BOC BOC Plumbing and Water Systems 2

Question 1

What is the primary cause of water hammer in a plumbing system?

Accepted Answer

Sudden stoppage or change in water flow velocity

Answer

Water hammer is a pressure surge caused by the momentum of water being suddenly stopped or redirected, such as when a solenoid valve closes quickly.

Question 2

Which bacteria is of greatest concern in a building's hot water and cooling tower systems due to risk of Legionnaires' disease?

Accepted Answer

Legionella pneumophila

Answer

Legionella pneumophila thrives in warm water (77–113°F) in building systems and causes Legionnaires' disease when aerosolized water is inhaled.

Question 3

What minimum hot water storage temperature does ASHRAE 188 recommend to control Legionella growth?

Accepted Answer

140°F (60°C)

Answer

ASHRAE 188 and the CDC recommend storing domestic hot water at or above 140°F (60°C) to prevent Legionella proliferation in storage tanks.

Question 4

Which type of pipe is most susceptible to pinhole leaks from aggressive water chemistry or dezincification?

Accepted Answer

Copper

Answer

Copper piping is vulnerable to pinhole leaks when water has low pH, high chloramines, or high dissolved oxygen, all of which accelerate pitting corrosion.

Question 5

What is the function of a thermostatic mixing valve (TMV) at a building's hot water system?

Accepted Answer

To blend hot and cold water to deliver a safe, scalding-free temperature at fixtures

Answer

A TMV mixes hot storage water (maintained at high temperature for Legionella control) with cold water to deliver tempered water at a safe use temperature, typically 110°F.

BOC - Building Operator Certification Practice Test

BOC - Building Operator Certification Practice Test

BOC BOC Plumbing and Water Systems 2