These security valves are used to avoid overcoming of a fixed pressure in the circuit. In this event probable breakages would occur. The valve job is very simple: the valve is set at a pressure a bit higher than the working one. In case this value is overcome due to a circuit problem, the valve opens, unloading the exceeding oil to the tank. Restoring will be done when the pressure set will decrease to the set value. The external body is made of high resistance steel and externally protected from oxidations by zinc treatment. On request we can supply a Zinc/Nickel treatment to increase the oxidation resistance when the valve has poor protection or it is located in external environments.