Abstract: This invention relates to a security system aimed at closing and locking a cover of an opening of a tank trailer to avoid any tampering of its content and to prove that the content of the tank has not been tampered. The security system comprises a locking member movable between a lock position to prevent the opening of the cover, and an unlock position to allow the opening of the cover. The invention also comprises an actuating device mounted to the tank trailer operatively connected to the locking member for moving it between the lock and the unlock positions. A sealing mechanism engages the actuating device when the locking member is in the lock position to prevent any movement of the locking member. The sealing mechanism comprises a breakable indicator which is broken upon disengagement from the actuating device, thereby indicating that the openable cover has been tampered with.

Abstract: The fill valve is responsive to liquid level by passing vented vapor through serial orifices. The inlet flow is stopped by shifting a valve spool which is responsive to the pressure between the orifices. A pressure booster adjacent the vent outlet serves to momentarily shut off the outlet when pressure rises in the region of the second orifice to aid in shifting the main valve spool when system pressure is low.

Abstract: The automatic fill-stop valve passes the liquid filling a tank. A level-sensing tube passes vapor until the tank liquid level rises that high, and, thereupon, passes liquid. Serial orifices in the sensing passage produce a valve closing signal when the liquid level reaches the sensing tube to automatically stop the filling of the tank.