A mechanical seal is a crucial device to prevent any type of leakage between the rotating shafts and fluid field vessels in the pump. The fluids of the pump remain good for the existence of this device. This essential tool gained popularity in the 1950s and was used in industrial sectors a lot.
They are used where the pump shaft enters or leaves the pump housing depending on their application fields. There are various types, sizes, and configurations of this device. It is mainly installed in rotating parts and stationary parts. The rotating part is generally attached to the shaft portion, whereas the stationary part is installed inside the casing.
It is designed to handle the sealing capability and packing can also be used for sealing purposes. Mechanical seals are mostly used in centrifugal pumps which are attached to the drive shaft inside the impeller housing.
Mechanical Seal Definition
It is a crucial piece of equipment for rotating shafts. It generally contains Primary sealing surfaces, Secondary sealing surfaces, a means of actuation, and a means of drive. It is mostly used in centrifugal pumps to prevent any leakages. It can be replaced by soft-packed glands because of low leakage and the absence of a requirement for routine maintenance.
This device is used at the seal point which is located at the point of entry or exit of a rotating shaft. It helps to prevent any leakages of one high-pressure fluid into a lower-pressure fluid.
Mechanical Seal Working Principle
It is an important device in most industrial sectors. It is used to contain fluid or gas within a pump, compressor, or vessel. There are various types of seals that are used depending on the characteristics of the products. Shaft seals are generally used in mixers, centrifugal pumps, or anything where a rotating shaft passes through a stationary housing to reduce the leakage must be reduced to a vapor. Seals are used in different fields such as automobiles, ships, rockets industrial pumps, compressors, and many more.
It is found in different forms single springs pump seals, multi-spring seal designs, mixer and agitator seals, compressor seals, metal bellows seals, and single and double cartridge seals. It is very important to identify the right seal based on the condition of temperature, pressure, and various environmental factors. The correct selection of seal for operation helps to prevent environmental contamination and results in cost savings, through improved machine operating efficiency, longer life, and machine safety.
Mechanical Seal Diagram
The diagram of the mechanical seal device is given below:
Types of mechanical seal
There are various types of this device which discussions are given below:
Internal Seal
It is installed inside the stuffing box of the pump. The internal seal installation procedure for the pump is very difficult.
External seal
It is installed outside the stuffing box of the pump. The internal seal installation procedure into the pump is very easy. This seal can be replaced easily. This seal is used for low-temperature, low-pressure, and low-speed application purposes.
Balanced seal
It is configured in such a way that the fluid closing forces act to the diameter on the seal faces equally and has been modified through seal design. The balanced seal can be installed easily and also removed.
Unbalanced seal
This seal is generally used in the cavitation area of the pump which is affected by fluid, available vibrations, and shaft misalignment area. It produces a high temperature and is installed where keeps low stuffing box pressure.
Pusher Type Seal
This type of seal is used in the industrial sectors based on the product characteristics. This seal helps to block the path of fluid between the shaft and the rotating seal face.
Non pusher type Seal
This type of seal is constructed of flexible material connected with a collar to one end and the other end uses a rotating seal. This seal is used in the industrial sector where abrasive fluids are transferred from one place to another.
Cartridge Type Seal
This type of seal is generally pre-assembled and contains various parts that can be installed to the pump shaft and no need for any extra fittings for installation purposes.
Mechanical Seal Parts
The design of this device is complex and comprises several primary components which discussions are given below:
Mechanical seal face
Rotating seal face
It moves in tandem with the rotating machinery shaft. It is made of hard and durable materials like silicon carbide or tungsten carbide. It helps to ensure the sustainable operational forces and friction generated at the time of machinery’s operation without any type of deformation or excessive wear.
Stationary seal face
This seal face is constructed to design a sealing pair with the primary ring. It helps with the movement of the primary ring while maintaining a strong seal. The stationary seal face is made of carbon, ceramic, or silicon carbide.
Elastomers (O-rings or bellows)
These are generally O-rings or bellows to provide the essential elasticity for maintaining the seal assembly and the machinery’s shaft or housing.
These are generally constructed with various materials depending on various factors like temperature, pressure, and the nature of the fluid being sealed.
Secondary Seals
These components provide a static sealing area within the mechanical seal assembly to increase the stability of the seal and reliability, especially in dynamic conditions.
Hardware
Springs
They provide the necessary load to the seal faces to ensure good contact between them. This contact is very essential to create a reliable and effective activity throughout the machine’s operation.
Retainers
It contains various essential components to maintain the proper alignment and position of the seal assembly. A good performance can be achieved by applying this tool.
Gland plates
They are used to mount the mechanical seal to the machinery. They support the machinery during the assembly of the seal and help to keep it in a secure place.
Set screws
They are small and threaded-type components. They can be used to secure the mechanical seal assembly to the shaft part. They help to maintain the seal at the time of operation and prevent potential displacement.
Mechanical Seal Functions
It helps to increase the machine’s efficiency and decrease the consumption of energy.
It helps to reduce the external and internal leakage.
It reduces the penetration leakage of the machine and helps to improve the volume efficiency of the machine.
It reduces the loss of friction and develops the mechanical efficiency of the machine equipment.
It reduces the energy consumption of the oil-sealing auxiliary system and improves unit efficiency in the
It helps to save the raw materials by the recovery of process fluid and eliminates the power steam and process fluid loss
It helps to improve the machine reliability of the machine.
It helps to save the environment because it reduces air pollution, water pollution, and workshop environmental pollution.
Applications of Mechanical Seal
It is used in different sectors like automotive, food, beverage, aerospace, industrial, residential, printing and publishing, and marine sectors. It is used within pumps, agitators, and mixers. It is very much used within gas seals and cryogenic seals. It is very important to select the right seal based on the application to get the efficient performance of your pumps.
For example, an unbalanced mechanical seal is more suitable than other seals when a centrifugal pump runs at a lower pressure. A balanced seal can be used for higher pressure and temperature purposes. Cartridge seals are used when low maintenance is required.
Frequently Asked Questions (FAQs)
What is the mechanical seal?
It is a mechanical piece of equipment used to prevent any leakage between two rotating or reciprocating components. It is generally found in centrifugal pumps, mixers, and other industrial equipment.
What are the parts of a mechanical seal?
The main parts of this device are the stationary face, rotating face, springs, seal faces, seal glands, and O-rings or gaskets.
What are the functions of mechanical seals?
It helps to increase the machine’s efficiency and decrease the consumption of energy. It reduces the penetration leakage of the machinery tools and helps to develop the volume efficiency of the machine.
What are the uses of mechanical seals?
It is used in the automobile industries, food industries, beverage industries, aerospace industries, printing and publishing industries, and various sectors. It is installed within pumps, agitators, and mixers based on the applications.
