Friday 9 October 2015

Fire protective system

In this post deals with the safety equipment that used to reduce the fire. Here we are going to show you some of the fire protection system that can protect lives and property.

1. Hydrant System
This is a semi-automatic system. A network of pipes is laid out depending upon the risk with hydrant valves placed at strategic places. Fire hydrant system is also known as fire plug. To increase water pressure the hose attached to the hydrant can be further attached to a fire engine to use a powerful pump. A fire hydrant system essentially consists of a network of pipes connected to a source of water supply and provided with necessary outlets to deliver water under pressure. These outlets may be divided into two classes according to their position relative to the ground level. Hydrant below the ground they are known as Ground Hydrant (public places) and when above the ground level they are known as Pillar or Post hydrant (private premises).

Types of Hydrants:

Ball type Hydrants
Screw Down type Hydrants
Sluice Valve type Hydrants
Pillar Hydrant

Types of Pipes:
Cast Iron
Cast Iron (which are Concrete lined)
Ductile Iron (which are concrete lined)
Cement Asbestos
Polyethylene (MDPE)- Modified High Density Polyethylene
Heavy Duty Polyethylene and Aluminum Alloy are often used for emergency water supplies.

Operation of Hydrant 
Open the hydrant valve slowly
Allow some water to pass off to ensure that no dirt or filth is left inside that might block or clog the flow at later stage.
When closing, close the valves slowly to prevent water hammer and possible burst of fire mains.
After use, see that the hydrant valve is properly closed so that no water leaks out the pit is left clear and in condition in which frost will not damage it.
The valves of hydrants should not be operated unless stand-pipe or hose is first connected.
The standpipe must not be disconnected from hydrant in which no water is available or from which the flow has failed until the valves has been shut. This will obviate the danger of the valves being left open with unfortunate consequences when the supply is restored.
Blank cap on outlet or bow lid of a ground hydrant, must be restored to position, when the service is over with hydrant.

2. Sprinkler System

Since most important principle of successful fire extinction is to attack an outbreak immediately, it follows that any device which can detect a fire automatically and then control or extinguish it with the minimum loss must be of great value. Automatic sprinkler system using water as the extinguishing medium has been universally adopted as one means of achieving this purpose.

The different types of sprinkler system are following.

Wet systems
Dry systems
Multiple control systems
Deluge sprinkler systems

Sprinkler heads
For normal occupancy situations, in temperate countries, the recommended operating temperature for sprinkler heads in 68 degree Celsius.
Fusible solder type
Bulb type sprinkler heads
a. Fast-response sprinkler heads
b. Fusible Strut Type
c. Bulb Type

Life of sprinkler heads
Close the main stop valve of installation.
Close alarm clock.
Open 50 mm drain valve
Remove operated sprinkler head.
Fix new sprinkler head of the same Operating temperature.
Partially open main stop valve.
When the water flows through drain valve without bubbles, close the drain valve and stop valve.
Strap and lock the main stop valve.

Open alarm clock and stop main pump

3. Drencher System
While a sprinkler system protects a building from internal fire, drenches are placed on roofs and over windows and external openings to protect the building from damage by exposure to a fire in adjacent premises.

Drencher types:

a. Roof drenches
b. Wall drenches
c. Window drenches

a. Roof drenches
Roof drenches have a deflector rather similar to that of a sprinkler head. From the roof ridge they throw a curtain of water upwards which then runs down the roof and any skylights, windows or other openings must be protected.
b. Wall or curtain drenches
Wall or curtain drenches throw water to one side only to the outlet in the form of a flat curtain over those openings or portions of a building most likely to admit fire.
c. Window drenches
As their name implies, window drenches are used to protect window openings.

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