Massachusetts Plumbers Journeyman Practice Exam

In new residential construction, what type of pipe may be exclusively used with PVC for sound reduction?

1. Galvanized steel

2. Copper

3. Cast Iron

4. ABS

The correct answer is: Cast Iron

In the context of new residential construction, the correct type of pipe to be used with PVC for sound reduction is cast iron. Cast iron is known for its excellent sound-dampening properties, which is particularly beneficial in plumbing systems where noise from water flow can be a concern. When installed alongside PVC (Polyvinyl Chloride), which is typically used for drainage and venting due to its lightweight and corrosion-resistant characteristics, cast iron effectively helps to minimize any noise that may arise from the plumbing system, creating a quieter living environment. While galvanized steel, copper, and ABS (Acrylonitrile Butadiene Styrene) pipes can be used for various plumbing applications, they do not provide the same level of sound insulation as cast iron. Galvanized steel may add weight and be resistant to corrosion but does not have significant acoustic properties. Copper can be noisy due to its rigidity and how sound travels through it, and while ABS has some sound-dampening ability, it is generally not as effective as cast iron in this regard. Therefore, cast iron's unique properties make it the ideal choice for reducing sound when paired with PVC in residential plumbing applications.