Abstract:
A magnetic safety valve for installation through a tank wall incorporates a piston movable within a valve body. The valve is held normally-closed by two opposite-pole magnets, one in the inner end of the piston, and one in the valve body. A vacuum produced by a pump connected to the valve will act upon the outer end of the piston, producing a force tending to move the piston outward. When the vacuum-induced outward force on the piston exceeds the attractive force between the two magnets, it pulls the piston outward and away from the valve body magnet, unseating the inner end of the piston from the valve body, and allowing outward fluid flow through the valve. A second valve seat may be provided for engagement with an outer portion of the piston to prevent uncontrolled fluid flow out of the tank in the event of valve damage.
Abstract:
In a method for manufacturing a plastic-lined metal tank, a permanent fitting having a flow passage is secured within an opening in the tank wall. A lower portion of the fitting has fitting anchorage means and protrudes into the tank interior. A temporary plug is disposed within the fitting's flow passage. A plastic material is introduced into the tank, which is then multi-axially rotated by a rotational molding apparatus while introducing heat to melt the plastic material. The molten plastic is deposited to form a liner over the inner surface of the tank shell and over exposed surfaces of the fitting and temporary plug. After the plastic liner has cooled and solidified, the temporary plug is removed from the fitting, and the liner is trimmed as required to allow fluid flow through the fitting's flow passage.