ITIUK’s DWT’s are a high-precision primary standard (comparison standard).
They are used as a reference device for calibration services and are suitable for testing, adjusting and calibrating pressure measuring instruments without using an external reference device.
The main components are measuring system, valve units, spindle unit for fine adjustment of the pressure and set of weights.
The measuring system consists of a fine lapped piston / cylinder pair. The weight-loaded piston is pressed down by the local gravitation of the weights. From below the test pressure, which is generated and adjusted by the spindle pump, acts towards the piston surface area. This test pressure is increased until the hydraulic force of the medium on the piston surface area (acting from below) compensates the weight force of the piston / weight system and the equilibrium of forces is reached. During this state of equilibrium, the piston floats freely in the cylinder.
In order to simplify the handling, the weights are already standardised to the specific determined piston surface area and the local gravitation at the installation site. The set of weights is available discreetly graduated in different pressure units (bar, Pa, psi).
Piston and weights are kept rotating with a motor while floating in order to minimise the influence of static friction of piston and cylinder and therefore to guarantee a sensitive discrimination threshold.
Features / Benefits
Stainless steel construction
Requires no power supply
High accuracy calibrations