Glossary of Terms

Here you will find a glossary of specialised terms commonly used in thermostating and metrology.

H

Hagen Poiseuill's Law (fundamental equation of the capillary viscometry)

This forms the basis for viscometry in capillary viscometers. If the differential pressure is generated by a height difference in front of and behind the capillaries, hence: Vkin = k x t, (k: capillary constant, t: measured run of a defined volume of liquid). In the case of very short times, the non-dissipated kinetic energy must be taken into consideration (kinetic energy / Hagenbach correction).

Hazard evaluation (HAZOP)

As far as hazard evaluation is concerned, which has to be generated by the operating company, the information relevant for safety from the operating manual of the manufacturer has to be considered. These are especially: mounting and integration of the temperature control unit into the total system, commissioning, operation, maintenance and inspection and indications for possible improper use, as far as such an application has not already been prevented by the lay-out/technical measures.

Heat capacity

The maximum electrical capacity of the installed heater. In all LAUDA thermostats the heating is controlled in a quasi-proportional way. Startup and reaching the operating temperature is done at maximum power that is reduced automatically as the set value gets closer.

Heat transfer medium/Fluids

These are liquids that supply or carry away energy at the consumer. The heat transfer medium is supplied through a circulating pump of the temperature control unit. The bigger the circulating quantity, the lower the temperature difference at the consumer. The lower the temperature difference the better the control precision.

Heating power

With electric heating, the heating power is identical to the power consumption of the built-in electric heaters. It is always the maximum possible heating power and, in the case of electric heating, it remains invariable at all operating temperatures. With medium heated heat exchangers, the heating power always depends on the temperature difference between heating medium and heat transfer fluid. The heating power reduces at increasing outflow temperatures, and tends to zero when it reaches the heating medium temperature. The brought-in pump output is helpful but not taken into account.

Heating thermostat

A thermostat whose working temperature range is primarily above the ambient temperature and preferably adds heat to the bath liquid.

Heating/cooling thermostat

A thermostat whose working temperature range is above and below the ambient temperature, and which can either add heat to or extract heat from the bath liquid.

Huggins formula (IV value according to Huggins)

Serves the purpose of the approximate calculation of the intrinsic viscosity of polystyrenes and others, for example. KH is an additional constant dependent on polymer.

^Back to top