EXERCISE 01
Close the exhaust
Reduce the exhaust opening, then close it. Compare the modelled inflow and smoke movement.
Discuss: Why does a powered fan not guarantee sustained flow through the building?
PRACTISE WITH PURPOSE
Lead the exercise.
Keep the context.
A practical guide to setting up a session, understanding the model and turning observations into useful discussion.
01 / SET UP
Build your ventilation exercise.
- Start with a layout. Open the PPV airflow lab and use the example or select New plan. Choose Floor plan to upload a PNG, JPEG or WebP image. For a PDF plan, export the required page as an image before uploading.
- Set the scale before tracing. Enter the image width in metres, or enter a known distance and choose Mark two points to calibrate. Click both ends of that distance on the image. Calibration changes the reference image scale, not rooms already drawn.
- Trace the rooms. Select Room and drag a rectangle for each compartment. Use the inspector to name rooms and adjust dimensions. Shared walls must align without overlaps. Represent an irregular area with multiple rectangular compartments and suitable connecting openings.
- Add the openings. Select Door or Window and click a wall. Check the connected rooms, opening width, height and open percentage. Plan images are reference backdrops: the app does not automatically detect their walls, doors or windows.
- Set the conditions. Add smoke to selected rooms or toggle an illustrative fire source. Drag the fan outside an entrance, aim it using Direction, choose a RAMFAN reference preset and set the speed. Use numeric fan coordinates when precise placement is useful.
- Run, pause and compare. Select Run simulation. Change a door or window opening, reposition the fan or vary its speed. Pause to discuss the result. Reset exercise restores the exercise starting conditions; Clear smoke removes the current smoke load.
- Keep the scenario. Save locally stores one saved scenario in this browser. Export downloads a JSON file for later use or sharing, including the reference image. Import opens a saved JSON scenario. Browser storage can be cleared, so export anything you need to retain.
Keep plans appropriate for the audience. Floor plans and scenarios stay in your browser unless you export and share them. An exported scenario includes its uploaded plan image.
02 / EXPLORE TOGETHER
Change one variable.
Begin with a smoke-filled layout, an open entrance and an exhaust path. Ask the crew to predict the effect before making each change. These exercises explore model behaviour, not operational ventilation tactics.
EXERCISE 02
Isolate a bedroom
Close the door to a smoke-filled bedroom. Compare it with a room that still connects to the flow path.
Discuss: Which rooms remain connected? What information is missing from this simplified view?
EXERCISE 03
Open a second outlet
Open another exterior door or window. Watch how the model divides flow between available routes.
Discuss: Which path has changed, and which compartments lie along it?
EXERCISE 04
Add a smoke source
Toggle a fire source in one room. Compare ongoing smoke production with clearing smoke after that source is switched off.
Discuss: How could supplying oxygen change a real fire? The model does not calculate that feedback.
Finish with the limits. Clearer shading or a lower smoke percentage is not evidence of safe entry, breathable air or successful fire control. Refer operational decisions back to current CFA procedures, incident conditions and command.
03 / UNDERSTAND THE MODEL
An educational airflow network.
The lab represents a building as a two-dimensional plan with one uniformly mixed smoke concentration per room. Room area and ceiling height determine compartment volume. Openings connect rooms to each other or to outdoors. A steady pressure calculation estimates the flow through those connections.
Q = Cd × A × sign(ΔP) × √(2 × |ΔP| / ρ)
Here, A is the effective opening area, ΔP is the pressure difference, and ρ is the assumed air density. The opening discharge coefficient is 0.7 and density is 1.2 kg/m³. These are model inputs, not measurements of your building.
- Pressure-limited fan: restricting the exhaust reduces sustained throughflow. A sealed connected layout does not continuously receive the fan's reference airflow.
- Geometric coupling: fan direction and position determine whether the model couples it to an exterior opening. Distance and alignment effects are illustrative approximations.
- Mixed smoke: a scalar smoke load moves between connected compartments with the calculated flow. A fire marker adds an illustrative smoke source. Smoke percentages are relative scenario values, not measured visibility or contaminant concentrations.
- Declared fan assumptions: the model uses an illustrative 100 Pa shutoff pressure, approximate flow scaling with speed percentage and pressure scaling with speed squared. These are not manufacturer-calibrated pressure curves or certified intermediate-speed outputs.
What it cannot predict
This is not computational fluid dynamics (CFD) or a validated fire model. It does not calculate thermal layers, buoyancy, turbulent jets, recirculation, wind, leakage, oxygen concentration, combustion, fire growth, temperatures or heat exposure. Closed openings are treated as sealed. It does not predict flashover, backdraught, tenability, safe entry, firefighter survival or ventilation clearance times.
Real fire smoke can move without a fan because of heat, buoyancy and wind. These effects are outside this model. The coloured arrows indicate the modelled flow direction; they do not establish that the air is fresh or safe to breathe.
Active fire is a critical limitation. Ventilation can supply oxygen and increase fire growth. The fire marker is a smoke source only and does not reproduce this response. Increasing fan speed must never be interpreted as automatically making conditions safer.
04 / EQUIPMENT REFERENCES
RAMFAN reference presets.
The presets identify particular manufacturer publications. Confirm the model and generation on the brigade's actual equipment before using the specifications for familiarisation.
| Reference preset | Published battery airflow | Published test arrangement |
|---|---|---|
| EX50Li Gen II, 40 VNot the newer G3 or 18 V versions | 17,194 m³/h10,120 cfm; approximately 4.776 m³/s | 3,045 rpm 4.3 m setback; 9° tilt |
| EX150LiBattery operation reference | 21,029 m³/h12,377 cfm; approximately 5.841 m³/s | 3,600 rpm 4.9 m setback; 11° tilt |
AMCA reference flow is not guaranteed building flow. The published rating is airflow entering a test chamber in a specified arrangement, including entrained air. It is not simply flow at the impeller outlet and does not establish performance in an arbitrary floor plan.
The lab's percentage control is an approximate model setting. It does not reproduce an actual control-knob position or certified RPM. The simulator does not model vertical tilt; the test angles above are source context only. A manufacturer pressure curve has not been incorporated.
05 / PANEL FAMILIARISATION
Use panel practice with context.
Open Fire indicator panels to access the available simulators. Ask members to identify the panel, interpret indications and explain the effect of a control before using it.
Simulator behaviour and generic illustrations do not establish the correct action for every installed system. Use the applicable manufacturer manual, site information and current CFA procedures. Verify panel-specific differences during supervised practical familiarisation.
06 / FURTHER READING
Primary source material.
These sources explain the equipment references and research context. They do not validate this simulator or make it an official CFA training package.
- RAMFAN EX50Li owner manual, revision H2, November 2021 (PDF)Certification table, operating controls and published test arrangement.
- RAMFAN EX50Li Gen II datasheet (PDF)January 2023 reference used for the 40 V Gen II preset. Manufacturer documents may be revised.
- RAMFAN EX150Li owner manual, revision C (PDF)Battery airflow and certification test conditions.
- AMCA Standard 240: testing positive pressure ventilatorsWhat a PPV aerodynamic performance rating represents.
- NIST CFAST technical reference, volume 1 (PDF)Background on compartment and vent-flow modelling. This lab is not CFAST.
- FSRI: Effectiveness of Fire Service Positive Pressure VentilationResearch on ventilation, flow paths and fire conditions.
- FSRI: Positive Pressure Attack online trainingResearch-based tactical considerations and training context.
- NIST: Positive Pressure VentilationFire research and experimental work relevant to PPV.