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Posted by kim gross on May 20, 2005, 3:46 am
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Why not just get a small pressure tank to put between the pump and the
RO unit? It would get filled up by the pump and then feed the RO until
the pressure dropped back down. You pump would not be cycling so much then.
Kim
> Here we go, plumbing experts...
>
> Reading about R/O membranes I figured out my tap water
> pressure (30-40 PSI) is not good enough to get good R/O
> performance. So I picked up the demand/delivery pump
> from Aquatec (DDP5800) with automatic pressure switch
> set to 60 PSI. I have installed it today and I see
> one big problem... the pump is too strong! :-)
> It takes about 1/8 second to pump water to 60-70PSI
> and then the pump turns off for next second, when the
> pressure releases through the membrane back to 40PSI
> and the pumps turns itself on again for another 1/8s
> and the cycle repeats. I am able to adjust the switch
> to make the pressure swings narrower, and then pump
> cycles between 55-70PSI but much faster...
>
> I don't have to tell you how annoying pulsing noise
> does it make... So I don't like it already... but
> how this pressure swings will affect the performance
> or reliability of the membrane ?
> Can I run the filter in such pressure cycling mode ?
> Is there a device known to plumbers to smooth the
> pressure charges like this ? Is there a different
> pump, better for my application ? It would be nice if
> I could find a pump which would work all the time and
> keep up with the demand from the membrane keeping the
> pressure at or around 60-70PSI without such pulses...
> Maybe there is a not expensive variable speed controller
> available to slow this pump down somehow?
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>
> Reading about R/O membranes I figured out my tap water
> pressure (30-40 PSI) is not good enough to get good R/O
> performance. So I picked up the demand/delivery pump
> from Aquatec (DDP5800) with automatic pressure switch
> set to 60 PSI. I have installed it today and I see
> one big problem... the pump is too strong! :-)
> It takes about 1/8 second to pump water to 60-70PSI
> and then the pump turns off for next second, when the
> pressure releases through the membrane back to 40PSI
> and the pumps turns itself on again for another 1/8s
> and the cycle repeats. I am able to adjust the switch
> to make the pressure swings narrower, and then pump
> cycles between 55-70PSI but much faster...
>
> I don't have to tell you how annoying pulsing noise
> does it make... So I don't like it already... but
> how this pressure swings will affect the performance
> or reliability of the membrane ?
> Can I run the filter in such pressure cycling mode ?
> Is there a device known to plumbers to smooth the
> pressure charges like this ? Is there a different
> pump, better for my application ? It would be nice if
> I could find a pump which would work all the time and
> keep up with the demand from the membrane keeping the
> pressure at or around 60-70PSI without such pulses...
> Maybe there is a not expensive variable speed controller
> available to slow this pump down somehow?