Green Coffee Buying Club
Coffee Discussion boards => Hardware & Equipment => Topic started by: FinerGrind on August 05, 2008, 05:30:34 PM
-
Hi Chris,
I saw a post about gas manometers with your screen name on it, and now I can't find it (I thought Google with manometer and crholliday would find it). I read way too many sites.
I wanted to ask you, and any others reading this about measuring gas pressure between the main and gas control valve. I'll be on propane for a while, and during my brief roasting training, I reduced the NG flow after first pop (crack) by turning the ball valve and watching the watlow for the temp. drop until I was ready to drop the roast. My question is - is measuring the pressure using the manometer a datapoint that I'll want to include in the profile? Is it different for NG and LP? I'll do the research, but I wanted to know your experience, or anyone else who uses one, and if I should consider spec'ing this out right now.
Terry Davis mentions doing this in the post response (that I can't find - why didn't I bookmark this!?) but I didn't retain everything he said.
Thanks in advance,
Woody
-
Here is the thread you are thinking of:
http://www.roastersguild.org/forums/viewtopic.php?t=6468
I believe there will be flow differences between LNG and LP but you can use the same meter / setup. We log the adjustments so that we can repeat whatever profile we are working on.
Lets say I warm up for 30 minutes at 1.0 feet water column (f.w.c.), I would expect the environment temp to be about 400 F at 30 minutes. Lets say my charge temp should be 425, I will raise the flow to 1.5 f.w.c. and drop the beans at 425 (while the heat is climbing). Then I wait for some specified event to occur (either some x amount of time, some y temp or some z bean variable) and I adjust the gas back down to 1.25 f.w.c. With gas flow adjusted for differences in ambient temperature, I can then repeat that profile pretty consistently. We have a pretty inexpensive data logger from Omega that connects via USB to a laptop and both logs and displays realtime temps on environment and a bean probe.
http://www.omega.com/ppt/pptsc.asp?ref=HH802_803
Chris
-
Chris, thanks for the info - I think I'll make the investments on this then. I don't want to get "instrumentation overload", but do want to monitor and log what's going on during the roast.
-
Also note that if you will be using propane rather than NG, you will need a WC gauge that measures at least 15 inch WC. For NG you can probably get away with a 10 in WC gauge. Be sure and check you NG service for "normal" and potential "spike" delivered pressure even if you have a regulator in-line.
Sam
-
Also note that if you will be using propane rather than NG, you will need a WC gauge that measures at least 15 inch WC. For NG you can probably get away with a 10 in WC gauge. Be sure and check you NG service for "normal" and potential "spike" delivered pressure even if you have a regulator in-line.
Sam
Thanks Sam - I'm becoming indoctrinated in ways of gas and such things....
I have a question to you and Chris - what mfg. did you go with? Chris mentions Omega for the data-logger, and I've checked the Grainger web site for manometer pricing, and gosh, the digital manometers are a bit pricey. I saw one installed on a Gothot, and it was beautiful - old german gothic script on the glass indicator and the colored oil matching the paint was fetching.
My other question is: Is it feasible to DIY this thing? I guess anything is feasible but I like to speak to someone who's done it before I play with flammable things. I've been reading a few sites and this is what theirs looks like:
(http://www.warehouseappliance.com/Logos/manome1.gif)
I want to go digital with the variables as much as possible, but I'm probably going to whiteboard a lot of this stuff at first.
Thanks,
Woody
-
I'll take a picture tomorrow which will show you the model and the install. Sam installed it (in case the finish isn't photogenic enough).
;D
I think on the scale of 1 to 5 coffee beans its probably about a 2.5 bean job.