Monitor, will this batch of Dow membranes have any problems?

The person who asked me this question is a customer I have worked with for almost four years. They are a functional sugar manufacturer. Basically, they buy a batch of Dow membranes every year for replacement.

This latest order includes 32 pieces of BW30 PRO-365. When workers took out old membranes and tried to install new ones on site, they found a problem. Simply put, the new membranes could not be fitted into the pressure vessels. The site has eight pressure vessels, and each vessel holds four membrane elements. After putting in new membranes, workers could not close the vessel end caps.

Workers measured the length of new membranes and old membranes. The old ones are 1016 mm long. Most newly arrived membranes are 1018 mm. Each new membrane is 2 mm longer. Four membranes together add extra 8 mm, so the end caps cannot be installed. The site also tried mixing two old membranes with two new membranes, and this combination could fit inside the vessel.

To be honest, we met this situation for the first time. We quickly contacted official Dow support. Dow replied that standard 8040 membrane length allows certain tolerance, around ±2 mm. Since this is the official reply, we helped the customer find the root cause.

The pressure vessels used on site are not standard models. An engineering company customized these vessels for the customer. There is no extra space reserved inside each vessel.

The vessel length cannot be changed, and we cannot make the RO membranes shorter. What could we do?

Finally we found a solution. We cut the adapters between RO membranes and pressure vessels to make them shorter. With this change, the installation problem was solved.

Now let us come back to today’s topic. The most popular RO membrane sizes are still 4040 and 8040. Although 6040 and 16040 RO membranes exist on the market, they are not mainstream products. Both 4040 and 8040 membranes have a standard length of 1016 mm. Their outer diameters are 99 mm and 201 mm separately.

Alright, that is all for today. I am Class Leader, founder of XBYMC Water Treatment Forum. I hope this platform can help more people avoid troubles in the water treatment industry. See you next time!