O-Ring seal is a common seal .

It is for use  in machine design.

O-ring seal can be use in static application such as cover or pin. If the machine parts being seal move relative to one another, the o-ring acts like a dynamic seal.

Easy to craft , reliable , inexpensive.

A packing device .

Commonly moulded in one piece from elastometric material.

Also use to offer structural support ,absorb energy, transmit energy, transmit fluid and seal fluid.

O-ring acts like a seal just by blocking any leaking of gas or liquid between two close mating surface.

O-ring are utilize to keep the air or fluid in/out of distinct space.

It is use in under water camera in order to keep the water out.

SCUBA regulator use O-rings to avoid air from moving out.

Also,use in automobile parts ,cups , drive , belts,body jewellery.

O-RINGS are made from rubbers, metals and plastics.


O-ring also called Toric joint

If the pressure of fluid contain is not greater than the mating stress of o-ring ,then sealing is completed.

To meet the explicit performance requirement of special seals like”ENERGIZED HYDRULIC SEALS” and ”OIL SEEDS” are available.


In vaccum system that must be immerse in liquid nitrogen utilise indium o-ring.

Rubber become brittle and hard at lower temperature.

High vaccum system make use of nickle or copper o-ring.


O-rings come in a variety of sizes. Society of Automotive Engineers (SAE) Aerospace Standard 568 (AS568)[15] specifies the inside diameters, cross-sections, tolerances, and size identification codes (dash numbers) for O-rings used in sealing applications and for straight thread tube fitting boss gaskets. British Standard (BS) which are imperial sizes or metric sizes. Typical dimensions of an O-ring are internal dimension (id), outer dimension (od) and thickness / cross section (cs)

Metric O-rings are usually define by the internal dimension x the cross section. Typical part number for a metric O-ring – ID x CS [material & shore hardness] 2x1N70 = defines this O-ring as 2mm id with 1mm cross section made from Nitrile rubber which is 70Sh. BS O-rings are define by a standard reference.











Instead of calculating why we not measure the stress?

Instead of calculating why we not measure the stress?


To check the temperature of water we need thermometer.

Ammeter used to measure the electric current,

Anemometer used to measure the wind speed,

Astrolabe used to measure the latitude and altitude of celestial body,

Audiometer used to measure the hearing purpose.

Instead of calculating why we not measure the stress?

Barometer used to measure the pressure,

there are to ways to  know the value of anything  i.e either you calculate or measure.

Like, In ancient time , instead of measuring we use to calculate the blood pressure of patient.

so from above , we can get the idea to measure the stress of  material  by using stress measuring device .

As we know , no practical possible without theory and theory based on observation.


stress measuring device can help to know about deformation occur on material by applying load at per unit area.

In engineering ,

stress is a internal resistive force to the deformation per unit area.






There are 3 type of stress ,

  • Tensile stress
  • Compressive stress
  • Shearing stress



So like that putting a theoretical formula and by designing and programming we can make stress measuring device.

Difference between the pressure and stress,


Normally , we say that” pressure is stress”

But its not like that , for any machine

stress is a internal resistive force to the deformation per unit area.

σ= applied load/cross section

unit – N/m²


Pressure is force per unit area.



Due to stress , the pressure will not develop .

But, Due to pressure the stress will develop

so we cannot say that pressure and stress and same .

So Basically the conclusion is pressure has measuring device ,but stress do  not have measuring device.

Although ,

we have stress measuring machine but not a stress measuring device.

S0, by using stress measuring device we can get the stress value of any material at any direction.