Looking for equipment to measure pressure? Try using a vacuum gauge. It is an effective tool for measuring pressure that is below the atmosphere’s vacuity. Most times, it has different values. Atmospheric pressure is usually zero but if it is less than zero, it is measured with a vacuum gauge. The value always carries a negative, that is, -1 barg or -15 psig.
However, vacuum gauges come in different types, sizes, and specifications. This is because it can be used in manufacturing, food and beverage production, chemistry, pharmacy, and automobile industries. They are important devices used to ensure that there is safety and optimal performance. If you need more information about these devices, you can visit: https://www.teledyne-hi.com/products-services/vacuum-measurement-and-control for some help.
In this article we will do a brief review of the meaning of vacuum pressure, the types and how to use it. Please keep reading as we explain more.
Table of Contents
What is Vacuum Pressure?
As stated earlier, vacuum pressure is expressed as the negative value of atmospheric pressure. In simple terms, if atmospheric pressure refers to the normal sea level pressure which is 101.325 kPa, vacuum pressure is the negative of this value. So, this type of pressure is the negative of atmospheric pressure.
Types of Vacuum Gauges
They are classified into two types based on how they measure compression. They are direct and indirect gauges. On one hand, direct ones refer to the type of vacuum measure that directly measures compression by exerting force on the gas molecules. On the other hand, indirect vacuum measures refer to types that does not exert force; it works by calibrating its readings to show the gas present.
Direct gauges are commonly used for low vacuum ranges while indirect ones are used for medium, high and ultra ranges. Both types can be used as mechanical, thermal conductivity, ionization, fore line, high, and mechanical pump gauges.
How to Use a Vacuum Gauge
The following are the steps involved in using a vacuum gauge:
Know How Your Engine Works
Knowing how your engine works goes a long way to help you detect if there is any change in its functionality. For instance, the engine of a car is like a big pump filled with air. The car draws in air on a low-pressure into a cylinder, compresses it, and allows it to mix with little fuel. During this process, it lights a fire which then produces the compression and heat finally expelled as smoke through the exhaust pipe.
It therefore starts with air pump into the cylinder. So, to start measuring the compression you will need to connect the device, that is, the gauge to the tap on the cylinder. This same process applies for all other engines. You will first need to locate the tap or pipe on it. This can only be done if you know how the engine works.
Understand the Pressure Range
Various gauges operate at different ranges. So, it depends on understanding how to read the gauge, the limit of pressure it measures and accuracy. Examples of some ranges include:
- Low range and high-pressure equipment within 10 Torr. They require bourdon tubes, capacitance sensors, active strain, and bellow gauges.
- Medium range vacuum equipment with 10+1-10-3 They require capacitance high manometer or thermocouple gauge.
- High ones from 10 -3– 10-6 They require Bayard-Alpert cold cathode or hot cathode gauges.
- Ultra high ones below 10-6 They require Bayard-Alpert cold or hot cathode gauges
Get a Suitable Gauge
Depending on the system you have; after understanding how it works and its range, you can go ahead to get one. Devices used to measure usually have different measuring units. They are made in inches of mercury (in.-Hg) or millimeters of mercury (mm-Hg). Some gauges are also digital; they show the results on its display.
However, before choosing any, it is necessary to understand how it works and the other options available so that you will make the correct choice. You will also need to consider the mode of operation, gas composition, gas sensitivity and its compatibility with your system. Getting the right choice ensures that you get best results.
After getting the suitable measuring device, read through the user manual to understand more of its features. After that, you can follow the instructions on it to check the pressure of your equipment at any time. If you need more information on how to read ranges, you can watch this video.
We have discussed the meaning of vacuum gauges, its, types, and how to use it in this article. However, it is pertinent to note that the processes vary depending on the type of engine or system you are using. So, there no-one-for-all procedure on how to use it, you need to understand how yours works. Also do not forget to always take accurate measurement. This will help you make the most of your system and control the compression at any stage of the process.