going to another small pilot section this is essentially a direct acting relief valve usually with a fairly fine thread
it allows the operator to make adjustments to the maximum system pressure which remember is being controlled over on the main pop it but it allows the operator at a distance to set that mane pressure
so right now our system pressure gauge shows five hundred p s I and that is the setting of the pilot section on the main relief valve so clearly the pilot section on top of the relief valve is controlling system pressure at the moment
but watch what happens as the system pressure passes over seven hundred and fifty p s I as we turn the adjustment on the main pilot section
we no longer have pilot flow moving through that built on bolt on pilot section our pilot flow is now moving out of port x the vent port
out to the operators remote pilot section and at a distance now this remote pilot control is in charge of the setting of the main pop it inside the main relief valve
so in this particular case the operator who is at a distance can now make changes to the system pressure are you watching the system pressure gauge and down we go and back up what do you think will happen if I dial the remote setting the spring here what happens if I had just that to attention above seven hundred and seventy p s I
the main pilot section takes over control again so let me ask you a question are these two pilots sections the remote and the bolt on pilot section at the relief valve are those two pilots sections plumbed in series or
and the other pilot section if it is open has flow back to tank their so they are plumbed in parallel and this is simply the case of path of least resistance