Xylem IM102 R05 Jet Pumps - Manual (Page 11)

11
CHECKING SUCTION LIFT ON A
SHALLOW WELL
A vacuum gauge indicates Total Suction Lift (vertical lift
+ friction loss) in inches of mercury (Hg.). One inch (1")
on the gauge = 1.13 feet of total suction lift (based on a
pump at sea level). Practical suction lift at sea level is 25'
or 22" Hg. Deduct 1 ft. for each 1000 ft. above sea level.
Install the compound vacuum/pressure gauge in the 1 ⁄
8
"
hole in the shallow well adapter or the 1 ⁄
8
" hole between
the suction and discharge pipes on a dedicated shallow
well pump. This is the same hole that is used to connect
an air volume control.
Interpreting the gauge readings:
High Vacuum (22" or more)
• Suction pipe buried in mud
• Foot valve or check valve stuck closed
• Suction lift exceeds lift capability of pump
Low Vacuum or 0 vacuum
• Suction pipe not submerged
• Suction leak (check joints and especially unions)
Gauge needle fluctuates rapidly
• Gaseous well
• Air leak in suction line
• Well producing less than pump capacity (throttle a
ball valve in suction line do not exceed 22" Hg.) to
reduce pump capacity
USE OF TAILPIPE ON
DEEP WELL JET PUMPS
If the capacity of a deep well jet pump exceeds the well
production, well drawdown will allow your pump to
break suction and lose prime. This can be overcome by
using a 34' tailpipe between the jet assembly and the foot
valve. Since the capacity of a pump falls off as the lift is
increased your well inflow and pump output will equalize
somewhere between the jet and foot valve. The drawing
shows the percentage of rated capacity you will get at
certain points. As in a normal situation the jet should be
set 5' below the static water level.
DRIVE PIPE
SUCTION PIPE
JET ASSEMBLY
TAIL PIPE
34 FT. WILL PREVENT
BREAKING SUCTION
STATIC LEVEL
100%
33.9' MAXIMUM
DRAW DOWN 0%
10' PIPE 80%
15' PIPE 70%
20' PIPE 57%
25' PIPE 40%
28' PIPE 25%
29' PIPE 17%
Vacuum
Gauge
22.6’
Vertical Lift
Plus Friction
A reading of 20" on a vacuum gauge placed on the suc-
tion side of the pump would tell you that you have a
vacuum or suction lift of 22.6 ft.
20" x 1.13' = 22.6 ft.
TECHNICAL DATA TECHNICAL DATA
Fig. 8
Fig. 9