sanitation ph23 part 2

What is the purpose of the main discharge stack in a secondary ventilated stack system?

• To provide a source of water for the system

• To act as a safeguard against positive and negative air pressure fluctuations

• To directly heat the water in the system

• To collect sewage from individual branch discharge pipes

Answer explanation

The main discharge stack in a secondary ventilated stack system serves to safeguard against fluctuations in air pressure, ensuring proper ventilation and preventing backflow or blockages.

How much air is required to maintain equilibrium within the system for every 1m³ of water utilised in a secondary ventilated stack system?

• 10m³ of air

• 20m³ of air

• 30m³ of air

• 40m³ of air

Answer explanation

To maintain equilibrium in a secondary ventilated stack system, 30m³ of air is required for every 1m³ of water utilized. This ensures proper ventilation and balance within the system.

What is the function of the rodding eye in a secondary ventilated stack system?

• To regulate the flow of water

• To provide access for cleaning and clearing blockages

• To measure the amount of water in the system

• To act as an additional water supply

Answer explanation

The rodding eye in a secondary ventilated stack system is designed to provide access for cleaning and clearing blockages, ensuring the system operates efficiently and preventing potential issues.

If a 50 mm waste pipe exceeds its maximum length, what is the next size up it should be increased to?

• 32 mm

• 40 mm

• 50 mm

• 100 mm

Answer explanation

When a 50 mm waste pipe exceeds its maximum length, it should be increased to the next size up, which is 100 mm. This ensures proper flow and prevents blockages.

According to the table, what is the maximum length for a 100 mm pipe?

• 6.0 m

• 4.0 m

• 3.0 m

• 1.7 m

Answer explanation

The maximum length for a 100 mm pipe is 6.0 m, as indicated in the table. This is the longest allowable length for this pipe size, making it the correct choice among the options provided.

What happens to the measurements if pipework is too steep or if bends are introduced?

• They remain the same

• They decrease

• They increase

• They change

Answer explanation

When pipework is too steep or has bends, the flow dynamics change, affecting pressure and velocity. Therefore, the measurements will change, making 'They change' the correct answer.

What is the maximum permissible pipe length (in meters) for a wash hand basin or bidet with a diameter of 32 mm?

• 1.7

• 3.0

• 3.03

• No limit

Answer explanation

The maximum permissible pipe length for a wash hand basin or bidet with a diameter of 32 mm is 1.7 meters. This limit ensures proper drainage and prevents issues like siphoning or blockages.

What can back pressure or positive pressure above bends and offset in the stack cause?

• Enhanced water flow

• Foul air to be blown through the trap water seal

• Increased water temperature

• Reduced noise in the plumbing system

Answer explanation

Back pressure or positive pressure can force foul air through the trap water seal, compromising the seal's effectiveness and allowing unpleasant odors into the space. This is why the correct answer is 'Foul air to be blown through the trap water seal'.

What size pipe is typically used for a sink, bath, shower, urinal, or sanitary towel macerator?

• 32mm

• 40mm

• 50mm

• 100mm

Answer explanation

The typical pipe size for a sink, bath, shower, urinal, or sanitary towel macerator is 40mm. This size provides adequate drainage for waste and is commonly used in residential plumbing.

What is the most suitable method of joining a MDPE buried water mains

• Solvent welding

• Any cheap fitting off the internet

• Electro fusion welding

• Brass compression fittings

Answer explanation

Electro fusion welding is the most suitable method for joining MDPE buried water mains as it provides a strong, leak-proof joint by using heat generated from electric current, ensuring durability and reliability in underground applications.