When a mechanical seal is used to seal a rotating pump shaft,it can be called a pump shaft mechanical seal or a mechanical shaft seal.A mechanical seal is composed of a carbon,silicon carbide,or tungsten carbide seal face and a ceramic, silicon carbide or tungsten carbide mating ring,it is also called an end-face mechancial seal.A mechanical seal required in a water pump is also called a water pump seal or a water pump mechanical seal. All the water pumps need mechanical seals and the mechanical seals assembled in water pumps can be called  water pump seals or water pump mechanical seals. Dyseals is specialized in manufacturing mechanical seals for water pump for 30 years.Thousands of types of mechanical seals are available from Dyseals.