Correct selection of mechanical seal is a key to prevent pump leakage

In recent years, separate seal has become another important additional features in the outer seal. Separate seal is a complete set of assembly, installed between the stuffing box and the bearing sleeve, in this design, when the seal need to be replaced, do not need to remove the pump every time. This type of seal combination to explore other design standard is gradually development. Because the design is easy to replace the seal, therefore should resist only replace the seal of the temptation, and for the root cause of failure is not to do further investigation, it is very important. Cartridge seal is a collection of all functions in one of the sealing device, its internal includes all of the sealing element, gland, and shaft sleeve. Because this kind of seal does not require any installation measures strictly, greatly simplify the installation program, at the same time, sealing surface and seal elastomer are very good protection, to prevent accidental damage. These advantages also means that reduces the maintenance and replacement of the seal. Almost all cartridge seal can be bought in the market, so can reduce the use of risk factors, but also can save use common seal inherent in the maintenance time. Double seal and liquid blocking device adopts double seal face seal instead of the single seal with a higher degree of leak proof properties. This kind of dual sealing are mostly applied in volatile strong, poisonous, easy to cause cancer, dangerous and poor lubricity of the liquid. Double seal generally there are three kinds of design type, every type of demands between the dual sealing surface using a liquid blocking system, in order to prevent leakage of liquid or gas. Double seal is a kind of low cost which are frequently used in installation of sealing back-to-back way, the rotating seal face in the opposite direction. It often requires a cut off the liquid, the pressure should be higher than the pressure of stuffing box, about 20 psi, so that it can guarantee the internal seal have always been able to get cut off the lubrication of the liquid, but also to ensure that the sealing surface reaches a certain sealing pressure. In structure more complex type sealing face to face, between the rotating seal face is arranged face to face, they are often in the same static sealing surface on the opposite direction of movement. This kind of seal cut off can adopt high pressure liquid systems, low voltage blocking liquid system may be adopted. The third design type seal USES a serial type arrangement, namely both rotating seal face away from the impeller, the same direction. Cut off the seal liquid pressure generally below the pump pressure. In fact is equivalent to two seal, two-stage step-down joint working device. All the various types of dual sealing device needs to be cut off the liquid system. They generally belongs to the outside of the closed loop system, its internal liquids are generally used by different, but it must match the process flow of the liquid. The system includes a reservoir, its location should be close to the seal. The design of these systems range is very large. Some system USES a pump in the sealing ring, while the other system USES the thermal siphon effect principle. The liquids in the reservoir often adopt the method of aided heating or cooling. In addition, you can add a warning device, liquid remind staff timely replacement. According to the nature of the sealed fluid barrier fluid system can be used below or above the packing box of work pressure. In order to make the whole driving operation process to achieve the goal of zero leakage, seal industry has also developed gases trap seal, this kind of seal use the kind of inert gas such as nitrogen to replace the liquid barrier system. In gases trap the double seals, if the sealing surface of internal fault occurs, the leak is inert gas, and its internal fluids from leaking, so as to not cause environmental pollution. Whether using liquid or gas, blocking system must be suitable for the specific seal is used, and once the sealing surface inside any fault, should be able to immediately identify alarm, so that they can take appropriate action in a timely manner.