The temperature profile of a commercial lever group - Page 7

A haven dedicated to manual espresso machine aficionados.
User avatar
drgary
Team HB

Postby drgary » Jan 18, 2013, 11:26 pm

Very interesting, Oliver. Thank you for measuring. I'm looking forward to providing better readouts with my Prestina reassembled and with dialed in pressure and shots. If I weren't doing the rebuild I would want to measure my Pavoni.

How do your shots taste? Are they layered and soft the way I describe? If so that would suggest you're getting that effect through the pressure profile of your machine.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

User avatar
Chert
Supporter ♡

Postby Chert » Jan 19, 2013, 1:11 am

dr gary, I like your use of logging software and congratulations on a successful Scace-lite. Mine needs something to seal the wire to the thermocouple within the hole so that water doesn't escape through during pre-infusion.

If you use the same grind setting but decrease the dose by 2-3 grams the water will more thoroughly saturate the puck during preinfusion and the shot's duration will decline. Will the temperature curve over ~30 sec extraction hold that shape?

I want to call attention to the useful diagram emils posted earlier:
Image

Is there a point on the outside of the group, the temperature of which equals the temperature of the water that initially enters the coffee bed? (Your measurements suggests 198 F with your current pressure setting.) The idea that there is some water in the path to the group in steady state with group and boiler prior to pulling down the lever suggests to me that there might be such a point.

EDIT: I have a probe on the bell so I know when the group reaches steady state temp of ~77C. (boiler cycles between 1.0 and .85 bar. I added a thermocouple probe and measured behind the group on the chromed brass below that ball-bearing valve chamber today. 92.5-93 C / 198.5-199.4 F.

How much "pop" in temperature if any does the Fellini move bring?

User avatar
drgary
Team HB

Postby drgary » Jan 19, 2013, 2:14 am

Hi Flint:

JB Weld should easily seal that hole. The Artisan part is also easy if you have a data logger that is compatible with it and your computer. I worked that out for roasting. I stumbled across and tried the magnifying feature to take a snapshot of the trace. And of course I can dial in shot timing by lowering dose. Your idea is worth testing that lack of saturation of the coffee cake influences temperature decline.

I can't measure my machine right now because I'm in the middle of the complex (to a beginner) rebuild of the plumbing to include a vacuum breaker and install the more precise Sirai PSTAT. The Prestina will be soon be working again but my day job comes first, and I have Saturday hours now.

I look forward to seeing others' measurements and will contribute more of my own when I can.

Gary
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

User avatar
MaKoMo

Postby MaKoMo » Jan 19, 2013, 9:05 am

Image

I just measured my Faema President after 5h idle time, PS set to 1.2bar with such a Schomer basket, probe within the puck. I kept the portafilter in for a while until the temperature rise (starting from 21C room temperature) almost stabilized around 70C.

N1 = 70.1C/158.2F lever down, pre-infusion start, PS just turned off
N2 = 91.3C/196.3F extraction start
N3 = 96.2C/205.16F lever fully up
N4 = 94.8C/202.64F last drops

max = 98.6C/209.48F

Seems to run a bit hot and in this case slow.

User avatar
Chert
Supporter ♡

Postby Chert » Jan 19, 2013, 3:40 pm

Marko, Thanks for adding to this collection of temperature tests.

I edited my post above to record the temperature I was curious about. Next step to revive my coffee puck temperature probe.

User avatar
JohnB.
Supporter ♡

Postby JohnB. » Jan 22, 2013, 10:45 am

Eric, Jim S. & myself have all run temp tests on the Strega's Astoria style group. Jim & Eric each used homemade T/C in a basket devices & I used a Scace 1 adapting the testing procedure to the way the spring lever functions. We all came up with very similar results. The brew water temp quickly ramps up to your peak temp (flush length dependent) as the group fills & then gradually tapers down 4*-5*F over the course of a 30 second shot.

cafebmw wrote:now i'm wondering about the KVDW idrocompresso's temp profile....


I exchanged a few emails with Kees over the weekend discussing the Idrocompresso & the various tweaks that he's added to insure temp stability. I mentioned the Strega's temp swing & asked about the Idro's. He said that the Strega's was quite good & that he typically sees a 2*-3*C temp decline with the Idro.
LMWDP 267

User avatar
allon

Postby allon » Feb 10, 2013, 1:11 pm

Just a wild data point, but...

I taped a thermocouple about 1" up from the flare on the bell of my single group dipper CMA lever.
After the machine had been idle for 1 hour (it had been on for several hours previous) the TC read 171°F. I went through my usual prep routine - weigh, grind, load basket, then flush the group with about 2 oz (until the autofill kicks in), tamp, then pull the shot.

I should point out that the boiler runs at 1.0-1.15 bar.

Immediately after the flush, the group TC read 185. By the time I had tamped, loaded the PF, and was pulling the shot the temperature was 181. During the shot, the TC held steady at 180, declining only after the shot tailed out, after I had pulled the cup.

After flushing to clean up the basket and screen the group was at 189.
It took 2:00 to get down to 181.
It took 5:00 before it was at 176.
It took 11:00 before it was back at idle, 171.

This tells me that if I'm pulling back to back shots, I do not want to flush - I could just pull shot after shot as long as it took me 2:00 between pulls. Faster than 2:00 and it might affect consistency.

After 11:00, I'm back to idle condition.
LMWDP #331

User avatar
Chert
Supporter ♡

Postby Chert » Apr 28, 2013, 1:23 pm

I was steaming some barrel staves for a couple hours using the steam wand. At the end of that time by TC on the bell read 83C = 181 F. I turned off the steam arm and wait 20 minutes and the bell had settle down to 78C.