Review Example 9-7. The usual method of measuring a vacuum in the United States vacuum pump industry is in inches of mercury. For example, atmospheric pressure is 29.92 inches of mercury. Convert the pressure found in the example to in. Hg.

Data From Example 9-7

After melting at atmospheric pressure, molten copper contains 0.01 weight percent  oxygen. To ensure that your castings will not be subject to gas porosity, you want to  reduce the weight percent to less than 0.00001% prior to pouring. Design a degassing  process for the copper.