Technical glossary

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Ambient Temperature Range

is the permissible temperature range of the environment in which the unit will function. lt is 5...40°C for all Huber units in this catalogue. The quoted cooling powers are for an ambient temperature of 20°C.

Automatic Compressor Control
is a procedure used in refrigeration machines to save energy. A microprocessor control decides if the the refrigeration machine is required or if it can be switched off.

Bath Opening
is the usable surface that is available for direct thermoregulation, as a rule over the entire usable depth.

Bath Thermostat
is a thermostat which is equipped with a pump and a bath that contains the object to be thermoregulated. The built-in circulating pump is used to mix the bath liquid, but can also be used if necessary to circulate the thermofluid through an extemally-connected circuit, eg. connection of a through-flow cooler to allow the cooling of heating thermostats.

Bath/Circulation Thermostat
is a thermostat with a bath opening which is allows objects to be directly thermoregulated in the bath as well as a pump (Compatible Control thermostats have pressure and suction pump) for closed (pressure pump) and open (suction and pressure pumps) external circuits.

Bath Volume (also fill volume)
is the volume of the bath liquid that is required for adequate operation of the thermostat, but without considering the volume of thermofluid in the extemal circuit. lf two values are given, the lower value indicates the minimum required volume with displacement insert, the upper value the permissible maximum amount. The difference is the socalled expansion volume. Especially in the case of external applications, the size of the expansion tank must be considered, since the circulating thermostat must also take up the expansion of the liquid in the extemal circuit. The smaller the surface area of the expansion tank the lower is the area of thermofluid open to attack from oxidation and air humidity absorbtion.

Calibration Thermostat (CAL)
is a bath thermostat with especially high temperature constance and especially consistent temperature distribution through the bath.

Chiller (UC®)
is a special cooling thermostat which is designed exclusively as a circulation thermostat. Circulation chillers have evolved from thermostats and form a separate range of units in terms of their type of construction (DeskTop, Tower), the cooling and pump capacities. Generally they have no accessible bath. They are often used as a substitute for cooling with tap water (exception: minichiller).

Clear-view Thermostat
is a bath thermostat with transparent walls for direct observation of the object being thermoregulated (models 106A to 118A).

Cooling Capacity Control, automatic

is a control routine to save energy. The microprocessor based controller determines whether it is possible to reduce the cooling power. In addition to saving energy (up to 90 percent), this also saves wear and tear of the compressor, reduces the amount of heat discharged into the environment, and results in better temperature control.

Discharge Pressure 
is the positive pressure of the circulating pump of a thermostat directly at the pump discharge. lf only one value is given in the tables, then this involves the maximum delivery pressure for flow rate zero. Pump curves illustrate discharge in relation to the flow rate.

Effective Usable depth
is the fluid depth available in a bath thermostat for direct temperature control.

Extended Working Temperature Range
is the temperature range that can be attained when using a factory-fitted cooling coil when operating with cooling water.

stands for electronic upgrade. E-grade can extend the functionality of the Pilot ONE. A unit specific activation code is required. This can be carried out in the factory. If ordered at a later date the activation code can be sent by E-Mail.

Flow-through Chillers (DC®)
are add-on coolers which are connected into an external circuit to upgrade a heating thermostat to a heating/cooling thermostat. They are used to replace water cooling, and also to extend the lower operating temperature.

Flow Rate
is the volume of liquid delivered per time unit by the circulating pump measured with water. If only one value is given in the table, this is the maximum flow rate for a zero discharge pressure. Pump curves illustrate discharge in relation to the flow rate.

Heat Load
is the maximum capacity of the installed electric heater. The heating is controlled proportionally. The heating is continually controlled, and as the set point temperature is approached the power is reduced automatically.

Heating Thermostat
is a thermostat whose working temperature range is primarily above the ambient temperature adds heat to the thermal fluid.

Intrinsic Temperature
is the operating temperature of a heat circulation thermostat which is achieved for a switched off heating in a stationary condition. It is dependent on the installed pump motor output, the bath fluid used (viscosity, density) and the insulation of the thermostats, for example without or with an attached bath cover.

Immersion Thermostat (CC®-E, KISS® E)
is a thermostat that can be combined with a bath and to form a complete unit. Immersion thermostats are equipped with a screw clamp to attach them to any desired bath wall or can be fixed on a stand. Immersion thermostats can also be fitted to a bridge and mounted permanently in a bath.

Immersion Cooler (TC®)
is an additional chiller with a flexible tube and a cooling coil (evaporator) for immersion cooling of any desired bath.

Industrial thermostats (UC®x-Hx)
are refrigerated circulators (Unichiller®) with factory fitted heating. The units have high cooling, heating and pump powers which allow quick cooling and heating rates due to the small internal volumes. They are ideal for temperature control in process technology, within a smaller temperature range (-20..120°C).

Interface, analogue
is used to input the set value or to output the actual value of temperature in analogue form, generally in the form of a current (0/4-20 mA or 0-10 V).

Interface, digital
is used to transfer data between connected units in digital form via data cable. The set and actual temperature values are the main items transferred. The serial RS 232 interface allows a point-to-point connection. This means that at anyone time only two participants such as the thermostat and the PC can communicate with each other via the interface. The RS 485 interface is an addressable interface where up to 32 participants can be connected. Each participant of the bus system has its address.

Net Cooling Capacity
is the effective capacity available in refrigeration thermostats or circulating chillers. This is the net cooling power of the unit after the frictional heat produced by the circulating pump and the heat entering as a result of non-ideal insulation has been subtracted.

Operating Temperature Range
is the temperature range that is limited by the permissible lowest and highest operating temperatures.

Pressure Pump
is used for circulation of the thermofluid in an extemal closed circuit and in the bath.

Pressure/Suction Pump
This pump has a pressure and a suction stage which are driven by the same motor. The thermofluid is delivered from the pressure stage from the thermostat into the circuit, and the suction stage draws the liquid back into the thermostat. A pressure/suction pump can be used in just the same way as a pressure pump for a closed circuit. lt has the advantage compared to a pressure pump that the pressure in the extemal circuit falls from positive values(pressure) in the flow line and to negative values (suction) in the return line and is almost zero in the application itself. Thus it is suitable for the hermoregulation of pressuresensitive glass vessels. Additionally it is possible to thermoregulate an open extemal circuit (e.g. a bath) with the aid of a pressure/suction pump. This cannot be done with a pure pressure pump, since this delivers thermofluid to the bath. The thermofluid can only be returned to the bath via a suction stage. In any case a so-called constant Ievel device is required to maintain a constant level in the bath and this ensures that the flows of both pump stages are controlled so that they are equal. This is the only way that the Ievel in the extemal bath can be maintained constant.

Process Control
(often cascade control) is when the temperature control is dictated by the temperature of the connected external application. A temperature sensor (often a Pt100, 4 wire configuration with a Lemosa plug) is therefore required in the external application, which is connected to the thermostat. The actual value measured at the external application is measured and a set point for the thermostat is continually calculated. Depending on the operating temperature, insulation losses and exothermic reactions, the bath temperature and thus the flow temperature of the thermostat can be considerably above or below the set point. (Always consider the safety limits of the fluid!!)

This is used in the refrigeration unit within the thermostat and extracts the heat from the thermoregulating liquid, when the compressed gas expands in the evaporator. Huber has been completely CFC free since 1992 and HCFC (e.g. R22) free since 1994. Huber uses only refrigerants which do no damage to the ozone layer (ODP Ozone Depletion Potential, ODP=0), and minimal Global warming potential (GWP, i.e. Green house effect)..

Refrigerated Thermostat
is a thermostat whose working temperature range is below the ambient temperature and draws heat from the thermal fluid. Huber refrigerated thermostats are strictly speaking cooling/heating thermostats, since their working temperature range is above and below the ambient temperature. Heat can be extracted from and added to the thermal fluid.

Refrigerated/Heating Thermostat
is 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.

Recirculation Thermostat (Unistat®)
is a thermostat in which thermal fluid is pumped through an open or closed external circuit. Recirculation thermostats e.g. the Unistats can have a thermally discoupled expansion vessel, whose surface temperature is not the operating temperature. They do not have an accessible bath. Unistats have a thermally discoupled active surface (expansion vessel), where by the surface temperature is not necessarily the same as the operating temperature.

Suction Pressure
is the negative pressure of the circulating pump of a thermostat directly at the pump suction. If only one value is given in the tables, then this is the maximum suction pressure for zero flow rate. Pump curves illustrate suction pressure in relation to the flow rate.

The safety requirements for electrical Iaboratory equipment, and especially also those for thermostats, have been defined in European standards EN 61010-1 and EN 61010-2-01 0, replacement for DIN 12879, among others. The terms and characteristic of characteristic data is defined in DIN 12876-1 and DIN 12876-2.

Safety Class
lt is possible to use non-flammable or flammable bath liquids with thermostats. The relevant safety requirements are given in DIN EN 61010-2-010. There is a distinction made between the NFL classes with built-in over-heating protection that are exclusively for non-flammable liquids and FL (flammable) with adjustable overtemperature protection and low level protection for flammable liquids (all Huber thermostats).

Temperature Homogeneity
is the temperature difference between the highest and the lowest measured temperature in a bath tank. In comparison with temperature stability it is determined not only over a defined time period, but also the spatial distribution of temperature within the bath. The temperature uniformity depends on various factors and is influenced for example by the nature and the viscosity of the thermal fluid, the level of circulation or by objects in the bath.

Temperature Stability
is the temperature difference between the highest and the lowest measured temperature divided by two. This value is determined at one point (e.g. the geometric centre of a bath tank or pump output) within a defined period of time (e.g. 30 min.). According to DIN 12876 the measurement must be made at 70 °C (with water) for a heating circulator and at -10 °C (ethanol) for a cooling circulator.

True Adaptive Control TAC
is a Huber designed dynamic adaptive controller that continually updates its PID parameters. The TAC controller constructs a virtual multidimensional model of the application in real time to cope with sudden changes in thermal load such a during an exothermic reaction.

Variable Pressure Control VPC
is an active pressure control capability that allows the operator to control to either a maximum set pressure or pump speed. Through this feature it is possible to maintain the highest HTF flow rates within application pressure limitations (e.g. glass reactors).

Working Temperature Range
is the temperature range which can be attained at an ambient temperature of 20°C by the thermostat alone and with the exclusive use of electrical energy. The operating temperature, that may only be reached by using auxiliary devices, is indicated in brackets.
In the case of a heating thermostat the working temperature begins above room temperature (as a result of the energy introduced by the pump and the effective insulation) and ends at the upper limit of the operating temperature.
In the case of a heating thermostat the working temperature begins above room temperature (as a result of the energy introduced by the pump and the effective insulation) and ends at the upper limit of the operating temperature.
The working temperature range of a refrigeration thermostat begins with the lowest operating temperature of the unit and finishes with the upper temperature at which the refrigeration machine can permanently operate.


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