The TD-4100XD is a ruggedized version of the TD-4100 continuous online oil in water monitor built for severe duty and hazardous area locations . . . .

TD-4100XDC Oil in Water Monitor
The TD-4100XDC is a “closed cell” version of the rugged, world industry standard TD-4100XD Oil in Water Monitor. It was designed for normally clean water applications . . . .