Simple and Effective Design
Rotometers are ideal for measuring the rate of liquids or
gases which are being utilized for an application. Rotometers are equipped with
a device called a “float” which rises and falls based upon the flow rate of the
material. If the float is high then that means there is a greater force in the
flow. These floats are engineered in different designs such as circular,
triangular or elliptical. The float is housed in a special tube known as a
tapered meeting tube. The diameter of a tapered tube gradually increases along
the vertical axis of the device. Rotometers are crucial pieces of equipment
when flow rate identification is essential.
Rotometers come in simple and complex designs. Some rotometers
can be equipped with multiple features for checking material properties such as
temperature, pressure, viscosity and more. There are many advantages and
disadvantages to rotometers. One of the major advantages to rotometers is the
fact that these devices have a simple design with few components which makes it
easy to mass produce. Most rotometer designs require no electricity to operate
which makes it ideal for applications where electricity would be a hazard or in
situation where no electricity is available. The placement of the tube is very
critical because gravity is a key factor for proper functionality of the
rotometer. Another disadvantage of rotometers is the accuracy of the readings
become less reliable at low flow rates. Rotometers come with an excellent value in
terms of repeatability and ease of use. These devices are quick to respond to
any changes in the flow path. An example of a common rotometer can be found in
the medical field. Medical personnel typically utilize a rotometer in oxygen
Rotometers are flow meters named for the rotating float which functions
as the meter's indicating element. A float moves up and down a tapered
tube according to the rate of flow. Rotometers are typically used to
measure low flow rates and are an economical method of indicating and
controlling gas and liquid flow for several applications.
Typically, rotometers are used to measure smaller flows and the reading is usually done locally, although transmission of the readings is possible. Most rotometers are made of glass with markings on the outside so that flow readings can be taken visually, similarly to flow indicators; however, metal rotometers are also available. Rotometers are advantageous due to the simplicity of the device and the constant pressure drop they offer. Also, rotometers do not require straight pipe runs for installation so installation can be performed almost anywhere. The selection of the appropriate rotometer for a particular application requires attention to a few key details. These include which gas will be used, the required flow rate, the number of streams to be measured and whether a metering valve is included. Rotometers are favorable for their simplicity, versatility, accuracy, and ease of use. For all these reasons, rotometers are the flow meter of choice for many industries.
Rotometers consist of a float that moves vertically through a slightly narrowing tube. As fluid enters the bottom of the rotometer, the float is forced upward until the force is balanced by gravitational forces. Like peak flow meters, graduations are marked on the tube so that the level of the float can be aligned with a gradient to provide an accurate, fast and easy-to-understand flow rate reading. Rotometer tubes are read directly in standard cubic feet per hour of air. Rather than using a constant restriction area and a variable pressure differential, rotometers use a variable restriction and a constant pressure differential to measure flow. Rotometers may be designed to measure the flow rate of single or multiple streams. Single tube rotometers are usually mounted directly on the piping and they are used with non-corrosive materials. Single tube rotometers are used if there are special conditions for the measurement or when a basic flowmeter will suffice. Multiple tube rotometers are mounted to a tripod base plate with feet to level the assembly. They may also be bench or wall mounted. This kind of rotometer takes measurements for flow rates of more than one stream of gas or liquid. Other variations are also available.
Rotometers - Hoffer Flow Controls, Inc.
Flow Meters – HydraCheck
Rotometer Informational Video