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Dear,

We have a fuel gas with various specific gravities in a wide range that enters into a boiler. I am looking for an instrument that measures the flow of the mentioned fuel gas.

Please help me.

Regards.

You must determine more exactly the ranges of density and flow. And accuracy. In Russia we work with Coriolis (for example Micromotion) flowmeters, when there is a wide range of density or viscosity.

A lot depends on the amount of gas you are using as to what solution you can afford.

In industrial gas flow measurements you could use the turbine or brooks type flow meters (Actaris http://www.actaris.com/html/eng/GAS/3-15.html) which are available for both clean and dirty gases.

These provide a volume measurement and you then need to determine if you simply provide a PTZ correction or use a gas density meter. In critical applications and especially where the gas quality varies you would also add in an SG analyser or relative density meter. These can help infer the Wobbe Index.

For gas density (7812) and gas relative density/SG (3098) visit Micomotion or the Mobrey site http://www.mobrey.com/products/density/index.php)

I would like to know the line size & flow rate before making a comment on the appropriate intrument. If it is small line sizes up to 6" a coriolis or inline thermal mass flow meter would be a good choice. For accurate measurement Coriolis would be preferred as it do handle density correction but if accuracy of +/-2% of reading is good enough you can also use an inline or insertion thermal mass flow meter.

Further use a Averaging Pitot Tube (ANNUBAR) or ACCELABAR with multivariable transmitter to give you mass flow reading. Visit http://www.chandakinstruments.com to know more.

Best Wishes,
Rohit

Thermal Mass flow meter would be a good choice, the only thing to make sure, gas should be clean & moisture free. since it works on thermal dispersion technology, it doesn't need pressure & temp compensation. it direct gives you compensated volumetric (SCFM) or Mass flow (Kg/hr for ex). and insertion style is really easy & cost effective to install. I would recommend to use it with Ball valve retractable assembly so that it can be maintain easily, if need be. feel free to contact me for further info if you wish at instrumentation_control @ yahoo. ca

Dear Maulik, I'm curious why you would suggest a Themal Mass Meter since their accuracy is dependent on the gas specific heat. The inquiry said they have a variety of gas types. Therefore I don't see this type any better than a turbine meter, etc. Thermal meters also tend to drift with time, have a slower system response, and are rather expensive compared to turbines, orifice, pitot tube, etc.

John Catch
www.inflowinc.com