What are the precautions for pneumatic quick connectors

How does the thread size of the pneumatic joint look like the thread behind pcf8-02 is 2 points? How was it measured? 
The PC connector is a connector with one thread and one end inserted into a plastic tube. F means internal thread, 02 means 2 points, and the external diameter of 2 points is about 12.5 (because it is a tapered thread, there is a difference between the upper and lower parts).

What are the precautions for pneumatic quick connectors? 
Do not use for applications other than quick fluid couplings, do not use for fluids other than applicable fluids, do not connect with quick fluid couplings from other companies, do not exceed the maximum operating pressure during use, do not use outside the temperature range To prevent wear or leakage of sealing materials.

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