22 Nov
2005
22 Nov
'05
2:07 a.m.
On 11/21/2005 at 7:06 PM Doc Shipley wrote:
I think that putting the computer higher than the
pump can push is
the point. If the computer's on the low-pressure side of the circuit,
(the pump is *pulling* water through instead of *pushing* ) it would
take a very large leak to get the system wet. It'll pull air into the
water lines, instead of pushing water out into the electronics.
I have such a sump pump as part of my septic system--the l500 gallon tank
drains overflow into a smaller 100 gallon tank and a float-actuated
submerged sump pump moves the waste water to the drainfield (which is
located about 20 ft. higher than the tank.
The sump pump works by means of an impeller; i.e., it sits submerged in the
water and centrifugally pushes it out the drain port. There are no check
valves. My own pump is rated at 28' lift and it can fully drain the 100
gallon holding tank in less than 30 seconds. If the tank is empty and the
pump continues to run, there are no bad effects and no air ends up getting
pushed out the drain line. A very robust design; my own pump has been
operating for more than 15 years without attention.
Here's a photo of such a pump:
http://www.pumps-in-stock.com/images/6-cia_large.jpg
Cheers,
Chuck
