When a cold room door opens, cold air pours out at the bottom and warm, moist air rushes in at the top. Over a busy day of deliveries and stock picking, that exchange adds a large load to the refrigeration system and brings moisture that turns to frost on the coils and floor. A strip curtain hangs just inside the door frame and closes behind people and trolleys as they pass, sharply reducing that exchange.
Strips come in different widths and thicknesses, with overlaps sized to the doorway and traffic. Freezer-grade strips stay flexible at low temperatures; standard PVC can stiffen and crack in a freezer. Strips need regular cleaning because they are touched constantly, and damaged or missing strips should be replaced, since gaps defeat the purpose.
A dairy distributor in Ludhiana loading crates from a chiller room into vans every morning might keep the main door open for long stretches. With a strip curtain in place, the room holds temperature better during loading and the evaporator frosts up less.