CAT Hydraulics and Plumbing Systems 2 — Questions and Answers
Question 1: What is the primary function of the hair and lint strainer (pump basket) in a pool plumbing system?
- To remove dissolved minerals from the water before it enters the filter
- To protect the pump impeller from debris that could cause damage (Correct answer)
- To regulate water pressure entering the pump housing
- To aerate the water and increase dissolved oxygen levels
Correct answer: To protect the pump impeller from debris that could cause damage
The hair and lint strainer captures large debris such as hair, leaves, and lint before they reach the pump impeller, preventing damage and blockages.
Question 2: Which type of fitting is used to make a 90-degree change in pipe direction in pool plumbing?
- Coupling
- Tee
- Elbow (Correct answer)
- Union
Correct answer: Elbow
An elbow fitting allows water flow to change direction at a 90-degree (or 45-degree) angle within a plumbing system.
Question 3: What is the main advantage of using a union fitting in pool equipment plumbing?
- It permanently joins two pipes for a leak-free seal
- It allows disconnection of components for maintenance without cutting pipe (Correct answer)
- It reduces pipe diameter to increase flow velocity
- It increases system pressure at the equipment connection point
Correct answer: It allows disconnection of components for maintenance without cutting pipe
A union fitting allows technicians to disconnect and reconnect plumbing components for maintenance or replacement without cutting or damaging the pipe.
Question 4: What is the function of a vacuum breaker installed in a pool plumbing system?
- To create the suction force needed at the main drain
- To prevent siphoning and backflow by admitting air when negative pressure occurs (Correct answer)
- To measure and display negative pressure in suction lines
- To boost pump suction capacity for above-grade pump installations
Correct answer: To prevent siphoning and backflow by admitting air when negative pressure occurs
A vacuum breaker admits air into the system when pressure drops below atmospheric, preventing siphoning and backflow that could contaminate potable water supplies.
Question 5: Which type of valve is preferred as a full-flow shut-off valve in pool plumbing because it provides minimal flow resistance when fully open?
- Gate valve
- Globe valve
- Butterfly valve
- Ball valve (Correct answer)
Correct answer: Ball valve
Ball valves offer full, unrestricted flow when open due to their through-bore design and can be quickly operated with a quarter-turn, making them ideal for pool shut-off applications.
Question 6: What does a sight glass installed in pool piping allow the technician to observe?
- Water temperature and thermal stratification in the pipe
- Chemical residual levels in the circulating water
- Flow conditions and the presence of air bubbles in the system (Correct answer)
- Pump motor speed and direction of rotation
Correct answer: Flow conditions and the presence of air bubbles in the system
A sight glass is a transparent section of pipe or fitting that allows visual inspection of water flow and detection of air bubbles in the circulation system.
Question 7: What is the purpose of an air relief valve located at the top of a pool filter tank?
- To introduce air for oxidation treatment of the pool water
- To release trapped air from the filter, preventing air locks that reduce filtration efficiency (Correct answer)
- To control the operating pressure within the filter vessel
- To prevent water hammer when the circulation pump shuts down
Correct answer: To release trapped air from the filter, preventing air locks that reduce filtration efficiency
An air relief valve releases air that collects at the top of the filter tank, preventing air locks that would impede water flow and reduce filtration effectiveness.
CAT Hydraulics and Plumbing Systems 2
What is the primary function of the hair and lint strainer (pump basket) in a pool plumbing system?