Which expression correctly gives drainage time in seconds given volume in mL and flow in L/min?

• A. (volume/flow)*60
• B. (volume/flow)*3600
• C. (volume/flow)*0.5
• D. (volume/flow)/60

Answer: (A)

Drainage time is how long it takes for a given volume to be drained at a given flow rate. The basic relationship is time = volume divided by flow rate, with the final unit depending on how you handle the time单位.

If you keep volume in milliliters and flow in milliliters per minute, time comes out in minutes. To get seconds, you multiply by 60. So the form volume divided by flow, then times 60, is the standard way to convert to seconds once the units are matched.

In practice, you just need to ensure the units are consistent: convert flow to the same units as the volume (milliliters per minute) and then apply the same division, followed by converting minutes to seconds. That’s why the expression that follows this structure (volume/flow) × 60 is the appropriate choice for obtaining drainage time in seconds.