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How to Use a Manometer for Gas Leaks

How to Use a Manometer for Gas Leaks

What Is a Manometer?

When there’s a suspected gas leak, gas fitters use a tool called a manometer to accurately detect the fault. But what exactly is a manometer, and how does it work?

Simply put, a manometer is a device which is used to measure pressure. A traditional device is U-shaped, hence why it is sometimes called a U-tube manometer. However, with modern technology comes change, and it’s common to see digital manometers in practice.

For most of us, it’s a tool which doesn’t really come up in conversation. At best you would recognise a sphygmomanometer, which is what is used to test blood pressure. But among many other useful applications, manometers are an incredibly accurate way to detect a gas leak.

Manometers show a pressure drop in the gas line, indicating that there is a leak present. We’ll go into further detail on how exactly that works in a moment.

First, there are two main types in use, the analog manometer (or U-tube) and digital manometer. There are also slight variations on the analog, included inclined, absolute and hydronic manometers. We won’t specifically touch on them in this article.

Without further adieu, let’s tale a look at what exactly a manometer does, and how it can uncover a gas leak.

Analog Manometers and Atmospheric Pressure

When talking about specialised equipment like a manometer it is easy to get bogged down with the details. That’s not our goal. Rather it’s to provide easily absorbed information that gives a quick insight.

Analog manometers are one of the most common types of manometers on the market. They’re a U-shaped tube which contains fluid, typically either water or in some case mercury. One end of the tube is directly connected to the gas line while the other end remains open to external pressure. Some models are also open at both ends and can be capped.

When the manometer is connected to the gas line, the internal fluid should remain level on each side of the U, indicating balance as it reacts to gas pressure. The liquid will move, however, it should quickly settle if the gas pressure and air pressure is even.

However, if pressure is applied unevenly then the fluid in one leg of the water column will be forced down. The difference between two sides of the U reveals additional positive pressure is pushing down, and there could be one of two reasons:

  • If the liquid is higher on the open side, gas pressure is higher than air pressure
  • If the liquid is higher on the closed side, air pressure is higher than gas pressure

With natural changes in atmospheric pressure the reading can vary from time to time. That’s why accurate instruments are necessary for measuring any differential pressure.

Other designs like the well-type manometer and inclined manometer provide even more sensitivity and are especially effective at picking up smaller leaks.

Digital Manometer Accuracy

Technology has seen rapid growth in the accuracy of digital manometers, also known as electrical manometers. Not only can they detect a drop in pressure, but they are also used to calibrate and commission gas appliances.

Digital manometers provide accurate readings with ease. Unlike the analog manometer, a pressure transducer is used to create a result. The elastic component of the transducer detects external pressure levels and converts the energy into an electronic signal. A perfect reading is displayed instantaneously in pascals or psi.

There is a range of digital manometers on the market for specific uses, too.

For example, there is a hydronic manometer and data logger which is specially designed to balance hydronic heating and cooling systems. It provides accurate measurements for pressure differential, while it can independently reveal the pressure on both the low and high side at the same time.

In conclusion, having a high quality instrument to measure differential pressure is the perfect way for a gas fitter to instantly detect faults. Whether it’s analog or digital, a manometer remains a leading tool for gas leak detection.

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