pilot pressure closes the check valves and allows flow to pass in one direction. 

and low pressure drop prevents reverse flow. 

the generated pilot pressure prevents flow from free flow. 

the pilot ratio is 2:1 and allows a lower pressure drop in pilot line to hold the valve closed.

oil flow is permitted from port 1 to port 2 and closed to prevent flow in the reserve direction. 

after the pilot pressure (port 3 ) is generated, there's no flow from port 2 to port 1, and can't flow from port 1 to port 2.

rated flow :

260 l/min  

max. pressure :

350 bar

leakage :

0.3 ml/min (5 dpm)

working temperature :

min. -20鈩?, max. 90鈩?, with standard bunan gaskets

min. -20鈩?, max. 120鈩?, with optional viton gaskets on request

fluid :

best use mineral oil with viscosity ranging between 10 and 200 cst

filter :

25 micron or better

cavities :

see cavity data st17a

installation :

before screwing the cartridge on the valve body, ascertain to provide suitable gasket lubrication with clean oil and also be sure to screw the cartridge manually in to reach against the gaskets in the valve body.