Dead weight testers are used for examination and calibration
of pressure gauges and other pressure measuring instruments
without using an external instrument. The main components are
the measuring system, the valve unit, the built-in screw pump for
accurate pressure adjustment and the weights.
The measuring system itself consists of a precise lapped-in pair
of piston and cylinder. During the measuring process the piston is
forced up by the pressure produced with the built-in screw pump
and eventually with additional external pressure supply, while the
regular weights and maybe further extra weights, if required for
the desired test pressure, press it down.
With the built-in screw pump the test pressure can be adjusted to
an equilibrium of the forces. When the forces on both sides of the
piston are in balance, the piston will be floating, and the desired
test pressure is reached exactly.
For simplifying the handling, the weights are already refered to each
relevant determined piston area and stamped with the pressure
unit (bar/MPa). When indicating the place of installation these are
being corrected (3.1 certificate)
The friction between piston and cylinder is minimized by keeping
piston and weights rotating while floating.
The models described in this data sheet are available for pressure
ranges 0.25 to 60 bar (PD 60) resp. 0.25 to 100 bar (PD100).