Piping; Service Connections - Milton Roy PRIMEROYAL Instruction Manual

Shut-Off Valves
Provide shut-off valves in both suction and discharge lines next to the pump. Locate
discharge line shut-off valve downstream from the inlet connection of the safety valve
Back Pressure Valves
A Milton Roy back pressure valve should be installed in the discharge line near the pump to
ensure sufficient discharge head pressure for proper pump metering action. Normally, the valve
should be located near the pump; however, back pressure valves for large pumps with long and
extremely small discharge lines may have to be installed near the point of discharge into the
process (to minimize siphoning tendencies). Contact Milton Roy Company for sizing
recommendations.
Accumulators (Surge Chambers)
An accumulator, surge chamber, surge suppressor, or pulsation dampener should be used with
the back pressure valve in the discharge line to absorb the flow peaks between the pump and the
back pressure valve (see figure 2). Without the pulsation dampener the valve mechanism will snap
open and closed with the surge from each pump stroke. The pulsation dampener will allow the back
pressure valve to oscillate about a partly-closed position, thus minimizing wear on the valve. Dis-
charge line pulsation dampeners offer the further advantage of limiting the flow and pressure varia-
tions characteristic of this kind of pump. Installing a properly sized pulsation dampener will improve
pump performance and may reduce system costs dramatically by permitting the substitution of
smaller piping. Please contact Milton Roy Company for further information on pulsation dampeners.
Safety Valves
Motor-driven positive displacement pumps can develop tremendous discharge pressures
long before thermal overload devices interrupt the motor electrical circuit. To prevent a blocked
discharge line from causing damage to the pump, piping, or process equipment, install a Milton
Roy Safety Valve in the pump discharge line. This valve is designed and sized to handle system
flow rates and pressures safely while resisting corrosion by the process liquid.
Install the safety valve in the discharge line between the pump and the nearest shut-off valve.
(This will prevent pump damage from accidental valve closure.) Pipe the safety valve outlet back to
the suction tank or to drain, but in either case ensure that the pipe end is continuously visible so
safety valve leakage may be detected. See figure 2 for construction and installation.
Piping Concentrated (95-100%) Sulfuric Acid
Packed plunger pumps are not recommended for this service. Diaphragm style liquid end
are more suited for this application.
8