how to choose the coupling

My company pump product use couplings mainly have three forms: claw type couplings and diaphragm coupling and hydraulic coupling device. 1, claw type coupling for iron, the material usually simple structure, convenient installation, the price is cheap, often used for small power (45kW below) and not too important occasions, including elastic block (generally between for rubber material) more easily damaged. Our company is generally use less.
2、2, the diaphragm coupling usually adopts a group of thickness thin metal spring films, made into any shape, bolts respectively with the master-slave shaft coupling could the two and a half, also called metal blade coupling. Its advantage is not to need lubricating and maintenance, high temperature resistant, fight no neutral good, high reliability, transmission torque. Our company is mainly the diaphragm couplings. At present, the company's independent brand of diaphragm coupling has reached the domestic first-class standard.
3, hydraulic coupling device is through working liquid in pump wheels and the energy conversion between turbine has transfer power (torque) role, hydraulic coupling implement have overload protection and stepless speed regulation function, use commonly in high-power or conditions need to regular change of big pump. As my company's SM series pump used in power plant when the piping cycle with hydraulic coupling ware, usually for hydraulic coupling is not my company product must pay attention to the power loss, when its transmission efficiency is commonly 96% ~ 97%, such as long time continuous operation and hydraulic coupling editor of working liquid cooling usually requires external cooler. The whole matching price is more expensive.