LAUDA Alpha RA 8 Cooling Bath, -25 to 100 °C, 5 to 7.5-litre Bath, L004603

Anyone who needs to maintain precise temperatures for small volumes in the laboratory, for example, when calibrating a viscometer, cooling a cuvette in analytical chemistry, or operating a small external reactor, requires a bath that can quickly reach sub-zero temperatures and takes up little floor space. With its 5.0 to 7.5-litre stainless steel bath, the LAUDA Alpha RA 8 caters precisely to this market segment. The operating temperature range extends from -25 to 100 °C, with cooling provided by a built-in compressor using the natural refrigerant R-290.

Compressor cooling with automatic control

The RA 8 actively cools via a built-in compressor; there is no need for an external cooling water connection or an additional circulation cooler. An automatic compressor control system switches the compressor on and off as required, which extends its service life and reduces energy consumption during continuous operation. The unit dissipates heat into the ambient air via an air-cooled condenser.

Cooling capacity across the operating range

With ethanol as the bath medium, the RA 8 delivers a cooling capacity of 0.325 kW at 20 °C, 0.26 kW at 0 °C, at -20 °C it is still 0.1 kW, and at the lower limit of -25 °C it is 0.07 kW. The maximum heating power is 1.5 kW, the total power consumption is a maximum of 1.8 kW, and the current draw is 8 A. LAUDA specifies the temperature stability as ± 0.05 K; a 1-line LED display and a fully electronic, continuous controller handle the display and control functions.

Circulation pump for external loads

A bath lid, a pump connection set and a short-circuit hose are supplied as standard. The built-in circulation pump delivers up to 15 L/min at a maximum pressure of 0.2 bar and can therefore also be used for small external loads such as a double-jacketed reactor or a cold trap. A drain connection on the rear facilitates the replacement of the bath medium.

Safety during continuous operation

Low-level protection and over-temperature protection monitor operation; in the event of deviations, the unit triggers an audible and visual alarm. The stainless steel bath vessel, with internal dimensions of 165 x 177 x 160 mm, is suitable for small batches of samples; the entire unit weighs 29 kg and measures 235 x 500 x 605 mm (W x D x H).

Typical applications

• Calibration and testing of viscometers at defined sub-zero temperatures
• Temperature control of cuvettes and small sample vessels in analytical applications
• Cooling of small external reactors or double-jacketed vessels via the circulation pump
• Training and routine operation where only a small bath volume is required

Selection guide within the Alpha series

If the bath volume of the RA 8 is insufficient for several vessels or a larger external load, the LAUDA Alpha RA 12 (9.5 to 14.5 l) and the LAUDA Alpha RA 24 (14 to 22 l) are available as two larger sister models with the same operating temperature range. If no active cooling is required at all, the LAUDA Alpha A 6 heating thermostat meets the same temperature control requirements without a built-in compressor.

Technical details

Scope of delivery

• LAUDA Alpha RA 8 cold bath thermostat with stainless steel bath vessel, order number L004603
• Bath lid
• Pump connection set
• Short-circuit hose for pump connections
• Mains cable with angled Schuko plug (CEE7/7)
• Operating instructions as a PDF download

Regulatory information

This device is an electrical appliance within the meaning of the German Electrical and Electronic Equipment Act (ElektroG). The WEEE registration number of the manufacturer, LAUDA DR. R. WOBSER GMBH & CO. KG, is DE 66424057. Information on the return of end-of-life equipment can be found on our Environment and Disposal page.

The appliance operates using the natural refrigerant R-290 (propane), with a charge of 0.052 kg and a GWP of 3. LAUDA states the CO2 equivalent as 0.0 tonnes.

Warranty and procurement service

LAUDA DR. R. WOBSER GMBH & CO. KG, Lauda-Königshofen, offers end customers a 5-year ‘Best’ warranty on this unit, effective from the date of delivery. This is subject to registration at lauda.de within three months of delivery and the use of genuine LAUDA temperature control fluids. The warranty covers material and manufacturing defects. Exclusions include, amongst others, wear parts such as filters and seals, damage caused during transport, damage resulting from unauthorised tampering, as well as cables, plugs, hoses and adaptors. LAUDA’s warranty terms and conditions (as at 03/2025) apply. Your statutory warranty rights remain unaffected.

For the RA 8, LT Laborhandel’s procurement service can, if required, put together suitable accessories, such as a temperature-control fluid for operation down to -25 °C, an additional bath lid or hoses for the external pump connection. We can also request spare parts from the manufacturer on your behalf.