Which of the following valves is unsuitable for high-pressure flow?

A needle valve is generally unsuitable for high-pressure flow because it is designed for precise control of small flow rates rather than managing high-pressure systems. Needle valves feature a narrow passage and a tapered plunger, which allows for fine adjustments in flow, making them more appropriate for applications where flow needs to be regulated with great accuracy. However, this design can lead to increased turbulence and potential wear when subjected to high-pressure conditions, which can compromise their performance and durability.

In contrast, check valves, ball valves, and gate valves are typically built to handle high-pressure situations more effectively. Check valves allow for unidirectional flow and can handle various pressures, while ball valves offer quick on/off control with minimal pressure drop. Gate valves are designed to provide a straight flow path and can withstand high-pressure environments, making them more suited for applications requiring high-pressure handling.