• Liberty Pumps 287 1/2-Horse Power 1-1/2-Inch Discharge 280-Series Automatic Submersible Sump Pump with VMF Switch
Liberty Pumps 287 is a 1/2HP Automatic Submersible Sump Pump with with magnetically operated vertical float VMF switch and 10ft power cord. Turn-on level of the not adjustable switch is 9-1/2" and turn-off level is 4". This pump can operate in a smaller 10" diameter sump pit.The Liberty Pumps 287 has 1-1/2" NPT discharge, 3/4" solids-handling, 37' shut-off head, a unique one-piece cast iron housing and thermally protected permanently lubricated motor.Liberty Pumps 287 is a 1/2HP Automatic Submersible Sump Pump with with magnetically operated vertical float VMF switch and 10ft power cord. Turn-on level of the not adjustable switch is 9-1/2" and turn-off level is 4". This pump can operate in a smaller 10" diameter sump pit.The Liberty Pumps 287 has 1-1/2" NPT discharge, 3/4" solids-handling, 37' shut-off head, a unique one-piece cast iron housing and thermally protected permanently lubricated motor.For Sump and De-watering Applications only. This Vertical Magnetic Float (VMF) model is not recommended for effluent applications due to their short On/Off cycle. Wide angle float models (Liberty Pumps 281 and 283) are better suited for effluent applications and are easily adjustable for different On/Off levels.For added protection, consider the addition of a back-up pump such as Liberty's SJ10 SumpJet, as well as an alarm such as Liberty's ALM-2 in applications where loss of pump function could result in property damage. If an alarm is used, it must be connected to a separate electrical circuit.CAUTION Do not let the pump run dry.
  • Pumps up to 67 GPM
  • Maximum head 37-Foot
  • Quick-disconnect 10-Foot standard power cord allows replacement of cord in seconds without breaking seals to motor
  • Efficient motor design reduces electrical usage by up to 40-percent
  • Includes a magnetically operated VMF switch for smaller pits down to a 10-Inch diameter

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Liberty Pumps 287 1/2-Horse Power 1-1/2-Inch Discharge 280-Series Automatic Submersible Sump Pump with VMF Switch

  • $358.80



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Dynamic Head

The effect of the Earths gravity on the "lift" or head pressure is fairly simple; for every vertical foot of distance the pump moves the water you are adding one foot of head pressure so the ratio is a 1:1 ratio. The effects of the friction, caused by water as it travels through your hose or pipes, on the total head pressure is a little more difficult to calculate especially as there are slight variations in pipe friction in different hose materials and the smoothness of the inner bore. Basically. for every ten feet of pipe through which the water has to travel travel horizontally will contribute 1 foot of head height; the ratio of the pipe friction loss is a 10:1 ratio.

Plumbing fixtures and bends and corners in your hose also increase the total head you must calculate to ensure the proper final volume from your pump. Every corner with a 90 degree elbow in your plumbing will add 1 foot of head pressure  with a 1:1 ratio. 45 degree elbows, tees and even insert couplers can all have an impact on the final flow.

If you install a pump 40 feet away from the top of your waterfall which is 6 feet above the pump and the tubing is a single run of 40 feet horizontally then you add 4 feet of head for the tubing length (the 10:1 ratio) to the 6 foot differnetial between the pump location and the final height of the waterfall so your final total dynamic head calculation would be 10 feet. This means your final volume of water flow in this water feature or application would be the volume of flow on the performance curve that equaled the gallons per hour at 16 feet. This volume will certainly be much less than the initial volume the pump can move at an open flow or a zero head.

If in the above example your 40 feet of horizontal tubing run also required 3 elbows of 90 degrees then an additional 3 feet of theoretical head would be added and your final flow result would be at 19 feet on the performance curve of the pump. In this example you would want to choose a pump that has the desired GPH rating at 9 feet of head pressure.  Tubing size is also an important factor in accounting for head pressure loss, in general you should never reduce the diameter of the tubing below what the output size of the pump is, this will drastically increase head pressure, and reduce pump performance.  For maximum pump performance, using the largest tubing that is practical is the best choice. A best practice is to use a hose with an inner diameter that is the same as your pumps outlet fitting.