The Mcleod gauge, Pirani gauge, and Ionization gauge I — Lesson 1

This lesson covers the principles and techniques of low pressure measurement, focusing on the McLeod gauge and Pirani gauge. It explains the operational principles of these gauges and how they can measure extremely low pressures. The lesson also discusses the potential sources of error in these measurements, such as the presence of vapour in the sample gas. It further elaborates on the steps to follow when using a McLeod gauge, including the movement of the reservoir and the compression of the gas. The lesson concludes with a brief introduction to the Pirani gauge and ionization gauge, which will be discussed in detail in the next session.

Video Highlights

00:33 - Introduction to low pressure measurement techniques
10:20 - Explanation of the steps to measure low pressure using McLeod gauge
21:39 - Mathematical analysis of pressure measurement
36:44 - Potential sources of error in pressure measurement
41:00 - Introduction to Pirani gauge and ionization gauge

Key Takeaways

- McLeod gauge and Pirani gauge are essential tools for measuring extremely low pressures.
- The operational principle of a McLeod gauge involves the movement of a reservoir and the compression of gas.
- Careful measurement and attention to detail are crucial when using these gauges to avoid errors, such as the condensation of vapour in the sample gas.
- The Pirani gauge and ionization gauge, which exploit the reduction in effective thermal conductivity of gas with pressure, are also used for low pressure measurements.