New Mexico Pipe Fitter Journeyman (JPF) Practice Exam

What feature of a pinch valve is similar to that of a diaphragm valve?

1. Both have adjustable openings

2. Both use a flexible diaphragm

3. Both are minimal in design

4. Both are exclusively for liquids

The correct answer is: Both use a flexible diaphragm

The feature that is similar between a pinch valve and a diaphragm valve is the use of a flexible diaphragm. In both types of valves, the diaphragm acts as a barrier that can be manipulated to control the flow of fluids. In a pinch valve, the flow is controlled by pinching a flexible sleeve, while in a diaphragm valve, flow is controlled by raising or lowering a diaphragm that seals against a seat. This design allows for effective sealing and flow control, making these valves suitable for various applications, particularly where a precise flow is desired. The use of a flexible diaphragm provides advantages such as reduced wear from corrosion and erosion, as the fluid does not come into direct contact with moving parts. This feature is significant in industries that handle corrosive or abrasive substances, as it helps prolong the life of the valve and maintain performance. While the other features listed may describe some aspects of these valves to varying extents, they do not represent the defining similarity between pinch and diaphragm valves as clearly as the characteristic of having a flexible diaphragm.