Singleacting mechanical seals are designed with two seal rings with one interface and without any seal liquid chamber. The proper selection of a mechanical seal can be made only if the full operating conditions are known. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis. Linkage this is the function of a part or organ which joins pieces of an assembly together. Introduction to failures failure of the mechanical shaft seal is the most common cause of pump downtime.
A bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts. This role was played by water or mercury in the first mechanical pumps but oil. This is commonly seen in centrifugal pumps although this challenge also exists in other equipment such as agitators, turbines, compressors, centrifuges, and blowers. Apr 14, 2014 where do we need seals source mechanical seals try to solve an age old problem of preventing pumped fluid from leaking into the environment. Fluid coupling main parts, principle, working and application june 22, 2017 december 26, 2018 pankaj mishra 4 comments automobile fluid coupling is also known as hydraulic coupling is. The elastic components of a mechanical seal spring or bellow, gaskets are. Summary of basic operating principles of liquid lubricated mechanical seals. All mechanical seals are constructed of three basic sets of parts as shown below. Mechanical seals are used on the shafts of centrifugal pumps and screw pumps, where the input shafts have to exit the pressure chamber. A few basic components and principles in mechanical seal design contribute to a working seal at the interface of the rotating shaft and stationary pumpmixer sealchamber housing. Packing is a material in the form of rings or threads which is placed in the stuffing box and makes a seal. Sealing systems for pumpssealing systems for pumps part i presented by. The main parts of the mechanical seals are please refer the figure above. Email this page download pdf download pdf printable page replacement seals for teel pump mechanical seals products.
Essential requirements for proper operation of a mechanical seal. Steam turbine basic parts mechanical engineering site. Rotary bearings hold rotating components such as shafts or axles within mechanical systems, and transfer axial and radial loads from the source of the load to the structure supporting it. Wherever a rotating shaft moves fluid, mechanical seals play a key role in sealing process fluids in, keeping contaminants out, or both. For the purposes of this discussion, consider that a mechanical seal will outperform common types of packing. Only parts supplied by flowserve should be used to repair a seal. Our collection of mechanical seals is supported by strong aftermarket services, and provides users with safety and environmental benefits. The obvious function is that of a check valve to prevent liquid under pressure from leaking out of the pump, or from drawing air into the pump when under vacuum conditions. John crane is an american company, now a subsidiary of smiths group and provider of engineered products and services including mechanical seals, couplings, hydrodynamic bearings, seal support systems, filtration systems and artificial lift.
Sealing systems for pumpssealing systems for pumps part i. This video was made using our mechanical seal basics training software which covers a large range of seal types like pusher seals, nonpusher seals, cartridge seals, split seals, double seals. Dynamic seals used for sealing fluid between parts that move in relation with each other application centrifugal pump gland, valve gland, bearing housing turbinecompressor inter stage and end sealing reciprocating compressors cylinder sealing types gland packings mechanical contact seals labyrinth seal. Installation instructions experience in motion cartridge seals. The remaining components are referred to as hardware. Rather than two flat rings, the sealing interface is a polymer material deflected against a hard material. These are the reasons why we planned a class about mechanical seals. The klozure mechanical seal technical manual is designed to facilitate product. In a lipseal type mechanical seal, a thin film of sealed fluid also lubricates the sealing interface. Before examining how mechanical seals function it is important to understand other methods of forming this seal. Figure 1 above shows a typical centrifugal pump, which highlights its constituent parts, including the mechanical seal. Their main job is to prevent the pumped product from leaking into the environment and are manufactured as single or double seals. Instead, the lubricating liquid will vaporize as it crosses the seal faces. One part of the seal, either to static or rotary portion, is always resiliently mounted and spring loaded to accommodate any small shaft deflections, shaft movement due to bearing tolerances and outofperpendicular alignment due to manufacturing tolerances.
To install a seal, the pump would have to be taken offline and disassembled. The elasticity of the bellows design enables a more robust operation. The initial closing force ensures that the seal will function properly from startup. Although somewhat simplified there are all types of service variations and designs, some of which may contradict this description, the above can be considered a general description of how most rotary pumps function. The shaft seal is exposed to widely varying operating conditions. The basic components in a mechanical seals include the following 1. Mechanical seals of conventional design and material can be selected to function at pressures up to 200 atmosphere, at speeds up to 50,000 rpm and with a temperature ranging from 200 deg c to 650 deg c. Mechanical seal basics and seal selection process training.
Years ago, most pump shafts were sealed using rings of soft packing, compressed by a packing gland, but this type of shaft seal. This article will explain what a mechanical seal is and the key design features that make them work. This video takes the viewer through the process of dismantling a pump, inspecting the real components, fitting the mechanical seal and assembling the pump ready for operation. Mechanical shaft seal types and sealing systems grundfos. Flowserve has been trusted for more than 80 years to design, manufacture and distribute mechanical seals, sealing systems and parts to customers worldwide. Secondary seals perform the function of sealing between internal seal elements as well as sealing between the mechanical seal and the pump. A mechanical seal consists of 2 principle components. Identification of the exact liquid to be handled is the first step in seal selection. Like packing, the mechanical seal faces must also be lubricated. Simple mechanical seals offered an alternative to fluid leakage.
A mechanical seal is simply a method of containing fluid within a vessel typically pumps, mixers, etc. With a lower k value, the safety against thermal overload will increase, but the mechanical seal may also lift off more easily. Mechanical seals first in a series by ann attenasio. Centrifugal pump seals mechanical seal installation youtube. Our components are designed to provide performance and service life equal to or better than the oe part when properly installed and properly applied. As mechanical seals can be used to seal a myriad of different. The following members of the mechanical seal division sponsor this sealing sense. One part of the seal, either to static or rotary portion, is always resiliently mounted and spring loaded to. Mechanical seals often have one face of a suitable solid lubricant such that the seal can still operate for a period without the fluid film. Unlike an oring seal, the hydraulic diameter of a bellows seal. Because mechanical shaft seal failures are the number one cause of pump downtime, we decided to dedicate this column to mechanical seal basics.
The manufacturer listings are alphabetical, refer to pages 7. To order replacement parts, refer to the part code and bm number. When pump suction is under vacuum pump take suction from condenser, external leakage is possible or when the working fluid is excessively hot to provide satisfactory cooling and lubrication to the packing then stuffing box not used. Mechanical seals vary in design, performance, and cost. Shelby scottshelby scott western region john crane incjohn crane, inc. Mechanical face seal replacement how to use this catalogue locate the manufacturer of the equipment. Dec 09, 2015 this video takes the viewer through the process of dismantling a pump, inspecting the real components, fitting the mechanical seal and assembling the pump ready for operation. Increasingly strict environmental standards and harsher operating conditions have made pump sealing. The wet end of the pump includes those parts that dictate the hydraulic performance of pump. This type of mechanical seal has therefore to be operated either under dry conditions or must be lubricated and cooled by the liquid product. Other metal parts except seal cover and shaft sleeve. The mechanical end includes those parts that support the impeller within the casing, seal the casing where the shaft passes through it and enable rotation the means by which the wet end creates flow and pressure. The seal ring which rotates with the shaft is called the rotary ring. Where do we need seals source mechanical seals try to solve an age old problem of preventing pumped fluid from leaking into the environment.
Some of the centrifugal pump parts play an important role in the centrifugal pump safe operation. A definition is better given after the functions of a seal are described. Bulletin number twentynine selecting mechanical seals. Most secondary seals are static meaning that there is no relative motion between the sealed com.
Several factors play a role in the selection of a mechanical seal, the mechanical seal type, the materials used, and the manner in which a mechanical seal will be operated. Mechanical seals are simply another means of controlling leakage of a process where other means are deemed to be less capable of performing the task adequately. Special attention must be paid to the elastomer components of the shaft seal. These mechanical seal are a result of two decades of experience in design, manufacture and operation of seals. The main parts of a centrifugal pump intro to pumps. Mechanical seals are leakage control devices, which are found on rotating equipment such as pumps and mixers to prevent the leakage of liquids and gases from escaping into the environment. The obvious function is that of a check valve to prevent liquid under pressure from.
When the sealing is achieved by means of packing, the chamber is referred to as a stuffing box. Two identical pairs of seal rings in a backtoback arrangement. Pumpnseal australia is an australian owned and operated company established in 2000. These seal are best suitable for application involving abrasive, corrosive and viscous fluids. The elastic components of a mechanical seal spring or bellow, gaskets are of paramount importance for good performance. The functional categories of a mechanical seal are. In end or rotatingface mechanical seal designs, the initial closing force is provided by a spring component, which can be a single coil spring, multiple coil springs, a deflected bellows unit elastomer or metal, or formed or flat springs. An internal combustion engine is the engine in which combustion burning of fuel takes place inside the. Ideal mechanical seal for applications in the medium pressure range up to 40 bar abs. The chapter describes mechanical shaft seals used in grundfos pumps as examples of the variety of shaft. Mechanical seal technology and selection eagleburgmann. Metal parts must be corrosion resistant, usually plated steel, bronze, stainless steel, or hastelloy. Pumpnseal pumps mechanical seals pumpnseal australia. The fluid in the pump and seal area and a few facts about the leakage and wear behavior of contacting mechanical seals.
Apr 24, 2011 this video was made using our mechanical seal basics training software which covers a large range of seal types like pusher seals, nonpusher seals, cartridge seals, split seals, double seals. In addition, fluidol offers nonstandard shapes and sizes as well. There are many different designs of a mechanical seal to meet specific applications. John crane is an american company, now a subsidiary of smiths group and provider of engineered products and services including mechanical seals, couplings, hydrodynamic bearings, seal support. Both the seal chamber and the stuffing box have the primary function. Sometimes operating conditions change to become quite different from the specific conditions for which the seal was intended. Seal basics a mechanical seal is a device used to seal the interface between a rotating shaft and a stationary housing figure 1. Nov 23, 2006 the function of a mechanical seal is to seal the opening where the shaft enters the pump, preventing fluid leakage.
Both the seal chamber and the stuffing box have the primary function of protecting the pump against leakage at the point where the shaft. This material could be a hardened, coated or plated metal, ceramic, or carbide face or sleeve. A few basic components and principles in mechanical seal design contribute to a working seal at the interface of the rotating shaft and stationary pumpmixer sealchamber. Mechanical seals technical manual brenner industrial sales. Bulletin number twentynine selecting mechanical seals what is a mechanical seal. In order for mechanical seals perform extended time periods with low surfaces friction, is necessary good maintenance monitoring for hydrodynamic lubrication. The mechanical seal acts as a check valve and a slider bearing. Seal parts identification drawing codes 3 head type reference page 4. Ic engine major parts and its function, materials,images,manufacturing method. Packing although mechanical seals had been around for many decades, by 1955 industry had converted only a small percentage of pumps from packing to mechanical seals.
With proper application and design however, the leakage is so minute that actual droplets of liquid are not detected. Use of the modular design opens up many different extension options. Parts or complete mechanical seals that have been dropped or otherwise have been. Years ago, most pump shafts were sealed using rings of soft packing, compressed by a packing gland, but this type of shaft seal required a fair amount of leakage just to lubricate the packing and keep. In end or rotatingface mechanical seal designs, the initial closing force is provided by a spring component, which can be a single coil spring, multiple coil back to basics. Evolution of double blockandbleed valves an alternative to the original twovalve system, the general valve twin seal plug valve has just one doubleseated bubbletight valve the upstream and downstream seals provide the same function.
Unlike an oring seal, the hydraulic diameter of a bellows seal is not a fixed geometric value. The importance and basic functions of mechanical seals. As part of their educational mission, they develop publications such as the mechanical seal handbook, a primer intended to complement the more detailed manufacturers documents produced by the member companies. The difference between single and double mechanical seals. Oem names, brands, model or part numbers are for identification purposes only. Instead, the lubricating liquid will vaporize as it crosses the seal faces and the leakage is a gas or vapor. The mechanical seal itself is the interface between the static and rotary portions of the seal. Jun 30, 20 because mechanical shaft seal failures are the number one cause of pump downtime, we decided to dedicate this column to mechanical seal basics.
Mechanical seals are devices that seal machines between rotating parts shafts and stationary parts pump housing and are an integral part to the pump. Vessel shaft mechanical seal for arresting leakage liquid agitator blade 23. Search by the oem part number using the search function at the top of the page or use search by specification. When noise is generated from the mechanical shaft seal, some parts of the seal vibrate. Review different pump types commonly used understand the difference between centrifugal pumps and positive displacement pumps understand the working principle of the tuthill. Mechanical seals are used in industrial pumps, compressors, and other applications to provide a leakproof seal between component parts. Sep 21, 2015 mechanical seals the basic design of a mechanical seal cosists of following elements.
The rotating and the fixed faces are the two vital parts of the mechanical seals. Style 04 component mechanical stationary seat seal fluidol offers a full range of stationary seats, including all standard designs, sizes and materials. Introduction the mechanical seal acts as a check valve and a slider bearing. General installation and operating instructions for. The chapter describes mechanical shaft seals used in grundfos pumps as examples of the. Basic mechanical functions all parts or organs that make up a technical object have a mechanical function. The purpose of these designs is, among other things, to control temperature, pressure or flow. The entire product portfolio of systems and components. Originally mechanical seals were developed to overcome the negative issues affiliated with packed stuffing boxes. Used in conjunction with the gas coffer dam system, the. A mechanical seal is a method of containing fluid within a vessel pumps, mixers. Before the advent of mechanical seals, pump users relied primarily on rope or braided style packing to achieve a.
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