GENERAL PURPOSE TUBES

The general purpose tubes and hoses are used for the general purposes which do not require high range of purity of the compound. These are mostly used in many domestic appliances and in the workshops or hobby applications because of their excellent flexibility.

MEDICAL/FOOD GRADE TUBES

These are specially designed hoses and tubes which are made in a manner so that they do not react with any medical or food material. They are sterilized in standard autoclaves in order to make them fit for the application in which they come in close contact with the food ingredients, body tissues and fluids or sensitive drugs. In this particular type of tubing the manufactured silicone tubes and hoses are completely tasteless, odorless, and non-toxic with a special property which does not support bacterial growth.

The high pressure tubes and hoses are made by strengthening their composition with wire or polyester braids which combats expansion and flattening. These tubes are mostly used when then the tubes are in direct contact with pressurized gases or suction is conducted. However, sharp edged clamps and fitting should be avoided near the tubes as they have low tensile strength and resistance to steam which may cause excessive wear and tear.

USES OF SILICONE TUBES IN THE INDUSTRIAL SECTOR

Silicone has a multiple usage in the industrial sector because of its excellent properties and types which provide a very wide area for functioning. Some of these uses are:

Ptfe ORings, Ptfe Bushes, Mumbai, India

Ptfe Or Polytetrafluoroethylene O-Rings

PTFE or PolyTetraFluoroEthylene is a form of a synthetic fluoropolymer derived from tetrafluoroethylene. PTFE has some extremely distinct characteristic which makes it a very popular choice in industrial applications. One such application is for the manufacture of O-rings. O-rings are a mechanical gasket in the shape of torus. It is a loop of elastomer with a round cross section, designed to be seated in a groove and compressed during assembly between two or more parts creating a seal at the interphase. PTFE is an excellent elastomer for the job because it provides one of the most versatile chemical compatibility as they are made with inert material. The PTFE o-rings are white in color and the material is extremely chemically inert, tough and abrasive resistant.

TYPES AND SIZES OF PTFE BUSHES

The PTFE or Teflon bushes are primarily produced in six varied types with multiple dimensions in each type. These types are:

Property	Value

MECHANICAL PROPERTIES
Shore Hardness (Shore, D)	>54
Tensile Strength (MPa)	>20
Elongation at Break (%)	350
Specific Gravity (g/cm3)	2.2
Coefficient of Friction	0 – 0.01%

THERMAL PROPERTIES
Operating Temperature Range (°C)	-150 to +250
Melting Point (°C)	327

CHEMICAL RESISTANCE PROPERTIES

The chemical properties of PTFE are:

It shows excellent resistance towards almost all the chemicals.
It has a near infinite shelf/storage life as it does not exhibit any signs of aging.
Due to excellent chemical inertness it can be used in food, chemical and medical industries.
It has low elasticity memory hence, making it unsuitable for dynamic applications unless it is treated and energized by suitable materials such as I.E. Rubber.
It has a low coefficient of friction.

ADVANTAGES OF PTFE O-RINGS

The main advantages of PTFE are:

The PTFE O-rings are compatible with most universal chemical compounds
PTFE O-rings are the best possible solution for low pressure systems
It can operate under wide range of temperature from -320 °F to +500 °F
It is appropriate as a back-up ring for vacuum to high pressure sealing
The PTFE O-ring comes in multiple sizing. However, special ring sizes could be designed on demand from the customer.

PTFE IS RECOMMENDED FOR…

The advantages of PTFE make it a suitable choice under the following environments:

Chemical environments
Use in the acidic or basic environment
Sealing for moving or sliding surfaces

PTFE IS NOT RECOMMENDED FOR….

However, the PTFE O-rings are not recommended under certain conditions such as:
Low compression vacuum sealing
High vacuum seals
Exposure to high temperature steam.

TEMPERATURE RANGE

The temperature range suitable for PTFE O-rings is:

Up to 260 °C (intermittent)
Down to -150 °C

INSTALLATION TIPS FOR PTFE O-RINGS

During installation ensure that the O-ring is not nicked or gouged during assembly as it might cause breaks in the seal.
During installation do not exceed the stretch of the o-ring and maintain it to a maximum of 10%.
PTFE, like most of the thermoplastics, has a tendency to creep.
The PTFE experiences a cold flow.
The cold flow can be reduced by the use of special PTFE compounds that can be used to fill the empty space.
It has an extremely long seal life.

PTFE OR POLYTETRAFLUOROETHYLENE O-RINGS