Old Flowmeter Gets New Certification
10 July 2009
Rotameter RAMC flowmeter certified for use in explosive areas—The Rotameter range has been in use in many areas of industry for 100 years, and includes designs with glass, plastic and metal measuring tubes. Units are available with mechanical displays and with additional components including transducers and limit switches.
Recently the Yokogawa Rotameter RAMC flowmeter was certified for use in areas with a risk of gas explosions and of dust explosions. The instrument now comes with many Ex certificates that are valid in Europe, America, Australia, China and many other countries.
Rotameters™, which are Variable Area Meters, are named after Rota, one of the European inventors of this flow principle in the beginning of the century. Rota invented the rotating float, which is self-guiding and has less friction in the pipe so that a more precise measurement is possible.
The RAMC short-stroke Rotameter allows the measurement of high flow rates using a relatively short metering tube. It is a stainless steel armored construction for the safe measurement of a variety of liquids, gas and steam. Its special application is for hazardous, dangerous or aggressive fluids, for high temperatures and high pressure rates.
Emphasis on safety
The FMEDA (failure modes, effects and diagnostic analysis) assessment of the design, carried out by test house exida®, permits operation of the RAMC even in safety-relevant systems that have to comply with the requirements for Safety Integrity Level SIL1 or SIL2.
The emphasis on safety in these Yokogawa products reflects the fact that, in all areas of industry, the explosion of combustible dusts presents a risk that is often underestimated.
According to estimates by the Munich Re Group insurance company, there is a dust explosion in Europe every day. A particular risk potential consists in the fact that even materials that otherwise are considered non-combustible can undergo explosion-like combustion when they are present in the form of a dust-air mixture.
In addition to avoiding gases and dusts and raising the awareness for the risk potentials, structural measures and the use of suitable instruments and systems such as the Rotameter RAMC flowmeter are some of the most important safety measures that industry can adopt.
The explosion protection for dust zones is available for instruments with the 'd' type flameproof protection in a robust aluminium housing with the marking II 1D Ex tD A20 IP67 T1...T6 or II 2D Ex tD A21 IP67 T1...T6.
For type 'i' intrinsic safety protection with the marking II 2G Ex ia IIC T6 or II 2G Ex ia IIB/IIC T4, the Rotameter RAMC is equipped with a stainless steel housing.
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