A rotameter is an example of a variable area meter.

A rotameter is a device that measures the flow rate of liquid or gas in a closed tube.

The volume flow rate of CO2 and air can be measured using a device called a "rotameter".

Filtered air was pumped through the chamber at a rate of 8.5 l/min monitored by a rotameter.

A rotameter is also a relatively simple device that can be mass manufactured out of cheap materials, allowing for its widespread use.

That authority named the machine a Rotameter.

Due to its use of gravity, a rotameter must always be vertically oriented and right way up, with the fluid flowing upward.

A rotameter requires no external power or fuel, it uses only the inherent properties of the fluid, along with gravity, to measure flow rate.

Either separate rotameters for different densities and viscosities may be used, or multiple scales on the same rotameter can be used.

Due to its reliance on the ability of the fluid or gas to displace the float, graduations on a given rotameter will only be accurate for a given substance at a given temperature.

A rotameter consists of a tapered tube, typically made of glass with a 'float', actually a shaped weight, inside that is pushed up by the drag force of the flow and pulled down by gravity.

However, as the inside of the rotameter is cone shaped (widens), the area around the float through which the medium flows increases, the flow speed and drag force decrease until there is mechanical equilibrium with the float's weight.

I attacked her with proportional dividers, planimeter, rotameter, Simpson's rule, Froude's coefficients, Dixon Kemp's formulae, series, curves, differentials, and all the appliances of modern yacht designing, and she emerged from the ordeal a theoretically perfect boat.

In 1958 the company developed a new, streamlined laboratory flow meter named Sho-Rate and a new type of full-view rotameter - with an improved packaging seal that represents one of the first innovations for the glass tube rotameter in 20 years.

The brand name Rotameter was registered by the British company GEC Rotameter Co, in Crawley, and still exists, having been passed down through the acquisition chain: KDG Instruments, Solartron Mobrey, and Emerson Process Management (Brooks Instrument).