In the mining industry u will not pump 2 pump's capacity in one pipeline. It will be close but not possable. Im pumping 3000 ft ,the pump's delivery is 4" & my pipe column is 6" (with a max of 2 pumps running).That is on a posetive displacement pump. On a sentrufical pump the loss will be greater as u are pumping into a bigger pipeline.

I work in the beverage industry, Coke, Pepsi, etc.  When mixing syrup to make beverage they are pumping sugar (HFCS55 cornsyrup) and water simultaineously.  the sugar is at 80 degreegs F or 800 centipoise.  the water is at 50 degreegs F.  The water and sugar are joined at a valve manifold on the way to the syrup blend tank.  When mixed they are at 80 centipoise making the pumping easier.  Sugar pump in a steady flow lobe positive displacement.  The water pump is a close tolerance centrifugal.
   The pressure at the joining points produced by the sugar is 90 psi.  Therefore the centrifugal has to overcome the PD pump pressure, which can go to 150 psi.  The sugar rate is 100 gpm and the water rate is 50 gpm.
    What should I be looking out for when sizing the centrifugal pump?  The PD pump?
    Thank you.

Positive displacement, reciprocating pumps, like CAT PUMPS, are ideal for this application.  Each pump is selected and installed with appropriate HP to deliver a specific flow and feed into a common feed line to the system.  The pumps can be as few as 2 or as many as needed and set to come on with additional demand or on a time schedule basis.  Each pump is fitted with a pressure regulating valve to set the desired system pressure  and a secondary safety valve.  Once the system flow and pressure are established, the only variance in performance will be due to a change in the down stream restriction [generally clogged or worn nozzles].
This type of set up is very popular due to its flexibility in capacity and its pump serviceablity without bringing the complete system down.   Lean more at the web site www.catpumps.com