New Mexico Pipe Fitter Journeyman (JPF) Practice Exam

What advantage do conventional disc globe valves have in service situations where flow leaves deposits?

1. The wide disc helps to clear deposits

2. They maintain steady pressure

3. The narrow disc breaks through the deposits

4. They require less maintenance

The correct answer is: The narrow disc breaks through the deposits

Conventional disc globe valves are particularly effective in situations where flow may leave deposits due to the design of the narrow disc. The shape and orientation of the narrow disc allow it to create a shearing action against incoming flows, which can help dislodge and break through any accumulating deposits within the valve or the piping system. This action is beneficial because it helps maintain the valve's functionality and can prevent blockages that might occur with other valve types. In applications where materials like sludge or particulates are likely to build up, the narrow disc's ability to circumvent these obstructions makes it a preferred choice. Unlike wide discs that might push material aside without adequately breaking it up, the design of the narrow disc is specifically advantageous for ensuring continuous flow and preventing buildup over time. Therefore, its capability to disrupt deposits is a key reason for its advantage in such service situations.