By Tom Eystad, CFPS
In a circuit system that uses directional control valves, the most straightforward circuit design to understand, both in industrial and mobile applications, uses individual components to perform individual functions or tasks. However, this exclusive use of individual components may result in extraordinarily cumbersome plumbing problems, many leakage points, increased pressure drops across the components, and additional heat loss by the system.
Additional directional control valve functions, such as flow controls, pressure controls, relief valve functions, and “blocked” or check valve functions, have been developed by the industry into a system of “stack valves.” Stack valves combine multiple functions into a single assembly by “stacking” various control functions together. This improves the circuit’s flexibility to combine different options and functions using a building block approach. A wide choice of hydraulic circuitry, operators, and flows can be combined into one assembly.
Stack valves increase system performance by greatly reducing the number of potential leakage points in the system. Generally, stack valves and their associated directional control valves are matched, designed to handle comparable flows, thereby reducing the worry of pressure drops and the resultant heat production in the system. Stack valves can be easily disassembled for service or for adding options and functions.