Pump Basics The difference between submersible pump and surface pump sizing is that surface pumps, including jet pumps, show performance in “charted” form versus “curves” for submersibles. Except for the “pumping level” (which is shown in feet in the charts) all other head/lift requirements should be converted to PSIG for surface pump sizing. (Feet X .433 = PSIG (Pounds per Square Inch Gauge). Aboveground Pumps MORE ABOUT... VERTICAL LIFT/ ELEVATION The vertical distance between the well head and the level at the point of use. It must be ADDED to the Total Dynamic/Total Discharge Head if the inlet is lower than the outlet and SUBTRACTED if the inlet is higher. As a rule of good installation practice, however, pipes should slope continuously upward from the inlet to the outlet to prevent entrapment of air. SERVICE PRESSURE The range of pressure in the pressure tank during the pumping cycle. FRICTION LOSS The loss of pressure or head due to the resistance to flow in the pipe and fittings. Friction loss is influenced by pipe size and fluid velocity, and is usually expressed in feet of head. HORIZONTAL RUN The horizontal distance between the point where fluid enters a pipe and the point at which it leaves. TOTAL DYNAMIC/TOTAL DISCHARGE HEAD or TDH TDH and capacity required determines pump size. The total pressure or head the pump must develop is the sum of Vertical Lift/ Elevation, The Service Pressure, and The Friction Loss. All of these measurements must be expressed in the same units, usually feet of head or pressure (PSI), before adding them together. For aboveground pumps, distance to water in feet are shown in the respective charts. PUMPING LEVEL The lowest water level reached during pumping operation. (Static level minus drawdown) STATIC OR STANDING WATER LEVEL The undisturbed level of water in the well before pumping. Not as important as pumping level. DRAWDOWN The distance that the water level in the well is lowered by pumping. It is the difference between the STATIC WATER LEVEL and the PUMPING LEVEL. 14 4 5 1 2 3 Vertical Lift / Elevation The vertical distance in feet from the location of the pump to the point of highest delivery (e.g. from a pump house near the well to the second floor of a two story house) Service Pressure The average pressure switch setting. Example 20/40 switch (1/2 HP) = 30 PSIG average (3/4 HP and larger pumps have 30/50 switch settings) = 40 PSIG average Friction Loss Water flowing through piping will lose head depending on the size, type and length of piping, number of fittings, and flow rate. Example: Pumping 10 GPM through 100 ft. of 1" plastic pipe with 3 elbows will cause a friction loss equal to: 100 ft. + 18 ft. (elbow loss) 100 ft. Feet of Pipe ___________Diameter of Pipe __________ Type of Pipe __________________________________ See Friction Loss Charts on Page 16 Total Dynamic/Discharge Head • 1 + 2 + 3 = Pumping Level/Depth to Water The vertical distance in feet from the pump to the water level including draw down level - if any. In Shallow Well systems, referred to as suction lift/head and is limited to 20 or 25 feet at sea level (deduct 1’ suction capability for each 1000’ above sea level). Note: Friction losses (3) in the suction piping must be added to the pumping level for total suction lift. Deep Well jet pump charts include the friction losses in the vertical piping only. See page 21 if long horizontal, offset piping cannot be avoided. Determining Flow Rate Although methods will vary, in general, the Water Systems Council bases pump flow selection for a residential system on total gallon usage during a seven minute peak demand period. This can be supplemented by using a properly sized pressure tank. Farms, irrigation, and lawn sprinklers demand more water. Gallons Per Minute (or hour) Needed See Page 20 for water demands After determining TDH and flow requirements in GPM / GPH, match these numbers with surface pump charts in sections 3 and 4. 800-356-5130 | [email protected] | bakerwatersystems.com 3/26 No need to convert- Charts are in feet X .433 Feet X 6.31 ft (loss per 100') = 7.44' X .433 = 3.2 PSIG = PSIG PSIG X .433 Feet PSIG + PSIG + Well Size (inside diameter in inches) _________ If 25' or less, use shallow well charts Ft. If more than 25' use deep well charts Pump Basics