UNIT 1 Flashcards
Define Water Purification.
This plays a role in supplying and ensuring safe and clean water to positively impact the health of communities.
What are the 5 steps if water purification.
Screening, Coagulation, Sedimentation, Filtration and Disinfection.
Define Screening
Water from natural sources have to go through the water treatment plant’s screen as it is an important function that removes the large physical impurities such as vegetation and organisms. Ground water may not have to go through this as it has already pass through the earth’s natural layers acting as a screen.
Coagulation.
This is when alum an other chemicals are added to the water to form tiny sticky particles knowns as floc. These particles attract dirt, sticking to them making them heavy and sink to the bottom of the storage tank
Sedimentation.
The water and floc flow into a sedimentation basin. As the water sits there the floc settles at the bottom until it’s removed..
Filtration.
The water passes through 1 ft deep gravel, 2 1/2 ft deep sand and charcoal to remove any remaining physical impurities.
Disinfection.
The water goes into a closed tank or reservoir to add chlorine and other chemicals to kill any remaining microorganisms and bacteria to make the water safe for distribution.
Define Direct heating.
This is when the water is heated via immersion heater or boiler.
Define Indirect heating.
The water is separate from the central heating system, therefore the water is heated using coils from the boiler.
What is a Stop Valve?
This is a system that totally stops the flow of liquid through a pipe.
What are the 2 stop valves?
Gate valves and Globe valves
Gate Valve.
This valve doesn’t restrict the flow of liquid when not in use, therefore it takes longer to move into position making it prone to leaks.
Globe valve.
This will interrupt the flow at all times, moving into position quickly.
Wet riser.
This is a pipe permanently charged with water that is immediately ready for use.
Dry riser.
This is a vertical pipe that is always kept empty and is only charged with liquid for a fire service pumps.
