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Flow Indicator for Low Pressure

Flow Indicator for Low Pressure

Flow Indicator for Low Pressure

(OP)
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?

RE: Flow Indicator for Low Pressure

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

RE: Flow Indicator for Low Pressure

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

RE: Flow Indicator for Low Pressure

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
www.muleshoe-eng.com
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RE: Flow Indicator for Low Pressure

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.

RE: Flow Indicator for Low Pressure

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.

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