The Original Rotameter

The Variable Area Flowmeter is one of the oldest and mature principles in flow measurement with its simple design: a float rises inside a conically shaped glass tube as the flow increases and its position on a scale can be read off as the flow rate.In the 1990s, Yokogawa strengthened its focus on flowmeters through cooperation with and the eventual acquisition of the German flowmeter manufacturer ROTA. In so doing Yokogawa gained access to 100 years of flowmeter expertise and completed its flowmeter portfolio by adding the Rotameter (variable area) and Rotamass (Coriolis) product lines.


Hello my name is John Dougherty, I am a Product Manager with Yokogawa. I am here today to introduce you to Yokogawa’s line of variable area flow meters, the true original Rotameter. Yokogawa has been manufacturing their Rotameters for over 100 years with an emphasis on both quality and accuracy. Yokogawa has a complete line of both glass and metal Rotameters. All of our Rotameters can be used to measure both liquids and gases. This is our RAGK and  our RAGL model Rotameters. Both meters are rated to 230 psi and 200 degrees Fahrenheit. They come with an optional needle valve which can be placed on the inlet or outlet. Adjustable limit switches are available and can be added. Here is the RAGN it is the largest of our glass Rotameters also rated to 230 psi and 200 degrees Fahrenheit. It has 3/16 stainless steel connections and a protective shield. The RAGN has a flow range of 10 gallons per minute liquid and 95 SCFM of gas. The connections can be threaded or flanged. The yellow background allows the for easy flow readings as well as showing if the flow material has become contaminated. Adjustable limit switches are also available

Yokogawa has a complete line of metal Rotameters the RAKD and the RAMC. The RAKD is used in high pressure and high corrosive sampling system. It can come with an adjustable needle valve, adjustable intrinsically safe limit switches and a 4-20 milliamp output. Finally we have the RAMC, the workhorse of industrial flow measurement. Its operating pressure can range from 30 inches of Mercury vacuum all the way to 10,000 psi. Its temperature range is from a minus 328 degrees Fahrenheit to almost plus 700 degrees Fahrenheit. The process connections can be threaded or flanged up to a maximum of 6 inches. The RAMC works on all fluids or gases. For really corrosive applications the RAMC can be manufactured to have teflon-coated internal parts. Hastelloy-C or Monel are also available upon request. The RAMC  has a large 4-inch easy-to-read local display with an optional 4-20 milliamp Hart compatible output. A pulse output is also available. With the electronic output, we added an LCD display to the local display that is field programmable. You can program it to show the actual flow,  a percentage of range or as a totalizer. Adjustable limit switches and fail safe limit switches are also available. Transmitter and limit switches are both FM and ATEX intrinsically safe and ATEX explosion-proof.





Related Products & Solutions

RAGK Short Rotameter

Thie Short Rotameter RAGK is designed for measurement of liquids and gases. The conical glass metering tube has a free rotating float. Measureable Flow Rate: Water = 0.002 l/h to 600 l/h; Air = 0.2 l/h to 6300 l/h


The RAGL rotameters are specifically designed for the measurement of low flows of liquid and gases. Their main application field is in purging, analyzer and gas sampling systems, laboratories and machinery equipment.


The RAGN Rotameter is designed for continuous flow measurement of liquids and gases. The borosilicate glass metering tube has a brightly colored easy to read scale. The RAGN comes standard with in-line 316 stainless steel fittings.

Air   Water

Custom Applications


The RAKD Rotameter is used for measurement of liquids and gases and is highly accurate, particularly for low flows and high pressure applications.


The RAMC combines all the advantages of the variable area principle with robust design and reliable measurement. A truly universal flowmeter for gases, liquids and steam applications.

Air   Water

Custom Applications