How Mechanical Seals Work - stuffing box - packing

Summary

The video script explains the function and importance of mechanical seals in hydraulic machinery, such as centrifugal pumps. Mechanical seals, offered by Jaws for over a decade, replace traditional stuffing boxes to prevent fluid leakage and reduce friction. They consist of a stationary and rotating part, creating a fluid film for lubrication and preventing direct contact, thus enhancing efficiency and reducing maintenance. Jaws Company provides a variety of mechanical seals from leading manufacturers, emphasizing their role in modernizing the industry.

Takeaways

• 🛠️ The mechanical seal is a device designed to isolate two environments, preventing fluid leakage between them.
• 🏭 Jaws has been a leading provider of mechanical seals for over a decade, offering a wide range of options from top manufacturers.
• 🔧 Mechanical seals are crucial in hydraulic machinery, such as centrifugal pumps, where they prevent fluid leakage and ensure efficient operation.
• 📍 The seal is positioned on the back plate to contain fluids within the pump, acting as a barrier between the pump's interior and the external environment.
• 🔄 The mechanical seal must withstand pressure and resist friction caused by the rotating shaft, which is a key function in its operation.
• 🔧 Traditional stuffing boxes, made of twisted wire rope, were used to seal around the shaft but have several drawbacks including wear, maintenance, and energy consumption.
• 🚀 Mechanical seals are increasingly replacing stuffing boxes due to their efficiency and ability to overcome the disadvantages of the older method.
• 🔄 A common mechanical seal features three sealing points, with the stationary part attached to the pump's back plate and the rotating part attached to the shaft.
• 💡 The moving element in the rotating part of the seal is pressed by a spring, ensuring contact with the stationary part and creating a sealing point.
• 🔧 The seal's operation involves the rotating part following the shaft's movements, compensating for misalignments and thermal expansions.
• 🛡️ The seal's faces, which are in contact, are made with extreme precision and smoothness to minimize friction and are lubricated by the fluid being pumped or an external source.
• 🌐 The mechanical seal can isolate the internal pump environment from the external environment, even with a rotating shaft, maintaining a sealed system.

Q & A

What is a mechanical seal?

A mechanical seal is a device capable of isolating two environments, typically used in hydraulic machinery to prevent fluid leakage between a rotating shaft and a stationary housing.

What is the purpose of a mechanical seal in a centrifugal pump?

In a centrifugal pump, the mechanical seal is placed on the back plate to contain the fluids inside the pump, preventing them from leaking through the space between the back plate and the shaft.

What are the components of a typical mechanical seal?

A typical mechanical seal consists of a stationary part fixed to the pump's back plate, a rotating part fixed to the shaft, and a sealing element between them that creates a seal.

How does the mechanical seal handle pressure and friction?

The mechanical seal is designed to hold pressure during pumping and resist the friction caused by the shaft's rotation, utilizing a fluid film for lubrication and preventing direct contact between the sealing surfaces.

What are the disadvantages of using stuffing boxes compared to mechanical seals?

Stuffing boxes require constant maintenance, wear out quickly, consume large amounts of water for cooling, and waste energy from the motor due to friction. Mechanical seals are more efficient and address these issues.

What is the role of the sealing basket in a mechanical seal?

The sealing basket is part of the stationary component of the mechanical seal, positioned between the stationary part and the rotating part to help maintain the seal.

How does the rotating part of a mechanical seal interact with the stationary part?

The rotating part of a mechanical seal rotates integral with the shaft and is pressed against the stationary part by a spring, creating a sealing point and following the shaft's movements to accommodate misalignments and thermal expansions.

What is the purpose of the fluid film in the mechanical seal?

The fluid film serves as a lubricant between the sealing surfaces, reducing friction and preventing direct contact, which can be formed from the fluid being pumped or introduced from an external source.

What are the benefits of using mechanical seals over older sealing methods?

Mechanical seals offer improved efficiency, reduced maintenance, lower energy consumption, and better containment of fluids, making them a more modern and effective sealing solution.

How can mechanical seals isolate the internal pump room from the external environment?

Mechanical seals can isolate the internal pump room by creating a barrier that prevents fluid leakage and interaction between the internal and external environments, despite the presence of a rotating shaft.

Outlines

00:00

🛠️ Mechanical Seal Overview and Function

This paragraph introduces the mechanical seal, a device designed to isolate two environments, particularly in hydraulic machinery like centrifugal pumps. It explains the seal's role in containing fluids within the pump and preventing leakage. The paragraph also contrasts the mechanical seal with the older stuffing box method, highlighting the inefficiencies and issues of the latter, such as wear, maintenance, and energy loss due to friction. The mechanical seal's design is presented as a superior alternative, addressing these disadvantages with a more efficient sealing solution.

🔧 Components and Operation of Mechanical Seals

This section delves into the components of a mechanical seal, detailing the stationary and rotating parts and their functions. It describes how the stationary part is attached to the pump's back plate, while the rotating part is affixed to the shaft. The paragraph explains the sealing mechanism involving a spring-loaded moving element that creates a dynamic seal against the stationary part. Additionally, it discusses how the seal accommodates shaft movement due to bearing play, production tolerances, and thermal expansions. The importance of the contact faces' precision and smoothness is emphasized, as well as the role of a fluid film in lubricating and preventing direct contact between the rotating and stationary parts.

Keywords

💡Mechanical seal

A mechanical seal is a device designed to prevent leakage by sealing the relationship between a rotating shaft and a stationary process vessel in various types of equipment. In the video, it's the central theme as it discusses the role of mechanical seals in hydraulic machinery, such as pumps, to contain fluids and prevent leakage while the shaft rotates.

💡Supply chain

Supply chain refers to the network of organizations, people, activities, information, and resources involved in moving a product or service from the supplier to the customer. The video mentions Jaws providing solutions for their customers' supply chain needs, emphasizing the company's role in offering a variety of mechanical seals from leading manufacturers.

💡Centrifugal pump

A centrifugal pump is a type of pump that uses a rotating impeller to generate a pressure increase, which moves fluid through the pump. The video uses a centrifugal pump as an example to explain how mechanical seals are used to prevent fluid leakage at the point where the motor connects to the impeller via a rotating shaft.

💡Back plate

In the context of the video, the back plate is a stationary component in a centrifugal pump where the mechanical seal is placed. It acts as a housing to contain the fluids inside the pump, preventing them from leaking through the space between the back plate and the rotating shaft.

💡Shaft

The shaft is a rotating component that transfers power from the motor to the impeller in a pump. In the video, the mechanical seal is crucial for containing the pressure and resisting friction caused by the rotation of the shaft.

💡Stuffing box

A stuffing box is an old method mentioned in the video for sealing the space around a rotating shaft. It uses a material similar to packing, which is pressed against the shaft to prevent leakage. However, this method has drawbacks such as wear, maintenance needs, and energy consumption due to friction.

💡Friction

Friction is the resistance that one surface or object encounters when moving over another. In the video, friction is a key concept as it discusses the wear and energy loss caused by the rotation of the shaft and the need for mechanical seals to reduce these issues.

💡Sealing points

Sealing points refer to the areas where a seal makes contact to prevent leakage. The video explains that a common mechanical seal has three sealing points, with one being the contact between the rotating and stationary parts, which is crucial for the seal's operation.

💡Sealing basket

A sealing basket is a component of the mechanical seal that is fixed between the stationary part and the back plate of the pump. It's part of the seal's design to ensure a tight seal and prevent fluid leakage, as mentioned in the video.

💡Spring

In the context of mechanical seals, a spring is used to apply pressure to the moving element of the seal, ensuring it maintains contact with the stationary part. The video describes how this spring action helps in creating the final sealing point.

💡Fluid film

A fluid film is a thin layer of fluid that is created between the contact surfaces of the rotating and stationary parts of a mechanical seal. As explained in the video, this film serves to lubricate the contact surfaces and prevent direct metal-to-metal contact, reducing wear and friction.

Highlights

The mechanical seal is a device designed to isolate two environments with a rotating shaft in between.

Jaws has been providing customers with the best solutions for their supply chain for over a decade.

Mechanical seals are used in almost every hydraulic machinery to contain fluids.

A classic example of mechanical seal operation is in a centrifugal pump where it prevents fluid leakage.

The mechanical seal is placed on the back plate to contain the fluids inside the pump.

Mechanical seals must hold pressure during pumping and resist friction caused by shaft rotation.

Stuffing boxes are an old method to seal around the shaft but have significant flaws.

Stuffing boxes require maintenance and use large amounts of water for cooling, leading to part wear and energy waste.

Mechanical seals are increasingly replacing stuffing boxes due to their efficiency and reduced disadvantages.

A common mechanical seal has three sealing points with a stationary and rotating part.

The stationary part of the seal is fixed to the pump's back plate, while the rotating part is fixed to the shaft.

The rotating part of the seal has a moving element pressed by a spring, creating the final sealing point.

The moving element of the seal follows the shaft's movements caused by bearing play, production tolerances, and thermal expansions.

The seal's faces are made of flat surfaces with extreme precision to prevent friction during rotation.

A fluid film created by the pump's pressure and rotation lubricates the seal faces and prevents direct contact.

Mechanical seals can isolate the internal pump room from the external environment despite the rotating shaft.

The video encourages viewers to like, comment, share, and subscribe for more information on mechanical seals.

Jaws Company's website is suggested for more details on their projects and services.

Transcripts

[Music]

the mechanical seal is a device that is

capable of isolating two environments

where between the two is found a

component like a shaft with a circular

or axial

motion Jaws for over a decade has been

providing its customers with the best

solution for their supply chain and in

its catalog every kind of mechanical

seal from the leading

manufacturers mechanical seals are used

in almost every hydraulic Machinery to

understand their operation we will take

as an example a classic centrifugal pump

in which a shaft connects the motor to

the

impeller the mechanical seal is placed

on the back plate in order to contain

the fluids that are inside the pump

which otherwise would draw from the

space between the back plate and the

shaft helped also by the internal

pressure in this case the back plate

acts as a stationary housing while the

shaft is the rotating part the

mechanical seal will have to be able to

hold the pressure during the pumping and

to resist the friction caused by the

shaft

rotation one of the old methods to

guarantee the ceiling that is still

widely used is to employ some stuffing

boxes A system that can keep tight

around the shaft a material similar to

the packing a twisted wires rope however

this method has some relevant flaws in

fact in order to work properly it has to

be pressed against the shaft this method

implies several problems a huge wear of

the packing its periodical maintenance

the necessity to use great quantities of

water to cool it down because while

making friction its temperature the

consumption of parts in contact with it

and even the wasted energy from the

motor to win the friction Force they all

increase that's why mechanical seals are

replacing old methods day byday since

they are designed more and more to be

efficient which is projected to remedy

these

disadvantages the most common mechanical

seal has three sealing points the

stationary part is fixed to the back

plate of the pump with the sealing

basket between

them the rotating part instead fixed to

the shaft with the seal between them as

well in this way the rotating part

rotates is integral with the

shaft one of the two parts in this case

the rotating part possesses one moving

element that is firmly fixed and pushed

from a spring this one presses against

the permanent part creating the last

ceiling

point this moving element follows the

shaft movements caused by the bearing

game the misalignments caused by the

production tolerances and from thermal

expansions during the

functioning the seal between the

rotating and the stationary part is the

element that the mechanical seals have

in common as you can guess the two parts

are in contact with each other and the

rotating one causes friction on the

other during the rotation for this

reason the faces of the two parts that

are in contact are made of flat surfaces

worked with extreme precision and

smoothness besides the pressure inside

the pump combined with the centrifugal

effect obtained from the rotating part

rotation cause a fluid film to be

created between the faces in the contact

made from the same fluid pumped from the

system that while it lubricates them

also prevents direct contact this

lubrication foil can also be introduced

from an external source

in this way the mechanical seals can

isolate the internal pump room from the

external

environment despite the presence of the

rotating

[Music]

shaft if you found this video useful let

us know by leaving a like and a comment

you can also share it and don't forget

to subscribe to our Channel we suggest

you visit our website Jaws company.com

to find out more about our next projects

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