Module 9 : Process Hazards and Safety Measures in Equipment Design

Lecture 2 : Safety Measures

 

5. SAFETY MESAURES

In the present global industrial scenario, for any industry to be successful, it is essential to inculcate safety culture, consciousness in health and environment aspects in each personnel of an organization. The word safety used to mean the older strategy of accident prevention through the use of hard hats, safety shoes, and a variety of rules and regulations. The main emphasis was on worker safety. Much more recently, ―safety has been replaced by ―loss prevention. This term includes hazard identification, technical evaluation, and the design of new engineering features to prevent loss. Safety, hazard, and risk are frequently-used terms in chemical process safety. All the manufacturing processes are to some extent hazardous, but in chemical processes there are additional, special, hazards associated with the chemicals used and the process conditions. The chemicals handled during different process poses hazards in the form of fire and toxicity to operators. The Material Safety Data Sheet (MSDS) of all chemicals used in the plant including raw material, intermediates, products, by products, etc provides information related to the toxicity and other hazards. The word hazard is associated with toxicity, flammability or combustibility. Flammable liquids burn more easily. On the other hand, combustible liquids do not burn that easily. Let us try to understand the commonly used terms associated with fire hazards.

 

5.1  Flammability

The hazards caused by the flammable material depend upon number of factors.

  1. a.  flash point of the material

    2. b.  auto ignition temperature of the material

    c.  flammability limit of the material

    d.  energy released in the combustion

5.2 Flash point

Flash point gives a relative idea of the lowest temperature at which enough vapour pressure exists to generate vapour that can ignite the from an open flame. It is a function of the vapour pressure and the flammability limits of the material. It is measured in standard apparatus (both open and closed cup apparatus). Flash points of many volatile materials are below the normal ambient temperature for example, ether -45°C, petrol (gasoline) – 43°C.

5.3 Auto ignition temperature

It is the temperature of material at which the material will ignite spontaneously in air, without any external source of ignition that may lead to uncontrolled fire and explosions.