RS AND RD SERIES PUMPS
OM-03989
PAGE B - 6
INSTALLATION
DISCHARGE LINES
Siphoning
Do not terminate the discharge line at a level lower
than that of the liquid being pumped unless a si
phon breaker is used in the line. Otherwise, a si
phoning action causing damage to the pump
could result.
Valves
Some pump models are provided with an integral
priming pump check valve in the discharge port.
This check valve is designed to prevent recircula
tion of air or vapor ejected during the priming cycle.
It will
not
serve as a discharge check valve in the
system piping. If the application involves static dis
charge head or suction pressures, a check valve
must
be installed to prevent siphoning or loss of
prime through the bypass line. If a system check
valve is required, it must be installed in addition to
the built‐in priming pump check valve.
Priming Lines
The integral Roto‐Prime
priming pump incorpo
rates a priming line which evacuates the suction
line effectively against back pressure ranging from
atmospheric pressure up to approximately 8 psi
(measured downstream of the discharge check
valve). If static discharge pressure exceeds 8 psi,
an Air Release Valve
must
be installed to permit the
escape of air or vapor to atmosphere during initial
priming or repriming cycle. This valve functions in
conjunction with three priming tubes installed be
tween the Air Release Valve, the priming pump and
the pump suction.
Air Release Valves (“BAR” Models)
Some pump models are provided with an Air Re
lease Valve. If the pump does not have an Air Re
lease Valve, it can be ordered as optional equip
ment. Since internal changes are required on the
pump to facilitate installation and proper function
of the Air Release Valve, it is recommended that
this be ordered as a
factory installed
option only.
The Air Release Valve works in conjunction with the
integral priming pump to expel and prevent recir
culation of air or vapor ejected during the priming
cycle. The Air Release Valve will
not
serve as a
throttling valve or check valve in the system piping.
If the application involves static discharge head or
suction pressure, system check valve
must
be in
stalled to prevent siphoning or loss of prime
through the pump.
If a throttling valve is desired in the discharge line,
use a valve as large as the largest pipe to minimize
friction losses. Never install a throttling valve in a
suction line.
With high discharge heads, it is recommended that
a throttling valve and a system check valve be in
stalled in the discharge line to protect the pump
from excessive shock pressure and reverse rota
tion when it is stopped.
If the application involves a high discharge
head, gradually close the discharge
throttling valve before stopping the pump.
Air Release Valve Venting (“BAR” Models)
When ordered as a factory installed option, the Air
Release Valve is shipped mounted on the pump
base with the valve tubing connected. If the Air Re
lease Valve is shipped separately, refer to the in
stallation instructions accompanying the Valve.
Remove the shipping plug in the head of the Air Re
lease Valve so that normal operation and venting
can take place. It is suggested that a length of 3/4
inch tubing be installed in the shipping plug open
ing so that hazardous vapors can be carried away
from the immediate vicinity of the pump.
NOTE
When two pumps equipped with Air Release Valves
are installed in parallel, a check valve must be in
stalled in the venting lines.
