Homeroasters.org

Posted by endlesscycles on 04/20/2011 12:23

Is anyone out there using a pressure gauge in their air roaster furnace section? Have you found any use?

I'm trying to detect bean flow indirectly, but I suspect pressure is going to be nearly constant but since I haven't tried yet, I have no real idea. Hence this thread/ question.

Posted by freshbeans on 04/20/2011 12:40

Hi Marshall,
This was my first venture into it;
http://www.homero...wstart=125

I haven't really incorporated it in any meaningful way for roasting yet, so far, I used it to balance the blower for the Max Heatgun. -Scott

Posted by freshbeans on 05/20/2011 07:38

I lost track of this one. Anyway, what I'm finding is that the most meaningfull reading so far is at the base of the RC, just above the distributor. Obviously, it's a bit warm there.
I used an extension tube to get some distance between the gauge and the heat. It's a bit bouncy.
Further, I think the only way that info will be useful, is if it is tied in with the intake CFM, and perhaps exhaust CFM.
....Still experimenting as time allows. Cheers, -Scott

Posted by allenb on 05/21/2011 09:27

freshbeans wrote:
I lost track of this one. Anyway, what I'm finding is that the most meaningfull reading so far is at the base of the RC, just above the distributor. Obviously, it's a bit warm there.
I used an extension tube to get some distance between the gauge and the heat. It's a bit bouncy.
Further, I think the only way that info will be useful, is if it is tied in with the intake CFM, and perhaps exhaust CFM.
....Still experimenting as time allows. Cheers, -Scott

I've wondered also if measuring at both inlet of the fan/blower and at the high pressure side would yield a more useful reading but would require a meter able to read a differential pressure with two ports. Obviously if there is not a negative pressure at the sensing point at the inlet of the fan then this would be no different than a single input manometer.

Another thing to ponder (as Scott stated above) is if it would be better to read the differential between pre-perf plate and roast chamber which might cause the reading to reflect the change in flow dynamics as the load lightens.

Add a restrictor orifice in the tube to get rid of meter bounce.

Needs some experimentation and I think if we found the right way to read this we could then put the TC4 to work controlling the fan.

Allen

Posted by freshbeans on 05/26/2011 13:58

Ok...Exhaust cfm probably won't be very helpful...heat changes volume.

I'll stay focused on the differential below and above the perf. I'll order a second gauge.
Negative pressure at the blower inlet; I'm not sure what it will be worth, but I do have a gauge for it.
Thanks Allen. Any thoughts Marshall? -Scott