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."

So the simplest method for checking dryness of tank bottom, MMC Model. "D'CHK-FW" can be done to slide wire by hand for touching Dipping scale to tank bottom and read-out the level adhered remaining oil on the Dipping Scale.

Also, the device is constructed with Reel Ass'y and Gas Sealing Attachment to be coupled with GROUNDING of the device in order to avoid accumulation of static electricity after tank washing.