# What is A Manometer?

A manometer measures the difference in air or liquid pressure by comparing it to an outside source, usually a sample of Earth's atmosphere. There are several types of manometers, the simplest being a piezometer tube, which is a single tube and a base that holds the liquid. More common manometers are U-shaped and have interconnected tubes. Manometers are used in atmospheric surveys, weather studies, gas analyses and research of the atmospheres of other planets. They are usually made of glass or plastic, and while most are scored for measurement, some can measure changes digitally. The single-tube manometer measures only the pressure of a liquid, since there is no alternate place to compare gases. A U-shaped manometer essentially pits two different gas pressures against one another, and measures the strength of the captured gas. The free-flowing gas is usually air at the current atmospheric level.

# How does work a Manometer?

For a very basic explanation, a manometer measures the pressure differential between a closed pressure applied at one end and an open pressure at the other. For example. If you have a typical u-bend manometer and you apply an air pressure at one end, the liquid will raise correspondingly, as the pressure on the closed side increases more and more above the ambient air pressure. The amount it rises depends on the density of the liquid used and the diameter of the tubing. So basically a manometer uses the height of a liquid to translate the amount above ambient air pressure, which is considered zero, of your pressure source.

# How To Use Manometer?

A manometer may be any device that measures pressure. The term "manometer" usually refers to a basic liquid column instrument, unless otherwise specified. However, there many specific types of manometers with more specific names, such as a piston gauge, McLeod gauge, aneroid gauge and Bourdon gauge.

## Instructions

1-Use a liquid column manometer for demonstration purposes. Fill a tube halfway with colored water and bend it into a U-shape. Connect one end to a source of pressure and leave the other end open to the air. The height differential will indicate the pressure differential between the two halves of the tube. 2- Measure pressure with a piston gauge. These types of gauges use a solid spring or weight to counterbalance a fluid's pressure. These types of manometers are commonly used to measure the pressure in a tire. 3- Employ a McLeod gauge for applications where the gas doesn't produce condensation when it's compressed. This type of gauge compresses a sample of gas down to a few millimeters. A McLeod gauge is not suitable for continual monitoring. 4- Make an aneroid gauge to measure pressure without a fluid. These instruments use a metal strip that flexes in response to a pressure differential. These gauges are not restricted to a particular fluid and are less likely to contaminate the system. 5- Monitor the pressure in an enclosed container with a Bourdon gauge. This device uses a coiled tube that expands in response to a pressure increase. The tube is connected to an arm which rotates to indicate a pressure reading. Bourdon gauges were commonly used in steam locomotives.

20th Jan 2015

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