I just bought a (relatively) cheapo pump today, and happened to notice something interesting in the manual:
Quote:
"Choosing the right output for the application
Laguna Statuary Pumps can be used in a wide variety of applications, and their wide range of output flows at various heights will accommodate almost every circumstance. What is most important is to define the needs of the application and ensure the pump will be adequate to the job. The factors that influence pump capacity include Head Height, hose and fitting resistance:
Head height: Vertical distance between water surface and water discharge.
Hose Resistance: For every ten feet (3 m) of hose, add one foot (30 cm) to the head height.
Fitting Resistance: For every elbow connector, add one foot (30 cm) to the head height.
Determine the head height first, the vertical distance from water surface to water outlet. To this, add the amount of hose needed to transport the water from pump exhaust to the water outlet. When pipe fittings are used to go around corners, the resistance to water flow created by a 90o elbow is equivalent to adding one foot (30 cm) per unit. If the installation requires a 90 cm (3 ft) lift from surface to output, requires 3 m (10 ft) of hose and one elbow, then the actual head is 150 cm (5 ft)."
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Obviously, this doesn't give you enough data to actually calculate the head of your system, but it is basically the same approach used in Crane tech doc. 410 (with much more detail on fittings). I just found it interesting to have it laid out so clearly in a cheapo pump manual. You can quickly understand my aversion to 90 degree elbows (or Ts that block flow) now I would hope...