Which component failure can prevent a valve from closing properly?

• A. Incorrect programming of the clock
• B. Torn diaphragm
• C. User error in operation
• D. Insufficient power supply

Answer: (B)

A torn diaphragm is a critical component in many irrigation valves, particularly in those that are diaphragm-operated. The diaphragm acts as a seal to regulate water flow; when it is damaged or torn, it can lead to improper sealing. This means that even when the valve is signaled to close, water may continue to flow because the torn diaphragm fails to form a complete seal or may get stuck, preventing the valve from shutting off completely.

The other components mentioned can affect system performance, but they don't directly relate to the mechanical operation of the valve itself. For instance, incorrect programming of the clock pertains to how watering schedules are set, whereas user error involves manual operation mistakes that don’t affect the mechanical integrity of the valves. An insufficient power supply can impact electrically operated valves but does not directly affect the mechanical closure of a valve that relies on a diaphragm.