ACC, Active Cooling Control
ACC is the working temperature range in which the refrigeration
system remains active as long as refrigeration is desired or required.
For all JULABO units the working temperature ranges are equivalent
to the ACC range. Thus the refrigeration system can also be
used at high temperatures (e.g. +200 °C) for a fast cool-down.
Access Rights
are the regulations deciding user access rights to functions and
features of a JULABO temperature control unit. The new PRESTO®
series is the line with the most extensive access possibilities: they
feature three user levels with password protection.
Air Cooling
If temperature control systems have a refrigeration unit, the heat
created by refrigeration must be dissipated. In the case of aircooled
units the heat is dissipated via the condenser of the
cooling machine into the ambient air. The air inlet of JULABO units
is always at the front. Heated air is dissipated at the back. Other
equipment placed on the sides of JULABO units will not be affected.
Ambient Conditions
All JULABO units can be operated at ambient temperatures
between +5 °C and +40 °C. The performance data as stated by
JULABO is based on ideal ambient conditions


Bath Fluids
are mainly selected for their temperature range. The limiting factors of the temperature range are viscosity, fire point, and flash point. Water: JULABO recommends the use of soft and decalcified water for working temperature ranges from +5 °C to +90 °C. Distilled and deionized water tends to absorb composites from components, thus causing corrosion. Alcohols (e.g. Ethanol): Due to their very low fire point these are only partly suitable. For working temperature ranges to -25 °C a water-glycol-mixture (1:1) can be used. JULABO Thermal bath fluids: are ideal for extended working temperature ranges and have the advantage of much lower specific heat capacities than water and alcohols.
Bath Opening/Bath Depth
is the size of opening which is available for immersing objects or samples into the bath. Usually bath depth is mentioned along with the bath opening.
BlackBox Function, Remote Diagnosis
JULABO circulators with RS232 interface feature a black box which is integrated in the unit and is activated unnoticed in the background recording all relevant data during operation. In the event of a problem the data can be downloaded and sent to JULABO by e-mail. This allows for fast and efficient support. The software Easy BlackBox is available as a free download from


Calibration Bath
is a bath circulator with extremely high temperature stability and uniformity (homogeneity). Typical applications are calibration tasks, gauging, and testing of temperature sensors, thermometers, etc.
Capacity Calculation, cooling/heating
The following formula can be used for a time-dependent calculation of the cooling/heating capacity: Q = (m * c* dT) / t Q = required cooling/heating capacity in kW m = mass of material in kg c = specific heat capacity (water = 4.2 / Ethanol = 2.5 / silicone oil = 1.8) dT = required temperature difference in °C t = desired cool-down/heat-up times in seconds One has to take into consideration that the total mass (m) is the sum of volumes of different sources: e.g. the mass of the circulator, the volume of the tubing, the volume of the reactor's jacket, and the volume of the reactor. The simple calculation of required cooling/heating capacity as seen above does not take into account differences in weight of the bath fluid or other factors reducing performance. Loss of performance is caused e.g. by: tubing (length, insulation), jacketed reactors (material, thickness, surface), high ambient temperatures, open applications (surface). To supply sufficient cooling/heating capacity a safety factor of 20-30 % should be added.
Classification according to DIN 12876-1
In temperature control instruments, flammable or non-flammable bath fluids may be used. Terms and classifications are specified in DIN 12876-1. JULABO units are part of the following classification: S1: class I: NFL, for non-flammable bath fluids. Units of this class feature a temperature limiting function called ‚overheating' protection. S3: class III: FL, for flammable bath fluids. Units of this class feature an adjustable high temperature cut-off and an additional low liquid level protection. For many models JULABO offers additional protection which clearly exceeds standard requirements.
is a laboratory circulator. Its bath fluid is circulated through a closed- or an open-loop.
Cool-down/heat-up times
are the times to reach a defined setpoint. When using JULABO Thermal bath fluids these times are shorter than when using water or alcohol. The reason is their significantly lower and better specific heat capacities.
Cooling Control, proportional
Refrigerated units without proportional cooling have refrigeration systems which are either switched on or off. Systems with proportional cooling have a special electronic valve which automatically controls the cooling capacity. This allows for accurate control of the required cooling power and at the same time saves energy (up to 90 %) and waste heat.


Data Recording, Data logging
JULABO circulators with the appropriate interface can be connected to a PC or a PLC. The JULABO software EasyTemp or a software programmed by the user permits data logging.
DIN 12876
is the German Industry Standard for laboratory circulators and baths. It defines product categories and technical specifications. Display Depending on the model JULABO units are equipped with different displays:
  • LED display to indicate actual and setpoint value.
  • Multi-Display (LED) to indicate actual and setpoint value as well as values high/low temperature warnings and high temperature cut-off. Depending on the model it is possible to display additional values (e.g. pump capacity stages, shaking frequency, etc.)
  • LCD display for easy, interactive user guidance with continuous text display
  • VFD Comfort Display for permanent, simultaneous indication of three temperature values (internal actual temperature, setpoint temperature and external actual value) and the pump stage.
  • TFT Touchscreen: The new PRESTO® series is equipped with 5.7"color industry touchscreens. The intuitive operation provides a fast learning curve.


Early Warning Systems
1. The early warning system for low liquid level: the lack of bath fluid is often the reason for a premature, undesired cut-off caused by the low liquid level protection. Depending on the application, such a cut-off might lead to damage to the objects or samples. The JULABO Early Warning System was designed designed to avoid this situation by indicating to the user that bath fluid needs to be refilled.
2. The early warning system for high/low temperature detects and signals undesired temperature deviations (e.g. due to exothermic reactions in time).
=> see Software, control
=> see Interfaces
External Sensor
is a Pt100 sensor which can be applied inside or outside the object being controlled. The sensor is connected to the temperature control unit via a cable. This permits direct measurement and control of an external system.


=> see Bath Fluids
Feed Pressure
is the pressure applied to the pump connection of the circulating pump. If there is only one value indicated in the technical specifications, it is the maximum feed pressure at flow rate zero. The diagrams show the suction in relation to the flow rate.
Feed Suction
is the suction applied to the intake of the circulating pump (pressure/suction pump). If there is only one value indicated in the technical specifications it is the maximum suction at feed pressure zero. The diagrams show the suction in relation to the flow rate.
Filling Volume
is the amount of bath fluid needed for proper operation. The value does not include the amount of fluid which is possibly needed in an external loop. If there are two values stated for the bath volume the smaller value stands for the required minimum amount and the higher value stands for the maximum amount.
Flow Rate
is the volume of liquid per time unit which is moved by the circulating pump. If there is only one value indicated in the technical specifications, it is the maximum flow rate at counter pressure zero. The diagrams show the flow rate in relation to the pressure.
Flow-Through Cooler
is often used as a substitute for cooling with tap water. A flowthrough cooler is an uncontrolled cooling unit without a circulating pump. The unit is installed into the external temperature loop in order to cool down the bath fluid. For applications using heating circulators, lower temperatures and/or faster cool-down times can be achieved.



Heating Capacity
is the maximum electrical capacity of the heater which is installed in the unit. The heating capacity is controlled continuously and reduced when getting closer to the pre-set setpoint.
Heating Circulator
is a circulator with a working temperature range that is mainly above ambient temperature and provides heat for the bath fluid.
Heating Immersion Circulator
is fixed with a bath attachment clamp to any bath tank. The bath tank is not included in delivery.
Highly Dynamic Temperature Control Systems
This product group contains model series which have been designed for external temperature control application only (PRESTO®, Magnum91 and Forte HT). Unique features are the extremely rapid heat-up and cool-down times and the unusually wide temperature ranges while using only one type of bath fluid, e.g. Thermal HL40 from -40 °C to +250 °C.


ICC, Intelligent Cascade Control
This is a highly precise PID Cascade Control which was designed for perfect results. The ICC Temperature Control is self-optimizing, i.e. the control parameters automatically adjust to the application.
Immersion Coolers
Immersion coolers are cooling devices with an immersion probe. This is fixed to a flexible tubing and can be used to cool down fluids in any bath tank. JULABO immersion coolers are optionally available with temperature control and display.



LCD Display
=> see Display
LED Display
=> see Display


Main Fuse Protection
The required fuse protection depends on the respective unit. In general the fuse protection has to be higher than the current consumption of the unit which is stated on the type label. When using a cooling machine, one must keep in mind that upon compressor start up the current draw might be three to five times the nominal current draw.
Mains Voltage
Information on mains voltages and net frequencies required for safe operation can be found on the type label of each unit.
Metal Tubing
=> see Tubing
=> see Interface
=> see Display


Noise Level, Sound Pressure Level
is the acoustic emission of a unit. Sources of noise within the unit are, e.g. the type of counter cooling as well as the ventilation of electronic components. The sound pressure level of JULABO units is determined according to standards, i.e. measurements are made with highly sensitive measuring sensors in the distance prescribed by the standards. The measured values are listed in the chapter 'Technical Specifications' or you can contact JULABO directly.


Open Bath Circulator
are circulators with a bath opening for the insertion of objects for direct temperature control in the bath. A circulating pump with pump connection for an external loop is included.
Open Heating Bath Circulators
are circulators with a circulating pump and an open bath tank. The objects or samples are placed directly into the bath. The circulating pump is used to circulate the bath fluid. Pump connections for an external loop are typically not included.
Operating Temperature Range
is the temperature range limited by the permitted minimum and maximum operating temperature. The adjustable operating temperature range corresponds to the temperature range determined by the control electronics.


Password Management

=> see Access Rights

PID Temperature Control

JULABO PID1, PID2, and PID3 controls offer fixed control parameters (Xp, Tn, Tv). These can be changed manually with PID2 and PID3 controls to reach an improved temperature stability especially for external temperature control.

Pressure Pump

is used for the internal circulation of the bath fluid in the bath tank and may additionally be used for fluid circulation in an external temperature loop. Pressure pumps are most frequently used in JULABO units.

Pressure/Suction Pump

Units equipped with a pressure/suction pump (e.g. circulators of the HighTech series) are equipped with two pumps that complement one another. While the pressure pump pumps the fluid from the internal bath tank into the external system, the second pump sucks the fluid through a return line into the bath. Each pump has its own capacity. Therefore, there are two separate values for the pressure and suction capacities stated in the technical specifications. Advantage: an especially high flow rate.


=> see Highly Dynamic Temperature Control Systems


=> see Interfaces

Pump Systems

JULABO uses immersion pumps which are designed to work virtually free from mechanical and thermal wear over extended time periods. The main task, beside the internal circulation of the bath fluid, is to constantly supply objects or systems with bath fluid in a loop. The units of the TopTech series as well as JULABO recirculating coolers, feature pressure pumps of different capacities for closed, external systems. MA and ME feature electronically adjustable pump capacities in stages. All HighTech circulators feature pressure and suction pumps which can also be adjusted electronically in stages. These pump systems can achieve remarkable pressure, suction and flow rate capacities in closed or open external systems. When working with a connected external glass apparatus the advantage is that by adjusting maximum pressure, damage to the glass vessel can be avoided. The new PRESTO® (except A30) feature pumps which can be adjusted in four stages via a pressure setpoint. In connection with the VCFpro the flow rate in liters per minute can be controlled.


Recirculating Coolers
are cooling units which are often used as substitutes to cooling solutions with tap water. They usually do not have an accessible bath. The units are equipped with a strong circulating pump with connections for an external application.
The refrigerant is pumped through a hermetically closed cooling cycle of a cooling machine and withdraws the heat from the bath fluid. For years JULABO has been using environmentallly-friendly refrigerants which are CFC-free. Alternatively, JULABO offers units with natural refrigerants.
Refrigerated and Heating Circulator
is a circulator with a working temperature range above and below ambient temperature. The circulator can either heat up the bath fluid or cool it down.
=> see Interfaces
Remote Diagnosis
=> see BlackBox Function


Software, Control
The JULABO software solutions offer the possibility to easily control, display, and record temperature and time related processes. EasyTEMP, which is available free of charge, is ideal for simple control tasks of just one JULABO unit. For complex tasks JULABO offers the EasyTEMP Professional software.
Systems, external
When connecting an external system, the following points have to be considered for optimal temperature control: 1. Tubing between the circulator and the external system has to be kept as short as possible and has to be secured. 2. Tubing, connections, and the external system have to be well insulated. 3. Use suitable JULABO bath fluid. 4. The exchange of energy between the circulator and the external system has to be optimized (e.g. by avoiding constrictions in the tubing). 5. When using an external temperature sensor, it has to be integrated into the system. 6. The viscosity of the heat transfer liquid has to be kept to a minimum.


TCF (Temperature Control Features)
The TCF Temperature Control Features allow access to all important control parameters. Thus, the user has full control over the control dynamics and can execute manual optimization. The following functions are available: 1. Band limit: When working in external control mode, this function allows the user to limit the difference between internal and external temperature to freely selectable values. Advantages: Protection of the objects or samples through careful temperature application, e.g. protection of glass reactors from thermal shock. 2. Control dynamics: Option to choose between aperiodic and normal PID behavior when using internal control mode. Aperiodic (factor setting): Perfect, but takes slightly longer to reach the setpoint without overshooting. Normal: reaches the setpoint fast but with minimal overshooting. 3. Limit settings. The limits "IntMax" and "IntMin" are applicable only when operating in external control mode. Fixed temperature limits (maximum and minimum values) can be set for the internal bath temperature. These limits cannot be exceeded by the controller. Advantages: Protection against overheating; Freezing protection when water is used in refrigerated circulators; Protection against unintended high temperature cut-off 4. Co-speed factor: This parameter influences the time for reaching the setpoint temperature when working in external control mode. Increasing the co-speed factor reduces the time to reach the setpoint but the possibility of overshooting increases.
Temperature control tubing
=> see Tubing
Temperature Uniformity
is the maximum difference in temperature at different measuring points in the circulator bath. This is especially important for calibration tasks. In JULABO circulators the temperature uniformity differs only slightly from temperature stability. Calibration baths offer the best temperature unifomity.
Temperature Stability
is the maximum difference in temperature at one specific measuring point in the circulator bath. The temperature stability is the maximum deviation of a temperature nominal value measured during a certain period of time and is listed in the catalog for every JULABO unit.
Temperature Control
=> see PID, ICC, TCF
TFT Touchscreen
=> see Display
Transparant Bath Circulator
is a circulator with transparent walls which allows direct monitoring of the objects and samples placed into the bath.
When used in the proper temperature range JULABO tubing is dependable, extensively chemically resistant and long lasting when used with the recommended JULABO bath fluids. Available tubing: 1. CR Tubing: for working temperatures from -20 °C to +120 °C 2. Viton tubing: for working temperatures from -50 °C to +200 °C 3. Metal tubing, flexible, single insulated: for working temperatures from -50 °C to +200 °C 4. Metal tubing, flexible, triple insulated: for working temperatures from -100 °C to +350 °C Metal tubing is tightly screwed onto the circulator or external system to avoid displacement.


Usable Bath Depth
is the depth which is available in the bath circulator for temperature control applications.
User Guidance, interactive
JULABO Circulators of the HighTech series (except for HE, SE) as well as the highly dynamic temperature control system Presto PLUS®, Magnum 91 and Forte HT feature an additional 4-line LCD Display in addition to the standard temperature display. All displays, messages and menus are shown as an easy-to-read text. The new generation of the highly dynamic temperature control systems PRESTO® guides the user via a comfortable TFT Touchscreen.
=> see Interfaces


VFD Comfort Display
=> see Display
describes the fluid thickness. High viscosity means low flowability and low viscosity means high flowability.


Warranty, Warranty Period
Standard warranty for all JULABO units is 12 months. The 1PLUSWarranty gives users the opportunity to extend the warranty up to 24 months, limited to a maximum of 10,000 operating hours. Registration for 1PLUS-Warranty is available at:
Water Cooling
When temperature control systems have a cooling machine the heat created by refrigeration must be dissipated. In case of watercooled units the heat is dissipated to the cooling water (tap water or industrial cooling water) via the condenser of the refrigeration unit. The advantages of water cooling are low noise level and almost zero emission of heat.
The WirelessTEMP® product range allows wireless monitoring and control of JULABO temperature control instruments from a large distance, thus allowing a great variety of operation possibilities. Typical scenarios are e.g. operation of a temperature control unit underneath a fume hood, in a shielded hazard zone, or at locations that are hard to access.
Working Temperature Range
is the temperature range within the operating temperature range which can be reached by the circulator without external cooling at an ambient temperature of +20 °C. The working temperature range for heating circulators starts between +5 °C to +25 °C above ambient temperature. By using a cooling coil (cooling water) or a cooling device the temperature range can be extended towards ambient temperature.





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