New CO2 refrigeration technology

New refrigeration technology: what has changed, what has remained the same

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New refrigeration technology with more power in the low temperature range

Our new CO₂ refrigeration technology achieves a test chamber temperature of up to −50°C in our climate chambers and temperature chambers. It is more powerful in the low temperature range than the previous −40°C refrigeration technology. At the critical point of −40°C for many test standards, the new refrigerating units still provide considerable cooling capacity and heat compensation. Traditional, single-stage refrigeration technology can hardly cool test specimens below −30°C.

In all Weiss Technik test chambers, the previous −40°C refrigeration technology is being replaced by new CO₂-based refrigeration technology without changing the design, connections, and dimensions of the units. The environmental parameters also remain the same. Infrastructure such as cooling water, connectors, and accessories can continue to be used. Only a few technical parameters have changed.

Advantages of the new CO2 refrigeration technology

Power reserve

The performance parameters are determined with an empty test space according to IEC 60068-3-5. The cooling rate is specified in the range of 10–90% of the temperature range. Thanks to the CO2 low temperature of −50°C, the test chamber will maintain the specified cooling rate down to at least −27°C (temperature range 180°C to −50°C corresponds to 230 K. 10% is 23 K. −50°C + 23 K = −27°C).

Not affected by F-Gas Regulation

Natural refrigerants such as CO2 are not F-gases. The EU directives therefore do not apply to CO2 refrigeration systems. Many recording obligations, quota regulations, and repair regulations no longer apply. Leakage tests are required only according to EN 378 and no longer according to the GWP value. Carbon dioxide as a refrigerant is given a GWP of 1.

−70°C cascade refrigeration is often no longer necessary

Many relevant test standards such as IEC 60068-2 contain preferred temperatures (e.g. −40°C). At this temperature point, previous single-stage units with R449A no longer have any cooling capacity. Users had to resort to cascade refrigeration systems with two refrigeration circuits. These are complex and therefore more expensive. Our cost-effective CO2 refrigeration still has sufficient cooling capacity/heat compensation even in the low temperature range.

Noise level

Climatic chambers and temperature chambers are a source of noise in the laboratory. Compressors and switching valves generate a disturbing noise. Components for CO2 refrigeration technology are considerably smaller and quieter with the same output. The housing fan is now often the loudest component. Because it typically only runs sporadically, CO2 test chambers are barely audible. The noise level is regularly below 50 decibels (quieter than in the office).

Notes on CO2 refrigeration

New: Fuses with 300mA required due to frequency converters

The cooling water temperature remains the same: 12-28°C.

Ambient temperatures of up to 35°C are no problem.

The dimensions, size and footprint of all appliances remain the same.

The new Simpac 2.0 controller has a ring buffer, Linux, and NTP.

An electronic cooling water regulator allows a lower water pressure.

The new CO2 refrigeration technology can cool down to -50°C.

Power consumption and power consumption are lower than before.

Lower sound pressure level: CO2 refrigeration has smaller, quieter components.

IEC 60068-2-14 Nb: Sufficient heat compensation in the holding phase at -40°C. No cascade system necessary.

System pressure up to 120 bar, but significantly smaller cross-sections and volumes. No problem with the Pressure Equipment Directive.

CO2 has GWP1 and is not flammable.

Changes during commissioning

Practical limiting value

The maximum permissible gas concentration in an occupied zone is determined by the practical limit value. Carbon dioxide has a higher value than R449A. A unit requires 14 m³ of installation space (0.072 kg/m³) per kilogramme of CO2 filling quantity. Nowadays, typical areas for test chambers with a floor area of 2 × 3 m and a ceiling height of 3 m are still sufficient. Alternatively, a warning device can be fitted.

Leakage current

Our CO2 refrigeration systems use frequency converters to control the compressors. The resulting leakage currents sometimes exceed the usual 30 mA in households. Although our units do not have to be protected with RCDs, many electrical installations contain such a fuse. In these cases, we recommend the use of fuses with a tripping current of 300 mA as required by the manufacturers of the frequency converters.

S!MPATI® software

The convenient programming, control, and recording with our S!MPATI® software naturally also works with our new CO2 refrigeration technology. However, because the units are equipped with the new, improved S!Mpac 2.0 control system, additional port releases are required in the network.

Tightness test

In accordance with the EU F-Gas Regulation, leak tests are prescribed depending on the GWP value and the amount of refrigerant. CO2 is not an F-gas and is therefore not covered by this regulation. We recommend an annual leak test carried out according to DIN EN 378-4 in order to fulfil the requirements regarding protective measures for work equipment in accordance with the German Health and Safety at Work Regulations.

Comparison of the unit parameters

Parameter	previous −40°C class	new CO2 refrigeration
Refrigerant GWP	1397	1
Energy consumption		lower
Sound pressure level		quieter
Rate of temperature change, cooling guaranteed up to	−18°C	−27°C
Temporal temperature deviation	0.1–0.5 K	0.1–0.5 K
Spatial temperature homogeneity	0.5–1 K	0.5–1 K
Cooling water temperature	12–28°C	12–28°C
Ambient temperature	28/35°C	28/35°C
Footprint		identical
Installation room (practical limit value)	2.8 m³ per kg R449A	14 m³ per kg CO2
Pressure equipment category	None	None
S!MPATI® ports		additionally 62542 for ASCII 2050 & 2051

Currently available and next-generation units

Type / Test Space	-40°C class (not available from 2025 anymore)	CO2 class (available)	-70°C class (available)
LabEvent (temperature / climate)
20 litres		on request	--
34 litres	5 K/min	4 K/min (-40°C)	5 K/min (-70°C)
64 litres	3 K/min	3 K/min (-40°C)	3 K/min (-70°C)
100 litres	5 K/min	4 K/min (-50°C)	3 K/min & 10 K/min (-70°C)
150 litres	5 K/min	4 K/min (-50°C)	3 K/min & 10 K/min (-70°C)
110/210 litres	3 K/min	3 K/min (-50°C)	3 K/min & 5 K/min (-70°C)
500 litres	3 K/min	3 K/min (-50°C)	3 K/min (-60°C)

ClimeEvent & TempEvent
180 litres	3 K/min & 5 K/min	3 K/min	3 K/min & 5 K/min
340 litres	3 K/min & 5 K/min	3 K/min	3 K/min & 5 K/min
600 litres	3 K/min & 5 K/min	4 K/min	3 K/min & 5 K/min
1000 litres	3 K/min & 5 K/min	10 K/min	3 K/min & 5 K/min
1500 litres	3 K/min & 5 K/min	7 K/min	3 K/min & 5 K/min
2000 litres	3 K/min	on request	3 K/min
270 litres	10, 15, 20 K/min	2025	202510, 15, 20, 25 K/min
480 litres	10, 15, 20 K/min	2025	10, 15, 20, 25 K/min
800 litres	10, 15, 20 K/min	2025	10, 15, 20, 25 K/min
1300 litres	10, 15, 20 K/min	2025	10, 15, 20, 25 K/min

XXL 1600 litres	3 K/min & 5 K/min	>4 K/min (-50°C)	3 K/min & 5 K/min
XXL 2450 litres	3 K/min & 5 K/min	>3 K/min (-50°C)	2 K/min & 4 K/min
XXL 3400 litres	3 K/min & 5 K/min	>2 K/min (-50°C)	2 K/min & 4 K/min

Walk-in (9m³ - 21m³)	2 K/min	>2 K/min (all -50°C)	>2 K/min (all -70°C)