Transportable High Vertical-Lift Emergency Water Pumping System

Abstract

A transportable high vertical-lift emergency water pumping system moves emergency water from a water source at a low elevation to a higher elevation. The pumping system has a first pump having a first-pump suction port at the higher elevation and a second pump having a second-pump suction port at the low elevation and a second-pump discharge port in fluid communication with the first-pump suction port. A variable speed driver is operatively coupled to the first pump. A load sensing hydrostatic drive system is operatively coupled to the variable speed driver and to the second pump. The load sensing hydrostatic drive system is configured to maintain a minimum net positive suction head at the first-pump suction port sufficient to prevent cavitation in the first pump when the variable-speed driver operates at any speed of a plurality of speeds across a range of flows.

We claim: 
     
         1 . A transportable high vertical-lift emergency water pumping system for moving emergency water from a water source at a low elevation to a higher elevation, the pumping system comprising:
 a first pump having a first-pump suction port at the higher elevation;   a second pump having a second-pump suction port at the low elevation and a second-pump discharge port in fluid communication with the first-pump suction port;   a variable speed driver operatively coupled to the first pump; and   a load sensing hydrostatic drive system operatively coupled to the variable speed driver and to the second pump, the load sensing hydrostatic drive system configured to maintain a minimum net positive suction head at the first-pump suction port sufficient to prevent cavitation in the first pump when the variable-speed driver operates at any speed within a range of flows.   
     
     
         2 . The transportable high vertical-lift emergency water pumping system of  claim 1 , wherein the variable speed driver is a diesel engine and the first pump is operatively coupled to the diesel engine by a gear assembly. 
     
     
         3 . The transportable high vertical-lift emergency water pumping system of  claim 1 , wherein the second pump is a submersible hydraulic pump and the load sensing hydrostatic drive system is operatively coupled to the variable-speed driver by a gear assembly. 
     
     
         4 . The transportable high vertical-lift emergency water pumping system of  claim 3 , wherein the hydrostatic drive system comprises a hydraulic pump operatively coupled to the gear assembly and a hydraulic motor in fluid communication with the hydraulic pump and the submersible hydraulic pump. 
     
     
         5 . The transportable high vertical-lift emergency water pumping system of  claim 1 , wherein the first pump is a fire pump, the second pump is a submersible hydraulic driven pump and the first-pump suction port is connected directly to the second-pump discharge port by a lay-flat hose. 
     
     
         6 . The transportable high vertical-lift emergency water pumping system of  claim 1 , wherein the first pump has a first-pump efficiency and the second pump has a second-pump efficiency less than the first-pump efficiency. 
     
     
         7 . The transportable high vertical-lift emergency water pumping system of  claim 1 , wherein the second pump is a floating hydraulically driven submersible pump. 
     
     
         8 . The transportable high vertical-lift emergency water pumping system of  claim 1 , wherein the second pump is an electrically driven submersible pump. 
     
     
         9 . The transportable high vertical-lift emergency water pumping system of  claim 1 , further comprising a third pump having a third-pump suction port at the low elevation and a third-pump discharge port in fluid communication with the first-pump suction port. 
     
     
         10 . The transportable high vertical-lift emergency water pumping system of  claim 9 , wherein the second and third pumps may independently be turned on or off so that either the first pump or the second pump or both the first pump and the second pump may be used to increase lift or flow capacity. 
     
     
         11 . The transportable high vertical-lift emergency water pumping system of  claim 1  wherein the pumping system is mountable on a mobile platform. 
     
     
         12 . A method for moving emergency water from a water source at a low elevation to a higher elevation relative to the water source, the method comprising:
 drawing water from the water source into a suction port of a hydraulically driven submersible pump in the water source;   discharging the water from a discharge port of the hydraulically driven submersible pump into a lay-flat hose connecting the discharge port of the hydraulically driven submersible pump to a suction port of a fire pump at the higher elevation;   maintaining a minimum net positive suction head at the fire-pump suction port sufficient to prevent cavitation in the fire pump when the water is discharged from a discharge port of the fire pump at any rate within a range of flow rates.   
     
     
         13 . The method for pumping emergency transportable water according to  claim 12 , further comprising the step of driving the fire pump and the submersible pump with a variable speed diesel engine. 
     
     
         14 . The method for pumping emergency transportable water according to  claim 13 , further comprising the step of coupling the fire pump to the diesel engine with a gear assembly and coupling the submersible pump to the gear assembly with a load sensing hydrostatic drive system. 
     
     
         15 . The method for pumping emergency transportable water according to  claim 14 , wherein the minimum net positive suction head is maintained by the load sensing hydrostatic drive system.