How Do Hydraulic Reservoir Isolators Work?

How Do Hydraulic Reservoir Isolators Work?

April 7, 2023

How Do Hydraulic Reservoir Isolators Work?

Hydraulic reservoirs are designed to fit within a hydraulic system’s space and work together with the rest of the components. They should re-circulate fluid enough to maintain stable temperature, keep it clean by passing through filters and help settle contaminants out of the tank.

Common Contaminants

Contaminants can enter a hydraulic system in a variety of ways, including during repairs and maintenance. Dust particles from a workshop atmosphere may find their way into a hydraulic port when it is opened during a repair, or dirt and sand could fall into a tank when new fluid is added. Oil, another common contaminant, can be contaminated during manufacturing or transportation. Even fresh oil can be contaminated by improper storage and filling of containers. Built-in contamination is present in new components, such as sand particles left over from metal casting or slivers of metal from boring holes. It cannot be excluded, but it can be minimized by flushing new components with fresh fluid and cleaning them properly after they are installed.


When air enters a hydraulic system, it causes problems such as cavitation and aeration. It can also slow down the system’s reaction time. One way to prevent air from entering the fluid is to use a hydraulic reservoir isolator. These devices can be installed in a tank, pump intake line or other location. They consist of a steel or fiberglass bottle with a bladder bag. They are sized to be about 25 to 50 percent larger than the volume displacement of oil in the reservoir during operation. This allows the isolator to draw clean air in from outside without allowing it to mix with the fluid. The bladder bag also helps trap contaminants that would otherwise settle in the sump of the reservoir.


Hydraulic reservoir isolation valves prevent water from entering the fluid and causing damage. They can be a variety of types, including ball valves, monoblock valves, and diaphragm isolation valves. Some are pressurized and seal from the atmosphere by engine bleed air or hydraulic pressure produced within the system. These isolation valves are useful for applications like oil and gas drilling where high temperature and pressure can lead to hose cracking or the release of hazardous energy from stored fluid in a system. They can also be used to protect downhole tools and rigs from fluid invasion during completions operations or well interventions. Isolation valves also allow a technician to access the fluids without affecting the formation.

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