Open Loop vs. Closed Loop Hydraulic Systems

There are a couple different types of hydraulic systems: open loop and closed loop. So, what’s the difference and how does it impact you?

Definitions and Differences

Closed Loop

Hydraulic systems can be placed into one of two categories: Closed loop and open loop. Closed loop circuits, also known as hydrostatic systems, connect a pump to a motor. The fluid flows in-between these

two components, through connecting hoses, without going back into a tank. A closed loop system still includes an oil reservoir, but they are smaller than those used in open loop systems.

Closed loop circuits are utilized in high power, high pressure mobile equipment because they are more compact, lightweight and less expensive. A couple of examples of where you can find closed loop systems include skid steers and refrigerating systems. Fine motor motion control can be more easily achieved by closed loop systems.

Open Loop

On the other hand, open loop systems include a pump, motor and reservoir tank. The fluid is pumped from the reservoir, through the components and back to the reservoir.

One of the benefits of an open loop system is greater heat reduction vs. a closed loop system. In an open loop system, the fluid cycles through, returning to the tank at the end of the cycle. There, it loses heat before being cycled through the system again. A closed loop system does not allow for this heat dissipation.

Open loop systems also are usually less contaminated as well. This is because any contaminants are given time to settle, wherein closed loop systems they will continue to circulate through the system. Because contamination is lower, the chance of damage is lower, too.

Examples of open loop systems include turbines and heat exchangers.

Other Notes

If cylinders are a part of your system, opt for open loop. The reason for this is to avoid a spike in pressure that could occur in closed loops with unequal amounts of fluid volume resulting on each side of a cylinder.

Review

If precision and compactness is what you’re going for, opt for a closed loop hydraulic system. If these concerns aren’t on the table, and you’re looking for longevity, opt for an open loop system.

Need pumps, motors, valves or filtration for your system? Call us or stop into one of our Express Hose Centers!