Well Wizard®
Installation and Operation Manual
Rev. E 06-05-2023
28
Bladder Pump Operation in Low-Submergence Wells
Pump submergence is defined as the height of the static water column above the top of the
pump. In wells in which this water column height is 5 feet or less, the pump is considered to be in
a low-submergence application.
Well Wizard
bladder pumps fill by hydrostatic pressure. As the inside of the bladder fills with
water, the bladder expands. This filling and expanding of the bladder is referred to as the “refill”
cycle. When air pressure is applied to the outside of the bladder, the bladder is squeezed, forcing
the water up the discharge tubing. This is referred to as the “discharge” cycle.
In low-submergence applications, there is less water pressure available to expand the bladder
during the refill. This can result in a smaller volume of water being pumped with each pump
cycle because the bladder may not fully expand.
In low submergence wells,
it is critical that the air pressure driving the pump not
be more
than 10-15 PSI greater than the minimum requirement of 0.42 PSI per foot of pump depth.
Higher pressures than this can cause the bladder to be squeezed too
tightly during discharge, a
condition which can prevent the bladder from expanding during refill. To avoid this condition in
deeper wells, it is suggested that the air pressure applied to the pump be gradually increased as
the water level in the pump’s discharge tubing rises. It is recommended that the air pressure be
set at 15 – 20 PSI initially, and then slowly increased in increments of 10psi as needed until the
water reaches the surface.
As a result of the lower volume per discharge cycle, more time will be required to initially bring
water to the surface. An easy way to verify that the pump is working, prior to the water reaching
the surface, is to submerge the discharge tubing in clean container of water. Each time the
pump goes into a discharge cycle, air in the discharge tubing, which is displaced as the water
level in the tubing rises, can be seen as air bubbles coming from the end of the tubing. To
optimize the pumping rate, the refill time should be set long enough to achieve the maximum
volume of air bubbles on each pump cycle, and the discharge time should be set long enough to
ensure that the air has stopped bubbling out of the tube before the pump controller switches
back into refill