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Thread: Rotary pump - adjustment and teardown question

  1. #1
    Senior Member artman's Avatar
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    Rotary pump - adjustment and teardown question

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hello

    My rotary pump produces too much pressure at the PF and I have tried adjusting it down by turning the adjustment screw/bolt. However, after 3 full turns, the pressure is still too high and doesnt seem to have made any change.

    How "sensitive" is the adjustment screw, ie normally how much pressure change do you get with each revolution of the adjustment screw?

    I suspect the adjustment part of the pump is seized up. I have searched extensively but have not found any information regarding the internals of the pump/adjustment and would like some info before I start taking it apart.

    Any help would be much appreciated.

    Cheers

  2. #2
    Mal Dimal's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Quote Originally Posted by 5D4E48515D523C0 link=1307593822/0#0 date=1307593822
    I suspect the adjustment part of the pump is seized up.* I have searched extensively but have not found any information regarding the internals of the pump/adjustment and would like some info before I start taking it apart.
    Gday mate.... :)

    Most likely theres some precipitated mineralisation on and around the valve seat that has captured the ball-bearing and locked the spring as well.

    Theyre not difficult to clean out, you just have to be careful of the Spring and the Ball (or other sealing valve arrangement), just in case they do spring out once youve completely removed the adjustment screw.

    Once youve removed these parts, the easiest thing to do for removing any calcification, etc is to use those Dentist Pick Tools you see in Jaycar and elsewhere, to remove all of the foreign matter. Another handy device is a Bronze Brush, of the type used by shooters for cleaning out rifle barrels; these make short work of anything thats a bit difficult to remove, when placed in a Drill Chuck and operated at a slow-ish speed.

    Once its all gone, give it a good flush-out. If the Spring and Ball are damaged, you might be able to source a replacement from a Bearing Service retailer and maybe even the spring as well. They should both be of s/steel too...

    Much easier to do all of this if you remove the Pump of course but I dont know how easy or difficult that will be on your machine....

    All the best,
    Mal.

  3. #3
    Senior Member artman's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Thanks for the info Mal.

    That sounds quite straight forward, the pump is a bit hard to access, but will give it a go, can always remove it later on if I cant get the access.

    The machine is a Faema E98 Compact A1, I have made another thread previously* with some other questions here:* http://coffeesnobs.com.au/YaBB.pl?num=1303139144

    Do you think if the ball in the pump is jammed, the pump will flow too much volume for the over pressure valve to handle?* Seems to be the issue by the looks of it.

    Just need to sort the pump pressure issue and then I can get this beast going, cant wait!!

    Cheers



  4. #4
    Mal Dimal's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Quote Originally Posted by 4C5F59404C432D0 link=1307593822/2#2 date=1307625984
    Do you think if the ball in the pump is jammed, the pump will flow too much volume for the over pressure valve to handle?* Seems to be the issue by the looks of it.
    It sure sounds like it "artman"....

    The valve itself is called a Bypass Valve and in essence, that is what its supposed to do. When the pressure in the system reaches the valve setting, the valve cracks Open and allows water to bypass the pump discharge and instead, circulate water around the pump body.

    Sounds like pump removal will be the ticket though if valve access is dicey....

    Cheers mate,
    Mal.

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    Re: Rotary pump - adjustment and teardown question

    are you sure it has an opv if its a rotary pump machine?

  6. #6
    Senior Member artman's Avatar
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    Re: Rotary pump - adjustment and teardown question

    I thought thats what this thing is (overpressure/bypass valve):



    It has a rubber seal forced closed by a spring, and the preload can be adjusted by turning the screw (red arrow).*

    This allows some water to bleed off into the waste from the pump supply line.* On my machine, this is bypassing water whever the pump is running, even with no real pressure, ie when filling boiler (which is a pain as the tank needs constant refilling).* The seal looks quite hard so probably needs replacing.

    Is this the over pressure/bypass valve you are referring to Mal? Or is this something different all together?*

    Should this be bypassing water all the time?

    Thanks for the help and info guys.

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    Re: Rotary pump - adjustment and teardown question

    Hang on, yours has a tank, but also has a rotary pump? are you sure about that? I thought that all the tanked cimbalis were vibe pump models? if thats true, it would also explain why theres an opv. If im wrong, then disregard :)

  8. #8
    Senior Member artman's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Yes definitely rotary pump (the rear of the motor can be seen in the bottom of the pic above, the pump head is on the other side). This machine can be changed between plumbed in and tank.* It seems to differ in its setup from the instruction manual though.* In the manual you divert the water inlet from tank to plumbed.* On mine, the plumbed water feed is controlled by a solenoid and simply fills the tank when the sensor detects low water, and the pump keeps feeding out of the tank.

    How does the rotary pump change things?

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    Re: Rotary pump - adjustment and teardown question

    Okay its possible someone has changed this over from vibe pump to rotary pump at some stage. If this was my machine, i would leave the opv fully open all the time or just remove it altogether and use the rotary pump to adjust the pressure (as with 99.99% of commercial machines). This is the only machine ive seen with a rotary pump and an opv. alternatively if you dont want to do that, you can add a hose from the outlet of the ovp back to the machines tank. A lot of machines come like that from the factory, its bloody stupid venting it into the drip tray in my opinion.

    in regards to your pump not adjusting, i would take as much of it apart as possible and soak it in citric acid.

  10. #10
    Super Moderator Javaphile's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Quote Originally Posted by 1C3822323930510 link=1307593822/8#8 date=1307687866
    Okay its possible someone has changed this over from vibe pump to rotary pump at some stage. If this was my machine, i would leave the opv fully open all the time or just remove it altogether and use the rotary pump to adjust the pressure (as with 99.99% of commercial machines). This is the only machine ive seen with a rotary pump and an opv.
    I would be hesitant to do anything to that valve other than making sure it is functioning/adjusted properly. It is unlikely that his machine is laid out any way other than as it came from the factory.

    The first picture below is a shot of my La Cimbali M28 Basic 2-group as I was taking it apart for refurbing after buying it. You will see the same overpressure valve as in Artmans Faema (Faema is owned by Cimbali.).

    The 2nd picture is a capture of the hydraulic circuit page from the manual for my machine. Ive circled the overpressure valve in red and put red arrows pointing at the listing in the legend that identifies that part.


    Java "Cimbalis R Us" phile




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    Mal Dimal's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Hmmm... :-?

    Interesting design Java. Whats the setup procedure re: the Pumps own Bypass Valve working in combination with the additional OPV?

    Mal.

  12. #12
    Gra
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    Re: Rotary pump - adjustment and teardown question

    Here is a shot of the Alex Duetto much the same setup.

    Gra


  13. #13
    Senior Member artman's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Looks like this valve and the rotary pump is standard equipment for my machine, the diagrams in the user manual show these.

    In my type of machine, is it normal for this valve to bleed water or should it only do so if an over pressure situation is present?

    My thoughts re adjusting these is:

    Set the bypass/OPV to around 12bar (could temporarily increase pump pressure to set this)
    Set the pump to 9 bar

    Would this be the right procedure or is it something different?

    Cheers

  14. #14
    Mal Dimal's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Thanks for that Gra.... 8-)

    Looks like the OPV in this case provides genuine Over Pressure protection and not just Brew Pressure Control. Excellent....

    Artman, I would leave the OPV alone, as Java suggests above, as it is probably the only thing between you and disaster when the Bypass Valve on the Pump failed.

    In referring to that excellent schematic attached by Java, the Item Pv refers to the Rotary Pump. That part of the Pump Housing pointing towards 5:00 Oclock is the Bypass Valve referred to above and it is this that you need to adjust when setting the Brew Pressure. It sometimes has a protective brass acorn nut over the adjustment screw for added protection.

    To get at this, you will probably have to remove the Pump so that you can do a proper job. Trying to clean it with the pump mounted in the chassis will probably compromise the end result.

    All the best mate.... :)

    Mal.

  15. #15
    Senior Member artman's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Thanks for the help guys.

    That is the screw I have been adjusting with no change (although my pump doesnt have the thing at the 5 oclock position, the adjustment is where the blob in the PV is at 3pm - its the one the manual says to adjust). Just had another look, the pump will definitely have to come out (and it will let me clean it better as mentioned above), the tank tray sits right above it, so I doubt I would even be able to remove the adjustment screw. Looks very tight for space in there, not sure how to remove the pump/motor without taking the boiler etc out, which I would rather not do as that would almost be a complete strip.

    How does the pump head attach to the electric motor? Looks like a couple of bolts holding the pump flange to the motor, but how is the drive shaft connected mechanically? I presume its a shaped drive spindle with matching "female" part in the pump head and should just slide off. If it only needs to move a 10mm or so to come clear, might be enough clearance to the side of the chassis to remove the pump head only and leave the motor in the machine.

    Cheers

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    Re: Rotary pump - adjustment and teardown question

    there is a screw on the pump you change to decrease the pressure
    I think that thing your turning is some sort of bypass but not 100% sure as it seemed to have no effect on mine ?

    thats the Faema E98 machine right ?

    dont take the pump off that one if you dont have to, really tight fit in there isnt it.....

    take the side panels off and you should be able to access the pump adjuster, it might either be a screw type bolt with a lock nut or more like a bolt with lock nut (depends on pump brand)

    "undo" lock nut slightly

    i "think" turn screw in is more pressure out is less on the pump by pass.

    i give them a light "tap tap" to try to make sure it "adjusts" if they are sticky.....

    readjust lock nut to "firm" to lock the screw.

    test pump / group head pressure over a few days to make sure the adjuster had not been sticky and moved after you "locked it"


    your right about the pump attachment, but again depends on pump / brand have a look at coffeeparts.com for the different pump model connection, faema ones are a bit different sometimes

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    Re: Rotary pump - adjustment and teardown question

    if the adjuster is running smooth you can actually run the pump with the pressure gauge on and adjust the pump up and down by the screw watching the gauge change up or down. 8-)

    (i dont do that for extended period but)

    full pressure profiling at the pump maybe ;D

  18. #18
    Senior Member artman's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Thanks Maheel, yep the Faema E98 Compact A1.* Thats what I have adjusted on the pump, and like you say its easy to access with the side panels removed (with spanners).* Removing the hole pump and/or motor will be a lot trickier.



    You can see in the pic the new exposed threads, thats 3 turns of adjustment with no effect on pressure (went way past a 14bar gauge), so I need to take it apart and see whats gunked up in there or other problem stopping the adjustment from working.

    Does anyone know if I can unbolt at the green arrow and remove the entire adjustment assembly for cleaning etc?* This is the only possibility, other than removing the hole pump/motor.

    Cheers

  19. #19
    Super Moderator Javaphile's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Quote Originally Posted by 507D797578140 link=1307593822/10#10 date=1307696728
    Interesting design Java. Whats the setup procedure re: the Pumps own Bypass Valve working in combination with the additional OPV?
    As you surmised in your following post:

    Quote Originally Posted by 507D797578140 link=1307593822/13#13 date=1307714543
    Looks like the OPV in this case provides genuine Over Pressure protection and not just Brew Pressure Control. Excellent....
    You are correct. The OPV in this case is there purely as protection for an overpressure condition. It has nothing to do with setting the brew pressure. That is done at the pump.

    Quote Originally Posted by 75666079757A140 link=1307593822/12#12 date=1307705378
    In my type of machine, is it normal for this valve to bleed water or should it only do so if an over pressure situation is present?
    No it is not normal! It should only be bleed water if there is an overpressure condition in the system. It can bleed water when there is not an overpressure situation if it is out of adjustment but such does not seem to be the case with your system from what you say.

    Quote Originally Posted by 75666079757A140 link=1307593822/14#14 date=1307718517
    How does the pump head attach to the electric motor?
    It is a slot type fitting. Think of a tight fitting screwdriver and a screw with a very deep slot. The only actual attachment between the pump and the motor is either via the bolted on flanges or with a band that is clamped around a ridge on the housing of both the pump and the motor.


    Java "Dont ya love playing with toys?" phile

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    Re: Rotary pump - adjustment and teardown question

    Quote Originally Posted by 4251574E424D230 link=1307593822/17#17 date=1307760572
    Does anyone know if I can unbolt at the green arrow and remove the entire adjustment assembly for cleaning etc?* This is the only possibility, other than removing the hole pump/motor.

    Cheers
    thats the one, i would try just turning the adjuster bolt out all the way and seeing if the spring and seal thing pops out behind it. water may pour out but if you have any in the tank.... (be careful of elecky bits)

    if its not coming out with a poke or two you should be able to get the green arrow segment to come out as well and then give it all a good clean.

    try the tap tap idea, i use a BIG flat head scrwdriver and tap it lightly with the hammer to direct the taps (not very hard).
    if that no worky then take it apart....

    your going to need long thin fingers... tight space in there

    from memory it doe not take much to go 1 bar on a gauge, maybe 1/4 turn = 1 bar maybe 1/2 turn =1 bar but not much etc



  21. #21
    Senior Member artman's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Thanks guys for all the help and info. Will have a crack and post findings.

    Cheers

  22. #22
    Super Moderator Javaphile's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Just out of curiosity did you try turning the adjustment screw/bolt on the pump the other way? :-?


    Java "Fun with toys!" phile

  23. #23
    Senior Member artman's Avatar
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    Re: Rotary pump - adjustment and teardown question

    No, didnt try turning the other way, but good idea as it often unsticks things.

    Unbolted the whole assembly (green arrow in above post) and removed it.* Complete* assembly below.


    The "piston" at the pump end was seized up in the surrounding piece.* A gently twist and it came unstuck.* It contains an o-ring for a seal.


    Below are all the parts.* Adjustment bolt (with lock nut), spring, the lower "body" with the "piston".* The spring sits between the adjustment bolt and this piston.


    Gave it a quick wipe and it slides smoothly now.* Might chuck it in some descaling solution to clean it thoroughly, but I doesnt look like its needed (the gunky looking stuff near the o-ring is just grease).

    Is there anything else in the pump head that should come out for an inspect/clean or is this it? (cant see into it due to access)?

    Cheers

  24. #24
    Senior Member artman's Avatar
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    Re: Rotary pump - adjustment and teardown question

    SUCCESS!!

    Screwed the adjuster back in and the pressure is down to a normal level and appears to be adjustable!! The OVP does not leak either. Woohoo!!

    I just need an accurate gauge to set the right brew pressure, make a drip dray of some sort and I can start using it!!

    Thanks for your help everyone, much appreciated.

    Cheers

  25. #25
    tek
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    Re: Rotary pump - adjustment and teardown question

    OK heres what youve got,

    the 1st pictured valve is the "Expansion" valve not the pump bypass valve
    What you will need to do is get a accurate Cimbali gauge handle and adjust the "pump bypass valve" (2nd picture) to 12 bar, once you have done that adjust the expansion valve so it just drips at 12 bar then reset pump pressure to correct level
    Dont just screw the expansion valve in till it doesnt leak it needs to be calibrated

  26. #26
    Senior Member artman's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Thanks Tek, that confirms what I was trying to say in my previous post, but got my terminology wrong:

    Set the bypass/OPV to around 12bar (could temporarily increase pump pressure to set this)
    Set the pump to 9 bar


    I presume the 12 bar is set as a closed system (ie with NO leaks at the GH), then the Expansion valve is set to just drip as you describe (this would be the failasafe over pressure condition setting).

    When setting the brew pressure back down to 9 bar, is this supposed to be in a closed system again, or should I adjust the tap tee-ed at the guage and let out some water to so it despenses 60ml in 30 secs (duplicating a shot pour?).

    Thanks

  27. #27
    tek
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    Re: Rotary pump - adjustment and teardown question

    Closed is fine

  28. #28
    Senior Member artman's Avatar
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    Re: Rotary pump - adjustment and teardown question

    Ok, all sorted!! Adjusted the pump to 12 bar, adjusted the expansion valve to just drip. Then reset the pump back to 9 bar brew pressure.

    Thanks heaps for all your help everyone, much appreciated.

    I will update my other thread tomorrow (http://coffeesnobs.com.au/YaBB.pl?num=1303139144) with a link to this one. I also did some other tinkering that I will post up.

    Cheers



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