Unique (Flughafen Zürich AG) converted the first air conditioning unit in an office building at Zürich airport to non-ozone-depleting DuPont™ ISCEON^® MO29 (R422D) in May 2009. The work was carried out by Walter Wettstein AG Kältetechnik, of Gümlingen, Switzerland, a contractor with previous experience of working with the R22 alternative refrigerant.

The water chiller unit is one of three used to air condition the so-called Operation Center 1 at Zürich airport. The nine-storey building, which is situated directly next to Terminal 1, has a total floor space of 38,000 m². The conversion of the two remaining units is due to be completed before the end of 2009. By doing so, the company is seeking to avoid future bottlenecks at suppliers and refrigerant specialists following the service ban on virgin HCFC refrigerants, which will be imposed by the Swiss Federal Office for the Environment (FOEN) as of 1 January 2010 (equivalent to the EU decree 1005/2009).  

Thorough preparation ensured that the conversion of the Sulzer Escher Wyss LQD 450 kt 5.5 unit (built in 1984, four semi-hermetic piston compressors, bypass evaporator with dry evaporator, 1 water-cooled tube bundle condenser per circuit) occurred without a hitch. Following removal of the R22 refrigerant, the service technicians replaced the O-rings and filter driers and installed a new, higher performance expansion valve.

As an additional measure, the original mineral oil was exchanged for POE oil of the same viscosity (single change and no need to flush), to remove any potential oil return problems. Following evacuation and leak testing of the unit, it was refilled with ISCEON® MO29 and restarted. 

A comparison of performance data before and after the conversion revealed a tolerable reduction in refrigeration performance. Following the identification of small leaks in the connection ducts during operation, the technicians replaced the relevant seals. Otherwise, no other anomalies were recorded. According to Unique (Flughafen Zürich), the converted chiller unit operated without problem over the summer months. As a next step, the conversion to ISCEON^® of the two remaining R22 units, located in the same service room, is due to be carried out before the end of this year.

The decision to use ISCEON^® MO29 as a replacement refrigerant was based on the recommendation of DuPont. The company’s specialist supported Unique every step of the way and provided comprehensive literature on how to carry out a retrofit.

Chiller unit technical data:

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