end face mechanical seal manufacturer

The exclusive face pattern contains special shallow grooves to provide both hydrostatic and hydrodynamic lift of the seal faces resulting in reduced energy consumption during ...

Single mechanical seal, balanced, independent of the direction of rotation with multi-spring configuration. The MTM180 Series represents the mechanical seal with the ...

... dual unpressurized arrangement, without outboard seals also incorporating the same non-pusher technology, the seal can be configured to suit both the operator and pipeline needs.

The AESSEAL® API Type A, B and C single-seal range offers the user an unprecedented range of API engineered sealing solutions to suit all application ...

Metal encased, rubber bellow seals to full DIN24960 (EN12756)L1K compatibility. The Stramek seal face is retained to avoiddamage during seal installation.

... 10T TS 10R Our Mechanical seal model TS10T TS10R can replace John Crane 10R 10T. 10T is integral rotary face ,10R is insert rotary face Operating Limits Pressure: 1.3MPa ...

Mechanical seals are end-face seals that use a pair of faces perpendicular to the rotating shaft (sliding surfaces) to seal. The sealing faces, smoothly finished with high accuracy, enable long-term maintenance-free usage.

Mechanical seals manufactured by Eagle Industry Co., Ltd. are products achieving excellent performance and low running costs that feature highly accurately finished flat sealing faces, enabling long-term maintenance-free usage.

Mechanical seals withstand usage in various applications in different pumps for automobiles, households, civil engineering and construction, and in processing and chemical fields such as petrochemicals, nuclear energy, and space development, and have a wide range of use.

Mechanical shaft seals are the best way to seal a pump. Face seals prevent leakage better than packing and if selected properly will last longer. Mechanical seals used in clean well lubricated applications can last 20 years. Seals can be constructed in single or double configurations, allowing only a vapor to escape.

Shaft seals are engineered forshaft-sealingapplications to serve Original Equipment Manufacturers or field replacement requirements, our seals will hold up to difficult applications. We can also asset in theconversion from braided pump packing to a mechanical seal.

American Seal and Packing delivers a full range of rotary mechanical seals configurations and component materials - to handle pump service requirements in a wide range of industries. . When you Specify a AS&P seals you have the advantage of proven reliability. When we need engineered seals for difficult applications we utilize the engineering departments of some of the top mechanical seal manufacturersin the world.

Validated by certificates from leading institutes and existing customers – make GOETZE® the first choice for face seals. GOETZE® manufactures their face seals completely in-house, from the casting to the finish grinding. State-of-the-art test rigs and optimized quality processes ensure the high quality of GOETZE® products. The materials, elastomer compositions and designs are perfectly adapted to the applications. Starting with an outer diameter of 50 millimeters, the dimensions reach up to 1,425 millimeters, a world record. In fact, the world’s largest cast face seals in open-castors, large-scale bogies and other large-scale machines bear the GOETZE® name.

Elements d1 and a1 bear and slide on each other, creating a seal at their interface. One group of parts is connected to the rotating shaft and the other to the machine"s case. The spring keeps the elements tight against each other, maintaining the seal and allowing for wear.

An end-face mechanical seal, or a mechanical end-face seal, also referred to as a mechanical face seal but usually simply as a mechanical seal, is a type of seal used in rotating equipment, such as pumps, mixers, blowers, and compressors. When a pump operates, the liquid could leak out of the pump between the rotating shaft and the stationary pump casing. Since the shaft rotates, preventing this leakage can be difficult. Earlier pump models used mechanical packing (otherwise known as gland packing) to seal the shaft. Since World War II, mechanical seals have replaced packing in many applications.

An end-face mechanical seal uses both rigid and flexible elements that maintain contact at a sealing interface and slide on each other, allowing a rotating element to pass through a sealed case. The elements are both hydraulically and mechanically loaded with a spring or other device to maintain contact. For similar designs using flexible elements, see radial shaft seal (or "lip seal") and O-ring.

An end-face mechanical seal consists of rotating and stationary components which are tightly pressed together using both mechanical and hydraulic forces. Even though these components are tightly pressed together, a small amount of leakage occurs through a clearance that is related to the surface roughness.

The seal ring and mating ring are sometimes referred to as the primary sealing surfaces. The primary sealing surfaces are the heart of the end-face mechanical seal. A common material combination for the primary sealing surfaces is a hard material, such as silicon carbide, ceramic or tungsten carbide and a softer material, such as carbon. Many other materials can be used depending on pressure, temperature and the chemical properties of the liquid being sealed. The seal ring and mating ring are in intimate contact, one ring rotates with the shaft and the other ring is stationary. Either ring may be rotating or stationary. Also, either ring may be made of hard or soft material. These two rings are machined using a process called lapping in order to obtain the necessary degree of surface finish and flatness. The seal ring is flexible in the axial direction; the mating ring is not flexible.

By definition, the seal ring is the axially flexible member of the end-face mechanical seal. The design of the seal ring must allow for minimizing distortion and maximizing heat transfer while considering the secondary sealing element, drive mechanism, spring and ease of assembly. Many seal rings contain the seal face diameters, although this is not a requirement of the primary ring. The seal ring always contains the balance diameter.

The shape of the seal ring may vary considerably according to the incorporation of various design features. In fact, the shape of the seal ring is often the most distinct identifying characteristic of a seal.

By definition, the mating ring is the non-flexible member of the mechanical seal. The design of the mating ring must allow for minimizing distortion and maximizing heat transfer while considering ease of assembly and the static secondary sealing element. The mating ring can contain the seal face diameters, although this is not a requirement of the mating ring. To minimize primary ring motion, the mating ring must be mounted solidly and should form a perpendicular plane for the primary ring to run against. Like seal rings, mating rings are available in many different shapes.

Secondary sealing elements are gaskets which provide sealing between the seal ring and shaft (or housing) and the mating ring and shaft (or housing). Typical secondary sealing elements include O-rings, wedges or rubber diaphragms. The secondary sealing elements (there may be a number of them) are not rotating relative to one another. The secondary sealing element for the mating ring is always static axially (although it may be rotating). Secondary sealing elements for the seal ring are described as being either pusher or non-pusher in the axial direction. The term pusher is applied to secondary seals that must be pushed back and forth by the movement of the shaft or primary ring whereas non-pusher secondary seals are static and associated with bellows seal rings.

In order to keep the primary sealing surfaces in intimate contact, an actuating force is required. This actuating force is provided by a spring. In conjunction with the spring, axial forces may also be provided by the pressure of the sealed fluid acting on the seal ring. Many different types of springs are used in mechanical seals: single spring, multiple springs, wave springs, and metal bellows.

The term "hardware" is used to describe various devices which hold the other components together in the desired relationship. For example, a retainer might be used to package the seal ring, secondary sealing element and springs into a single unit. Another example of hardware is the drive mechanism which is necessary to prevent axial and rotational slippage of the seal on the shaft.

There are a number of different ways in which “seals” may be classified. Sometimes a reference to a “seal” may be to a sealing system whereas other times the reference is to a device such as a gasket, an O-ring, compression packing, etc. In this article, the reference is to an end-face mechanical seal.

One such method of classification considers design features or the configuration in which these features may be used. Classification by Design accounts for the details and features incorporated into a single seal ring/mating ring pair. Classification by Configuration includes the orientation and combination of the seal ring/mating ring pair.

In general, design features are not completely independent; that is, emphasis of a particular feature may also influence other features. For example, selection of a particular secondary sealing element may influence the shape of the seal ring.

The most common seal face design is a plain, flat, smooth surface but there are many special treatments intended for specific applications. The most common objective for the face treatment is to reduce the magnitude of mechanical contact. In general, face treatments provide a means of modifying the pressure distribution between the seal faces through hydrostatic or hydrodynamic topography. Seal face topography refers to the three dimensional aspects of the seal face surface.

In addition to the spring force, the seal faces are pushed together through pressure acting hydrostatically on the geometry of the seal. The ratio of the geometric area tending to close the seal faces to the area tending to open the seal faces is called the balance ratio.

Pusher seals employ a dynamic secondary sealing element (typically an O-ring) which moves axially with the seal ring. Bellows seals employ a static secondary seal (such as an O-ring, high temperature graphite packing, or elastomeric bellows and axial movement is accommodated by contraction or expansion of the bellows.

In addition to retaining the other components, the seal hardware includes the drive mechanism which is necessary to prevent axial and rotational slippage of the seal on the shaft. The drive mechanism must withstand the torque produced by the seal faces while also allowing the seal ring to move axially. In addition to torque, the drive mechanism must withstand the axial thrust produced by hydrostatic pressure acting on the components. The various types of drive mechanisms include: dent drive, key drive, set screws, pins, slots, snap rings and many more. Typically, the retainer for the seal ring might include set screws, a dent or slot drive, recesses for the spring and a snap ring to complete the assembly. In contrast, mating ring hardware might be only a pin or slot to prevent rotation. Corrosion is a major consideration when selecting seal hardware.

Both the seal ring and mating must accommodate secondary sealing elements. In some designs, various retainers, sleeves and other components may also include secondary sealing elements. Whereas a simple O-ring might require only a groove for fitting, some secondary sealing elements (for example, packing) might require mechanical compression. Although O-rings are available in many elastomers, sometimes an elastomer might not be compatible with the fluid being sealed or might be considered too expensive. In such cases, a secondary sealing element might be manufactured from perfluoroelastomer and shaped in the form of a wedge, V or U.

Although all end-face mechanical seals must contain the five elements described above, those functional elements may be arranged or oriented in many different ways. Several dimensional and functional standards exist, such as API Standard 682 - Shaft Sealing Systems for Centrifugal and Rotary Pumps, which describes the configurations for used in Oil & Gas applications. Even though the scope of API 682 is somewhat limited, it may be extended to describe end-face mechanical seals in general.

Configuration refers to the number and orientation of the components in the end-face mechanical seal assembly. For example, springs may be rotating or stationary. Single or multiple pairs of sealing faces may be used. For multiple seals, the individual pairs of sealing faces may be similarly oriented or opposed. Containment devices such as bushings may or may not be used as part of the configuration.

The basic components of an end-face mechanical seal may be installed directly onto the shaft but a popular approach is to pre-assemble the components into some sort of package for ease of installation.

Either the seal ring or the mating ring may be the rotating element. Seals with rotating seal rings are said to be "rotating" seals; seals with stationary seal rings are said to be "stationary" seals. Because the springs are always associated with the seal rings, sometimes the distinction is made as "rotating springs" versus "stationary springs". For convenience, rotating seals are used in most equipment; however, stationary seals have some advantages over rotating seals. In small, mass-produced seals for modest services, the entire seal may be placed in a package which minimizes shaft and housing requirements for the equipment. Stationary seals are also used to advantage in large sizes or at high rotational speeds.

When classifying end-face mechanical seals by configuration, the first consideration is whether there is only one set of sealing faces or multiple sets. If multiple sets are used, are the sets configured to be unpressurized or pressurized.

A tandem seal consists of two sets primary sealing surfaces with the space in-between the two seals filled with a compatible low pressure fluid called the buffer fluid. This buffer fluid/space may be monitored to detect performance of the assembly. Unfortunately, the definition of “tandem seal” was often stated in a confusing manner. In particular, a tandem seal was usually described as two seals pointing in the same direction; that is, in a face-to-back orientation. This orientation is not necessary to the function of the configuration and the API chose to use the term Arrangement 2 instead of tandem in the API 682 standard.

A double seal consists of two sets primary sealing surfaces with the space in-between the two seals filled with a compatible pressurized fluid called the barrier fluid. This barrier fluid/space may be monitored to detect performance of the assembly. Unfortunately, the definition of “double seal” was often stated in a confusing manner. In particular, a double seal was usually described as two seals pointing in the opposite direction; that is, in a back-to-back orientation. This orientation is not necessary to the function of the configuration and the API chose to use the term Arrangement 3 instead of double in the API 682 standard.

An end-face mechanical seal generates heat from rubbing and viscous shear and must be cooled to assure good performance and reliable operation. Typically, cooling is provided by circulating fluid around the seal. This fluid, known as a flush, may be the same as the fluid being sealed or an entirely different fluid. The flush may be heated, filtered or otherwise treated to improve the operating environment around the seal. Collectively, the flush and treating systems are known as piping plans. Piping plans for mechanical seals are defined by American Petroleum Institute specification 682 and are given a number. Some piping plans are used for single seals and some only for multiple seals. Some piping plans are intended to provide a means of monitoring the seal. Some sealing systems include more than one piping plan. See the table below for a summary and description of piping plans.

The first commercially successful mechanical seal to be used on centrifugal pumps was probably made by the Cameron Division of the Ingersoll-Rand Company. The Cameron seal was installed in a number of centrifugal pipeline pumps in 1928.

Mechanical seals in the 1930s often used a face combination of hardened steel versus leaded bronze. Carbon-graphite was not widely used as a seal face material until after World War II. Soft packing was used as secondary sealing elements. The O-ring was developed in the 1930s but not used in mechanical seals until after World War II.

In the late 1930s, probably about 1938 or 1939, mechanical seals began to replace packing on automobile water pumps. The famous Jeep of WWII used a rubber bellows seal in the water pump. After WWII, all automobile water pumps used mechanical seals.

In the mid-1940s pump manufacturers such as Ingersoll-Rand, Worthington, Pacific, Byron Jackson, United, Union and others began to make their own mechanical seals. Eventually most of these companies got out of the seal business but the Byron Jackson seal became the Borg-Warner seal (now Flowserve) and the Worthington seal was sold to Chempro (now John Crane - Sealol).

Cartridge seals were used on a regular basis by 1950; this convenient packaging of seal, sleeve and gland was probably developed by C. E. Wiessner of Durametallic about 1942.

By 1954, mechanical seals were used with such regularity in the refining and process industries that the American Petroleum Institute included seal specifications in the first edition of its Standard 610, "Centrifugal Pumps for General Refinery Services".

By 1956, many of the conceptual designs and application guidelines that are in use today had been developed. Commercially available designs included both rotating and stationary flexible elements, balanced and unbalanced hydraulic loading, rubber and metal bellows, and a wide variety of spring designs and types. Secondary sealing elements included O-rings, wedges, U-cups and various packings. Carbon-graphite was widely used as a seal face material; the mating seal face was often cast iron, Ni-resist, 400 series stainless steel, Stellite or aluminum oxide although tungsten carbide was coming into use. Stainless steel was widely used for springs, retainers, sleeves and glands. Single and multiple seal arrangements were used as necessary to accomplish the required performance. In 1957, Sealol introduced the edge welded metal bellows seal. Previously, metal bellows seals had used a formed bellows which was much thicker and stiffer.

In 1959, John C. Copes of Baton Rouge, LA filed for a patent on a split seal and was awarded Patent #3025070 in 1962. In the Copes design, only the faces were split. Copes chose to provide custom split seals which he manufactured himself so very few of his split seals were produced.

The Clean Air Act of 1990 placed limits on fugitive emissions from pumps. Seal manufacturers responded with improved designs and better materials. In October, 1994, the American Petroleum Institute released API Standard 682, "A Shaft Sealing Systems for Centrifugal and Rotary Pumps”. This standard had a major effect on the sealing industry. In addition to providing guidelines for seal selection, API 682 requires qualification testing by the seal manufacturers.

Today, in addition to face patterns such as spiral grooves and waves, materials have been developed that have special surfaces to promote hydrodynamic lift. Lasers can be used to etch microscopic, performance enhancing textures on the surface of the seal face. Piezoelectric materials and electronic controls are being investigated for creating truly controllable seals. The application of specialized seal face patterns, surfaces, and controls is an emerging technology that is developing rapidly and holds great promise for the future.

API Standard 682, Fourth Edition, 2014, “Pumps – Shaft Sealing Systems for Centrifugal and Rotary Pumps,” American Petroleum Institute, Washington D.C.

Schoenherr, K. S., "Design Terminology for Mechanical End Face Seals", Society of Automotive Engineers Transactions, Vol. 74, Paper Number 650301, (1966).

Buck, G. S., Huebner, M. B, Thorp, J. M., and Fernandez, C. L. “Advances in Mechanical Sealing – An Introduction to API-682 Second Edition”, Texas A&M Turbomachinery Symposium, 2003.

Mechanical seals are utilized when sealing between a rotating shaft and a vessel, such as a pump housing. They are made to keep liquids from entering or exiting a container while enabling the shank to move, allowing machinery to run smoothly and without interruption. The application, installation, and operation must be considered to ensure reliability when choosing a mechanical seal.

A mechanical seal consists of two flat faces, one rotating and one stationary, mounted perpendicular to the shaft. The rotation of the rotary seal ring against the stationary seal ring causes a rapid pressure drop across the primary seal interface caused by friction on the liquid molecules between the seal faces. Liquid molecules also act as miniature ball bearings to lubricate and reduce friction, reducing heat and wear.

Cartridge, component, and air are the three most widely utilized types of mechanical seals. The types differ in their design, structure, and distribution of the hydraulic forces on their faces.

A cartridge-mounted, end-face mechanical seal is a self-contained mechanism with sealing components, including a gland, sleeve, and hardware. A cartridge seal enables the manufacturer to preassemble and calibrate the unit. Installation and maintenance are simplified because the manufacturer handles these tasks. Cartridges may be supplied with either one or two seals, depending on the application’s needs.

Component mechanical end-face seals consist of a rotating part and a stationary seal that mount to a gland or housing. Since they are not preset, maintenance and installation are more involved than cartridge seals, and installing them requires skilled professionals who can configure them effectively.

Pneumatic, non-contacting air seals are used to seal rotating shafts. These seals are often used when dry powder or slurry is present. Product loss, emissions, and contamination are avoided by using small amounts of air or inert gas, and this air is restricted to provide positive pressure and an efficient seal.

Stationary primary face.This part is attached to the stationary housing of the pump, mixer, or other apparatus where the rotating shaft travels and is sealed against the moving primary sealing component.

Mechanical loading devices.This mechanism presses primary sealing parts together and closes them. Single, multiple, wave or metal bellows can be used.

Static or dynamic secondary seals.These seals are used when there is motion between surfaces, serving as mechanical protection that adjusts on shaft movement that could harm the seal faces.

Mechanical seals are preferred for most industrial applications, especially by pump manufacturers, as mechanical seals reduce fluid leaks better than other approaches. Among its many benefits includes:

Efficient leakage prevention. Mechanical seals are perfect for procedures involving chemicals such as hydrochloric acid, sulfuric acid, and other hazardous substances.

Component durability. Sleeves and shafts do not wear out quickly. Mechanical seals reduce preventive maintenance if well-installed and can ensure durable seals.

Mercer Gasket & Shim offers a variety of high-performance mechanical seals that provide superior sealing capabilities in even the most demanding environments and conditions. Our practical and durable mechanical seals help reduce operational costs and improve production and system reliability.

Amechanical seal is the most common type of sealing component used on pumps in modern industry. Replacing out packing over the last 50 or so years, they have served to drastically reduce industry emissions, energy usage and downtime globally.

A mechanical seal for pumps can be subdivided into variable options depending on the type/specific application/design components/location and mechanical seal characteristics;

The major advantage of a cartridge seal over a component seal is ease of installation. Incorrect installation is a major cause of seal failure, cartridge seals remove many of the problems associated with seal change-out in the field.

Slurry Seal – mechanical seal engineered to cope with a heavy slurry process – i.e. abrasive, corrosive and viscous. Can handle up to 60% slurrys by weight.

A Pusher Seal is where there is a spring element in the seal (used to maintain contact of the seal faces). Spring types include Belleville, multi-spring, etc. This type of seal requires a dynamic secondary seal.

A gas seal is a double seal where the barrier fluid is a gas – in pumps, this is usually a gas lift-off seal. In a gas lift-off seal the faces are not in contact while the machine is running. They are separated by a thin gas film (flow). If operated correctly they have very low wear.

The above seal types can be combined (though it is not always best to do so i.e. a component gas lift off seal would require very close collaboration between the machine and seal manufacturers to achieve a reliable installation).

There are many other options for mechanical seals, if you have any technical queries on other combinations not listed above,  just contact one of our Mechanical Seal Specialists who will gladly discuss your application.

A mechanical seal flush is a piping set-up on a pump and seal assembly where a flow is induced in the seal chamber in order to improve MTBF of the mechanical seal. It is used to improve cooling, heating, remove solids and increase pressure (in combination with a neck or throat bush).

A mechanical seal quench is a piping set-up where a fluid is piped over the atmospheric side of a seal. It is generally used to prevent precipitation or crystallisation of a product or in some cases to aid cooling.

High Slurry process using Flowserve’s UNCD ® – Ultrananocrystalline diamond  seal face technology. Flowserve UNCD ® coatings offer material properties and performance advancement over all other seal face materials.

Slurry seal design expertise applications which previously required double mechanical seals can now be reliably run by using single mechanical seals, saving costs of barrier fluid systems, the costs of the barrier fluid itself & the associated running costs. This reduces energy usage & carbon footprint.

If you have a technical query around the installation of mechanical seals for pumps or have some concerns around seal failures, why not contact one of our seal specialists below to discuss it in more detail and find out how we can help solve your issues and get your process running again.

Fluid motion systems rely on pumps and valves for regulating flow control inside and outside the system boundary, such as the casing of the pump or valve. A unique challenge in shaft-driven equipment is maintaining a dynamic sealing interface — one that prevents fluid from exiting the system while still allowing rotational motion between the shaft and the system boundary. End face mechanical seals have proven to be an effective way to solve this engineering.

Early pump models created a seal in one of two ways: 1) packing pliable rings around the shaft and compressing them into a seal housing until they contacted the shaft; 2) filling the seal housing with multiple bushings with close clearances over the shaft. Both methods create a sealing flow restriction along the equipment shaft, utilizing the shaft as a key part of the dynamic sealing interface.

With these designs, the amount of flow through the sealing interface — and the potential for process emissions — is proportionate to the size of the sealing interface gap. Since wear occurs as the shaft rotates and rubs inside these stationary radial sealing devices, process emissions are likely to increase as material wears away and expands the sealing interface gap. As a result, radial sealing methods are characterized by inadequate process emissions control and high rates of equipment wear, power consumption and maintenance time requirements.

Increasing concerns about plant efficiency, equipment life and excess process emissions necessitated a reliable sealing solution that did not use the equipment’s shaft for the dynamic sealing interface. The introduction of end face mechanical sealing was the answer to this problem. This method consists of two primary components:

1. A pair of seal rings, one attached to the rotating shaft and one fixed to the stationary body of the equipment, effectively moves the dynamic sealing interface from the equipment shaft surface to the mating face ends of the two rings. This establishes a planar, rather than annular, sealing interface.

2. Secondary sealing elements (i.e., O-rings) are then set to form a seal between the equipment and the seal rings. A spring is also added to push one ring against the other to compensate for face wear.

Together, these components comprise the essential elements of axial-sealing, end face mechanical seals. By significantly reducing the sealing interface area and narrowing the interface gap, end face mechanical seals give operators an effective means to control process emissions.

Another measure of the effectiveness of end face mechanical seals is their ability to be engineered and optimized for specific process applications. Through manipulation of seal ring geometry and the mechanical properties of different seal ring materials, the seal rings and ultimately the sealing interface can be controlled down to 10 microinches (0.25 micrometers) of sealing gap. In comparison, packing and bushing seals operate with a sealing gap in the range of 0.0001–0.010 inches (2.5–250 micrometers). This means that end face mechanical seals operate at a sealing gap 10–100 times narrower, and as such, provide a significant reduction in process emissions.

Continued advancements in end face mechanical seal design — in the areas of construction materials, seal ring tribological pairing, sealing interface topography, and component interface design and control — allow for increased optimization of the sealing interface gap. Modern analytical techniques are leading to the adoption of end face mechanical seal installations in more diverse applications, including: dry gas, ultra-high speeds (>10 000 RPM) and high pressures (>2000 psi or 137.9 bar). This specialization of end face mechanical seals has resulted in sealing solutions capable of minimizing process emissions to parts per million (PPM) levels over years of service — while requiring little to no maintenance of the seal.

Mechanical seals are critical components in centrifugal pump systems. These devices preserve the integrity of the pump systems by preventing fluid leaks and keeping contaminants out. Mechanical seal systems are used on various seal designs to detect leakage, control the seal environment and lubricate secondary seals.

Depending on the pump type and the process variables, there are various mechanical seal types to choose from. Each seal variant has its unique design and characteristics which make it suitable for a specific application. MES has years of experience with industrial mechanical seals and support systems, making us an authority in this area.

Mechanical seal types vary in design, arrangement, and how they disperse the hydraulic forces acting at their faces. The most common seal types include the following:

Balanced mechanical seal arrangements refer to a system where the forces acting at the seal faces are balanced. As a result of the lower face loading, there is more even lubrication of the seal faces and longer seal life. Learn about our mechanical seal lubrication systems today.

Balanced mechanical seals are particularly suited to higher operating pressures, typically above 200 PSIG. They are also a good choice when handling liquids with low lubricity and higher volatility.

Unbalanced mechanical seal types are commonly employed as a more economical option to the more complex balance seal. Unbalanced seals may also exhibit less product leakage due to tighter control of the face film, but as a result can exhibit much lower mean time between failure. Unbalanced seals are not recommended for high pressure or most hydrocarbon applications.

Pusher seals utilize one or multiple springs to maintain seal closing forces. The springs can be in the rotating or stationary element of the mechanical seal. Pusher type seals can provide sealing at very high pressures but have a drawback due to the elastomer under the primary seal face that can be subjected to wear as the face moves along the shaft/sleeve during operation.

Non-pusher seals utilize a metal or elastomeric bellows to maintain seal closing forces. These seals are ideally suited to dirty and high temperature applications. Bellows seals are limited to medium/lower pressure applications.

Conventional seals are typically lower cost and often installed on general service equipment. These seals require higher operator skill to service as they installed as individual components.

Cartridge type mechanical seals incorporate all of the seal elements into a single assembly. This dramatically reduces the potential for assembly error and the time require for seal replacements. Learn more about the difference between cartridge and non-cartridge mechanical seals today.

When deciding on the type of seal system for a centrifugal pump, operators must choose according to their unique application. Failure to select the proper seal type can lead to loss of pump integrity, breakdowns and costly repairs. To avoid these undesirable results, all operators must consider the following factors before deciding.

The amount of pressure exerted at a mechanical seal’s faces has a significant effect on its performance. If a pump is to be operated at low pressures, an unbalanced mechanical seal will be suitable. However, in conditions where higher pressures are anticipated, balanced seals will prove a more reliable solution.

Balanced mechanical seals perform better than their unbalanced counterparts in conditions where the operating temperatures are higher than normal. Heat sensitive components are better preserved in balanced mechanical seals compared to other seal types.

As it goes for all types of machinery, operator safety is the top priority. The use of double mechanical seals in centrifugal pumps provides additional protection as they have increased sealing capacity and are generally more reliable.

An end-face mechanical seal is a device used on a rotating shaft to keep fluids in and contaminants out. It prevents the fluid moved through an asset, most often a centrifugal pump, from leaking. These seals are located in the asset’s stuffing box or seal chamber. This is the area of the pump where the pump shaft connects to the drive (an electric motor, for example).

Except for air seals, which will be discussed later, most types of mechanical seals consist of two flat faces that are installed perpendicular to the shaft. One of the faces is mounted stationary to the seal chamber housing. The other face rotates with the shaft to provide the primary seal. Axial mechanical force and fluid pressure maintain the contact between the seal face materials. This contact prevents leakage and retains the fluid within the pump.

Component, end-face mechanical seals consist of a separate rotating member and a stationary seat that mount in a gland or housing. Since they are not preset, installation and maintenance are more complicated than cartridge seals. Installing these requires experienced technicians who can properly install and adjust them.

Air seals are noncontacting, pneumatic devices engineered to seal rotating shafts. These seals are primarily installed in dry powder or slurry applications. They protect against product loss, emissions, and contamination by using small amounts of air or inert gas. This air is throttled to create positive pressure and an effective seal.

Most mechanical seals have five parts:Rotating primary face– Fixed to and rotates with the shaft and seals against the stationary primary sealing element

Stationary primary face– Fixed to the stationary housing of the pump, mixer or other equipment through which the rotating shaft passes and seals against the rotating primary sealing element

Mechanical loading devices– Biases the primary sealing elements in contact to initiate sealing. These can be a single spring, multiple springs, wave springs, or metal bellows.

Static and/or dynamic secondary seals– Seal between the mechanical seal components and the equipment shaft and housing that compensates for any shaft movement that may damage the seal faces.

In summary, knowing the mechanical seal types and the parts that make them up is only the beginning. Assessing the application, installation, and operation (with leakage limits) helps determine which seal type will be selected and how well it will perform in the system. This important decision factors into overall system reliability.

An end face mechanical seal, also referred to as a mechanical face seal but usually simply as a mechanical seal, is a type of seal utilised in rotating equipment, such as pumps, mixers, blowers, and compressors. When a pump operates, the liquid could leak out of the pump between the rotating shaft and the stationary pump casing. Since the shaft rotates, preventing this leakage can be difficult. Earlier pump models used mechanical packing (otherwise known as Gland Packing) to seal the shaft. Since World War II, mechanical seals have replaced packing in many applications.

An end face mechanical seal uses both rigid and flexible elements that maintain contact at a sealing interface and slide on each other, allowing a rotating element to pass through a sealed case. The elements are both hydraulically and mechanically loaded with a spring or other device to maintain contact. For similar designs using flexible elements, see Radial shaft seal (a.k.a. "lip seal") and o-rings.

A mechanical seal must contain four functional components, primary sealing surfaces, secondary sealing surfaces, a means of actuation, and a means of drive:

The primary sealing surfaces are the heart of the device. A common combination consists of a hard material, such as silicon carbide, Ceramic or tungsten carbide, embedded in the pump casing and a softer material, such as carbon in the rotating seal assembly. Many other materials can be used depending on the liquid"s chemical properties, pressure, and temperature. These two rings are in intimate contact, one ring rotates with the shaft, the other ring is stationary. These two rings are machined using a machining process called lapping in order to obtain the necessary degree of flatness.

The secondary sealing surfaces (there may be a number of them) are those other points in the seal that require a fluid barrier but are not rotating relative to one another. Usually the secondary sealing elements are o-rings, PTFE wedges or rubber diaphragms.

In order to keep the two primary sealing surfaces in intimate contact, an actuation force is required and is commonly provided by a spring. In conjunction with the spring, it may also be provided by the pressure of the sealed fluid.

The primary sealing surfaces must be the only parts of the seal that are permitted to rotate relative to one another, they must not rotate relative to the parts of the seal that hold them in place. To maintain this non-rotation a method of drive must be provided.

Mechanical seal face geometry is one of the most critical design elements within a mechanical seal. Seal face properties such as: balance diameter, centroid location, surface area, surface finish, drive mechanism, and face topography can be altered to achieve specific results in a variety of liquids. Seal face topography refers to the alteration of an otherwise flat seal face sealing surface to one with a three-dimensional surface.

All mechanical seals must contain the four elements described above but the way those functional elements are arranged may be quite varied. Several dimensional and functional standards exist, such as API Standard 682 - Shaft Sealing Systems for Centrifugal and Rotary Pumps, which sets precise configurations and sizes for mechanical seal used in Oil & Gas applications.

Mechanical seals are generally classified into two main categories: "Pusher" or "Non-Pusher". These distinctions refer to whether or not the secondary seal to the shaft/sleeve is dynamic or stationary. Pusher seals will employ a dynamic secondary seal (typically an o-ring) which moves axially with the primary seal face. Non-pusher seals will employ a static secondary seal (either an O-ring, high temperature graphite packing, elastomeric bellows or metal bellows). In this case, the face tracking is independent of the secondary seal which is always static against the shaft/sleeve.

A "cartridge seal" is a prepackaged seal that is common in more complex applications and were originally designed for installation in equipment where a component type seal was difficult due to the equipment design. Examples of this are horizontally split and vertical pumps. In 1975 the A W Chesterton Company designed the first cartridge seal that fit pumps with varying stuffing box bore sizes and gland bolt patterns. To accomplish this the seal utilized internal centering of the stationary parts and slotted bolt holes. This "generic" cartridge seal could be manufactured in higher production quantities resulting in a cartridge seal that could be used in all applications and pumps types. Cassette seals, patent no. 6,685,191 introduced by Gold Seals, Inc., utilize a replaceable inner "cassette" mounted in the cartridge end plate or gland, while modular cartridge seal systems makes it possible to replace only the parts subject to wear, such as sliding faces, secondary seals and springs, while keeping the seal"s hardware (gland, sleeve, bolts).

Cartridge seals can suffer from clogging due to the bigger space occupied inside the stuffing box, leading to dense or charged fluids not moving enough to centrifugate the solid particles.

Gap seals are generally used in bearings and other constructions highly susceptible to wear, for example, in the form of an O-ring. A clearance seal is used to close or fill (and join) spacing between two parts, e.g. in machine housings, to allow for the vibration of those parts. An example of this type of seal is the so-called floating seal which can be easily replaced. These seals are mostly manufactured from rubber or other flexible but durable synthetic materials.

Since the rotating seal will create heat from friction, this heat will need to be removed from the seal chamber or else the seal will overheat and fail. Typically, a small tube connected to either the suction or the discharge of the pump will help circulate the liquid. Other features such as filters or coolers will be added to this tubing arrangement depending on the properties of the fluid, and its pressure and temperature. Each arrangement has a number associated with it, as defined by American Petroleum Institute "API" specifications 610 and 682.

The majority of mechanical seal manufacturers offer seals that are dimensionally interchangeable with each other. The only difference being material quality and price. Also component seal is expensive to assemble as it will be assembled on the pump.

Since almost all seals utilize the process liquid or gas to lubricate the seal faces, they are designed to leak. Process liquids and gases containing hazardous vapors, dangerous toxic chemicals or flammable petroleum must not be allowed to leak into the atmosphere or onto the ground. In these applications a second "containment" seal is placed after the primary seal along the pump shaft. The space in between these two seals is filled with a neutral or compatible liquid or gas (generally nitrogen) called a buffer seal (unpressurized) or barrier seal (pressurized).

In a tandem seal [face-to-back], the seal will leak into the buffer fluid contained in the unpressurized cavity commonly known as thermosiphon pot. If the cavity registers a dramatic increase in pressure or fluid level, the operator will know that the primary seal has failed. This can be achieved by using pressure/level switches or transmitters. If the cavity is drained of liquid, then the secondary seal has failed. In both instances, maintenance will need to be performed. This arrangement is commonly used when sealing fluids that would create a hazard or change state when contacting open air. These are detailed in API 682 [Currently 3rd Edition] Piping Plan 52

In a double seal [Generally Back to Back], the barrier liquid in the cavity between the two seals is pressurized. Thus if the primary seal fails, the neutral liquid will leak into the pump stream instead of the dangerous pumped fluid escaping into the atmosphere. This application is usually used in gas, unstable, highly toxic, abrasive, corrosive, and viscous fluids. These are detailed in API Piping Plan standards #53a, 53b, 53c; or 54. Plan 74 may also be considered a double seal piping plan, although it is used exclusively when describing a dry gas barrier seal support system. The barrier fluid used in a Plan 74 system is simply a gas, not a liquid. Typically, nitrogen is used as its inert nature makes it advantageous due to mixing with the process stream being sealed.

Tandem and double seal nomenclature historically characterized seals based on orientation, i.e., tandem seals mounted face-to-back, double seals mounted back to back or face-to-face. The distinction between pressurized and unpressurized support systems for tandem and double seals has lent itself to a more descriptive notation of dual pressurized and dual unpressurized mechanical seal. This distinction must be made as traditional "tandem seals" can also utilize a pressurized barrier fluid.

The mechanical seal was invented by George Cook and was originally called a "Cook Seal". He also founded the Cook Seal Company. Cook"s seal (which actually did not have a means of drive) was first used in refrigeration compressors. The Cook Seal company was a sideline product for Cook and he sold the company to Muskegon Piston Ring Company where it was renamed as The Rotary Seal Division of Muskegon Piston Ring Co. Muskegon Piston Ring sold the Rotary Seal Division to EG&G Sealol who in turn was largely acquired by John Crane Industries of Morton Grove, IL.

At ROC Carbon, we’re pleased to manufacture carbon/graphite mechanical seal faces from your drawings or samples, using the same high-quality materials and tolerances that are found in original equipment manufacturer parts. As experienced mechanical face seal manufacturers, our team at ROC is experienced in machining intricate details such as flow channels and ports. Our lapping capabilities encompass both carbon and hard faces up to 16 inches in diameter and to as flat as 1 helium light band. We can insert the carbon seals in metal housings (machined by us or furnished by you) by heat shrink fitting or by using specialty high-temperature adhesives.

Mechanical Face Seals are a special form of mechanical seals. They are also known under other designations, such as lifetime seals, floating seals, duo cone seals, toric seals and heavy duty seals. There are two different types of Mechanical Face Seals: Type DO is the most common form that uses an O-Ring as a secondary sealing element. Type DF has an elastomer with a diamond-shaped cross section as a secondary sealing element instead of the O-Ring. To search for available articles, please use the Electronic Catalog.