DLSW bellows seal small-caliber single-base regulating valve is of bellows seal construction on its upper valve cap which completely eliminates the possibility of process media leaking outward from motion clearance of the valve rod. This is one of distinguished characteristics of the bellows seal valve. For the bellows element itself will deform and obviously resist ageing, such regulating valve may totally overcome the weakness such as stuffing ageing and temperature sensitivity commonly owned by stuffing seal valves. For another reason, the bellows stuffing and dual seal structure ensures favorable safety and reliability. Therefore, it is widely applied in auto control systems using rare media of severe toxicity and strong corrosion and radiation . The regulating valve is provided with multi-spring diaphragm actuator with compact conformation and big output force.