How much will the PSIG pressure rise for every 1°F of heat exposure in an ammonia liquid line with liquid trapped?

The rise in pressure in a liquid ammonia line due to heat exposure is determined by the thermodynamic properties of ammonia. For ammonia, the pressure increase in a liquid line can be significant due to its properties as a refrigerant. Specifically, when ammonia liquid is subjected to a temperature increase, the pressure within that liquid line rises significantly.

In this case, it is commonly accepted that the pressure in a liquid line can increase by approximately 100 to 150 pounds per square inch gauge (PSIG) for every degree Fahrenheit of temperature increase. This relationship stems from the fact that ammonia will vaporize and increase pressure dramatically when heated, particularly when some amount of liquid is trapped in the system.

Thus, the answer indicating a rise of 100 to 150 PSIG aligns with established principles in thermodynamics and the behavior of refrigerants under thermal stress, making it the accurate choice for understanding how heat exposure affects pressure in an ammonia system.