Gas Flow Measurement

[Beegle]

It seems like it should be simple but I can't find it covered anywhere. I'd love to have a gauge or a meter that tells me what my gas consumption is at any given moment. My thought is to have somethingbin the line between the control valve and the burner jet but I can't find this anywhere. It would be nice to record more specific data in my profiles rather than just recording I had it on 'high', 'medium', or 'low'. This is either such a simple task that nobody has thought there would be somebody as dumb as me that would not figure it out on their own or it just isn't something people do. Any help is greatly appreciated. Thank you.

 

[ellatas]

Beegle,
Not many coffee roasters measure gas flow into their roasters. Typically pressure measurements before and after the regulator will tell you if there is variation in the gas supply. The most frequent example is when the supply cannot keep up with the demands of the burner at high fire. In these instances, if the pressure before the regulator drops then there is insufficient gas pressure to run the roaster. If the pressure aftier the regulator drops, but not before, then it is likely that the regulator is not large enough.
If you still wish to incorporate a gas flow meter, the least expensive solutions are "orifice flow meters" or "venturi flow meters". Karl Dungs sells them, but you may have to buy them through the OEM or a local reseller. They can be installed on the high pressure side or the low pressure side.

 

[Beegle]

That is interesting and is what I had started to realize on my own. It seems sad to me that nothing exists. It seems to me that people would like to include burner settings in tgeir profiles that are a little more specific than "high", "medium", and low. I thought for sure thee would be people measuring their kpa or wc into their burners. I know what the gas flow is coming in and out of my regulator and that is useless data even if it varied anyway. I want to know what my burner is receiving. Thanks for the reply.

 

[Beegle]

Would something like this installed in the line before the burner jet do what I am wanting?

https://www.dwyer-inst.com/Product/Pressure/SinglePressure/Gages-Dial/SeriesLPG4

 

[imiller]

A gauge like that should work. A range of 0-15" would be better. Put it between the valve and the burner and you'll be good to go. We just added a Dwyer gauge and a valve to our roaster and it works great.

 

[Beegle]

Hey, that's great to hear! Thank you. Which model did you opt for? How did you go about coupling it into the line?

 

[ellatas]

"Gas Pressure" (as measured in kPa or "wc) is not the same as "Gas Flow" (as measured in cfm). Measuring Gas Pressure prior to burner is quite common and you can pick up suitable gauges at Grainger (Vacuum Gauges and Pressure Gauges - Pressure and Vacuum Measuring - Grainger Industrial Supply) and they are inexpensive. Be sure to properly plumb in a Tee with a gas cock so you can isolate the gauge and replace if needed.
From the gas pressure and knowing the capacity curve of the burner, you can infer the gas flow.

 

[Beegle]

Very sorry to have used the wrong terminology. My apologies.

Is there a particular gauge that you would recommend?

 

[AdventureCopan]

This is great question and one of many I am getting ready to address my self as we just got our first used large roaster. Cleaning and updating now! Following...

 

[ellatas]

Hi Beegle,
No worries. To determine the right gauge, you should look at the documentation on the roaster burner. If you still have the roaster manual, it should have the pressure ranges for the burner (but not the gas train - since this will be higher). These figures may also be located on the burner itself. Once you have the maximum pressure (likely to be between 2" wc & 8" wc), choose a gauge that is slightly higher. The more you use the gauge's range the better the resolution on the gauge. Alternatively, you could purchase a 0-5" wc pressure gauge, install it, then see if it is the right size (as they're relatively inexpensive).
This is different if you have a pre-mix burner with a combustion blower.

 

[slurp]

It is not just a gauge you need. You need to know how much gas and how long then how much you pay for the fuel. Do you change your burner output when roasting? Surely you do not turn the burner on and leave it the same the entire roast. Only Topher roast like that

Roaster Dynamics has this build into their controls.

 

[Beegle]

That is precisely why I want the gauge because I don't leave my burner at a constant rate during the roast. I don't have a variable drum so my only controls are heat and air which of course means my only real control is heat. I want to be able to add indicators to my profiles that show what the gas pressure is at given points. I am not interesting in calculating the cost of fuel.