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Size & Metering Plate Configurations
ARINC 404 Size Configurations
ARINC 404 avionics equipment comes in a variety of sizes which fit within a short or long box configuration and are designated as a fraction of a basic 1 ATR box size in width (1/4ATR, 3/8ATR, 1/2 ATR, etc.). In meeting ARINC standards, tray sizes are designated in the same manner as avionics equipment. In other words, ARINC 404 equipment sized at 3/4 ATR will need a 3/4 ATR mounting tray.
To ensure successful equipment installation, trays are designed to accommodate the proportion variances of avionics equipment by adopting short/short, short/long and long/long size configurations. These configurations will allow for different proportioned equipment to be installed side-by-side on the same shelf. For example, short avionics equipment will require a short/long tray when mounted on the same shelf as long equipment. Using similar terminology, industry height configurations for avionics equipment and trays are normally designated as dwarf, short, medium and tall.
When specifying mounting trays, it is important to know the equipment width, length and height. By matching your equipment size to the charts on the following pages you will be able to determine the proper tray size for your needs.
Metering Plates
ARINC 404 trays that are mounted on forced air cooling shelves will require a metering plate to regulate the movement of air. Metering plates are mounted in a deformation in the tray bottom, sealed with a gasket, and equipped with metering plugs to regulate air flow as needed.
Inlet holes for ECS metering plates run 0.38" in diameter for 1/4 ATR ARINC 404 trays and 0.81" in diameter for all other ARINC 404 tray sizes.
The metering plate diagram above illustrates typical ARINC cutouts and metering plate sizes. Contact the ECS Customer Service department if you need additional size or cooling information for putting together a design analysis.