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|The most helpful favorable review||The most helpful critical review|
3 of 3 people found the following review helpful:
By Barry from USA on 2010-12-21 18:32:22Things I liked:Good quality. It is doing just as it is designed.
What others should know:Follow instructions. Pump slow and deliberate.
0 of 0 people found the following review helpful:
By ZipnZim from USA on 2014-01-13 17:35:04Things I liked:I have two of these pumps. The first one I got with my first disco.(Liked the disco so well, I built two more. Disco upper, 2250 lower.) It worked well for charging my discoveries for about 4yrs, until I decided to tune them "up". Charging them to 2300-2400psi, it didn't take long for the pump to fail. So I began the tribulations others have described. Finally, I considered that my time would be better spent shooting, than poopn with that pump, so I bought another one. Whoops. It was definitely new, but it didn't work well at all, straight out of the box. By then I had researched these pumps online, and the conclusion I reached, was that if I couldn't fix it myself, it wasn't going to get fixed. So, I bought a Hill pump. The Hill got me going again.(And is a higher quality machine.) In the meantime, the ~$400 I've got into these pumps has motivated me to continue to work on getting a reasonable service life out of them. Having studied them to where I understand how they accumulate and transport a charge, and having studied the operational theory for the teflon packing ring that accompanies the piston ring, I see that there is an engineering error in these pumps. The engineer that drew the plans for these pumps, was familiar with the Fluid Dynamics of Hydraulics(liquids), but not the Fluid Dynamics of Gases, which is a more rarefied atmosphere of Fluid Dynamics.(So to speak) The teflon packing ring is the indicator. In Theory, that packing ring should be above/upstream of the
Things I would have changed:piston o-ring, even though the split in the ring represents a defect in the seal. And if these pumps were transporting liquids, it would probably work well enough. But, the density and viscosity of water(liquids), is so-o much higher than the density and viscosity of gases, that the split in the teflon ring represents a significant breach in the seal. And the pump won't work with that ring in the position where it should theoretically be located. In order for the o-ring itself to make the seal, at the pressures the pump is capable of, the tolerance between the piston head and the cylinder walls must be at minimum, so that the o-ring is not extruded into the gap between the piston head and the cylinder wall by the pressure. That extrusion effect is why these pumps require significantly greater force beyond ~2500psi, because the ring is forming a wedge between the piston head and the cylinder walls, which is what that teflon split-ring was intended to prevent. With a 90durometer Viton o-ring on the piston head, these pumps will charge discoveries in good order. Going near or above 2500psi, will greatly reduce service life. If you want to charge to 3000psi, get a Hill. The Hill pump doesn't have a teflon ring, because the Hill pump, doesn't Need one. The piston diameter on the Hill pump is smaller than on these pumps, which provides a greater mechanical advantage. It takes a few more strokes with the Hill, but the Hill will produce 3000psi with ease. I use it on my Marauder.
What others should know:I bought another Hill pump for my son, to go with the .25synrod I gave him for xmas. I also taught him how these pumps operate, so that the Hill pumps will probably be giving service long after I am gone. What else would I tell you? If you have one of these pumps, I feel your pain. The Treatment I recommend, is the Hill Pump. Accept No Substitutes.