What is the safety standard of carabiner snap hook？

Carabiner Snap Hook Safety Standards
There are a few different categories of carabiner, each with slightly different standards for strength and other specifics.  Most locking and non-locking carabiners climbers use will be Type B (Basic) or Type H (HMS).  We’ve outlined some of the minimum safety standards for those types of carabiners below: –

Major Axis Minimum Strength: 20kN
Minor Axis Minimum Strength: 7kN
Open Gate Minimum Strength: 7kN (Type B), 6kN (Type H)
Gates must open by hand when 800 newtons of force pulls on the major axis
Locking gates must still be functional after 10 newtons of force are applied to the fate
Minimum gate opening width of 15mm
Minimum force to open the gate must be at least 5 newtons
As you can see, it's not just strength that is tested.  Carabiners in the past had problems with loose gates opening when it was dangerous.  Some carabiners also stopped opening when too much force had been applied.  A minimum gate opening width allows for easy clipping and unclipping of a rope to the biner.