Flexible hose passive shut down system

A method of interconnecting a portable tank with another tank and transmitting hazardous fluids between the portable tank and the another tank, the method comprising:

• providing a back housing containing a valve member and a seating surface for closing off flow through the back check housing;
• providing a flexible hose extending downstream from the back check housing;
• providing a piston movable between a locked position and an unlocked position, the piston being responsive to pressure in a sensing line extending downstream from the valve member;
• and
• connecting the valve member and the piston such that the valve member is in the open flow position when the piston is in the locked position, and low fluid pressure within the sensing line allows the piston to move to the unlocked position to release the valve member to the closed flow position.

A flexible hose assembly interconnecting a portable tank with another tank and transmitting hazardous fluids between the portable tank and the another tank, the flexible hose assembly comprising:

• a back check housing containing a valve member and a seating surface for closing off flow through the back check housing;
• a piston interconnected with the back check housing and axially movable between a locked position and an unlocked position, the piston and valve member being connected such that the valve member is in the open flow position when the piston is in the locked position, and the valve member is allowed to move to the closed flow position against the seat when the piston is in the unlocked position;
• a sensing line extending downstream from the valve member for transmitting fluid pressure to the piston to move the piston to the unlocked position;
• and
• a biasing member for biasing at least one of the piston and the valve member to the unlocked position.