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Thread: Pressure regulator?

  1. #1
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    Pressure regulator?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I asked in another thread, but figured Id stop hijacking that and start a new topic...

    I reckon I could find a spare pressure regulator lying around at my work, and a couple of tube fittings. I reckon it would be quite easy to plumb it in to my machine. It would act to limit the pressure entering the *cough*thermoblock*cough* to a defined (but adjustable) level.

    Does anyone think this would be a good or bad thing to do? I am sure that such a setup would improve my singles, which presently are too hard to slow down.

  2. #2
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    Re: Pressure regulator?

    Hrmmm ... sounds good. Two questions, though:

    (a) How are you going to measure the pressure?

    (b) Will it change the temperature of the water coming out of the thermoblock?

    Cheers,

    Luca

  3. #3
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    Re: Pressure regulator?

    a) pre-set the regulator before installation (I have calibrated gauges at work). The adjuster knob can be locked in position. There might be a small dynamic pressure loss across the thermoblock, but I dont think its significant.

    b) It would be installed before the thermoblock, so I cant see how it could...

    admittedly, the regs we have we normally use for gas, but Im sure they could handle such low water flow rates... Theres a slight drop off in pressure as flow rate increases from zero, but its pretty small...

    worst case, I can always remove it and join the lines back together with a union...

  4. #4
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    Re: Pressure regulator?


    An interesting idea. Im not sure how the membrane will respond to a liquid, which has a density about 1000 times greater than a gas (and hence considerably more momentum at the flow rate youll need), but if you have one kicking around it might be worth a go. The other option is to use the standard overpressure expansion valve. Coffeeparts sell them for about $16. They are the ones that come with Fluid-o-tech pumps and they work well. However, youll need a pressure gauge somewhere in the line to measure the set point pressure. Thats no real problem as you can get damped pressure gauges for about $12 around the place. A few extra brass connections and youre away... Then you can PID control the temperature of the thermoblock....

    The thermoblock will have no problem with a lower regulated pressure, as it is only flow rate dependent, so once you get within the standard espresso flow rates, it should be transparent to your system. Lowering the pressure to 8-9 bar makes a huge difference in the crema and mouthfeel of the shots. Its well worth trying to get it sorted.

  5. #5
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    Re: Pressure regulator?

    The temp regulation is something electronic already (thermistor to a PCB, not a termostat). Im curious to hook up a light to it so I can see what the switching cycle is...

    mattyj says theyre temp adjustable on the PCB too (I spot a potentiometer there), so I might tweak that one if I get inspired. (Can borrow some thermocouple gauges from work.)

  6. #6
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    Re: Pressure regulator?

    Wow, this is everything I once wanted to do to my sunbeam and more!

    the 6-million-dollar sunbeam!

  7. #7
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    Re: Pressure regulator?

    :D I checked the Norgren catalog for specs, the R07 I wanted to try is rated only for air only :(

    Theres an R06 which is suitable for water, might work... I saw one for 4 quid in the UK! http://www.engsurplus.btinternet.co.uk/pneumatics.htm

  8. #8
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    Re: Pressure regulator?

    Behmor Brazen - $249 - Free Freight
    There are plenty of fuel pump pressure regulators on ebay... Im not sure if theyll got to 10 bar though.

    If you get a 240 V neon bezel and connect it across the element terminals, youll be able to see the on/off period. It would be interesting to see what it does during a shot, as thats when youll need the element to really work.



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