Carbon Dioxide

The vast majority of CO ₂ used for industrial purposes is obtained as a by-product of another process. Carbon dioxide is used to freeze foods and for pH control in various industries. It is also used for fumigation, as a replacement for mechanical refrigeration, cleaning, and solvent extraction. The most attractive characteristics of CO ₂ are that it is environmentally benign, creates no long-term health hazard, is easy to handle, and requires few safety precautions.

The standard most commonly used is CGA G-6.1, Standard for Low Pressure Carbon Dioxide Systems at Consumer Sites.

There are three grades of purity available. Food, or standard grade, which is 99 percent pure, is the most often used grade. The most pure is that employed for laboratory work and other specialized uses, and it is discussed earlier in this chapter. The least pure, with no purity requirements, is that used for general industrial purposes such as in fracturing rock in oil recovery operations. CO ₂ is usually delivered and stored at 0 F ( ?18 C).

Following are common uses:

1. At 90 F and 1100 psig (32 C and 7600 kPa), CO ₂ reaches its supercritical state where it becomes a dense gas with the versatile solvent properties of a liquid.

2. CO ₂ is widely used for pH control, replacing sulfuric acid. CO ₂