This standard was developed primarily for passenger and truck application@ but may be used in marine@ industrial@ and sim applications. Purpose-The purpose of this standard is to provide dimensions for the different pressure ratings of radiator pressure caps and filler necks. Use of these dimensions will preclude the use of a high pressure rated cap on low pressure system. This standard will allow use of a low pressure rated cap on a nominal high pressure system. Design of some foreign manufactured pressure caps and filler necks not made to this stand will allow the installation of a high pressure cap on a low pressure syst.