In an SCR apparatus mounted on a vehicle, the concentration of a reducing agent or a precursor thereof contained in an aqueous solution of the reducing agent or the precursor is accurately detected. In the preferred embodiment, the user enters the historical daily maximum and minimum pump run times for the specific pool and the system calculates the required time the pump will run on a given day. The phase of the inverted code sequence is advanced before transmitting as the communication breaking wave and the pilot signal, can appropriately be compensated with the advanced inverted code sequence. Upon setting the setting means to the amount of time, the timing device is activated causing the timing device to count down from the amount of time value to a zero value. In accordance with aspects of the invention, a dispensing assembly dispenses the fusible material and a gas environment surrounding a portion of a seal structure of the dispensing assembly is controlled to regulate an oxidation rate of the fusible material.