Specifications

Aluminium flange type manhole cover/tank truck manhole cover

Size	20 inch
Emergency Breathing valve	10 inch
Pressure resistance	0.254MPA
Emergency open pressure	21KPA-32KPA
Max air flow rate	7000m³ /H
Connect way	Flange
Temperature	-20 to 70 °C

 

installed on the top of oil tanker and used for injecting oil,checking gas recovery,mending the internal inlet.

Also can protect the tanker under the emergency. 

When inject oil,the outside temperature's change will lead the tanker's inside pressure to change.

Then the manlid's breathing valve can automatically make the tanker pressure to the normal level.  If some emergency happen , like the tanker overturn,the breathing valve will automatically close toavoid the tanker's  explosion when under the fire condition.