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Thread: Faema E98 brew pressure and gicleur

  1. #1
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    Faema E98 brew pressure and gicleur

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi All

    So I'm using the plug under the group (about 1/2" allen socket one) for the location of the gauge to set my OVP/brew pressure regulator (vibro pump). NOw, do I set it to 9 bar with a blind basket (giving about 4-5 bar during an extraction, or wind it way up to get 8-9 bar during an extraction?

    Also I need a very very fine grind to get required extraction times with a pool of water on the puck, and have discovered my gicleur/injector whatever is 1.25mm, and I believe the machine should have a 0.8mm one? I think the injector on the water fill solenoid might still be a 0.8 so might try to swap them? (parts listing shows the same part number for both, but my machine has been played around with by the previous owner -shitty restaurant- to whack out coffees in the shortest possible time). Even the OVP was jammed closed when I got it!!

    Ramp up time is always 4-7 sec.

    Thanks

  2. #2
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    Ideally you would measure the pressure in the group with a portafilter mounted gauge and set that to 10 bar. That should roughly translate to 9 bar during extraction.

  3. #3
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    If you only getting 4-5 barg at the pump during extraction, but 9 barg with the blind, then my first thought is that you have a puck problem (followed by a pump/supply problem). Put simply, there is not enough resistance across the puck to increase backpressure at the pump to 9 barg.

    This could be any/all of:
    - dose too low
    - grind too coarse
    - underroasted coffee
    - stale coffee
    - puck "damage"


    Was the machine plumbed in previously?
    Last edited by MrJack; 26th May 2016 at 01:25 PM.

  4. #4
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    Tried all sorts of diff beans, grind is generally finer than most other people. Pool of water on puck after extraction, temp of about 96degc of water flow when machine nicely warmed up. Machine takes water from it's own reservoir, which is plumbed in , yes.
    So I should set the blind filter pressure to 10? I should have 8-9 bar DURING EXTRACTION right?

    I found the 0.8mm gicleur in the water inlet line, will swap and see what happens.

    I work in a coffee cart on occasion, but purely am an amateur.

  5. #5
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    A gicular in the inlet line to the pump? I don't know if that is common in espresso machines, but its a terrible idea from a pump operability point of view. Pump system design typically aims to minimise pressure drop on the inlet...
    Dimal likes this.

  6. #6
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    It's an E98 A1 - the high pressure inlet from the tap (modified by the 0.8mm jet) fills up the reservoir which is then sucked up by the vibro pump. If you had no injector on the water inlet you'd blast the contents of the reservoir everywhere.

  7. #7
    Senior Member artman's Avatar
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    The A1 is a rotary pump. It sucks straight from the tank. From memory there is a restrictive disc in the line feeding the group, as well as a metal gauze disc.

    Cheers

  8. #8
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    Quote Originally Posted by floatingkiwi View Post
    It's an E98 A1 - the high pressure inlet from the tap (modified by the 0.8mm jet) fills up the reservoir which is then sucked up by the vibro pump. If you had no injector on the water inlet you'd blast the contents of the reservoir everywhere.
    Thats alright then
    So from a hydraulic perspective, it being plumbed in is irrelevant (and the restrictor in the tank inlet line has no influence on what happens during extraction).

  9. #9
    Senior Member artman's Avatar
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    I just noticed the OP mentions a vibe pump so my comment might not apply to his machine.

    For the A1, when plumbed in the machine still draws water out of the tank. It just tops up the tank if it gets low by opening a solenoid that the mains water is connected to.

    Cheers

  10. #10
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    Quote Originally Posted by artman View Post
    The A1 is a rotary pump. It sucks straight from the tank. From memory there is a restrictive disc in the line feeding the group, as well as a metal gauze disc.

    Cheers
    Correct, that is the injector/gicleur whatever you want to call it and restricts the pump flow to the group. I have a vibro pump so only 1 injector in the system (apart from the water reservoir inlet). The rotary pump versions also have one in the hot water dispenser line, i.e 3 in total including the water feed to the inbuilt reservoir.

  11. #11
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    Quote Originally Posted by MrJack View Post
    Thats alright then
    So from a hydraulic perspective, it being plumbed in is irrelevant (and the restrictor in the tank inlet line has no influence on what happens during extraction).
    Yes, but as mentioned there is also the injector (now back to 0.8mm from 1.25mm) in the brew supply line that I'm playing with. Frankly the 0.8mm injector seems to be the same as the 1.25mm. I haven't noticed any difference.

  12. #12
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    Having a larger restriction wouldn't explain the additional pressure drop anyway. I gather most people experience 0.5 -1 bar pressure drop, so your observation of 4-5 bar flowing pressure drop suggests a different root cause.

  13. #13
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    So I should actually have a 9 bar pressure at the group DURING an extraction?

  14. #14
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    Or there abouts, yes.

  15. #15
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    crikey my vibro pump must be knackered then - I can easily get around 12 bar with a blind basket but only about 4-6 bar during an extraction of 60ml in about 28 secondsish. Or something else is wrong.....

  16. #16
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    I wouldn't assume it was knackered (but it is a possibility).

    The pump produces flow, the downstream system resists that flow, which manifests as pressure. The flow that a pump can achieve with a given resistance depends on the power available to it (and since power is limited, there is a trade off between flow and pressure).

    Insufficient resistance will result in high flow and low pressure.
    If you look at the pump curve below you can see that at 4-5 barg the normal pump output is 6-7mL per second; 30 - 50% greater than at 9 barg (and much greater than one might expect for espresso pour rate).
    A knackered pump may exhibit a different pump curve (they typically vary with pump operating speed and efficiency).
    Last edited by MrJack; 1st June 2016 at 11:20 AM.
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  17. #17
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    I'm getting a delivery rate of 2.1ml/sec, which should be easily achievable at anything up to about 10 bar, so I must have leakage elsewhere, or indeed the pump is no good .

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    On another note, I have just realised that I stuffed up with the gicleur:

    Neglecting the gicleur/injector/jet in the water reservoir input line,

    1) vibro models only have an injector in the hot water dispensing line
    2) Rotary models have the hot water dispensing one and one in the brew line.

    So, my playing around with the one that I thought was for brew flow is only for the hot water dispenser....

    So, I still have a vibro pump issue I think. Not enough flow, or possibly the wrong pump has been put in at some point.

  19. #19
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    Folks, the coffee parts website says the EX4 for a replacement pump (mine still has the original Ulka NH26!!) but the pressure/flow curves would suggest an Ex5 as the better match - EX4 goes up to 22 Bar with little flow which may blow stuff... Plus I can't very readily find an EX4 on any of the common websites. Thoughts on this?

    Plus any good places to buy from that ship to NZ?

  20. #20
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    Looking at the E series "datasheet" on the website of the manufacturer (CEME Group), the E5 looks to be the most suitable w.r.t. capacity. The E4 shut in pressure is uncomfortably high as you've mentiones. The E4R would not allow more than around 50mL / min at 9barg - not quite enough. Only concern would be making sure you source one with the appropriate connections!

  21. #21
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    Thanks that's what I thought too.



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