How do hydraulic sequence valves differ from priority valves?

Hydraulic sequence valves and priority valves serve distinct purposes in hydraulic systems, and understanding their operation helps clarify the differences between them.

Priority valves are designed to ensure that specific hydraulic functions receive hydraulic pressure before others in the system, effectively prioritizing flow to certain circuits. They operate automatically based on hydraulic pressure; when the pressure in the prioritized line reaches a certain threshold, the valve allows flow to that line while potentially restricting flow to less critical functions. This is crucial in systems where certain operations must be performed first to ensure safety and efficiency.

In contrast, sequence valves are typically used to control the order of operation of multiple hydraulic cylinders. They are designed to open a specific hydraulic line after a predetermined pressure is reached in another line, thus creating a controlled sequence of operations. Sequence valves usually incorporate spring tension to remain closed until the pressure specifications are met, at which point they open to allow fluid flow to the next intended operation.

This understanding underscores why the statement regarding priority valves being opened by hydraulic pressure stands out as the correct one. It clearly identifies the operational principle that sets priority valves apart, highlighting their role in managing system flow based on pressure conditions.