Xylem JO5X Instruction Manual page 11

TECHNICAL DATA
TECHNICAL DATA
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 over-
come 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
Fig. 8
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
tween 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)
STATIC LEVEL
Low Vacuum or 0 vacuum
Gauge needle fluctuates rapidly
100%
10' PIPE 80%
15' PIPE 70%
20' PIPE 57%
25' PIPE 40%
28' PIPE 25%
29' PIPE 17%
33.9' MAXIMUM
DRAW DOWN 0%
A reading of 20" on a vacuum gauge placed on the
suction 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.
" hole in the shallow well adapter or the
8
• Suction pipe buried in mud
• Foot valve or check valve stuck closed
• Suction lift exceeds lift capability of pump
• Suction pipe not submerged
• Suction leak (check joints and especially unions)
• 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
Vacuum
Gauge
22.6'
Vertical Lift
Plus Friction
⁄ " hole be-
1
8
Fig. 9
11