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  • Flojet pumps

    I have a 1 group commercial machine which Im about to over haul. At the moment the procon pump is happy drawing from a bottle. What I want to do is fit an inline filter in between the bottle and the rotary pump.

    What I was thinking that a flojet pump would do the job of providing a simulated mains water pressure to the inline water filter, which the rotary pump will draw from. Is my thinking flawed?

    machine ------ pump ------ water filtration unit ------- flojet ------ bottle

    the reason why I want to do this is because I just want to fill the water bottle up with tap water.

    These flojet pumps are quite pricey. Are there any other pump do the same job? I know a similar set up was used for the Barista Championships this year. I may just ask John from Coffee Machine Technologies how he did it.....but would appreciate some feedback.

    Cheers,

    Dave

  • #2
    Re: Flojet pumps

    Gday Dave,

    Would it be possible to position the water bottle/tank above the machine..... This would provide a positive head on the pump through the filter and much less complex and inexpensive by comparison. If youre using bottled water mate, why do you need to filter it? I can imagine why you might want to control the water hardness via a small water softener but most decent bottled water is already filtered to a high standard....

    Mal.

    Comment


    • #3
      Re: Flojet pumps

      Mal he said he wanted to use tap water in a bottle not bottled water.

      Comment


      • #4
        Re: Flojet pumps

        Originally posted by Mal link=1217679658/0#1 date=1217681986
        Gday Dave,

        Would it be possible to position the water bottle/tank above the machine..... This would provide a positive head on the pump through the filter and much less complex and inexpensive by comparison. If youre using bottled water mate, why do you need to filter it? I can imagine why you might want to control the water hardness via a small water softener but most decent bottled water is already filtered to a high standard....

        Mal.
        Hey Mal,

        Thanks for the reply, firstly as TG said, I want to use tap water in the bottle. The procon pumps have no dramas drawing out of a tank/bottle. My problem is getting pressure to an inline water filtration system before it hits the rotary pump from the water tank.

        Cheers.

        DS

        Comment


        • #5
          Re: Flojet pumps

          Dave,
          What I do for my 2 group La Pavoni is filter the water as it comes from the tap, then put it into the bottle. Above counter water filters can be found online ( PM me for the people I use ) for around $100.

          John

          Comment


          • #6
            Re: Flojet pumps

            Originally posted by jmc link=1217679658/0#4 date=1217729715
            Dave,
            What I do for my 2 group La Pavoni is filter the water as it comes from the tap, then put it into the bottle. Above counter water filters can be found online ( PM me for the people I use ) for around $100.
            Ooops, sorry Dave..... :-[

            Id always opt for the most simple method mate and what "jmc" has outlined makes a lot of sense. Have a look at the "Bombora" website and check out all the options available from just one distributor. Theres a heap of ways to do this without adding unnecessary complication....

            Mal.

            Comment


            • #7
              Re: Flojet pumps

              morning Dave

              what sort of filtration are you intending to use
              what is the minimun pressure required for the filter

              in most cases the procon will draw water from a tank through a filter, depending on the micron size of the filtration

              graham

              Comment


              • #8
                Re: Flojet pumps

                Hey Graham,

                Standard 0.5 micron Aqualife water filter. The procon pump will not pump from the water filter, which is why Im looking for solutions.

                Cheers,

                DS

                Comment


                • #9
                  Re: Flojet pumps

                  Hmmm,

                  Just thinking mate (yeah I know, thats dangerous).... Why not just use the mains pressure to push water through the filter system into the plastic container/water bottle, say from the water spout in the sink or bathroom and then transfer the refilled container/bottle back close to the espresso machine?

                  Seems like a lot simpler way of doing it and when youve completed a refill, just roll up the hoses for the filter system and put it away in the cupboard. No need for any extra pumps or complication, just a cleverly arranged set of filters and hoses.... 8-)

                  Mal.

                  Comment


                  • #10
                    Re: Flojet pumps

                    I think Dave wants to just set it up and forget about it without having to mess around. Makes sense to me though Mal

                    Comment


                    • #11
                      Re: Flojet pumps

                      NPSH (Net positive suction head) is the reason you cant get any water into the pump past your filter. Below is the simple version.

                      10m is approx atmospheric pressure or about 14 PSI

                      Pumps dont suck !!! Atmospheric pressure is the only thing that makes water enter a pump. From this we need to look at the losses from the rest of the system that prevent that from happening.

                      Pressure losses across the filter are the big problem especially when dirty. A 5 micron filter will drop about 1m but a 0.5 micron wil drop more like 10-15m

                      Pipe Friction and valve losses need to be considered, also under sink tank (say an extra metre), the pump itself requires some left over as well including a safety margin (2-3m). There is also a correction for temp but it doesnt matter much unless you are getting above 40 C.

                      So in a basic system with 10-12mm pipe or hose and a 5 micron cartridge it will work but a 0.5 wont.

                      NPSH is a lot more involved than this but basically the less restrictions on the suction side of a pump the better. The only way to run the 0.5 filter is to fit it to the output side of the pump and maybe a course one on the inlet of around 20-30 micron.

                      best of luck.

                      Comment


                      • #12
                        Re: Flojet pumps

                        Well actually,

                        The pumps found in most espresso machines, be they reciprocating or eccentric vane types, are positive displacement pumps and will indeed "suck" through a filter by virtue of evacuating the air in the pipeline. Although, I wouldnt try doing this at both a negative head AND through a filter.... Just asking for trouble for sure. If you had a means of easily bleeding the pump to ensure that the incoming water line from the filter was 100% full of water at all times, this situation would probably remain ok but might require the fitting of a non-return valve upstream of the filter to ensure the water didnt drain out of the line.

                        Not all pumps are happy to operate in this way of course as some of them rely on water to lubricate the pump seals and without it, will just sit there happily turning the seals into a molten mass. Not very pretty. Procon pumps will certainly be happy to operate this way, within specification but Im not sure what sort of -ve head most Vibe pumps (found in espresso machines) are rated at. No doubt this sort of info could be gleaned from the Ulka or Fluid-o-Tech people.

                        As you point out though "beanflying", much better to maintain a positive head at the inlet of a pump and avoid all risk; that was why I suggested a simple arrangement to use mains water pressure to supply the prerequisite positive pressure. Still dont believe that a feed pump arrangement is necessary to provide this.

                        Cheers,
                        Mal.

                        Comment


                        • #13
                          Re: Flojet pumps

                          Hi Mal and all,

                          Repeat after me "Pumps dont suck"   Positive displacement pumps such as sliding vane or impulse piston pums only pump fluid and are limited by atmospheric pressure.

                          One of the benifits of the Procon vane style of pump is that they move the water constantly and have a low NPSHr (NPSH required) this translates to a greater ability to cope with higher suction lifts etc.

                          Rubber diaphram (flojet) pumps or UCLA type of pumps will suffer badly when you place restrictions on the inlet side of the pump as the outlet performance will degrade. The rubber diaphram will not deflect as much so you lose volume for a given RPM. In the case of the UCLA the plunger will not move as much (based on there performance curves). In a true piston pump this is not the case as they have rigid valves and pistons so for a given RPM you get a given volume unless you have exceeded the NPSHa (NPSHa).

                          When NPSHa is less than 0 (normally less than 1-1.5m is considered the safe lower limit) you get cavitation. Cool sound like marble going through the pump but destructive  

                          For a system to work

                          NPSHa >= Atmospheric pressure (10m) + Water Level (- if under bench) - Vapour Pressure (not that important for cold water) - Pipe and Filter Losses - NPSHr (what the pump needs)

                          NPSHr is not listed for any of the common pumps used in espresso machines but the procon will be in the order of 2-3m based on similar pumps. The UCLA will be more but it is anyones guess.

                          Welcome to pumps 101  : When I was taught this it was nearly a full day so feel free to be confused  :-?

                          15 years in the industrial pump trade BTW Pumping lots of good and really ugly stuff :P

                          Comment


                          • #14
                            Re: Flojet pumps

                            25 years in engineering in heavy industry, mining and petro-chem "bf"... I know pumps dont suck but they (positive displacement types) do evacuate the inlet side of the pump and providing the pump is capable of being primed from a dry state without harm, then they can "self-prime" quite well, even with a filter in the way. As are you, I am also drawing from personal experience, not theory alone....

                            Mal.

                            Comment


                            • #15
                              Re: Flojet pumps

                              when we set up mobile coffee units we

                              * install a non return valve near the pump and another at the tank
                              (generally find these units do not seal 100%, so 2 units gives us more protection

                              * keep supply line to a minimun length

                              * 3/8 tubing or braided hose minimun internal size
                              (under this decreases the flow causing pump vibration)

                              * 5micron (absolute) water filter (culligan GW)
                              this is generally the finest filter used, and recomended these days for coffee machines
                              we used to use .5micron filters for mains connected machines but the cartridges use to block very quickly
                              (if you visit the Aqualife site you will find the water filter they use for coffee machines is 5 micron (absolute) and .5 micron for drinking water

                              * on some of the machines which have lazy pumps, we fit a 5 micron (nominal)

                              * in most instances the pump bypass will need to be readjusted


                              graham

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