Canadian Entry To Practice (CETP) Practice Test

If an ASME rated container has a WC rating of 120 gallons, how many gallons of propane can be safely stored in it?

1. 80

2. 120

3. 96

4. 100

The correct answer is: 80

The correct answer stems from the principles of propane storage safety as governed by ASME (American Society of Mechanical Engineers) regulations. An ASME rated container with a water capacity (WC) of 120 gallons indicates its maximum volume capacity for holding water. However, when storing propane, which is a liquefied gas, the liquid phase occupies less volume due to its differing density compared to water. For propane, there is a standard guideline about filling ratios to ensure safety and prevent overfilling. It is typical to use a fill density of approximately 80% for liquids like propane to allow for expansion, which occurs with temperature changes. By applying this fill ratio to the 120-gallon capacity of the container, the calculation would be: 120 gallons x 0.80 = 96 gallons. This calculation indicates that the maximum safe storage capacity for propane in a 120-gallon ASME container is 96 gallons. Thus, while the option of 80 gallons may seem plausible, it does not represent the ideal utilization of the container's capacity as safely allowed by regulations.