## How to Calculate the Rate With an Area Flow Meter

A variable area flow meter operates on mechanical principles. Their construction is simple yet durable, making them suitable for a variety of applications. The basic operational principle is that changes in flow rate can be observed and measured as the flow displaces a piston, float or vane until it reaches a steady state. As the liquid or gas passes thorough the housing tube, the movement of the measuring part indicates rate. This type of meter can be placed almost anywhere along the pipe and does not require complicated maintenance routines. It is also highly versatile and can be used to measure flow rates of liquids, gases and steam.

Generally, flow rate meters measure the volume or mass of gas or liquid that is displaced during a specific period of time, for example, liters per second. Density is an important factor in determining rate.

## Best Rotameter Designs

Rotameters, also referred to as variable area flow meters, are widely used to measure gas and liquid flow. The basic principle of rotameter design includes a float that rotates as it is pushed by the flow. The rotation speed of the float indicates the rate of the flow. With today’s new technology, the basic rotameter has evolved its capabilities to provide highly precise flow rate measurements and to withstand a variety of extreme temperature and pressure conditions.

## Exploring the History and Designs for Variable Area Flow Meters

Variable area flow meters are devices designed to measure the flow of gases or liquids through pipelines and similar enclosed structures. Over time, different types of VA flow meters have been developed, usually in response to some specific need. Here is some background on the meters and how the various designs came to pass.

## The Beginning

Karl Kueppers is credited with developing the first true variable area flow meter. Designed and launched in 1908, the device was patented in Germany that same year. The initial function had to do with measuring water flow.

Felix Meyer was among the first to recognize the significance of Kueppers’ work and implemented the process for offering the meter for sale. In 1909, the firm of Duetsche Rotawerke was created in Aachen Germany. It didn’t take long for the new device to capture attention in Europe, the United Kingdom, and other areas.

In the first decades of the 20th century, Kueppers continued to refine the basic design. Specifically, he enhanced the shape of the float used in the glass tubing so that the results of the water flow testing were more accurate.

During this period, the Kueppers product became known as a rotamesser, which can be roughly translated as a rotation measurer.

## Here Comes the Rotameter

Prior to the Second World War, a version of the VA flow meter appeared in the United Kingdom. Still designed for measuring liquids, the newly dubbed Rotameter and registered by the UK firm of GEC Elliot. For years, the meter was manufactured by a division known as Rotameter Inc and based in the Croydon area.

During the 1970’s the manufacturing operation was moved to Crawley, where it is still in operation. Over the years, ownership of the operation has changed as acquisitions and buyouts have taken place. As of 2016, the patent and the registration for the rotameter are held by the Yokogawa Electric Corporation.

## Variable Area Flow Meters for Natural Gas Measurement

While originally designed for liquid measuring, further developments too place from the middle of the 20th century and continue today. Some models make use of heavy-duty plastic tubing rather than the traditional glass. The shape and materials used after 1950 for the floats have also changed. Designs that make it easier to measure the flow of gas or steam through a system serve the same basic purpose as the originals, making it easier to determine if the flow is efficient, or if some factor is impeding the progress of the gas.

While the meters are still relatively simplistic in design, contemporary meters sometimes include equipment that makes it possible to monitor and download results to a computer program. This helps to limit the potential for human error in reading the test results.

This more modern approach also aids in the collating of data over a specified period of time. For example, if there is the need to compare test results over the last six months and assess what differences have occurred after structural changes or other adjustments are made, accessing the history is quick and efficient.

While variable area flow meters may be inexpensive to produce, they have saved a great deal of time and money in a number of settings. Today, the meters are no longer used exclusively in manufacturing settings. The meters are also used in managing municipal water systems, laboratories, and mining operations. There is no doubt that additional uses for the meter will come about as the technology continues to develop.

For more information on Flow Meters and other flow related products visit Flowmetrics HERE

More on the history of flow meters visit Flow Control HERE