# OPV Adjustment



## gazbea (Jul 11, 2011)

I know this particular topic has been done to death so I apologise now.

Looking at getting my own gauge set up to do the mod and was wondering if anybody knows if this gauge would do the job or not? eBay Link

If not, what else should I be looking out for? I know I need a 1/4" elbow as well


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## gazbea (Jul 11, 2011)

There is this one too eBay


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## rodabod (Dec 4, 2011)

Both look fine.

You usually want a 3/8 to 1/8 BSP adapter. Note those values don't equate to width in inches, confusingly.


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## xiuxiuejar (Jan 24, 2012)

I did it by measuring the return water with a blind disk in place and it makes a huge difference, That was a while ago but I suppose I should build one too. Problem is here in Spain, these parts are hard to come by - we don't have shops where the public can go and buy plumbing equipment. Make sure you get a gauge that goes up to 15 bars - just in case! If you don't, make sure you loosen off 3/4 of a turn before you take your first measurement. Also, make sure the portafilter, the tubes and gauge are filled with water when you take the measurements or the readings won't be accurate.


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## gazbea (Jul 11, 2011)

So what size pressure gauge do I need? I don't want to be putting adapters in. Basically want, pf > elbow > gauge.

I was looking at doing the return rate thingy but would rather just get it at the required pressure without guessing if it was right or not.


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## xiuxiuejar (Jan 24, 2012)

Usually, I think you'd need one adapter after th elbow but I'm not sure. For sure you should do it properly if you can, as I say, I'm never in UK during the week to make up my own gauge. It's complete guesswork doing what I did. I hope to be around 10 bars, but I could be at 8 or 12, who knows???? Anyway, coffee is much nicer. You'll find you get darker crema, 'thicker' coffee with much deeper taste.


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## xiuxiuejar (Jan 24, 2012)

http://coffeeforums.co.uk/showthread.php?3859-Adjusting-the-OPV-(over-Pressure-Valve)-Gaggia-Classic

thought this might help.


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## Pedro083 (Nov 16, 2011)

gazbea said:


> So what size pressure gauge do I need? I don't want to be putting adapters in. Basically want, pf > elbow > gauge.
> 
> I was looking at doing the return rate thingy but would rather just get it at the required pressure without guessing if it was right or not.


If you don't want to use adaptors you will need a 3/8 pressure gauge and elbow. You can go into a plumbing wholesaler like bss and pick up the pressure gauge elbow and any adaptors rather than ordering from all over the place and spending more on shipping than the items. I went into one had no 3/8 elbows but gave me a 1/2 elbow and a 3/8 adaptor for one end and 1/4 for the other. Already had the pressure gauge but the guy told me they stocked them as well. I actually preferred using the adaptors as had a better thread on them for attaching to my portafilter


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