The IMO requirement on Tanker Safety and Pollution Prevention, 1978 - Resolution A.446 (XI) 4.4.4. states "Means such as level gauges, hand dipping, and stripping system performance gauges as referred to in paragraph 4.4.8. shall be provided for checking that the bottoms of cargo tanks are dry after the Crude Oil Washing. Suitable Arrangements for hand dipping must be provided at the aftermost portion of a cargo tank and in three (3) other suitable locations unless other approved means are fitted for efficiently ascertaining that the bottom of every cargo tank is dry."
This Vapor Lock Valves is hand-operated (open/close) 1-inch ball type valve which was developed for the purpose of dry detection, so, the Hand Dipping operation can be done without releasing the dangerous vapors into the atmosphere.

Installation: This valve is designed/manufactured as it to be installed on the sounding pipe installed on the deck [ Parallel Pipe Thread (ISO 228/G1) ]