Vertical air curtain plus existing high-speed roll-up door cuts monthly energy and maintenance costs

When an eastern Ohio food processor sought to curb exorbitant energy losses and icing maintenance costs at its cold storage freezer doorway, industrial door equipment dealer Fairborn Equipment Company, Ohio, reportedly solved the challenge with a customised air curtain installation. Revealing this as a case study, the company gave details of how the challenge was overcome.

Case study:

The client had already installed a high-speed, insulated rollup door that reduced -5°F freezer air emigration and 60 to 95°F summertime ambient air infiltration from the shipping door area, which was 50 feet away. Despite the high-speed door, humid ambient air still infiltrated through the top of the 12 x 12-foot doorway during its hundreds of daily cycles, causing energy losses combined with maintenance costs amounting to thousands of dollars per month. The greatest concern was a freezer temperature fluctuation of eight degrees, which was unacceptable to the client’s internal product quality, refrigeration equipment wear-and-tear and energy conservation standards.

Besides energy losses, humidity infiltration also required periodic ice removal from the ceiling-hung ammonia refrigeration system’s piping, coils, valves and controls just inside the 20,000-square-foot freezer’s doorway. The fire door roller tracks also were continually iced. Additionally, there was a potential hazard of forklift accidents due to icy floors near the threshold, which also required ongoing maintenance.

Fairborn co-opted the services of Berner International Corporation, an air door/air curtain equipment manufacturer, which recommended installing the air curtain vertically. Because the unit was originally designed for horizontal mounting, Berner’s engineering department modified the air discharge nozzles to produce a thinner, higher velocity air stream, so that the air curtain reached the volume, velocity and uniformity required to seal a doorway. The modification helped minimise doorway air balance issues between adjoining rooms with significant temperature differentials that are inherent in cold storage facilities.

The freezer door activation was executed with the following sequence:

• A Falcon motion sensor, manufactured by BEA, Pittsburgh, detects an oncoming forklift and activates the air curtain, which needs one second to ramp up to full air velocity.
• A second Falcon sensor activates the rollup door, which opens after the air curtain is at full velocity.
• After the forklift passes through, the door closes and the air curtain shuts off one second later.

Fairborn claimed that the customised air curtain installation has reduced the eight-degree freezer temperature fluctuation to less than two degrees, the ice maintenance costs have been significantly reduced and the potential for slippery floors has been eliminated, claimed Fairborn.