The method
Before using the result
- Straight segments only, using internal dimensions. No end faces, fittings, fan housings or labour-time estimate. Exclusions cannot exceed segment surface area.
Worked examples
These original training examples illustrate the method for IKECA Certified Exhaust Cleaning Technician (CECT) Examination. Use the matching “Load example” button above to explore a variation; example values are not equipment settings or prescribed criteria.
1. Worked example
Build a straight-segment internal cleaning-area takeoff from actual dimensions. Subtract documented openings without treating area as a complete labour or access estimate.
Supplied duct segments
| Segment | Shape | Length (m) | Width (m) | Height (m) | Diameter (m) | Excluded opening area (m²) |
|---|---|---|---|---|---|---|
| Duct A | Rectangular | 5 | 0.5 | 0.4 | 0.5 | 0.1 |
- Duct A: 9 − 0.1 = 8.9 m².
- Net internal surface area: 8.9 m²
2. Comparison example
Compare a different supplied condition using the same method. For Kitchen Exhaust Exam, the important check is that the input meaning, units and method assumptions still match the problem.
Supplied duct segments
| Segment | Shape | Length (m) | Width (m) | Height (m) | Diameter (m) | Excluded opening area (m²) |
|---|---|---|---|---|---|---|
| Duct B | Circular | 8 | 0.5 | 0.4 | 0.6 | 0.2 |
- Duct B: 15.079644737231007 − 0.2 = 14.879644737231008 m².
- Net internal surface area: 14.87964 m²
Check your understanding
1. Which relationship is used?
Internal lateral area = perimeter × length − excluded openings; rectangular perimeter=2(w+h), circular perimeter=πD.
2. Which assumption should you check first?
Straight segments only, using internal dimensions. No end faces, fittings, fan housings or labour-time estimate. Exclusions cannot exceed segment surface area.
3. How should you verify a different unit system?
Convert every input to the displayed calculation units first. Equivalent physical inputs must give equivalent results; a unit label alone does not convert a number.
Continue with the matching exam topic
This tool connects to IKECA Certified Exhaust Cleaning Technician (CECT) Examination free practice. Work through a question independently, then use the calculation steps to identify where your method differs. The tool stays free whether or not you choose paid preparation.