How to Select water pipes of RO system

For the material selection of RO system, should consider internal and external condition, internal is to consider the corrosion raw water caused for water pipes, external is for operation condition. If operation condition is good, normally adopt the surface coating (such as painting or galvanizing, etc.) is okay. As for the corrosion raw water caused for water pipes should consider the residual chlorine, chemicals, PH value, temperature, etc. of raw water. Normally the supplier will select UPVC and Stainless steel as material for water pipes.

Stainless steel pipes

The basic advantage of stainless steel is that it has good resistance to general corrosion. Stainless steel rarely produces galvanic corrosion and stress corrosion damage, but stainless steel is prone to pitting corrosion and crevice corrosion. Pitting corrosion means that the metal is locally eroded and caused depressions on its surface. If the chromium oxide passivation layer is destroyed, chloride ions will attack the bare metal to form pitting corrosion.

Crevice corrosion is related to pitting caused by a small amount of still water in small holes, on the surface of the gasket, around the deposits, and under cracks in the screws. In order to avoid the pitting corrosion and crevice corrosion of the high-pressure water pipes, it is recommended to design as below:

1) For general water sources can select SS304

2) If TDS value of raw water between 2000-5000ppm, recommend to select SS316 with the carbon concentration less than 0.08%.

3) If TDS value of raw water between 5000-7000ppm, recommend to select SS316L with the carbon concentration less than 0.03%.

4) If TDS value of raw water between 7000-30000ppm, recommend to select SS904L with the molybdenum concentration of 4%-5%.

UPVC pipes

1) Strong corrosion resistance: Compared with general cast iron pipes and galvanized pipes, PVC pipes have extremely strong corrosion resistance, can withstand strong acid and alkali, and will not rust and scale.

2) Low fluid resistance: the inner wall of PVC pipe is very smooth. The surface roughness coefficient is only 0.009, the fluid resistance is very small, and the water pressure will not be excessively reduced.

3) High mechanical strength: UPVC pipes have good water pressure resistance, impact resistance and tensile strength, and can withstand 110 atmospheres for 1 hour at room temperature without breaking.

4) Hygienic and non-toxic: The UPVC pipe we use adopt a unique green environmental protection lead-free formula system to replace the traditional compound lead salt formula system, so it will not damage the water quality and affect human health.

5) Light texture and easy for installation and construction: The density of PVC pipe is one-fifth of that of ordinary cast iron, be convenient to carry and unload. By using special adhesive paste or elastic seal sleeve, the installation and construction will be easy and fast.

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