In the past few years, there has been incredible development in the pump packing technology. While materials formerly used were the simple asbestos type, more complex, high-tech ones are used today. One of the glaring evidence of application of the latest technology is in Durco pumps where the packing is done with an eye on the application needs.
In most rotary and centrifugal pumps, a sealing system aimed at preventing fluid leakage and protection against the outer environment is needed. In some cases, more advanced mechanical seals are put into use. In others, however, braided materials are applied around the shaft.
Modern machines used for braiding utilize advanced technology for packing, coming up with various designs in inter-braiding. They can either be diagonally-braided or cross-braided. In the end, the manufacturer can determine the density of the packing in accordance with the requirements. Owing to the technology, the packing is not likely to go loose during operation.
One of the most notable contributors to increased efficiency of packing is the development of filaments and synthetic fibers. Today, there is a variety of materials used in different applications. Due to their high resistance to negative effects of heat and chemicals, carbon filaments and polytetrafluoroethylene (PTFE) are the most popular.
Carbon-fluorine bonds in PTFE equip it with chemical inertness. It is, therefore, ideal for packing pumps used for almost all gases and fluids including highly corrosive acids and alkalis. In addition, it helps in greatly reducing wearing off of shafts and stems as well as cutting down on the energy used to power the machinery.
With the development of the pump packing technology comes the introduction of more efficiency lubricants which fill the space between the inter-braids. They can be applied in three stages: before braiding, in the actual braiding process, or after braiding. Colloidal PTFE in an aqueous dispersion is a favorite since it modifies the fiber qualities and even brings up others.
Keep in mind that lubricants help reduce friction when starting-up or breaking-in and can be obtained in any type or form. They include solid, liquid, natural and synthetic. However, the necessary measures should be taken in ensuring that they are compatible with the kind of application in packing.
While most of the pump packing in use today leaves no room for leakage, applications are becoming more complex by the day. In some cases, more than one pump packing type is needed especially where soft packing is required or when there is a need to bar abrasive material from getting into the stuffing box. To sum it up, pump packing engineers are working round the clock in a bid to satisfy the increasing demands in the industry, especially in regard to efficiency and compliance to environmental regulations.