What are the technological processes of water injection equipment
- 2019-07-22-

Distillation is a classic method that we are all familiar with for preparing water-for-injection equipment. So what are the general process flow of WFI equipment, specific details are as follows.

1. Raw water treatment.

Raw water refers to pre-treated tap water whose quality should meet the sanitary standards of domestic drinking water. Raw water generally contains impurities such as suspended particles, soluble inorganic salts, organic matter, microorganisms, pyrogens, and volatile gases. It needs to be treated to be purified water before it can be used as a source of water for injection preparation by distillation.

Raw water treatment methods mainly include ion exchange method, electrodialysis method and reverse osmosis method.

The ion exchange method for treating raw water requires ion exchange resin. Generally, a combination of a cationic resin bed, an anionic resin bed, and a mixed resin bed is used in series. A degassing tower is added after the cationic resin bed to remove carbon dioxide from the water to reduce the burden on the anionic resin. The water obtained by this method has high chemical purity and simple equipment, which can save fuel and cooling water, and the cost is relatively low.

The electrodialysis method removes ions according to the directional migration of the ions under the effect of the electric field and the selective permeability of the AC membrane. This method does not require the consumption of acids and bases used in the regeneration of ion-exchange resins, but the purity of the water obtained is low.

The reverse osmosis method sets a semi-permeable membrane in the U-shaped tube. The two sides of the semi-permeable membrane are separated by a salt solution and pure water. Water molecules on the pure water side are transferred to the salt solution side through the semi-permeable membrane, so that the salt solution level rises High, this is the soaking process. The pressure formed by the height difference between the two liquid columns is the osmotic pressure that this salt solution has. If a pressure greater than the osmotic pressure of the salt solution is applied to the salt solution, the water molecules in the salt solution permeate to the pure water side, and the salt and water are separated. This is the reverse osmosis. The permeable membrane material is an acetate fiber membrane and a polyamide membrane.

(2) Distillation.

Small-scale production is generally used for tower distilled water, mainly including three parts of the transpiration pot, frothing device and condenser. Generally, in mass production, a multi-effect distilled water device or an air pressure type distilled water device is commonly used. The distilled water device for the preparation of water for injection should be equipped with an effective frothing device to ensure that it does not bring in pyrogens.

(3) Collection and storage of water for injection.

Discard the initial distillate, select a closed collection system with sterile filtration equipment after checking, collect it, store it in a temperature above 80 ℃, keep it in a temperature above 65 ℃, or store it in a sterile state below 4 ℃, and use it within 12 hours of preparation.

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