A helical membrane module is a filter that consists of a semipermeable membrane wrapped tightly around a central tube, like a roll of fabric. The membrane paper is sealed on one side of the edges, and a special spacer net is placed between each of its two layers so that the saltwater entering from one side of the module can flow between the membrane plates. Inside the module, when high-pressure water enters, only pure water passes through the membrane surface and filtration occurs. On the other side of the module, the purified water exits from the central pipe and the salty wastewater exits from around it.

To achieve the desired separation and concentration levels, these modules can be arranged in parallel and series inside fiberglass or stainless-steel housings, with high-pressure piping connections on both sides of these housings. Before these housings, pumps are installed to create a high-pressure flow of about 55 to 60 bars inside the filter module. A pressure control valve is also used on the outlet of the effluent flow to adjust the output flow rate and create pressure resistance inside the module. The speed of the pump motor at the inlet is controlled to create the desired pressure level. Spiral membrane filtration systems manufactured by Pars Avin Trava have instrumentation equipment on the pipe path to measure the flow, pressure and electrical conductivity of the liquid during filtration.