1. Seals

2. Explanation
A seal is a device designed to form a barrier between atmospheres.
It will prevent anything on the inside from escaping such as oil, and anything from the outside from entering into the process such as dirt or other contamination.
Oil leaking out from a process would contaminate the surrounding area, and potentially end up with the process running dry.
Any debris entering into process is a serious issue and could end up with the lubricant contaminated and / or the components within becoming damaged.

3. Explanation
Oil seals are usually made from a flexible rubber type material that will allow a degree of flexibility and resistance to the chemicals that it may be coming into contact with.
Oil seals must always be fitted using the correctly specified method and changed when required. Failure to change these may result in the seal material becoming worn down from the process it is operating within or material degradation over time and the seal material becoming brittle.
The material that the oil seal is made from will differ according to the temperature and chemicals it is coming in to contact with

4. Explanation
Seals are classified as either being ‘static’ or ‘dynamic’.
A static seal means that it simply remains within a stationary situation. An example of this is one that is used within a hydraulic application, usually an O ring.
A dynamic seal is one that is used within a moving situation. An example of this is a lip seal that fitted within an end cap that acts / fits in conjunction with a moving shaft
A mechanical seal is another type of mechanism that will work in the same way as a lip seal, that is to form a barrier between atmospheres. One good example is a labyrinth seal.

5. Explanation
A seal has a number which is usually etched onto the face of it, which refers to the size of it (inside diameter, outside diameter, thickness, type of seal it is & the material it is made of. This number can also vary on the manufacturer / supplier of the seal. A cross reference chart can be used to select the correct seal from competitive suppliers

6. Types of Seal
Seals are generally split into different categories, depending upon their application & how they achieve their aim:
Lip Seal
‘O’ Ring
Labyrinth Seal
Gasket

7. Types of Seal – Lip Seal Used to provide barrier in many applications
For industrial machines, cars & domestic
Made of Rubber, Nitrile, Neoprene.
Construction: case, spring ,rigid interior, lip.
Retained in place via interference fit
Has numeric codes denoting size / type.
Must be replaced at specified intervals.

8. Types of Seal – Lip Seal

9. Lip Seals
Rubber Case
Bonded Metal Case
Garter Spring
Sealing Contact

10. Lip Seal in Contact with Shaft

11. Fitted Lip Seal in Use

14. Types of Seal – ‘O’ Ring Same basics applied as with Lip Seal
Retained within a face or side recess or groove
Used for: hydraulics, fuels, gases, water
Care must be taken when fitting

15. O Ring

17. Static – Non Moving

18. Dynamic - Moving

19. Type of Seal – Labyrinth Seal
This type of seal falls into the category of mechanical seals and has its physical appearance in rigid metallic form. A labyrinth is defined as a complicated network of passages. A labyrinth is provided to prevent the easy passage from the entry to the exit.

20. Type of Seal – Labyrinth Seal
The labyrinth seal provides the same function as a regular seal.  The Labyrinth Seal restricts the passage of solid, liquid and gaseous contaminants into the sealed area and also restricts the leakage of fluid out of the sealed containment. Non-contacting rotary and stationary elements provide a restricted flow path and utilize centrifugal force and gravity to prevent leakage.

21. Type of Seal – Labyrinth Seal
The 2 separate halves of the labyrinth seal are made from different materials, such as aluminium and steel. Application for where a labyrinth seal would be use include machine tools, drive units, gas turbine engines and conveyor belts. An advantage of using a labyrinth seal is that it can operate at high speeds.

22. Labyrinth Seal Images

23. Labyrinth Seal in Application

24. Eddies formed in grooves
Labyrinth
Reduce Leakage
Eddies formed in grooves
Increases resistance
Commonly Used
Gas and Steam

25. Type of Seal – Labyrinth Seal
The following youtube link shows & explains the basic working principle of a Mechanical
Labyrinth seal

26. Gaskets
A gasket is a mechanical seal which fills the space between 2 mating surfaces, preventing leakage from whatever is within the mechanical process and preventing whatever is outside from getting inside. The gasket fitting between the mating surfaces is often likened to the filling between 2 slices of bread in a sandwich.

27. Gaskets
Gaskets are made from a wide range of materials to protect against or tolerate many different situations such as temperature, chemicals & abrasion. These materials can be either rigid with no yield to compression or mildly soft / flexible to allow for compression so an air / liquid tight seal may be made.

28. Gaskets
When 2 mating surfaces do not have a completely smooth finish between them, the gasket can take this up and effective ‘mould itself’ to the adjoining surfaces to complete a tight and even seal.

29. Gaskets
Whenever a gasket is fitted between 2 mating surfaces, care must be taken to ensure that the bolts / nuts / studs are fastened in an even fashion, known as sequence fastening. This will ensure that then the mating surfaces meet, they will sandwich the gasket evenly.

30. Gaskets
Gaskets can be purchased off the shelf as a standard manufactured size or type. They can also be made from a sheet of material that is readily available from a manufacturer and manufactured to a bespoke sizing to specific requirements.

31. Gaskets
A gasket can be seen here located between two mating flanges.

32. Gasket Materials

33. Rubber
Is generally used for gaskets that will work with water These gaskets can be either be purchased or manufactured for bespoke sizing

34. Neoprene
Gaskets made from this material are intended to work with such fluids as seawater and limited amount of greases Can be purchased in sheet form so bespoke size gaskets can be manufactured by the end user to suit

35. Paper
The cellulose fibre paper material can be treated / impregnated with a plasticised chemical to withstand a wider range of liquids such as oil, Petrol, water, alcohol, grease and most Solvents. Gaskets of this kind are used throughout the automotive, marine, aero and agricultural industries

36. Nitrile This material is generally used to provide
gasket material that has to resist such
liquids as Fuels, Oils, Acids and Solvents
Nitrile also boasts a Good impermeability
to gases and an excellent abrasion resistance
It can be used at a wide range of temperatures,
ranging between -40 to 120 degrees Celsius

37. Cork
The material used for gaskets is usually a blend of cork material and rubber / nitrile (usually 70% cork to 30% rubber), the rubber which acts as a binder and sealer. Gaskets are generally used in the electrical and automotive industry and is able made from to his provide resistance to a range of liquids including oils, solvents, fuels and can withstand a range of operating temperatures between -25C to 135 degrees Celsius.

38. Asbestos Free
Gaskets that are made nowadays have a requirement to be made from materials that are resistant to heat but need to retain these properties This material is also resistant to water, petrol and natural gas, and boasts an operating temperature of up to 500 degrees Celsius

39. Graphite
This material is usually used for gaskets that have to withstand high pressures and temperatures (up to 2700 degrees Celsius) and is frequently used in applications such as Steam Cycling and Exhaust Handling