- Two off, three way valves.
- Don't equalise the hours on the pumps, they might both reach their end of
life at the same time.
- two plastic tags which say STANDBY PUMP. One goes on the valve, one on
the switch.
- Run on the A pump, test run on the B pump once per .... week, month ( I'd
say month )
And a jerry can with a hose attachment

It was getting too complicated.
Alternatively, two pumps in parallel with only check valves. Still run on A
and test B regularly. When something fails you will have to pull it all
apart to fix it, but there is much less to go wrong.

DF


"Doug Dotson" wrote in message
...
So perhaps a valve on both ends plus a check valve or maybe
two check valves. This is getting too complicated to be
worth it.

Doug
s/v Callista

"Rich Hampel" wrote in message
...
Further thoughts against paralleling such pumps:
If the internal check valves in one pump fails then the fluid will
flow retrograde in the pump that failed.... and damn little volume is
pumped by the pump that remains intact.
Typical industrial installation of such a 'system' would require a
block and bypass system of cocks/valves and bypass/lock-out piping.

In article , Steven Shelikoff
wrote:

On Mon, 12 Apr 2004 13:33:26 -0000, Larry W4CSC
wrote:

(Steven Shelikoff) wrote in
:


That begs the question why are you going to put two pumps in
parallel
if
you only want to run one at a time?

Steve


Backup?

Then I wouldn't put them in parallel without isolation valves. Even
if
it works when both pumps are good, you don't know how the pump will
fail.

Steve