suitable instrument to calibrate the pressure gauges?

• A. Ionization guage
• B. Bourdon Guage
• C. Mc Leod guage
• D. Dead weight tester

Hint:

A Dead Weight Tester is a primary standard because it relies directly on fundamental physical quantities (mass, length, time) to define pressure.
This makes it highly reliable for industrial gauge calibration.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks to identify the standard calibrating instrument used to verify and calibrate pressure-measuring gauges.

Step 2: Detailed Explanation:

• Let us analyze each of the instruments listed:

• Ionization Gauge: A sensor used to measure extremely low vacuum pressures. It is not a calibration standard.

• Bourdon Gauge: A common type of mechanical pressure-indicating instrument. It needs to be calibrated itself and is not a calibration standard.

• McLeod Gauge: A mercury-filled vacuum-measuring gauge used as a primary standard for low pressures (vacuum), not for general high-pressure gauges.

• Dead Weight Tester: A primary calibration standard that uses the definition of pressure ($P = \text{Force}/\text{Area}$) to generate precise, highly accurate, and repeatable pressures.

• In a Dead Weight Tester, certified standard weights are placed on a piston of known cross-sectional area. By pumping fluid into the chamber until the piston floats, a highly accurate pressure is generated:
\[ P = \frac{M \cdot g}{A} \] where $M$ is the mass of the weights, $g$ is local gravitational acceleration, and $A$ is the piston area.

• The pressure gauge under test is connected to the same fluid chamber, and its reading is compared directly to the calculated pressure to perform calibration.

Step 3: Final Answer:
The Dead Weight Tester is the most suitable instrument to calibrate pressure gauges.