Final answer:
The normal and minimum de-ice pressure refer to the pressures required in pneumatic de-icing systems to prevent or remove ice effectively. These pressures would align with atmospheric pressure and the vapor pressure of ice under specific conditions.
Step-by-step explanation:
Understanding the pressure exerted by ice in various conditions is crucial in fields like engineering and environmental science. As you learn about pneumatic instruments and their applications such as de-icing systems, it's important to consider the normal and minimum de-ice pressure required to ensure safety and efficiency.
For instance, the information provided indicates that vapor pressure of ice isn't zero even at the melting point. At -1°C, the vapor pressure is 4.2 torr. This detail is particularly relevant because it affects how de-icing systems function, especially in scenarios where sublimation or deposition points for water are considered.
The general principles of pressure in pneumatic systems also apply here. In the context of a pneumatic de-icing system, the normal de-ice pressure would be the one required to prevent ice from forming or to remove it during adverse weather conditions, which depending on system design could align with typical atmospheric pressures like 101.5 kPa or as per specific engineering requirements.
The minimum de-ice pressure, on the other hand, would be the least amount of pressure still capable of preventing or removing ice formations effectively, potentially aligning with lower pressures such as the vapor pressures mentioned. The specific values for normal and minimum de-ice pressure would depend on the pneumatic system's design and operational environment.