Final answer:
Without specific data, the pressure of the R-12's defuel pump cannot be accurately determined. It typically would be within the operational pressure range of similar systems, which can be several hundreds of psi.
Step-by-step explanation:
The pressure of the R-12's defuel pump can be determined using principles from fluid dynamics, specifically Bernoulli's equation which relates pressure with fluid flow, height, and cross-sectional area changes. To compute the pressure in a Type III hydrant system, factors such as the height difference that the fuel must be pumped over and changes in hose diameter would be considered.
However, the provided details do not give enough information to directly calculate the pump's pressure for the R-12's defuel pump in psi units. Typically, such pressures are in the range of operational pressures for similar pumps used in fire hoses and fuel delivery systems, which can be several hundreds of psi.
In Example 14.7, a fire hose nozzle pressure can be calculated which is around 344 lb/in² or 23.7 atm when considering factors like height and diameter differences, but this example is not directly applicable to the student's question without more context on the specifics of the R-12 defuel pump setup.