1. Inner cleanliness requirements: the weight of removable insoluble impurities ≤ 0.27g/m2；maximum size ≤ 200um.
2. Tension test: more than 2500N
3. Burst test：high-pressure cooling pipe burst pressure ＞ 14.7Mpa；Low-pressure cooling pipe burst pressure＞9.8Mpa.
4. Hose vacuum resistance characteristic: OD change cannot be more than 20% camparing with nature condition.
5. Hose length variation：Under certain pressure, length variation is between -4% to +2% after test.
6. O-zone resistance:：Under 8X magnification glass, no visible cracking on hose surface.
7. Hose Volume variation ratio：rubber material hose volume variation ratio is between -5% and +35%;
? 8. hose tightness：Allowed max tolerance of R134a, nominal bore diameter≤2.0g/md，nominal bore diameter>3.0g/md