Fiorenzato Bricoletta - A Pro's Perspective - Page 5

July 14th, 2005, 11:20 am

Discussion of "clarity" and pressure/temp moved to new thread in Barista Tips.

July 14th, 2005, 2:40 pm

mmm mmm good

a wonderful shot (half consumed pre-photo)

#43: Post by **Abe Carmeli** » July 14th, 2005, 5:43 pm

I checked brew pressure on the machine and it was higher than I like (10.25BAR)

Chris,

How did you measure Brew pressure? Using a P/F gauge? if so I assume you measured it with no flow. If so, during a shot, the pressure will be different ~ 1 bar lower on a 25 sec 60 oz flow. so the 10.25 bars with no flow, actually translates to ~ 9.25 bars during a shot

July 14th, 2005, 5:56 pm

I borrowed a trick rig from the Stumptown tech crew that mimics both resistance and flow rate (which I suppose are the same thing you could say) and shows pressure.

You have seen a full BAR difference on the gauge fitted portafilters? In my experience it's been a lot less than that (more like 0.5BAR to at most 0.66BAR).

Hmmm... Actually, let me run over to the roastery and verify those numbers.

July 14th, 2005, 6:03 pm

I tested it on Vibe pumps, but not on a rotary. On a vibe it is ~ 1 Bar. That is: 10 bars with no flow will become 9 bars with a flow of 2 oz in 25 seconds.

So that I fully understand, what flow rate did you use when you reduced brew pressure to 9.25 bars?

July 14th, 2005, 6:26 pm

Just got back.
On the Linea the PF fitted gauge reads almost exactly 0.66BAR high (as compared to both the rig and the in-machine gauge).

Honestly, I don't know what they've got it set to but would have to guess (given the Stumptown parameters) that it is 1.75oz in 27sec.

July 14th, 2005, 8:43 pm

In order to continue my tweaking for experimentation on this whole clarity/temp/pressure thing, I decided it would be best to turn the Bricoletta (temporarily of course) into a "skeleton" version. I thought you all would dig the photos (grin).

July 15th, 2005, 11:53 am

Hey Abe.... to further complicate things I borrowed a different PF fitted gauge from the S-town techies and this one reads a little over 0.8BAR high on the Linea.

D'oh...

July 15th, 2005, 12:32 pm

Chris,

I found that fluctuations in voltage greatly affect brew pressure at least on a vibe pump. 5 volts fluctuation will produce ~0.3 bar difference. I don't know how it applies to rotary pumps though. On my home Machine I use a variac to reduce voltage from 115 to 100 volts and saw 1 bar difference in brew pressure.

July 15th, 2005, 12:45 pm

I doubt that would explain it.
I had the two PF gauges side by side on the Linea and saw the same results test after test. I fear at least one of the gauges is inaccurate.