In the design and operation of reverse osmosis and nanofiltration installations, it is important to predict the CaSO₄, SrSO ₄, and BaSO₄ scaling properties of the concentrate stream. Because of the increase in total dissolved solids and the increase in concentration of the scaling salts, the scaling properties of the concentrate stream will be quite different from those of the feed solution. This practice permits the calculation of the scaling potential for the concentrate stream from the feed water analyses and the reverse osmosis or nanofiltration operating parameters.

Scaling by CaSO₄, SrSO₄, and BaSO₄ will adversely affect the reverse osmosis or nanofiltration performance. This practice gives various procedures for the prevention of scaling.

1.1 This practice covers the calculation and adjustment of calcium, strontium, and barium sulfates for the concentrate stream of a reverse osmosis or nanofiltration system. The calculations are used to determine the need for scale control in the operation and design of reverse osmosis and nanofiltration installations. This practice is applicable for all types of reverse osmosis devices (tubular, spiral wound, and hollow fiber) and nanofiltration devices.

1.2 This practice is applicable to both brackish waters and seawaters.