When changing elements, what is the required frequency and marking?

• A. Every 24 months and the serial number should be recorded
• B. Every 36 months and the month and year should be stenciled on there
• C. Every 12 months and the day should be noted
• D. Every 48 months and the week should be stamped

Answer: (B)

The test is about how to track when replaceable elements have been changed and how to mark them for quick maintenance reference. When you replace an element, you should indicate the month and year of the change on the element itself. This simple stamp or stencil keeps everyone from guessing how old the part is and helps you schedule the next service on a clear, uniform timeline.

Why this timing makes sense: marking month and year gives a clear, clock-based reference for the element’s age. Maintenance intervals are typically measured in months, not days or weeks, so stamping just the month and year avoids unnecessary detail while providing a reliable reminder for the next replacement window. The 36-month interval corresponds to a three-year service life in this context, offering a practical balance between part life and reliability.

Other options aren’t as suitable because recording a serial number doesn’t convey how long the element has been in service, noting the day adds little value for routine maintenance, and stamping weeks or using a 48-month span introduces unnecessary complexity or exceeds the standard replacement window.