Building a Portafilter Pressure Gauge - Page 3

#21: Post by **gscace** » June 20th, 2007, 2:41 pm

TroyR wrote:Thanks, $30 ish CAD at ColeParmer.ca for the gauge.

Actually, I have yet to convince myself that dialing down my OPV from 13 bar to anything else is a good idea (or at least that it will make a difference to most of my shots). I am of the mind that a good shot will naturally create a system pressure in the 8 or 9 bar range and that the 13 bar OPV is a max limit for the system to allow flow and prevent damage in the case of a choked system.
Anybody want to support that or change my mind?

Regards,
Troy

My experience is that much over 9 bars at the group makes the taste quite sharp and bitter, regardless of the pressure profile or pre-infusion scheme. I'm fortunate to have an electronically controlled pressure system that allows me to program brew pressures, profiles and pre-infusion while holding other variables constant. It is also by no means true that the system pressure will self-regulate to 9 bars if the flow is correct thru the cake. Pressure thru the cake is dependent on the upstream pressure established by the pump, the pump type, pressure relief valve configuration, and the configuration of the flow path between the pump and the group (diameter, length, gicleurs, solenoid location and type, etc.). The right way to do the measurement is to do it under flowing conditions. It's the only way you're gonna make any meaningful correlation to taste that can be transferred to other machinery. The 13 bar number that you quote may work as a static pressure measurement for a machine that uses a vibe pump with a long-stroke pressure relief valve, but it will not work at all for a machine with a short-stroke pressure relief valve scheme, or rotary pump. Best to do the measurement properly so that there is no performance variation due to flow path variability.

-Greg

#22: Post by **Juanjo** » June 11th, 2009, 6:32 pm

here is one I made with some fittings of an old gaggia.

#23: Post by **Vad** » June 12th, 2009, 12:09 pm

Here is what mine looks like:

#24: Post by **gj91** » June 18th, 2009, 8:50 pm

I need to build one of these to test my Silvia. Does anyone know if the spout on the original portafilter that came with with Silvia can be wrenched off so I can use it. I have tried it and it doesn't budge. I have a nice LM but I would rather not mess with it.

My other option is to just buy the e61 portafilter from chris's that comes with the pressure gauge and modify it to allow flow, not just blind.

Anyone in Chicago want to share

#25: Post by HB » June 18th, 2009, 8:57 pm

gj91 wrote:I have tried it and it doesn't budge.

I assure you it does come off. Try clamping the spout in a padded vice and pulling the handle really hard.

#26: Post by **gj91** » June 18th, 2009, 9:35 pm

Woo-hoo! A screwdriver in the spout and a little more persuasion and it came off.

Now off to source a gauge.

#27: Post by **Juanjo** » June 18th, 2009, 10:49 pm

If building a simple one this may help..
https://www.coffeegeek.com/forums/espre ... nes/422639

#28: Post by **gj91** » June 19th, 2009, 9:38 am

I have looked at a ton of these now between HB and Coffeegeek. I am going to give a non-liquid gauge a shot. I am going the flow through route. Otherwise I am going to get one of the liquid filled ones. I just don't see the liquid filled ones at local hardware stores. I am going to try HD and Lowes.

I first need to test my Silvia then I will probably have to get the new OPV valve if I need to adjust. It seems that 9 bar without the flow is a good target, that means it's a little less when there is actually flow.

#29: Post by **SJM** » June 19th, 2009, 10:50 am

Given my own experience, which involved visiting every hardware and plumbing supply in the area, I'd suggest you just go online and buy a liquid-filled one that way. I spent a couple of days going into every store in the area and asking every clerk and having to 'splain every time why the ones they had (not liquid filled) were not appropriate to my needs. If your time is valuable to you, just cut to the chase and source one online.

Susan

#30: Post by **Juanjo** » June 19th, 2009, 11:32 am

Given my own experience, which involved visiting every hardware and plumbing supply in the area, I'd suggest you just go online and buy a liquid-filled one that way. I spent a couple of days going into every store in the area and asking every clerk and having to 'splain every time why the ones they had (not liquid filled) were not appropriate to my needs. If your time is valuable to you, just cut to the chase and source one online.

Susan

Susan,

every, but EVERY espresso machine with gauges (boiler pressure gauge or pump gauge), have dry gauges..
I, personally try few dry gauges for the boiler and pump pressure.. and even the cheap $2-3 from ebay work no problem..
I can tell you that FOR SURE dry gauges work..