The Visolite 700H is a handheld or bench-mounted instrument for the measurement of viscosity of fluids by insertion. The actual sensor has a solid construction with no moving parts. It is connected toa ench - top microprocessor (HP550) unit by a flexible cable, and the whole instrument is powered by a transformer/adaptor unit. The Viscolite can be used with any volume of fluid. Unlike conventional rotating cylinder viscometers there is no specific quantity of fluid, or size of vessel, required to ensure accuracy. Hence the same instrument can be used for testing liquids in vessels of virtually any size, from a large tank down to a small beaker.
The sensor element consist of a shaf with an end mass, or bob, which is made to vibrte (also called resona) at its natural frequency. When vibrating, the moving parts of the sesor shear through the fluid. As this shearing takes place energy is lost to the drag forces on the sensor caused by the viscosity of the fluid. The loss of the energy in each cycle of vibration is measured by the sensor electronics and the microprocessor in the Display Unit. From this energy loss, the actual viscosity of the fluid is determined. The Viscolite is therefore in a class of instruments sometimes called "resonant" or "vibrational" viscometers. The response of these devices is not purely with viscosity but with product of viscosity and density, i.e. viscosity x density. In practice, viscosity changes on a far greater scale than density, and the fluid density can be accomodated by simply entering its nominal value in the Display Unit.