Sodium chloride solution aka brine, Salt water or saline solution is used in many industrial processes.
Brine used in industry is commonly produced by electrolysis to a specific concentration depending on usage. This commonly ranges from 5% as a dilute solution to approximately 25% for more concentrated applications. As water temperature rises, the quantity of salt that can be dissolved increases, however at about 26%, brine becomes saturated.
The S.G. ranges from 1 – 1.15, viscosity from 1 – 1.6cPs.
The main issue concerning any engineer specifying a pump for brine/sodium chloride solution is the choice of wet-side materials.
For more dilute concentrations metals such as stainless steel and other alloys are acceptable, however where more concentrated solutions are being handled it is recommended a non-metallic wet-side material be specified such as ETFE.
It is very common to specify a mag drive centrifugal pump for brine solution as the viscosity and S.G are very low and it is very efficient for the pumping principle and ensures containment of the fluid.
Where high system pressures occur such as in desalination processes, a mag drive pump is a prerequisite for circulatory applications.
The mag drive pump will circulate the brine after it has been passed through a membrane, requiring it handle huge system pressures of approximately 200 bar.
A mag drive pump is the ideal pump for this application as there are no mechanical seals. This means that there is no danger of any seal wearing and failing as the pump casing is sealed using an o-ring assembly.
Where brine is being handled in a hygienic or 3A application, the pump must adhere to the industrial standard; models such as SS316L stainless steel double diaphragm pumps with an electro-polished surface finish on the pump body to RA<0.8 µm.
The connection may also be required to be DIN11851 compatible to remove crevices from flange/pipework joints.