a strainer device for straining debris from a fluid source on the suction side of a pump, the strainer device comprising:
- (a) a housing body comprising,
- an outer housing surface,
- a single cavity defined by an inner housing surface,
- a suction inlet passing through a first end region of said housing body,
- an open ended strainer fixed in a strainer housing fluidly connected to said suction inlet, wherein said strainer housing is fluidly connected to a source of fluid by a strainer suction fitting,
- a backwash outlet passing through said first end region of said housing body,
- a filtered suction outlet passing through a second end region of said housing body, wherein said filtered suction outlet is fluidly connected to the suction side of the pump,
- a backwash inlet passing through said second end region of said housing body into said single cavity, wherein said backwash inlet is fluidly connected to a discharge side of the pump,
- a stem borehole passing through said housing body,
- a central axis of said housing body coaxial with said stem borehole and extending through said single cavity and beyond said housing body,
- wherein said suction inlet is separated from said backwash outlet by a first angle defined as an angle greater than or equal to approximately 60 degrees but less than or equal to approximately 180 degrees as measured from the center of said suction inlet to said central axis and to the center of said backwash outlet, and
- wherein said filtered suction outlet is separated from said backwash inlet by a second angle defined as an angle greater than or equal to approximately 60 degrees but less than or equal to approximately 180 degrees as measured from the center of said filtered suction outlet to said central axis and to the center of said backwash inlet;
- (b) a trim assembly positioned within said single cavity of said housing body, said trim assembly being rotatable about said central axis between a strainer position and a backwash position, said trim assembly comprising,
- a bore formed in a conduit with first and second conduit ends,
- a basket strainer fixed in a basket strainer housing, said basket strainer fluidly connected to said bore,
- said basket strainer housing and said conduit disposed between first and second shutter plates,
- said first shutter plate having an outer surface distal to said conduit and shaped to slide over a portion of said inner housing surface proximal to said suction inlet and said backwash outlet to fluidly block said backwash outlet and simultaneously fluidly couple said suction inlet to said conduit when said trim assembly is in said strainer position and further fluidly couple said backwash outlet to said conduit and simultaneously fluidly block said suction inlet when said trim assembly is in said backwash position,
- said second shutter plate having an outer surface distal to said conduit and shaped to slide about a portion of said inner housing surface proximal to said filtered suction outlet and said backwash inlet to fluidly block said backwash inlet and simultaneously fluidly couple said filtered suction outlet to said conduit when said trim assembly is in said strainer position and further fluidly couple said backwash inlet to said conduit but not block said filtered suction outlet when said trim assembly is in said backwash position, and
- a stem attached to and extending away from said conduit, wherein said stem is coaxial with said central axis and at least a portion of said stem extends through said stem borehole to allow rotation of said trim assembly between said strainer and backwash second positions from a location external to said outer housing surface;
- and
- (c) a shunt fluidly connected between strainer housing and said single cavity to allow fluid to flood said single cavity regardless of said trim assembly's position and further direct fluid to flow across said open ended strainer when said trim assembly is in said backwash position.