Choosing a Gas Flow Meter

Gas flow meters are used in many applications. Effectively they measure the flow of a gas which could be air, so there are many uses for these types of meters in the HVAC industries. They are need to check that air is flowing freely, that there are no contaminants in the air flow. another application is a natural gas flow meter.

When you are choosing a gas flow meter, it requires a bit of research. Essentially, you need to know what type of flow meter suits your industry. You need to set a budget and you need to be aware of the kind of setting up, care and maintenance that will be required to keep the flow meter operating.

There are all sorts of gas flow meters. The standard flow meter is the positive displacement meter that uses some kind of float mechanism within the tube or chamber that is being measured. The float is displaced or moved by the gas flow. The float is located against a scale or measure. The distance that the float moves correlates to the flow rate of the gas.

More complex flow meters use wave dynamics to get an accurate measure of the gas flow rate. Ultrasonic flow meters and Doppler shift flow meters measure the change in the frequency of a ultrasonic wave or numerous waves. In the cases of the ultrasonic flowmeter, two waves are propagated through the tube or pipe being measure. One wave is in the direction of the gas flow and the other is in the opposite direction. The difference between the two waves indicates the flow rate of the gas or substance flowing through the tube. A Doppler shift flow meter is more often used with liquids as it can measure liquids like effluent and waster water that have particulate matter within them.

Turbine flow meters have a turbine inside the tube or pipe that is being measured. The turbine is turned by the gas and this turn rate is analogous to the gas flow rate.

All these types of flow meters vary in price and have their advantages and disadvantages. The ultrasonic flow meter is probably the latest thing and will cost more money, but this really depends on what you are going to use it for, in terms of quantity or volume of gas being measured.

The ultrasonic flow meter can be installed easily as a clamped on device outside the pipe it is measuring. It can be calibrated for various gases quickly. It requires little maintenance because it never comes into contact with the substance it is measuring. This is not the case with the displacement meter or the turbine meter but these types of meters are generally made for a specific use and will be installed in the pipe and operate for a long time.