Company Announcement - South Africa’s increasing electricity costs are forcing companies with cold storage facilities to re-examine the efficiency of their environmental control, and managers involved in maintaining the cold chain will increasingly have to seek the best possible sealing solutions for cold storage rooms. One company well positioned to help customers meet their energy saving targets is DDL Equipment, whose Frigo rigid motorised traffic doors, manufactured by European company Nergeco, allow high traffic while delivering one of the most efficient insulation barriers available.

The commonly encountered flexible door curtain rolled up around a drum fitted above the lintel is not ideal because of the ice layer which seizes the door when hot air meets cold during door activation, preventing the curtain from unrolling smoothly upon closure. Nergeco’s alternative (and safe) solution to this problem is to incorporate horizontal stiffening tubes into the flexible curtain of the Frigo door, to press the sides of the curtain firmly into vertical guides on both sides of the door frame.  This results in an airtight curtain with an even resistance to air pressure, and no need for any heavy bottom beam for smooth closure.  There is also no need for the potentially dangerous heavy steel bar often found attached to the bottom of roll-up door curtains, to overcome the friction of the ice layer.

Frigo doors are divided into three broad categories.

Frigo I is designed to separate two below-freezing cold storage areas with only a small temperature differential.  The speed of operation of the roll-up curtain is 1,2m/s, allowing for short opening and closing times while the tight seal within the frame maintains the airtight barrier between the two areas without any danger to pedestrians.  The design facilitates high traffic while preventing air draughts and ice deposits, and the curtain’s flexibility prevents product damage due to impact. 

Frigo II separates a refrigerated (above freezing) storage area from a storage area at room temperature.  Additional insulation is added by welding air cushions between the curtain’s flexible fabric double skin.  The curtain, airtight within its frame, folds up quickly to provide low heat and cold loss, preventing air draughts and ice deposits while allowing high traffic.  Activation is wear-free since the curtain is held deeply within the guides and friction is kept to lowest values. Frigo III separates a below-freezing storage area from either a refrigerated storage area or a warm storage area.  The Frigo III curtain has the highest level of insulation in the range, achieved by welding two air cushions between a folding, flexible triple-skin fabric curtain, which ensures a tight seal to all four sides of the frame to establish an airtight barrier.  It is further designed to prevent warm air from going over the curtain by means of a patented sealing system which prevents air draughts and ice deposits while facilitating high traffic.  Curtain icing is kept under control through a combination of insulation properties, airtight design and above-freezing door frame temperature.

A spectacular example of the capabilities of the Nergeco product range can be found at Montbartier in France, where the 90 000m2 Grand Sud logistics platform processes 50 million fresh fruit, fresh vegetable and frozen packages each year, requiring intense logistical flows to be carried out between the external ambient temperature and two controlled temperatures of -25 and +7 degrees C.

Based on the design principle of the double wall, the freezer and chilled product areas are insulated from the external skin by air locks, gas loading areas and movement areas opening onto the packaging section. When Montbartier was being planned, the insulation between these various units operating at separate temperatures and relative humidities was to have been handled by a combination of high-speed flexible doors with composite frames, air curtains and automatic isothermal sliding doors sourced from several different suppliers.

However, the commissioning company decided to seek out a single supplier of high-speed flexible doors offering a range able to cover the multiple configurations on the site, and Nergeco was chosen to supply all 27 doors at Montbartier.

Very large Star folding productivity doors protect the building from the outside, while corrosion resistant doors from the multi-composite framed Agro range are installed in the positive ambient fruit and vegetable areas.  There are also two Enduro doors to divide the building between dry and fresh products.

At the heart of the cold chain are various models of Frigo doors fitted with flexible curtains and one, two or three walls depending on the refrigerated areas they need to separate.

The complete Frigo range is sold and supported in South Africa by DDL Equipment, alongside Agro, Star and Enduro doors.