C4 - Storage, Handling, Processing Of Dangerous Substances

Question 1

A suitable store for flammable liquids should have

Answer 1

• secure to prevent unauthorised access
• Clear signage to indicate hazards of contents (no smoking etc)
• A floor impervious to contents being stored
• A bund containing up to 110% of largest container
• A slope to floor so any spillages in bund come to a place of visibility
• Suitable fire rating of building materials
• Self closing fire rated doors
• Fire rated glass on windows
• Lightweight roof that will lift off easily in event of confined vapour cloud explosion
• good ventilation through high and low level vents
• Segregation of incompatible materials

Question 2

Categories of electrical equipment

Answer 2

Cat 1 = suitable for all zones
CAT 2 = Zones 1 (21) or 2 (22)
CAT 3 = Zone 2 (22)

Question 3

Effects of 10C on a chemical reaction

Answer 3

An increase of 10C will double the reaction rate of a substance.

Question 4

Effects of pressure on a gas or vapour

Answer 4

When gases and vapours are compressed it means that the molecules are closer together. This means they are more likely to bump into each other, as they collide they react.

Low pressure reacts at a slower rate to a high pressure

Question 5

Exothermic and endothermic

Answer 5

Exothermic = chemical reaction produces heat

Endothermic = chemical reaction reduces heat

Question 6

What is a catalyst

Answer 6

A catalyst is something that added in small quantities can notably affect the rate of chemical reaction

Question 7

Vapour clouds

Answer 7

Vapour clouds can be confined or unconfined
explosions are as a result of flammable vapours being within the upper and lower explosive limit when exposed to an ignition source of sufficient energy to ignite the vapours.

Question 8

Types of protection used in electrical equipment used in explosive atmospheres

Answer 8

• Flameproof enclosure -Parts that can ignite are contained in an enclosure that can withstand the pressure of an explosion
• Increased safety -additional measures are taken to increase safety level of components
• Pressurised apparatus- containing a inert pressurised substance within the appliance
• Intrinsically safe -circuits give off no heat or sparks under specified test conditions
• oil immersion -Electrical parts are immersed in oil or other protective fluid to prevent ignition
• Powder filling - Parts are contained within a powder to prevent electrical arcs
• Encapsulation - parts which may ignite are covered in a protective sealing compound

Question 9

What is meant by inerting

Answer 9

Inerting is the partial or total substitution of the oxygen content in a flammable atmosphere with an intert gas