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Main
Date: 01 Sep 2007 11:19:01
From:
Subject: pressure FAQ
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Single boiler, selonoid, no OPV:
Q. freshly roasted beans, finest grind+1, regular machine, 14-18 g.
fill, tamp: what's the expected brew pressure?
A. 8-10 bar.
Q. is it possible to brew a ristretto with 9 bar?
A. not possible.
Q. is it possible to brew a ristretto?
A. yes, at higher pressure.
Q. is it possible to choke?
A. with a good grinder: yes.
Q. is it possible to brew a 9 bar lungo?
A. not possible.
Q. does the temp influence the pressure
A. no (roughly)
Q: is the pressure constant during the shot?
A: not constant: end of the shot pressure is less due to deterioration
of coffee puck.
Single boiler, selonoid, OPV set to 9 bar
Q. ristretto at 9 bar?
A. possible.
Q. lungo at 9 bar?
A. not possible.
Double circuit HX with OPV:
Q. is the brew pressure any different from single circuit?
A. not at all
E61:
Q. anything special with respect to pressure?
A. nothing special
Lever machine with spring control of pressure:
Q: does it need an OPV?
A: yes and no.. A perfectly calibrated or adjusted spring could
theoretically provide an ideal pressure sequence during the shot
without OPV. More feeling required for the barista. Better chance for
different coffees (ristretto, lungo).
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Date: 02 Sep 2007 16:44:56
From: Danny
Subject: Re: pressure FAQ
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yuvali300@gmail.com wrote:
> Single boiler, selonoid, no OPV:
-snip weirdness-
What's all the rubbish about OPV, pressure and solenoids? As David
noted, original espresso machines (spring lever - as mine are) didn't
have or need the later additions, and are more than capable of
producing ristretto or lungo shots. It's *all* in the grind - you are
completely hung up on *pressure*.
--
Regards, Danny
http://www.gaggia-espresso.com (a purely hobby site)
(apparently bad grammar but I like it that way...)
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Date: 01 Sep 2007 19:12:38
From: Barry Jarrett
Subject: Re: pressure FAQ
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On Sat, 01 Sep 2007 11:19:01 -0700, yuvali300@gmail.com wrote:
>Single boiler, selonoid, OPV set to 9 bar
>
>Q. ristretto at 9 bar?
>
>A. possible.
>
>Q. lungo at 9 bar?
>
>A. not possible.
>
a lungo is certainly possible @ 9 bar.
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Date: 02 Sep 2007 17:10:39
From: D. Ross
Subject: Re: pressure FAQ
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Barry Jarrett <barry@rileys-coffee.com > wrote:
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Date: 01 Sep 2007 19:53:03
From: lockjaw
Subject: Re: pressure FAQ
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On Sep 1, 2:19 pm, yuvali...@gmail.com wrote:
> Single boiler, selonoid, no OPV:
>
> Q. freshly roasted beans, finest grind+1, regular machine, 14-18 g.
> fill, tamp: what's the expected brew pressure?
>
> A. 8-10 bar.
>
> Q. is it possible to brew a ristretto with 9 bar?
>
> A. not possible.
>
> Q. is it possible to brew a ristretto?
>
> A. yes, at higher pressure.
>
> Q. is it possible to choke?
>
> A. with a good grinder: yes.
>
> Q. is it possible to brew a 9 bar lungo?
>
> A. not possible.
>
> Q. does the temp influence the pressure
>
> A. no (roughly)
>
> Q: is the pressure constant during the shot?
>
> A: not constant: end of the shot pressure is less due to deterioration
> of coffee puck.
>
> Single boiler, selonoid, OPV set to 9 bar
>
> Q. ristretto at 9 bar?
>
> A. possible.
>
> Q. lungo at 9 bar?
>
> A. not possible.
>
> Double circuit HX with OPV:
>
> Q. is the brew pressure any different from single circuit?
>
> A. not at all
>
> E61:
>
> Q. anything special with respect to pressure?
>
> A. nothing special
>
> Lever machine with spring control of pressure:
>
> Q: does it need an OPV?
>
> A: yes and no.. A perfectly calibrated or adjusted spring could
> theoretically provide an ideal pressure sequence during the shot
> without OPV. More feeling required for the barista. Better chance for
> different coffees (ristretto, lungo).
who are you talking to?
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