Velocity from a smoke tube
Used on the ASP. The worked example below is computed by code and checked against the source.
V = D ÷ T
D = distance the smoke travels (ft); T = time (min). Convert seconds to minutes first.
Worked example
OSHA example: smoke travels 2 ft in 2 seconds.
2 ft ÷ (2/60 min) = 60 fpm
The source prints this result, and our code reproduces it.
Where it appears on the exam
ASP: ASP11 Domain 1, Mathematical Calculations
Blueprint: ASP11 Domain 1, task 3: flow rates (ventilation)
Practice: Ventilation Calculations
Source
The formula comes from
OSHA Technical Manual, Section III, Chapter 3 (Ventilation Investigation), IV.F.3.d and Appendix III:3-2(opens osha.gov in a new tab)“Velocity = Distance/Time, or V = D/T Squeeze off a quick burst of smoke. Time the smoke plume's travel over a two-foot distance. Calculate the velocity in feet per minute. For example, if it takes two seconds for the smoke to travel two feet, the velocity is 60 fpm. ... Slot velocity is calculated by dividing the total volume flow rate by the slot area”
Questions
- What is the formula for velocity from a smoke tube?
- V = D ÷ T. D = distance the smoke travels (ft); T = time (min). Convert seconds to minutes first.
- Will this formula be given on the BCSP exam?
- BCSP says the formula is included in the question whenever one is needed, unless the question is testing whether you know the formula. You can't bring a formula sheet into the exam, so learn what each formula does and when to use it.
BCSP on formulas at the exam
BCSP, What to Expect When Sitting for a BCSP Exam (item 7)(opens bcsp.org in a new tab)“For any question requiring a mathematical formula, the formula will be included within the exam question (unless the question is specifically testing your knowledge of a formula). You will not be provided or permitted to bring a formula sheet.”
Related
- 8-hour TWA exposure (air contaminants)
- Mixture of air contaminants
- Dilution ventilation
- ASP formula sheet
Checked 2026-10-16. Spot a problem? Email hello@passcited.com.