While vulcan seals operates its own global mechanical seal coding system, we also incorporate common american coding systems for all standard american mechanical seals to ensure we. The seals are classified as h, m or l according to load, with h and m indicating heavy load and l indicating light load. Pdf principles and design of mechanical face seals. The seal faces are the elements that define the sealing interface. With a lower k value, the safety against thermal overload will increase, but the mechanical seal may also lift off more easily. The abcs of mechanical seal leaks and impact on thermal fluid operations sat d d o seal s r s d primary ring mating ring o gland plate stationary s rotating typical single shaft seal the need to leak mechanical seals.
For operation outside the limits and additional materials consult chesterton mechanical seal engineering. Mechanical seal technology and selection eagleburgmann. A mechanical seal can now be defined as a device which prevents fluid leakage where a rotating shaft extends through a pressurized. There are some advantages that are obvious and easy to understand, and. The seal between the rotating 3 and stationary faces 1. Each of these materials plays an important role in the operation of the seal. The standard also describes the shaft seal designation and material codes to be used. In the late 1920s, a self contained shaft seal was created from oil resistant leather assembled into a metal case. The initial closing force ensures that the seal will function properly from startup. There are many different designs of a mechanical seal to meet specific applications. Bulletin number twentynine selecting mechanical seals what is a mechanical seal. Alox aluminum oxide ceramic, tungsten carbide, silicon carbide, etc.
One must identify the application data or operating conditions to properly select the type of seal and materials of construction to ensure maximum performance from the seal over its lifetime. Fluid seal division dura seal selection guide introduction this dura seal selection guide is a general service guide intended to assist in the selection of materials of construction for the dura seal line of endfaced rotary equipment shaft seals manufactured by flowserve fluid sealing division. Mechanical seals are leakage control devices, which are found on rotating equipment. Fda compliant mechanical seal materials important all wetted materials must be considered. Preferred materials 3 din 24960, june 1980 1 en 12756, dec. Stationary face the mating ring against which the seal face runs. The majority of hvac centrifugal pump applications use water as the heat transfer fluid. 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. European standard en 12756 defines the principal dimensions for the installation of single and multiple mechanical shaft seals into pump housings.
Type designation shaft seals grundfos type designation mechanical shaft seals are classified according to a grundfos type designation based on the design of the shaft seal. 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. The manufacturer listings are alphabetical, refer to pages 7. The shaft seal is exposed to widely varying operating conditions. Sometimes operating conditions change to become quite different from the specific conditions for which the seal was intended. Gras approved materials for our sanitary sealing solutions which include, mechanical. Most important materials the following table shows the codes of the most important materials.
Probably the most widely recognized and also most common mechanical seal used in general service, low pressure applications. Mechanical seals for pumps how mechanical seals work. Mechanical seal materials monday morning minutes by norm hall, july 17, 2017 part 6 of how to pick an hvac centrifugal pump explained the value of internally flushed seals. European standard en 12756 dimensions according to en 12756 european standard en 12756 defines the principal dimensions for the installation of single and multiple mechanical shaft seals into pump housings. Mechanical seals technical manual brenner industrial sales. The stationary part of the seal is fitted to the pump housing with a static seal this may be sealed with an oring or gasket clamped between the stationary portion and the pump housing. Unlike an oring seal, the hydraulic diameter of a bellows seal.
The principle of the mechanical face seal is quite simple. Materials see inside end cover of manual for the material code nominal diameters d 1 and d 10 of the mechanical seal shaftshaft sleeve diameters are always threedigit numbers beneath the stationary seat for types u and b seal face stationary seat secondary seals spring other metal parts except seal cover and shaft sleeve. Grundfos type designation mechanical shaft seals are classified according to a grundfos type designation based on the design of the shaft seal. Table of materials for mechanical seals compared with former designations dd 1 11. This was the firstradial lip seal to be press fitinto an outside diameter od bore. Secondary seals consisting of orings or other suitable gaskets.
Mechanical seals are designed to handle a range of motions and conditions, but they are just one machinery component in a larger system. B seals model h7n can be coupled with different sorts of materials, so in the request the materials the seal is made of must be quoted. Mechanical seals are used in industrial pumps, compressors, and other applications to provide a leakproof seal between component parts. The stationary part of the seal is fitted to the pump housing with a static seal. Automatic adjustment compensates for abnormal shaftend play, runout, primary. Prices are indicative only and may vary by country, with changes to the cost of raw materials. Tungsten carbide is ideal for high pressure applications with little face distortion. A bellows type mechanical seal is similar in overall concept but uses a metal bellows to achieve the flexibility in the design. There are metal parts, a metal spring, a stationary seat, a rotating seat also called the primary ring, and elastomers. Mechanical seal guidelines for wastewater treatment introduction wastewater treatment plants have two basic purposes. The mechanical seal division of the fsa is one of six divisions with a specific product technology focus. One question that our customer service team fields every week concerns the material of construction of seals. Tungsten carbide is a versatile seal face material. The seal ring which rotates with the shaft is called the rotary ring.
As seal technology has advanced, the standard has expanded to incorporate new seal designs, materials, seal selection guidance, and piping plans. Staticdynamic secondary seals the sealing elements must be secured to the rotating shaft and stationary housing of the equipment being sealed. This article will explain what a mechanical seal is and the key design features that make them work. Mechanical seal configuration codes for torishima mechanical seals a number and a code indicate the configuration and materials used in each torishima mechanical seal. Infinity seal carries the best materials for maximum reliability, including compression set, hardness, tensile and tear strength, abrasion resistance, elongation and modulus. They exclude delivery charges and customs duties and do not include additional charges for installation or activation options. The seal between the rotating member and shaft or shaft sleeve 4. Material list for mechanical seals according to en 12756. Our technical staff is available to help you just give us a call.
Most important materials the following table shows the codes of the most important materials, selected on the basis of the grundfos range of products and their fields of application. Our generalpurpose type 21 mechanical seal has become the industry standard for oem designers. One must identify the application data or operating conditions to properly select the type of seal and materials of construction to ensure maximum performance from the seal. A mechanical seal is simply a method of containing fluid within a vessel typically pumps, mixers, etc. Carbon graphite is a selflubricating mechanical seal face material, generally used as a mechanical seal rotating face. Mechanical seals are designed to overcome these drawbacks. A question that comes up often is, why should i use mechanical seals instead of packing when packing is cheaper. The general attitude towards sealing device technology. Seal manufacturers have narrowed the list of available materials through years of successful field experience. Although the faces can be manufactured from a myriad of different materials, one is typically carbon, while the other is usually a hard material. Bulletin number twentynine selecting mechanical seals. Mechanical seals are constructed of a wide range of materials including metals, elastomers, and ceramics. A mechanical seal has 4 main sealing points indicated by orange circles as per figure 3.
The seal between the stationary member 1 and stuffing box face, i. Mechanical shaft seal types and sealing systems grundfos. A mechanical seal is simply a method of containing fluid. Sometimes operating conditions change to become quite different from the specific conditions for which the seal. Mechanical seals explained aesseal component seal division. In fact, nearly all the common seal face materials. Mechanical seals come in a wide range of designs however the most important factor when determining how long a seal is going to last, is deciding on the right seal face materials. In this type of seal often there are no metallic parts in contact with the product or, if there are any, special materials such as hastelloy or titanium are used. First, they duplicate and speed up the purification process that takes. You must consider the environment the seal will be exposed to. The complete cross reference for mechanical face seal replacement how to use this catalogue locate the manufacturer of the equipment. Included in this list is the selection of the materials of construction of the seal. It is also applied into extreme debris mechanical seal. Although the standard is not yet published, the final draft has been prepared and gives us notice of the upcoming requirements.
Above this, other materials for secondary seals are. At utex, we refer to this type as rs1 the assembly shown in the pump is configured with a. Carbon carbon grade fh82z5 aesseal standard supply. Mechanical seals can operate for many years without issue, as long as theyve been properly selected for their application. Oring loaded pistonrod seals in various materials wear rings rod wipers, metal encased and various materials. Global profile seal excellence starts with superior design the power of the flowserve flow solutions division. Seal manufacturers have narrowed the list of available materials. Thinking of making the switch from packing to mechanical seals. Select category couplings packing mechanical seals seal systems bearing isolators filtration systems seal face technology solutions face treatments face technology.
This articles describes some of the commonly used mechanical seal types like cartridge type mechanical seals, balanced type, unbalanced type, conventional, pusher, and nonpusher type of mechanical seals. Type 21 elastomer bellows seals john crane mechanical seals. There are various types and arrangement of the mechanical seals being used for the centrifugal pumps. Unlike an oring seal, the hydraulic diameter of a bellows seal is not a fixed geometric value. In mechanical face seals, the friction between the seal. Service and maintenance mechanical seals basics characteristics accessories materials. The old adage pay me now or pay me later applies to seals. In a liptype mechanical seal, the initial closing force is typically from the deflected polymer of the liptype seal or a garter spring for less resilient materials.
It has combined the aspects of seal design, testing, standardization, and applications to provide the users and oems alike with a common source of information for mechanical seals. The reliability and safety, as well as the total life cycle cost, of mechanical seals. Cartridge mechanical seals gaddis mechanical seals gaddis. Figure 1 shows a typical centrifugal pump, which highlights its constituent parts, including the mechanical seal. 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. Mechanical seals are complicated pieces of equipment, with a wide variety of materials and configurations to choose from, be sure that what you invest in is exactly what you need for your application. The mechanical seal faces are obviously the most critical sealing point of a mechanical seal assembly. What is the best wear face material for my mechanical seal.
Mechanical seals areconstructed of a wide range of materials. Single spring and elastomer bellows mechanical seals. Mechanical seals the shaft seals used in rotating machinery such as pumps, hydraulic. Seal type the mechanical seal shown in the pump photograph is a type 1 mechanical seal. One seal face will be mounted onto and rotating with the shaft. 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. It has superior wear characteristics with a broad chemical resistance. In fact, nearly all the common seal face materials used today were developed during this period. For severe applications, antimony filled carbon can be applied to assist with any mechanical seal face issues. Must be finished in the same manner as the rotary face. The mechanical seal mechanical seals have the purpose of preventing leakage of a fluid liquid or gaseous through the clearance between a shaft and the fluid container.
Mechanical seals consists primarily of a rotary seal face with a driving mechanism which rotates at the same speed as the pump shaft, a stationary seal. A definition is better given after the functions of a seal are described. Monday morning minutes looks at the seal material you should specify. Mechanical seals technical manual industrial bearing s. However with the right design features and face materials, it is possible to. Mechanical seals first in a series by ann attenasio. This facilitates the exchange of shaft seal information between shaft seal suppliers and users. Material code designation example preferred materials 3 din 24960, june 1980 1 en 12756, dec. For the purposes of this discussion, consider that a mechanical seal will outperform common types of packing. Various seal face material and oring can be used for wide range of application. Seals 7 mg1 seal with independent rotation with silicon.
The smaller the gap between the two surfaces, the less leakage. Every centrifugal pump must accommodate a spinning shaft while mechanically maintaining fluid or gas contained in the wet end of the pump. With the use of special material v ring assemblies as secondary seals, the limit can be increased to 650f. The functional categories of a mechanical seal are. We are very experienced with the use of special materials such as vespel, aflas and kalrez, as well as other high performance materials. The ability of a mechanical seal to meet its performance objectives depends upon a wide range of factors involving equipment design, operating conditions, and support systems. A bellows seal avoids the use of a dynamic secondary seal and only requires static secondary sealing. Mechanical seals explained the basics 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. About esp esp offers a suite of products and services that are critical to. Gaddis incorporated mechanical seals solution provider.
Mechanical seal components mechanical seals are simple devices. Make note of materials used for the old seal parts using u. The standard also describes the shaft seal designation and material. 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. To install a seal, the pump would have to be taken offline and disassembled. John crane is an american company, now a subsidiary of smiths group and provider of engineered products and services including mechanical seals, couplings, seal support systems, filtration systems and artificial lift. G1 cartridge seal range drawing for ansi pumps standard bore pdf. Mechanical seals american coding system vulcan seals. Understanding the basics of mechanical seals and how they may be adapted for different application requirements is critical for choosing the best seal. Home about stb lexicon material list for mechanical seals. Introduction to failures failure of the mechanical shaft seal is the most common cause of pump downtime. The secondary sealing elements are often elastomer but sometimes ptfe or other materials may also be used. The most significantdevelopment in the evolution of the radial lip seal happened toward the end of world war ii. Mechanical seal leakage in pumps how much, if at all, mechanical seals do, must or must not leak is a controversial subject for which there are few clear answers.
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