The correct choice of packing or mechanical seals for rotating equipment is based on important system parameters that lie above the cost issues. Pay attention to the following considerations, if you are responsible for selecting these components. Correct application of these bases can increase the service life, reliability and operation of your technological and machinery equipment.
Any part of the rotary equipment (including pumps, agitators, boilers, coolers, etc.) that needs to be sealed sometimes will need periodic replacement of spare parts, due to the properties of the system itself. Do not think that the packing or mechanical seal will be the weakest link, or just a one-time piece. For maximum benefit on the cost-to-wear ratio, consider them as part of a regular investment, making sure that this part is synchronized with the main repair schedule for the rotating equipment. From MPF Products Inc you will have the best of the lot.
The use of packing, rather than mechanical seals has some noticeable advantages. As a rule, packing is easier to install. It is more budgetary than the mechanical seal and, usually, less demanding to axial shaft displacements. However, since the sealing characteristics of the packing are not perfect, small leakages of process fluid should be expected. If such leaks are permissible and properly disposed of, the packing is a very good choice for the equipment of your system.
The three most common packing materials are graphite fibers, carbon fiber and Teflon (PTFE). Despite the fact that the terms graphite and carbon fibers are often incorrectly replaced, the packing of carbon fibers is less expensive and can work longer in abrasive environments. The packing made of graphite fibers is smoother. Therefore it has less frictional force, which contributes to better lubricity and heat removal. That’s why at high shaft speeds, graphite packing is usually better than carbon.
Mechanical seals are preferable to wicker packing for some functional and economic reasons. Padding is more prone to leaks. Understand that one drop of process fluid leaks per second, per day is poured into the amount of liquid, more than 1 gallon. In most processes, government regulation has tightened the norms for these types of emissions.
In addition, safety and cost issues are associated with leakage of liquids. Above this, a mechanical seal with a lower coefficient of friction usually consumes less energy than packing. When properly installed, mechanical seals generally do not need to be adjusted or replaced as often as the packing requires. In general, mechanical seals work at higher requirements than oil seals, without replacement, which is directly related to an increase in the time between maintenance. The longer the compaction serves, the better the return on long-term investments. The correct choice of mechanical seal consists of three steps: the initial design, the start of the system equipment, and the current evaluation.