How to systematically maintain and maintain waterproof and breathable membranes

1. Preservation of waterproof and breathable membrane:

When the membrane is stored for a long time, it must maintain good performance and have practical value, so the life of the waterproof and breathable membrane is an important issue. Therefore, special attention should be paid to actual storage. The storage of waterproof breathable microfiltration membranes is divided into two methods: wet storage and dry storage. No matter which method is used, the purpose is to prevent hydrolysis of the membrane, the growth and erosion of microorganisms, shrinkage and deformation of the membrane, etc.

1. Wet storage

The key to wet preservation is to always keep the membrane surface covered with preservation solution and in a moist state. The preservation solution can be formulated as follows: water: glycerin: formaldehyde = 79.5: 20: 0.5. The function of formaldehyde, a waterproof and breathable membrane material, is to prevent the growth and reproduction of microorganisms on the surface of the membrane and to prevent erosion of the membrane. The purpose of adding glycerol is to lower the freezing point of the preservation solution and prevent damage to the membrane due to freezing. The formaldehyde in the formula can also be replaced by copper sulfate and other fungicides that are not harmful to the membrane. The storage requirements for cellulose acetate membranes are 5 to 40°C and PH = 4.5 to 5, while the storage temperature and PH of non-acetate cellulose membranes can be wider.
2. Dry storage:

Waterproof and breathable membranes are often supplied in the market as dry membranes because they are easier to store and transport. In addition, if the wet film needs to be stored in a dry method, the film must be processed using the following methods. The specific method is: soak the cellulose acetate membrane in 50% glycerin aqueous solution or 0.1% sodium dodecyl sulfate aqueous solution for 5 to 6 days, and dry it at a relative humidity of 88%. The polysulfone membrane can be dried at room temperature using 10% glycerol, sulfonated oil, polyethylene glycol and other solutions as dehydrating agents. In addition, surfactants also play a good role in protecting the film pores from deformation.

2. The following issues should be paid attention to in the care and maintenance of waterproof and breathable membrane systems:

1. Depending on the membrane, special attention should be paid to the environment in which it is used, especially the temperature and pH value of the feed liquid, and even the chlorine content in the feed liquid.

2. When the membrane system is stopped for a short period of time, attention should be paid to keeping the membrane moisturized, because once the membrane surface loses water and there is no remedial measure, the waterproof and breathable membrane pores will shrink and deform, causing the membrane performance to decline.

3. When out of service, contact with high-concentration liquids should be avoided.

4. Regularly clean and maintain the membrane with maintenance solution to reduce membrane pollution, etc.

5. During use, strictly operate according to the operating conditions that the membrane system can withstand, and avoid overloading and long-term operation to avoid irreversible damage to the membrane.