20% hydrogen peroxide sodium hydroxide solution transfer pump
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Dear seniors, I checked the data sheet and it shows that a 20% sodium hydroxide solution at room temperature has an effect on
I’m sorry everyone; I didn’t finish writing it. I don’t know how to send it or where to make the corrections, so I can only add this here. Can a cast-iron pump transport hydrogen, oxygen, and sodium hydroxide solutions at 20% concentration and below 50 degrees Celsius? The corrosion data sheets I checked show that there is no corrosion effect on cast iron, but what I found online, as well as what many people in our forum have said, indicates that corrosion does occur. How should I choose the material for the pump? I hope someone can help me figure this out
It is mainly caused by alkali embrittlement, under conditions of high concentration, high temperature, and stress. Use it with confidence only if one condition is met; use it cautiously if two conditions are met.
Based on my experience, cast iron cannot withstand 20% sodium hydroxide; at the very least, 304L material should be used, and 316L is preferable for long-term use. Our pumps that operate at 100°C with 48% sodium hydroxide are not very durable when made of 316L material; we plan to replace them with nickel-based materials.
A fluorine-lined pump will suffice; make sure to use a pressure-free sintered type for the mechanical seal. . .
Try a titanium alloy pump; I’m not sure if the price will be acceptable
A 316L pump is sufficient. ‘It is generally believed that alkali washing causes virtually no damage to titanium materials. However, literature indicates that it is generally stipulated that titanium can be used safely in alkaline solutions below 80°C, but it will definitely suffer from hydrogen embrittlement in high-temperature, highly alkaline environments. ’
Colleagues, in the past for handling sodium hydroxide at normal temperatures, I used pumps that were manufactured by stamping and welding; for higher temperature applications, I used cast stainless steel pumps. Basically, I never deliberately chose fluoroplastic pumps or those made of titanium for working with sodium hydroxide. . . This time, it’s mainly about taking a break from using this medium due to its corrosive effect on cast iron; after all, cast iron has hardly ever been used for transportation purposes
The temperature is a bit high; it’s fine at room temperature, but it’s recommended to use a fluorinated lining
Are you still hesitating between stainless steel and cast iron for these operating conditions? ? ? ? Don’t use cast iron; isn’t 316L expensive? A directly fluorinated lining material would be fine; it also offers good cost-performance.