OPV / Active regulators 101

System

OPV's and other like systems...
Over Pressure Valve

"How does the OPV Valve work -

It

Muscles

If a gauge probe in a machine were connected imediately after the OPV set to 9bar then I should expect to always see a reading of no higher than 9bar (even if the input pressure was higher than 9bar, assuming of course the OPV is working as intended). But, say for example an OPV was installed immediately after the pump with a return to the tank and a gauge probe was installed right before to the group in a machine, If overdosing or using too much pressure while tamping could backpressure result and affect the reading of the gauge and showing a higher than 9bar reading? Am I way off track? Forgive my ignorance here but I am interested and thinking out loud...

shape_shifter

What does this mean?

shape_shifter

Ok another question. The SB dual floor gives me 8.5, the blind gives me 12 but my extractions are at 9-10 so far. I am yet to look at the timing of things but if they are spot on, wouldn't that mean that I should leave the OPV where it is?

Muscles

I got myself a full blind basket on Friday and a few tests over the weekend show the gauge reading 9.5 bar with the blind. I am very happy with my pours, they look like lava flowing now compared to brown water running before. During extraction the gauge reads 8.5 - 8.75 bar.

Brett H

Great info guys.  It's funny AM how we both commented that it must have been the roast contributing to the thin watery shots on the unit you and I played with.  We also noted how high the gauge went but who knew that we... largely you... were on to something back then.  I'd love to revisit an adjusted maching and try bean I know.  I had Yirg with me on that night but our lovely host had provided everything so it seemed rude to change everything.  Feels a bit like a missed opportunity in some respects but it's great to see vigilent quality conscious members here getting great information and great results out of this little Aussie wonder!

shape_shifter

...and to think I gave them back the SB basket, should have kept it I can't believe everyone wants $10 postage to send a blind filter out!!!  I don't need anything else to make it worth while. Anyway...AM you wouldn't be telling me how to change the OPV myself would you :P

shape_shifter

I just spoke to the Breville service agents here and interesting enough one of the comments was "he might be able to talk you through doing it yourself", I think that might still void the warranty. They haven't done one before.

shape_shifter

Oh no way am I going to do it, OH is fixing an old TV and didn't even want to let me near that but he had to, strict instructions not to touch the part that has 30000 volts coming out of it !!! I guess when it comes to things like this I am torn as OH is more than qualified and experienced to do it, whereas the person at the service centre is only a technician of sorts and has never done it before (yes same as OH) and would only be going on directions from Breville and not being shown. I really don't want to void the warranty but it's very hard trusting service people, the Mazda service people couldn't even fix the MX-6 after 4 goes, OH did it himself in the end.