The disclosure of U.S.
patent application Ser. No. 11 / 161,914 including the specification, drawings and abstract is incorporated herein by reference in its entirely. An improved
pilot-operated, “instant-on”, solenoid
isolation valve discloses a new fluid passage
route to save cost of drilling a longitudinal hole within the primary
piston. Also, a new feature of primary
piston assembly with a movable seal
piston having a specific circumferential
surface matching to valve body chamber to
restrict fluid from front side into back side of the primary piston to produce
pressure difference to induce instant valve open when solenoid is energized initially. It also introduces a channel hole in the
flange of the sleeve
assembly as a
communication channel of supply of gas into the chambers of the back side of primary piston
assembly. The
diameter of the channel hole is not critical to determine in this new invent. As long as the size of the hole is smaller than that of the bleed hole, it can maintain
pressure difference between the front side and back side of primary piston during
valve opening operation. In addition, since the
pilot piston and the primary piston assembly operate independently, the travel
stroke of the primary piston assembly is unconstrained by the input electrical power.