Hi Yvon;

In Fluid Control systems these are known as "Check Valves" their

purpose

is to

hold or prevent the fluid on reverse flow. In other words once the

fluid

flows

thru the valve it can not go back through it. So in order to answer your
question of whether they are necessary or not a sketch of your fuel

system

(schematic) is needed.
                                                    Butch

Fuel system schematic attached:
Yvon.

    I am using Bosch high psi injection pump and a bypass regulator to
cut it down to 4 psi.
  I have been running the check valves after the pump before the tee
or to be more specific I am using a Mallory regulator with a multiple
port manifold that I running the lines into.
  I cant blow through these pumps so I am going to try it without the valves.
   Ken Welter

********************************************************************************

Hi Yvon, Ken;

Seems like both of you have identical systems, plumbing wise that is, so I'll
shot-gun my opinion:......In fluid systems the primary purpose of installing
check valves in the outlet of pumps is very obvious, and that is to keep
upstream surges and residual pressures from motoring the pump backwards,
especially if there is an accumulator (pressure vessel divided by a sealed free
floating piston which is air or nitrogen gas charged to 1/3 system pressure on
one side, and the other side is connected to the system pressure line) upstream
of the system, this is basically a system self modulating spring.....wheuuuu
mouthful!
And also to hold/capture pressure upstream.

Ken, you have a built in outlet CV on your pumps and Yvon most likely does to,
and in my opinion you should keep the CVs in question even though the system
will most likely work satisfactorily.......The CVs offer an element of safety
by acting as a firewall keeping upstream residual/system pressure feeding the
downstream circuit. A lot of people don't understand that HOSE upstream of a
circuit is an accumulator which acts as a pump.....The other bonus is
redundancy, pumps built in CVs have a tendency to fail by mis-seating, debris
enlodgement especially plastic pumps, due to the nature of turbulence. these
two (2) reasons alone are worth the puny extra weight and room they occupy.

                                                       Butch

 
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