This standard has been developed for use on drawing. Architects, contractors, and engineers, by the use of these symbols on their plans, will have a standard method of indication for heating, air conditioning, and allied items. Confusion in the interpretations of requirements can thus be avoided.
ASME Y32.2.4-1949 history
0000 ASME Y32.2.4-1949(R1998)
1949ASME Y32.2.4-1949 Graphic Symbols For Heating, Ventilating And Air Conditioning (Y32.2.4 - 1949)