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  • Rotary Pumps...what are the technical specs?

    Hi guys, I know there is going to be some variance between machines, but im just hoping to get some more information about the technical specs of these pumps used in commercial machines.

    For instance, i saw a pump and motor today that had the following info:

    90w, 2800rpm, 0.4A, 220v, 3.5uF and 10L/min.

    Now i think this would be a bit too small, but i want to know why its too small, and what exactly about it needs to be bigger (if that makes sense?)

    Im away from home for the next few weeks so i cant check the stats against the pump and motor off my San Marco, and coffeeparts only tells you the voltage.


    Basically, what is the minimum specs required for say, a 2grp machine?
    And is there a way to work out the pumps BAR-rating using any of the above info?


    hehe as you can tell, i dont really know anything about this area and am just hoping to get a bit more informed about what is required to drive your average 1 or 2grp commercial machine.

    Thanks in advance for any advice.



  • #2
    Re: Rotary Pumps...what are the technical specs?

    Hi Zakal1

    Yep, that is too small alright!

    The power rating for 2grp machines is typically around 160 Watts. The pressure delivered (BAR) has nothing to do with the electrical ratings but is determined by the pump design and the over pressure valve - generally you would need to know the make and model of the pump and then find its ratings (most dont seem to have them displayed). And to add to the confusion, the volume delivered depend on the pressure.... so you might get for example 120l at 4.5Bar but only 60l at 9Bar.

    The pump needs to be fairly big because it is required to fill the boiler and supply water to both groups (all at the same time if necessary).... without any loss of pressure.... ie it must maintain 9 bars regardless of whether you have one group brewing or both groups and the autofill filling the boiler....

    If the pump is too small, when the autofill kicks in - the brew from the group will either stop or just be a slow trickle because of the reduced pressure.

    Comment


    • #3
      Re: Rotary Pumps...what are the technical specs?

      Yep,

      What JB said above. As you know, the pump delivery pressure is set in rotary pump machines and is in effect, a Bypass Circuit built into the pump body. Since the pumps are of a type that are classified generically as Positive Displacement Pumps, they are designed to deliver a fixed volume of water per revolution (simplistically) so if such a pump is pumping against a closed head (all valves shut and no water being delivered) then the entire delivery capacity of the pump is effectively short circuited around the pump via the Bypass Circuit as soon as the delivery pressure setting is reached.

      In essence, as soon as you operate one group, a portion of this volume delivery capacity is provided to that group with the pressure building until the pumps pressure setting is attained whereupon the pump Bypass Circuit is activated again causing the difference in volume between that flowing through the group and the rated capacity of the pump to flow through the Bypass Circuit. This can go on ad infinitum, operate more and more groups, top up the boiler, pull some hot water until the stage is reached where the pumps volume capacity is exceeded. Once this happens, the pressure will start to fall since the pump is incapable of delivering the water flows being demanded.

      So, the trick is, you need to know the maximum demand for water flows in your system, add a margin for safety and wearntear and then Bob is your uncle. You have the water delivery capacity in Litres/Minute that your pump needs to be rated for. The pressure setting once set, does not really enter into the equation any more as so long as the pump can deliver the volume required, the pressure will be maintained. Heres a link to the manufacturer of Procon Pumps, widely used in Espresso Machines. Hope thats helpful,

      Mal.

      Comment


      • #4
        Re: Rotary Pumps...what are the technical specs?

        ahh okay, well thats quite informative, thanks you guys. Ill check out that link as well Mal.

        Anyone wanna hazard a guess at what my waterflow requirements would be? heheh.

        On the otherhand though (and i think this was mentioned in the Vibe vs Rotary thread) a pump with a smaller flow rating would suffice, but if autofill or something kicked in mid-shot, itd simply spoil that shot, and as this doesnt happen every time (in fact oin my machine it rarely happens mid-shot) you could get away with a lesser pump if youre using it in a home environment. In a cafe its a complete no-no of course, but for the home, if its costing significantly less, itd have to tempt you. Tempts me at least.

        I mean that pump i mentioned above (pump and motor i should add) was only about $17.

        However, i think the killing factor of that pump at least is going to be its ability to even deliver 9 bar. I was reading around and i found a conversion for head (in metres) to BAR, and it was something like P(bar) = h / 9.81, and on that conversion, i think that pump was only like 1.5 bar or something.



        Although now that i think about it, it was stamped with say, a head of 15m and all of the above specs were for that 15m, that would mean it could produce 1.53bar AT 10L/min right?

        10L/min is 600L/hr, and from my reading of standard espressomachine pumps (see here http://www.espressoparts.com/product/V_41) the required flow rate is about 100L/hr.



        Does this mean that if it can do 1.53bar at 600L/hr, it can do 9.18bar at 100L/hr?
        Are my calculations correct?


        If so, the above pump may come close to working except for the fact its only half the desired wattage. Though i note that CoffeeParts has a 100W rotary pump...whats that for?




        Comment


        • #5
          Re: Rotary Pumps...what are the technical specs?

          Originally posted by Zakal1 link=1164357406/0#3 date=1164371297

          Although now that i think about it, it was stamped with say, a head of 15m and all of the above specs were for that 15m, that would mean it could produce 1.53bar AT 10L/min right?

          10L/min is 600L/hr, and from my reading of standard espressomachine pumps (see here http://www.espressoparts.com/product/V_41) the required flow rate is about 100L/hr.

          Does this mean that if it can do 1.53bar at 600L/hr, it can do 9.18bar at 100L/hr?
          Are my calculations correct?
          Yep, the pump you are looking at can produce about 1.5 Bar pressure at 600l per hour......

          And that is the maximum pressure it can provide.... if you fitted a higher rotational speed motor you MIGHT get more litres per hour at a lower pressure but the reverse isnt true. The pump wouldnt be designed to handle the pressure on the vanes etc at 9 Bar.... it also wouldnt have the pressure regulator (which is part of the pump - not external) so of no use!!

          You have to buy a real espresso machine pump - like a procon - which has the pressure regulator built in (and is designed for at least 135 psi - 9Bar ...... in fact procon are designed for 250 psi or 17 Bar ) Hence the high cost (CoffeeParts prices for these are relatively cheap)


          Though i note that CoffeeParts has a 100W rotary pump...whats that for?
          Probably a single group machine would be my guess - possibly even a prosumer machine

          Comment


          • #6
            Re: Rotary Pumps...what are the technical specs?

            Originally posted by Zakal1 link=1164357406/0#3 date=1164371297
            Anyone wanna hazard a guess at what my waterflow requirements would be? heheh.
            No idea mate :-?.
            For example though, my Single Group (Commercial) Bezzera has a pump fitted that is rated at 100 Litres/Hour or 20-25 GPH depending whether you use US or UK gallons, and this is the same pump that is used on their 2-Group machines as well. The motor fitted is rated at 100 Watts. I think La Cimbali use higher rated Pump/Motor combos than this so you would have to check with JB, Mauricem or Javaphile about this.

            Originally posted by Zakal1 link=1164357406/0#3 date=1164371297
            On the otherhand though (and i think this was mentioned in the Vibe vs Rotary thread) a pump with a smaller flow rating would suffice, but if autofill or something kicked in mid-shot, itd simply spoil that shot, and as this doesnt happen every time (in fact oin my machine it rarely happens mid-shot) you could get away with a lesser pump if youre using it in a home environment. In a cafe its a complete no-no of course, but for the home, if its costing significantly less, itd have to tempt you. Tempts me at least.
            I think any high pressure Procon or similar pump rated for 100-150 Lt/Hr would be plenty for a home situation, doubt if boiler fills would have any effect when pulling a shot.

            Originally posted by Zakal1 link=1164357406/0#3 date=1164371297
            I mean that pump i mentioned above (pump and motor i should add) was only about $17.
            You sure about that price? Or do you mean $317.00? New 100Lt/Hr, 100W motor combos retail for not much less than $500.00 all up :-?

            Originally posted by Zakal1 link=1164357406/0#3 date=1164371297
            However, i think the killing factor of that pump at least is going to be its ability to even deliver 9 bar. I was reading around and i found a conversion for head (in metres) to BAR, and it was something like P(bar) = h / 9.81, and on that conversion, i think that pump was only like 1.5 bar or something.
            You need to make sure that the combo youre looking at is designed for espresso machine use... e.g. most Procon pumps fit for purpose are rated at up to 250 PSI for their flow ratings, so you need to be careful you are looking at a real espresso machine pump/motor.

            Originally posted by Zakal1 link=1164357406/0#3 date=1164371297
            Does this mean that if it can do 1.53bar at 600L/hr, it can do 9.18bar at 100L/hr? Are my calculations correct?
            You really need to locate the performance curves for the pump in question to know what its capable of.... Pressure/Flow relationships are not necessarily linear and in fact, rarely are.

            Originally posted by Zakal1 link=1164357406/0#3 date=1164371297
            If so, the above pump may come close to working except for the fact its only half the desired wattage. Though i note that CoffeeParts has a 100W rotary pump...whats that for?
            Probably for most 1-2 Group Commercial machines

            All the best,
            Mal.

            Comment


            • #7
              Re: Rotary Pumps...what are the technical specs?

              Originally posted by Mal link=1164357406/0#5 date=1164374757
              The motor fitted is rated at 100 Watts. I think La Cimbali use higher rated Pump/Motor combos than this so you would have to check with JB, Mauricem or Javaphile about this.
              Yep....

              Thats why Java and I love our La Cimbali....

              They infact have a 250L pump with the bigger motor to match....

              They are truly very well engineered (some might say - "over engineered" ;D)

              Comment


              • #8
                Re: Rotary Pumps...what are the technical specs?

                Oh no, its almost definitely not a proper espresso machine pump and motor. Quite different from what ive got at home because the pump and motor are built together in a much more "fused" manner. I.e. are not fastened by a clamp ring, but instead seem to be built together instead of a motor driving a pump.

                Having said that its still seperate enough to see where teh motor ends, and the brass of the pump begins.

                And yes im quite sure of the price, thats what got me interested in the first place.
                I was walking around Shanghai and kept seeing all these shops selling various plumbing fittings (god knows why there are so many, but anyway) one shop had a set of motors and pumps out the front, and electric motors without pumps next to them, and as they looked similar (though not entirely) i thought id see what they cost over here, knowing the $500 odd dollars tehy cost at home (albeit for a proper espresso combo). Imagine my suprise when i was told a price i worked out a the time to be about $20.

                Which is what got me thinking if i could find a bigger one (and there are a few around) that is close to sufficient, for $20-30 i could just bring it back with me and see if it works. If it does, id have a back-up incase my exising one ever broke and could perhaps use it while trying to justify a $500 outlay on a proper one. hehe.

                After some more looking ive found a heap of motors ranging from 50 to 370w all for under $50, though while most are a clamp-ring fitting, they mostly use a different kind of drive-mechanism. Where mine uses a kind of tounge-and-groove type drive system, these motors use a kind of drive-shaft / spindle system like ive seen on some of the older rotary pumps. So to use the motors that dont come with pumps, i think itd involve either modification (i,e cutting a grove in the drive shaft, probably not all that difficult) or a change of pump type which kind of makes it a bit pointless.

                Which brings me back to the combined units, if i can find one a bit closer to the requirements, like say 150W or thereabouts (though from what you say re the smaller 100W pumps, this may not be necessary) and 9bar at 100L/hr; it might make a very cheap bandaid measure in the event of a pump or motor failure. At the very least may minimse downtime. hehe.

                Comment


                • #9
                  Re: Rotary Pumps...what are the technical specs?

                  Zakal1...

                  If you could get one which will deliver 9 bar AND has a built in pressure regulator!

                  Remember flow in the coffee machine varies from zero (blind filter in a single group whilst back flushing) to how many groups you want to use at once...

                  And the pressure MUST remain at 9 Bar (or pretty near to it) under this range of conditions..... Most pumps will increase in pressure when there is no flow at all and could cause damage to the pump - or even worse the machine itself.

                  As Mal described, the correct pump has a bypass system built in so once pressure gets to 9 bars the valve opens and water flows from the outlet back to the inlet..... It is unlikely these pumps have such a device built in but supply a (nominal) Bar rating at the quoted flow rate.

                  If you can find one with a built in (adjustable) regulator which can deliver 9 Bar pressure - grab it!!!!

                  Comment


                  • #10
                    Re: Rotary Pumps...what are the technical specs?

                    Originally posted by JavaB link=1164357406/0#6 date=1164377239
                    Thats why Java and I love our La Cimbali....

                    They infact have a 250L pump with the bigger motor to match....

                    They are truly very well engineered (some might say - "over engineered" ;D)
                    Indeed! The motors in them are monsters! I was amazed at how big the motor was when I got my M28 and opened it up.


                    Java "Loves his Cimbali!" phile
                    Toys! I must have new toys!!!

                    Comment


                    • #11
                      Re: Rotary Pumps...what are the technical specs?

                      Yep,

                      Youve gotta hand it to those La Cimbali guys, I think they use a 100 year design philosophy with all of their gear, especially the units you guys have..... If it aint gonna last for 100 years of abusive use, then we dont use it ;D. I actually used to work for a major engineering manufacturer years ago, did my training with them as a matter of fact... They used to have similar design principles with everything they manufactured. It was designed to last a lifetime +50%. Hence I learned how machinery should be designed and made, a great place for a young bloke to learn.

                      Im happy with the Single Group Bezzera though, may not be an LC but its probably only one level down from there , and it wont be long now before its finished.... Cant wait for that first brew, can almost taste it now :P

                      Mal.

                      Comment


                      • #12
                        Re: Rotary Pumps...what are the technical specs?

                        Hey guys, i just got the person who is staying at our house to peek under the sink and check the details of the motor from my LSM, and this is what they sent back to me (via email):

                        220-240V
                        330-1/5W


                        Could that possibly be correct? (ignore the voltage cos obviously thats right hehe).

                        But 330W...i know i had 300W in my head as being what it was, but after you guys were saying 165W is the norm i thought i had to be mistaken.

                        Also what could the "1/5" mean?


                        I know its a bloody big looking motor, and heavy, but surely it cant be 330W can it?, and is it a coincidence that it is EXACTLY double the figure of 165?

                        Comment


                        • #13
                          Re: Rotary Pumps...what are the technical specs?

                          Okay i have some more questions:

                          After reading thru that link Mal sent for Procon, ive seen a couple of accessories that may be of some assitance.


                          Firstly, at the very bottom of the page, they have a bypass system that can be fitted to any pump...well does that mean that one of the pumps i found (if it can produce 9bar) can be fitted with one of these and which will then mimic the performance of a conventional espresso pump (except for durability of course)?


                          Secondly, just above the bypass system is some adaptors for pumps to fit onto different kinds of drive-shaft motors. If i get one of the motors i mentioned that use the more cylindrical drive-shaft system as opposed to the tongue-and-groove system, can i just fit one of those adaptors and use it with a conventional procon-style pump?


                          Thanks,

                          Comment


                          • #14
                            Re: Rotary Pumps...what are the technical specs?

                            I do mech eng...and without going in to nitty gritty details of fluid mechanics and electromechanics....just a little more info....when you say "small" pump....all pumps are generally small.....its the motors whether AC/DC/petrol that power them that are large in comparison.

                            Comment


                            • #15
                              Re: Rotary Pumps...what are the technical specs?

                              Zakal1

                              Remember when you were trying to fix your pump you posted a picture....

                              and I said it looked like mine. Well mine is a 250L pump not the more usual 120L or there abouts.....

                              A 250L pump would need twice the wattage motor.... so 330W sounds reasonable..... but I dont know whats with the 1/5 - doesnt mean anything to me.

                              Yes, you could use an external bypass - but cant see any listed on CoffeeParts - so you would probably have to import one from someone like Procon direct..... and Im amazed at how cheap CoffeeParts prices are compared to normal retail - sometimes only 1/2 to 1/3 the price....

                              You would want to know how much an external bypass would cost - might be almost as expensive as a whole new pump!

                              You certainly could use an adapter between pump and motor. The ones readily available (from Procon or their agents) would adapt a procon pump to various "standard" espresso machine motors..... so you could fit a procon into a La Cimbali - which normally uses their own pump.

                              To get an adapter between a chinese pump (of god knows what standard) and a standard motor would be fairly hard I would think..... you could probably have one made to order - but that wouldnt be cheap - and would wipe out you savings - and some probably.

                              Now if only Sunbeam used a rotary pump..... you could go visit the factory and get one ;D ;D

                              EDIT: and by the way, the bypass is completely different to the ones used in high quality vib pump machines (OPV valve).... these simply open when there is a pressure differential of 9 bars between the output and the supply - the reservoir at 0 bar (room pressure). Excess water is just returned to the reservoir.

                              In a rotary pump it must open when the output is 9 bars and the supply could be anything from negative pressure (pump drawing from a water container below the machine) to about 5 Bar - normal mains supply pressure - or anywhere between depending on how many taps are on in the house etc.... So it is a far more complex device than just a standard OPV.

                              Anyone for a puddle on the floor when the OPV activates You could always just send it to the drain if the machine is plumbed in

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