[ Problem Point ]
One operator is doing transferring in a drain 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.16 Residual quantity shortage warning of softener 
No.10 Remaining quantity warning of liquid and oil 
No.2 Temporary storage of food wasted oil 
No.6 Refill of waste paint 
No.7 Supplement of hydraulic operating fluid 
No.8 Centralized storage of Specified Chemical Substance 
No.9 Automatically Changeover of Drums