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The piston cylinder assembly is the heart of the dead weight tester and responsible for its high accuracy. We
manufactures piston cylinder with accuracies from 0.05% up to 0.005% of reading. To give an idea of the manufacturing
skills, the space between the piston and the cylinder is in the um range and can only be measured in a climate room. To
guarantee an excellent metrology-logic characteristics, all pistons and cylinders are made of tungsten carbide. Because of
the extreme hardness of this material, the pressure distortion (expansion) coefficient is negligible. The low friction
coefficient provides minutes of turning with just a little swing of the masses.
1.6 Effective Area
For all dead weight testers, the effective area is determined by cross
floating with a known reference primary standard deadweight tester. The
exact pressure can be calculated. As per the formula of the item 1.4,
compensation factors are listed for air buoyancy, local gravity, surface
tension of the used oil and temperature and pressure expansion of the
piston cylinder assembly. All necessary data are listed in the calibration
certificate provided with each dead weight testers.
1.7 Mass Set
The masses of the dead weight tester are made of carbon steel or nonmagnetic stainless steel. They are laser marked
with a serial number and mass or the equivalent pressure. The weights are tare out to add stainless steel to an internal
chamber. This is easy for recalibration or adjustments for gravity compensation. The mass of all weights are listed in the
certificate. For small pressure steps, a box with small weights is optionally available.
