The doors of industrial medium- and low-temperature refrigerators and freezers, or, as they are more often called, refrigeration doors, are quite complex autonomous devices of various designs, designed to provide maximum thermal insulation. Therefore, their most important element, in addition to the heat-insulating materials laid directly in the plane of the doors themselves, are the end seals made of frost-resistant rubber, located around the entire perimeter.
Depending on the design and purpose, the doors of the heat and cold chambers can be equipped with additional equipment in the form of heating systems, inspection windows, pressure stabilization valves, etc. And since industrial refrigeration chambers and refrigerated warehouse terminals are large-volume premises, and their doors, Due to their impressive size, they experience significant mechanical loads, so they are equipped with fairly strong hinges, lever-type locks and other fittings designed for use in extreme conditions. In addition, the opening and closing of the refrigeration door can be done either manually or using an electric drive.
In essence, any refrigeration door is a thermally insulating sandwich panel, framed on both sides with metal sheets made of stainless steel, chrome-plated or painted with special enamels. Thermal insulating panels can vary in thickness, which also determines the thickness of the door itself. To ensure a tight fit of the refrigeration door to the frame of the opening, frost-resistant end replaceable rubber-magnetic seals are used, which are installed in two rows in low-temperature chambers. To prevent freezing of the seals and the formation of ice crust, which can lead to loss of sealing properties, the end perimeter of the refrigeration door is equipped with electric heating elements. Compensation for the pressure difference inside and outside the chamber is provided by stabilizing valves. The locking devices provide an emergency door unlocking function from the inside and an emergency alarm button: this eliminates the possibility of accidents if there are people left inside the chamber after closing the door.
By type, refrigeration doors are divided into swing and sliding. Hinged doors for the refrigerator compartment - single or double leaf - are hinged and open outward. Their dimensions vary in width from 800 to 1500 mm, in height - up to 2000 mm.
Sliding doors for the refrigerator compartment are opened by sliding to the right or left along the guides. As a rule, they are used in industrial warehouse refrigerators that have large door openings and are therefore more massive and expensive to manufacture. Their dimensions in width are 2000-2400 mm, in height - up to 2400 mm.
As additional equipment to enhance the thermal insulation properties, the doorway of the refrigeration chamber can be equipped with a strip or roll-type curtain installed from the inside and preceding the door of the refrigeration chamber. To make such curtains, PVC films are used. In this case, strip curtains have the form of mutually adjacent, overlapping transparent flexible strips attached to the doorway from above; the tapes easily diverge to the sides and do not interfere with the movement of people and equipment. Roller curtains are automatic and are designed for refrigerated terminals with intense cargo flows. To raise and lower them, carried out remotely, high-speed roll mechanisms are used, ensuring uninterrupted and, most importantly, fast operation, which reduces thermal losses to a minimum.
There are also air curtains, the operating principle of which is based on the fact that thermal insulation is provided by a directed air flow forced by compressors, which prevents heat from penetrating into the refrigeration chamber from the outside when the door is open.
