Valve for BioGas 1

[JPete78]

I have a client with a biogas scrubber which we are replacing along with the valves. They are currently using plug valves for shut-off and I was wondering if I should stay with plug valves or replace with another type of valve. Pressure is -0.1 PSI typically.

Thanks.

 

[JimCasey]

It takes a strong arm to turn plug valves. Aside from that they have very low restriction, they are comparatively inexpensive if exotic metallurgy is required, and they can be adjusted to restore shutoff if they begin to leak through. They have extraordinarily low leakage to atmosphere.

Ball valves sometimes do not seal well at low pressures, and gate valves leak anyway.

 

[JPete78]

Thanks for the response.

Are butterfly valves ever used in low pressure gas?

 

[vpl]

How leak tight do you want it to be?

Patricia Lougheed

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[gerhardl]

As known biogas could be relatively 'clean' or on the other hand have a content of agressive gases or droplets of fluid.

Depending on type of biogas, pressure/temperature, pipeline sizes and requiremant for thightness/leakage I believe a typical European solution would be ballvalves for smaller sizes, and types of qualifying butterfly valves (suitable for chemical process plants) for larger, or in some cases also membrane valves.

All valves qualified or certified if necessary for leakage to athmosphere if required.

Plug valves are not that much used in Europe.

 

[JimCasey]

Yes, butterfly valves are used in low-pressure gases, with great success. Forgive me for overlooking that option. Basic, flat-disc, rubber-seated valves would be operating well within their ratings.

The peril with butterfly valves would be possible solids carryover if the biogas fermentation bubbles energetically or overflows for other reasons. Fibers in bagasse could bridge the disc-edge and cause leakage. If the application demands, it is necessary to jump to a double-offset or triple-offset valve if firesafe ratrings are a consideration.