A microfluidic control apparatus and operating method thereof. The exhaust heat recovery apparatus makes it possible to effectively use surplus motive power produced by an exhaust heat recovery unit. Thus, hot molten metal just after poured into the pool does not instantly reach the nip along the side weirs, and molten metal decreases in temperature with lapse of time after the pouring streams into the nip as the rolls are rotated. Sensed acoustic pressure signals and sensed strain measurements are compared to each other and to stored profiles to detect and locate leaks. A projecting element projects from the assembly flange.