[ Problem Point ]
One operator is doing refill in the waste paint by himself,
so it isn’t possible to see through until it’ll be fill up the drum.
[ ⇒Kaizen Point ]
Started using the DLC-100B Bell type.
So loud 80 horn Bell Type.
Can work backwards and do not worry.
Related page:
Drum Level Communicator products 
No.4 Landing of shipping waste oil 
No.1 Transfer of drain 
No.5 Automatic collection of food wasted oil-Telephone line version. 
No.7 Supplement of hydraulic operating fluid 
No.8 Centralized storage of Specified Chemical Substance 
No.9 Automatically Changeover of Drums 
No.13 Repacking of waste oil