Which sae standard must be referred to on the label of approved hfc-134a refrigerant recycling machines?

Answer is: SAE standard that must be referred to on the label of approved HFC-134a refrigerant recycling machines are J1770 and J2788.
J1770 is to establish the specific minimum equipment requirements for recovery or recycling equipment intended for use with R134a.
J2788 is intended to establish requirements for equipment used to recharge HFC-134a.

Idon't mean to be a smart alec, length of atoms' bonds is the simplest way to define it.