crholliday - manometer on your L12?

[FinerGrind]

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

[crholliday]

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

[FinerGrind]

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.

[SamDiscusFlyer]

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

[FinerGrind]

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:


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

[crholliday]

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).

 

I think on the scale of 1 to 5 coffee beans its probably about a 2.5 bean job.