OPD Valve – DT 6.5 – This OPD Valve has a Dip Tube length of 3.6 inches (DT 3.6). This valve may be used for various propane tanks that require a dip tube of 3.6″. Your cylinder should be stamped with the appropriate dip tube requirement which is usually found on the collar of the tank. Has an integral safety relief valve set to discharge at 375 psig. Also has a backcheck to prevent gas from flowing until the valve is properly connected to the hose. Must be installed by qualified personnel only.