During the expansion and drainage test, note and record the level of accumulated solution every how many seconds?

• A. 60 seconds
• B. 15 seconds
• C. 30 seconds
• D. 45 seconds

Answer: (C)

In an expansion and drainage test, you’re building a time-based picture of how the liquid accumulates and then drains, so regular measurements are essential. Recording the level every 30 seconds provides enough data points to see how quickly drainage occurs without creating an excessive workload. Measuring more often, like every 15 seconds, would add data that’s often not necessary for the overall analysis and can be cumbersome, while waiting a full minute could miss the faster changes that happen early in the test. The 30-second interval gives a practical balance and is the standard approach.