• Liberty Pumps PC257-441 1/3-Horse Power PC-Series Sump Pump Combo, Models 257 and 441
PC 1/3HP Sump Pump with Battery Back-Up System A fully assembled pump combination that features a primary 115 volt sump pump and the model 441 battery back-up pump. Liberty Pump PC257-441 Features: Fully assembled and automatic operation Ready to connect to 1-1/2" discharge Provides uninterrupted pumping in the event of power outage or main pump failure Compact profile will fit minimum 15" diameter sump pits Back-up pump (Model 441) offers 5 stage battery charging and protection from battery burn-out or overcharging System includes primary pump check valve and back-up pump check valve Note: 12V deep cycle battery not includedPump Features: Rugged 1/3 hp motor, oil filled with thermal overload protection Able to handle 1/2" solids Hermetically sealed motor and switch cavities Liberty's UNI-BODY casting - a solid, one-piece housing that eliminates the lower motor seal ring found on other pumps Vortex style impeller for superior solids-handling Impeller is constructed of engineering polymer Fasteners are constructed of non-corrosive stainless steel Rotor shaft is constructed of 416 stainless steel Quick-disconnect 10' standard power cord allows replacement of cord in seconds without breaking seals to motor Includes vertical magnetic float for smaller pits Liberty Pump PC257-441 Specifications: Category: Sump Pump Connection Size: 1-1/2" Flow Rate (GPM): 50 Maximum Head Height: 23 Motor HP: 1/3 Maximum Fluid Temperature(F): 140 Degrees Voltage: 115 V Weight: 35 lbs.
  • 1/3 horse power primary pump with maximum discharge head of 23-Foot
  • Back-up pump with a maximum discharge head of 23-Foot
  • Ready to connect to 1-1/2-Inch discharge
  • Compact profile will fit minimum 15-Inch Diameter sump pits
  • Offers 5 stage battery charging and protection from battery burn-out or overcharging (12V deep cycle battery not included)

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Liberty Pumps PC257-441 1/3-Horse Power PC-Series Sump Pump Combo, Models 257 and 441

  • $779.99
  • $724.14

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.