Close the discharge valve in the manual pump manually and without straining it. The use of tools would damage it.
Basic hydraulics instructions
A pressure change occurring anywhere in a confined incompressible fluid within a container with nondeformable walls is transmitted throughout the fluid such that the same change occurs everywhere.
Hydraulic pressure is the physical quantity that measures the instantaneous force in a unit of surface: kg / cm² = bar
The force exerted by a cylinder equals the hydraulic pressure multiplied by the effective pressure area of the piston. Force (Kg) = Operating Hydraulic
Pressure (bar) x Effective Pressure Area of the Piston (cm²). F =P x A This formula can be used to determine force, pressure or area when two of the three variables are known.