the psi it takes to move concrete thru any boom or pipe depends the diameter of the pipe and the slump of the concrete, the smaller the pipe and the stiffer the mud the more psi the wetter the mud the less psi, the pressure on the the pumps max out at 320 bar. my A.C.P.A book is in my truck i see if i can get more specfic info.

PSI has to do with pump face pressure, in my line pump it is 1150 pounds because concrete takes 800 pounds before you compress the water out of the mix causing a plug.

i use rubber hose that has a lot of friction so what is required is a six sack per yard mix that is acheved by ordering a 3500 specification.

3000 pound minumum test can be a 3/4 rock with a five sack mix and some of that can be fly ash that are fines but not really a lubricant like cement powder. this might not be a good pumpable mix for my application.

the concrete plant is glad to save you a few bucks on the material but you will have to dump it out of a truck or use a telebelt to place it.

you can achieve high psi by not adding much water that is a 3.5 inch slump that the architechs call for but you can not get the material to flow down the truck chute so why try to work harder to pump it slow just because the customer has no clue of how the risk can change the perameters of a job.

school is a a good base line but the real world is do what works and that is safe. 

every job is not the same, everything is a factor, hose size, pipe size, is it pipe or hose, 90's, 45's, reducers, how many feet you are pumping, elevation change, is everthing clean, just like pumping water, the big change is SG of the materal being moved, it all = head pressure.

OK Guys:A house water line ONLY puts out around 45-60 lbs of pressure,yet you can use it to push a paper plug beat tight with a hammer through 200' of 3" line! How? The weight of the water backing up that 45-60 lbs is greater than the weight of the concrete it is pushing,thus theoretically 14 psi,or 1 bar,should be enough. Any thoughts??