D/G-04 Installation
Inlet Piping (Suction Feed)
CAUTION: When pumping at temperatures above 160° F (71° C), use a
Install draincocks at any low points of the suction line, to permit draining in freezing conditions.
Provide for permanent or temporary installation of a vacuum gauge to monitor the inlet suction. To maintain maximum flow, vacuum at the pump inlet should not exceed 7 in. Hg at 3 gpm and 70° F (180 mm Hg at 11.4 liters/min and 21° C). Do not supply more than one pump from the same inlet line.
Supply Tank
Use a supply tank that is large enough to provide time for any trapped air in the fluid to escape. The tank size should be at least twice the maximum pump flow rate.
Isolate the pump and motor stand from the supply tank, and support them separately.
Install a separate inlet line from the supply tank to each pump.
Install the inlet and bypass lines so they empty into the supply tank below the lowest water level, on the opposite side of the baffle from the pump suction line.
If a line strainer is used in the system install it in the inlet line to the supply tank.
To reduce aeration and turbulence, install a completely submerged baffle plate to separate the incoming and outgoing liquids.
Install a vortex breaker in the supply tank, over the outlet port to the pump.
Place a cover over the supply tank, to prevent foreign objects from falling into it.
Hose Size and Routing
Use the shortest,
Do not install any 90° elbows in the pump inlet.
•Use flexible noncollapsible hose between the pump and rigid piping or supply tank. This will absorb vibration, and allow for expansion or contraction.
•Use the largest practical hose. The smallest permissible size is 5/8 in. (16 mm) I.D.
•All valves, fittings, and unions must also have
•Support the pump and piping independently.
•Make sure all joints are sealed and tight, to prevent the pump from drawing air into the inlet.
•Do not use a line strainer or filter in the suction line unless regular maintenance is assured. If used, it should have a
Inlet Piping (Pressure Feed)
Provide for permanent or temporary installation of a vacuum/ pressure gauge to monitor the inlet vacuum or pressure. Pressure at the pump inlet should not exceed 500 psi (34 bar); if it could get higher, install an inlet pressure regulator.
Do not supply more than one pump from the same inlet line.
Inlet Calculations
Acceleration Head
Calculating the Acceleration Head
Use the following formula to calculate acceleration head losses. Subtract this figure from the NPSHa, and compare the result to the NPSHr of the
Ha = (L x V x N x C) ⎟ (K x G) where:
Ha = Acceleration head (ft of liquid)
L= Actual length of suction line (ft) — not equivalent length V= Velocity of liquid in suction line (ft/sec) [V = GPM x (0.408 ⎟
pipe ID2)]
N= RPM of crank shaft
C= Constant determined by type of pump — use 0.066 for the
K= Constant to compensate for compressibility of the fluid — use: 1.4 for
2.5for hydrocarbons with high compressibility G= Gravitational constant (32.2 ft/sec2)
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