Double-diaphragm Pumps

I have been offered a good deal on a new double-diaphragm pump. But I can't try it out before buying. Judging from the design, it seems like the pumped liquid would surge quite a bit. Has anyone ever used one of these? How bad is the surging?

Are you talking about those industrial twin chamber pneumatic driven pumps? The large 20" diameter ones we used pumping glue for making cardboard pumped out in large volumes but in surges. My thinking any diaphragm pump like a Thomas compressor it comes out in pulses needing a surge chamber to smooth out these pumping pulses. The cost also can be rather high with rebuild kits.

BrewBeemer said:

Are you talking about those industrial twin chamber pneumatic driven pumps? The large 20" diameter ones we used pumping glue for making cardboard pumped out in large volumes but in surges. My thinking any diaphragm pump like a Thomas compressor it comes out in pulses needing a surge chamber to smooth out these pumping pulses. The cost also can be rather high with rebuild kits.

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Something like that. The pump I can get is like the one described here:
www.roxspur.com/pumps/4001.pdf
Except it is the Yamada NDP15-BSS, which has a 1/2" port, stainless steel chassis, and santoprene diaphragm.

I guess if it surges as much as you say, it wouldn't be good for pumping wort out of a mash tun!

Those pumps have a discharge per cycle hence pulsing per stroke back and forth operating each diaphragm mounted on each end. The larger SS versions I worked on weighed 85# and danced around under load using large volumes of air with 2" glue lines. I say a no go you need a smooth flowing pump.

I use those pumps a lot at work and they have their place but you're right, they do surge. We have one place where we put an accumulator after it and it helps but still surges. Centrifugal is prob best for what you want to do.

Here are some other great specialty application diaphragm pumps that are very durable, stall free, and should last you a long time: http://www.ingersollrandproducts.com/IS/Category.aspx-am_en-3809

Hope your search goes well

at my work we use aro double-diaphragm pumps with surge chambers for pumping glue, we don't have any surging issues but that's because we run a low flow rate and use the surge chambers. but, these pumps are waay too expensive for home use, even if you get them for free (they use quite a bit of air, which takes electricity to produce... ) and as someone else said, repair kits are also pretty expensive.

i do have one that i use at home for pumping gasoline and diesel when working on cars and boats, one nice thing about air-driven pumps is that they are non-sparking when properly used and grounded.

Can a double diaphragm pump be driven with steam rather than compressed air. Just tinkering with an idea and wanted to know if some one has tried it out.

moreshk said:

Can a double diaphragm pump be driven with steam rather than compressed air. Just tinkering with an idea and wanted to know if some one has tried it out.

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NO! the the air diaphragms are not rated at the elevated temps required to maintain steam. I rebuilt many of these pumps operated by air pushing glue.

marzsit said:

at my work we use aro double-diaphragm pumps with surge chambers for pumping glue, we don't have any surging issues but that's because we run a low flow rate and use the surge chambers.

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Same here at this end many years ago I worked at Weyerhauser box company as a maintenance mechanic.
BTW, your just a step north above Longview Washington, a major Weyerhaeuser lumber operation that I toured on the way up to Canada on a rambling motorcycle trip.
I got stuck working on diaphragm pumps pushing glue for the corrugator, an animal almost a block long making A, B & C flute cardboard as well double wall.
So true the large diaphragm pumps are air hogs but have a constant and smooth output.

Thanks, so is that the only possible problem with running a double diaphragm pump pm steam? What if a diaphragm that can sustain steam temperatures is used? Some different material? What changes would be required to make the system work with steam?

Regards
Moresh

The diaphragm pumps were never designed for steam use, no way to get condensed steam out of the diaphragm housing and valve components made from plastics these days. Why would steam be used?, it would be easier and safer to just used compressed air and use steam to heat fluid after the pump. With the volumes moved with even the smallest double diaphragm pumps and the compressed air requirements, you would end up spending way more than needed to move same volume with centrifugal pump.

thank you

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