Flow Indicator for Low Pressure

[FranciscoG]

I am looking for a flow indicator for a 12" pipe at low pressure (8" water column). It is a Biogas installation (65% Methane, 35% CO2)

Any Idea?

 

[quark]

Check for Annubar type(averaging pitot) flow transmitters. These are used to check air flow rates even in air conditioning ducts.

http://www.rosemount.com/products/flow/m3095mfa.html

Regards,

 

[MortenA]

Annubar are quite expesive - any biogas are usually quite low tech.

If your pipesize were smaller and you dont need a signal then a simple "floater type" would propably be the best?.

A pitot type (same principle as annubar). They are however sensitive to fouling. These can be made "yourself" and if you dont require a signal then they can be fitted with a waterfilled U tube. They must however be calibrated.

A simple turbine flow meter may also work?

Best regards

Morten

 

[FranciscoG]

Thank you, but I dont know if I made myself clear, I need to detect the direction of flow not to measure the flow.

 

[zdas04]

I would stick an orifice flanged union (OFU) in the flow stream with a pretty small orifice plate (maybe a 2.5 plate for a 0.2 beta). Then a differential pressure gauge (or transducer) which reads from -10 to +10 inches would tell you the direction of flow. If use a gauge, you can mount it such that the arrow will point in the direction of flow for a visual indication.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The Plural of "anecdote" is not "data"

 

[1969grad]

If your objective is to determine if flow is present and not measure the amount of flow then some sort of "sail" switch might work. Seems like they are also called "target" switches.

 

[berro]

Just joined eng-tips, Maybe you got sorted with your flow indicator. I constructed one by making a bubble sight glass. A further benefit is that it acts as a check valve and condensate eliminator

The flow pipe comes half way down, vertically into a larger chamber (acryllic tube as sight glass) It bubbles through water indicating flow.