Selection of valves
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Since the process requires the addition of sodium hypochlorite, the original usage was 10–20 m3 per day, transported via PPR pipes with a DN20 diameter. It seems that the amount used is a bit high now; reducing it to around 3 m3 will result in the valves being almost completely closed. I want to reduce the dosage further; what methods should I use to control it? What valves can meet this requirement?
Needle valves for small-diameter pipes, and globe valves with parabolic valve discs for large-diameter pipes
I took a look; it is recommended to use needle valves in most cases. Most needle valves are made of stainless steel, right? Sodium hypochlorite should be corrosive, right?
It is recommended to use needle valves, as they provide good control over small flow rates, but corrosion issues need to be taken into consideration...
Added using a pneumatic diaphragm pump
The disadvantage of using needle valves is that with the medium being sodium hypochlorite, free Cl ions are present, which can easily cause pitting and perforation. These are the disadvantages of using carbon steel and stainless steel. Using duplex stainless steel is also more expensive. The costs need to be weighed in this regard.
Use a metering pump – you can adjust the amount to whatever you need, as long as it’s within the pump’s allowable range