A vaporizer filling system includes a filler assembly, a sump, and a valve. The valve controls fluid communication into the sump. A retaining device retains the valve in an open position. A delay is connected to the retaining device. The delay controls the operation of the retaining device in order to retain the valve in the open position until the delay detects a release condition. The delay then controls the retaining device to release the valve. A method of filling a vaporizer includes engaging a bottle of liquid anesthetic agent with a filler assembly. The bottle and the filler assembly are moved from a first position to a second position. The bottle and filling assembly are locked in the second position with a retaining device. Then the retaining device is released and the bottle and filler assembly are returned to the first position.