In a water supply line, what is typically the first shutoff valve located before the meter?

Study for the NOCTI Plumbing Test. Engage with flashcards and multiple-choice questions, each supported by hints and explanations. Prepare effectively for your exam!

Multiple Choice

In a water supply line, what is typically the first shutoff valve located before the meter?

Explanation:
When isolating the incoming water supply right before it enters the building, you want a valve that closes quickly and reliably with minimal effort. A ball valve fits that need because its ball-and-seat design provides a tight shutoff with a simple 90-degree turn. This makes it easy to operate, even in tight or buried locations, and it’s durable against debris and corrosion, giving a dependable seal to stop all flow when needed. Other valve types don’t meet that combination as well: a check valve isn’t a shutoff at all, it only blocks backflow. A globe valve throttles flow and can require more turns to close, which isn’t ideal for a quick, full shutoff. A gate valve can also be prone to sticking or leaks after long-term burial and may not seal as reliably with minimal effort. So, the ball valve is the best choice for a ready-to-use, reliable first shutoff before the meter.

When isolating the incoming water supply right before it enters the building, you want a valve that closes quickly and reliably with minimal effort. A ball valve fits that need because its ball-and-seat design provides a tight shutoff with a simple 90-degree turn. This makes it easy to operate, even in tight or buried locations, and it’s durable against debris and corrosion, giving a dependable seal to stop all flow when needed.

Other valve types don’t meet that combination as well: a check valve isn’t a shutoff at all, it only blocks backflow. A globe valve throttles flow and can require more turns to close, which isn’t ideal for a quick, full shutoff. A gate valve can also be prone to sticking or leaks after long-term burial and may not seal as reliably with minimal effort. So, the ball valve is the best choice for a ready-to-use, reliable first shutoff before the meter.

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