Because pulp is processed and paper is made in an aqueous vehicle that is up to 99.5% water, water management is essential for productive mill operations. Level controls monitor the storage of cold, warm and hot process water, potable water, boiler feedwater, liquor production water, process wastewater, and open effluent weirs, sumps, and stormwater basins.
Process, reclaimed and service water storage may range from small tanks to large bulk tanks with heights of 40 feet (12.2 meters). Controls are specified according to the size and geometry of the bulk storage vessel. Level controls in open atmosphere reservoirs must withstand punishing weather conditions. Firewater storage must conform to NFPA standards.