The Home Screen
The home screen presents four entry points. Each is independent — you can use any of them without the others.
Guided Scenarios
Self-paced training on a single device. The app drives the meter automatically through 40 scripted real-world incidents across 10 substance types. No instructor needed.
Sampler
Simulates the trainee experience. The meter display is live and fully interactive. Use this to practice button navigation or connect to a Controller-mode device.
Controller
The instructor control panel. Set sensor readings manually, run quick scenarios, and broadcast live to one or multiple trainee devices.
Training Library
Reference materials: the comprehensive Meter Guide, 14 sensor training modules, and weekly real-world incident scenarios.
Guided Scenarios
Guided Scenarios is the fastest way to build interpretive skill independently. Each scenario runs from start to finish in under five minutes without any setup.
Selecting a Scenario
The scenario list shows 10 pre-built incidents, each with four variants — 40 total. Each card shows the substance type and a brief description. Tapping a card loads a random variant, so no two runs of the same scenario are identical.
During a Scenario
The meter powers on and boots automatically. Sensor readings then begin changing on their own — rising, holding, or falling according to the scenario script. A progress bar shows elapsed time. Alarm lights flash at the appropriate alarm level: amber for LOW, red for HIGH/STEL/TWA. The YES button silences the alarm and transitions the lights to solid.
Stop and Think Prompts
At key moments the scenario pauses and a prompt appears. The meter shows a set of readings and the operator is asked to interpret them before seeing the answer. Read the question, consider what each sensor is showing and what it is not — absence of a reading is often as diagnostic as a positive reading. Tap Reveal Answer when ready.
Debrief Card
When the scenario ends, a debrief card appears with Key Teaching Points — the most important takeaways from that substance's behavior, including IDLH values, ionization potentials, vapor density, cross-sensitivity patterns, and tactical considerations.
Recommended Run Order: CO Incident and Natural Gas establish the baseline LEL-vs-PID interpretation pattern. H₂S Signature and Hydrogen Leak demonstrate cross-sensitivity false readings. Fuel Vapor and Ammonia introduce response factor thinking. Fire Atmosphere is the most complex — run it last to see CO + HCN synergy, O₂ displacement, and all sensors responding simultaneously.
Sampler Mode
Sampler mode puts a fully interactive meter on screen. The display, alarm indicators, and physical buttons are all functional.
Solo Use
Without a Controller connected, the meter powers on and sits at normal atmospheric readings. Practice navigating the display: cycle through sensor pages with the MODE button, acknowledge alarms with YES, and explore the interface as you would a real instrument.
Connected to a Controller
When a Controller is running on another nearby device, the Sampler advertises itself and waits. Once the instructor taps the Sampler on the Controller screen to invite it, the Sampler accepts automatically with no action needed from the trainee. The Sampler then displays whatever readings the Controller sends — including live adjustments, quick scenarios, and vapor-density tilt.
Metering Level Report
The Sampler reports its metering level (Low, Mid, Ceiling) back to the Controller so vapor-density tilt can be applied automatically — lighter gases read higher at ceiling, heavier gases read higher at floor level. The Controller uses this to model real atmospheric stratification.
Walking Speed
The Sampler reports walking speed, which the Controller displays as a trainee activity indicator. The Controller uses this to show whether trainees are stationary or moving through the hot zone.
Button Navigation: MODE cycles through sensor display pages. YES acknowledges the current alarm, silences the buzzer, and transitions alarm lights to solid. NO is secondary navigation — behavior varies by display state. Hold MODE enters the instrument menu. Hold NO cycles alarm states in the simulation.
Controller Mode
Controller mode is the instructor panel. It gives complete control over what connected trainee devices display. Every change transmits to all connected Samplers in real time.
Manual Sensor Sliders
Each sensor has a slider that sets its current reading. Drag to increase or decrease any value. Changes transmit to all connected trainees immediately — the Sampler display updates in real time.
Quick Scenarios
The Quick Scenarios panel provides 24 pre-configured multi-sensor snapshots. Tap any scenario name and all sensor values jump to match that incident pattern instantly. Each quick scenario includes the incident context and sensor rationale. Adjust individual sliders after loading to introduce cross-sensitivity noise, partial sensor failure, or mixture complexity.
Vapor-Density Tilt
The Controller automatically receives each trainee's reported sampling height and applies vapor-density tilt before transmitting. Heavier-than-air gases (H₂S, propane) read higher at Low Level; lighter-than-air gases (methane, hydrogen) read higher at Ceiling. Mid Level applies no tilt.
Trainee Status
The Controller screen shows each connected trainee's metering level badge and walking speed. Use metering level to verify trainees are sampling at the correct elevation. Use walking speed to assess procedural compliance with the floor-to-ceiling search protocol.
Best Practice: Resist loading clean, unambiguous scenarios for class. Add a small CO cross-response on the H₂S scenario, suppress a sensor, or drop O₂ while raising LEL. Realism comes from the noise operators encounter in the field. Use the Unknown Atmosphere Decision Matrix in the Meter Guide to build scenarios matching each of the 11 diagnostic patterns.
Connecting Devices
The app uses MultipeerConnectivity, which works over Wi-Fi and Bluetooth without requiring an internet connection or shared network credentials. Both devices must be nearby and have Wi-Fi or Bluetooth enabled.
How It Works
The Sampler begins advertising itself as soon as it opens. The Controller scans for nearby Samplers and displays them in a discovered-devices list. The instructor taps a discovered Sampler on the Controller screen to send a connection invitation — the Sampler then accepts automatically with no action needed from the trainee.
Single Device Mode
The default. The Controller connects to the first Sampler the instructor taps and stops browsing after that connection is established. Suitable for one-on-one scenarios or individual trainee practice with instructor observation.
Multiple Devices Mode
Switch to Multiple Devices before the first connection. The Controller continues browsing after each connection, allowing additional trainees to join. All connected trainees receive identical readings simultaneously. Each trainee's metering level and walking speed are tracked independently. Tap + Add Device at any time to allow a new Sampler to join a running session.
No Internet Required
MultipeerConnectivity works without an internet connection or shared network credentials. The app is fully functional at remote training sites, in the field, or on aircraft — for all features except Live Scenarios.
Training Library
The Training Library contains three reference and learning resources, all accessible without connecting to another device.
Meter Guide
A comprehensive technical reference for multi-gas meter interpretation. Organized into navigable sections building from foundational concepts through advanced field protocols — from pre-use preparation through mixture effects, vapor density stratification, and the 11-pattern Unknown Atmosphere Decision Matrix.
Sensor Training
Fourteen self-study modules covering every sensor type in a multi-gas instrument: LEL, O₂, H₂S, CO, HCN, PID, IR, SO₂, NH₃, Cl₂, NO₂, PH₃, CO₂, and O₃. Each module includes technical background, operational considerations, and a quiz. 84 quiz questions total across all modules. Pair each module with the matching Guided Scenario for the deepest learning loop.
Live Scenarios
Weekly scenarios drawn from verified real-world hazmat incidents. Each scenario presents the sensor readings from the actual event alongside operational context, teaching points, and response considerations. Updated on a subscription basis — requires an internet connection.
Recommended Reading Order: New users — read Five Critical Physical Properties and the five sensor sections before your first Guided Scenario. Experienced operators — jump directly to Exposure Standards, the Decision Matrix, or PID Response Factors as reference during planning or debrief.
Classroom Setup
For instructor-led sessions, the recommended setup is one device running Controller mode and one device per trainee running Sampler mode.
Before Class
Verify all devices have Wi-Fi or Bluetooth enabled. Open the Controller app first and select Multiple Devices mode before any trainees connect. Have trainees open the Sampler on their devices — it begins advertising immediately with no setup required. On the Controller, each discovered Sampler appears in the nearby-devices list. Tap each one to send a connection invitation. Confirm each trainee appears on the Controller's connected list before beginning.
During the Exercise
Use Quick Scenarios to establish a baseline pattern, then adjust individual sliders to introduce cross-sensitivity noise, vapor-density effects, or sensor ambiguity. Watch each trainee's metering level badge to verify they are sampling at the correct elevation for the gas type. The walking speed indicator shows whether a trainee is stationary or moving — use this to assess procedural compliance with the floor-to-ceiling search protocol.
Advanced Drills
To test the CO+HCN gap: set CO to an elevated value and remind trainees the PID cannot detect HCN — ask what additional information they need before making an entry decision. To test the O₂-deficient LEL gap: drop O₂ to 16% and raise the IR LEL channel; watch whether trainees recognize that the catalytic bead reading is no longer valid. Tap + Add Device at any time to add a late-arriving trainee.
Debrief
After an exercise, the Meter Guide sections serve as structured debrief references. The Exposure Standards section is useful for reviewing why a given reading required a specific protection decision. The Mixture Effects section supports debrief of fire atmosphere and sour gas scenarios. The Decision Matrix can be walked through to review the sensor constellation the exercise presented.
Tips for Getting the Most Out of the App
Read First, Then Run
Read the Five Critical Physical Properties and all five sensor sections in the Meter Guide before your first Guided Scenario. Understanding why each sensor behaves as it does makes the Stop and Think prompts significantly more meaningful.
Run Each Scenario Twice
First run: watch what the sensors do. Second run: apply the Unknown Atmosphere Decision Matrix phase by phase before revealing each answer. The second run is where real interpretive skill develops.
Absence Is Diagnostic
Pay as much attention to what is NOT reading as to what is. A flat PID alongside a positive LEL is often the most diagnostic clue in a scenario — it identifies a fuel the PID cannot see.
Look Up Exposure Thresholds
Before forming a protection decision, consult the Exposure Standards section in the Meter Guide. A meter alarm is not the same as an IDLH event. IDLH, PEL, and TLV values for each metered gas are in the guide.
Check Your LEL Sensor Technology
Identify your meter's LEL sensor technology before deploying to a hydrogen environment. The IR Sensor Technology section explains why an IR-only meter reads zero LEL in an explosive hydrogen atmosphere — a lethal gap in coverage.
Correct PID Readings
When the compound is known, apply the PID response factor before acting on the reading. The PID Response Factors section includes tables for BTEX, chlorinated solvents, alcohols, and other common field compounds. An uncorrected PID reading is not a concentration.
HCN in Every Structure Fire
In fire atmosphere scenarios and overhaul training, remember that HCN is produced in every modern structure fire. The Mixture Effects section covers CO+HCN synergy and why the standard meter gives no indication of HCN presence without a dedicated sensor channel.
Add Noise to Controller Scenarios
When using Controller mode for classroom exercises, resist loading a clean, unambiguous scenario. Add a small CO cross-response on the H₂S scenario, suppress a sensor, or drop O₂ while raising LEL. Realism comes from the noise operators encounter in the field.
Pair Sensor Training with Scenarios
Pair each Guided Scenario with the matching Sensor Training module for the deepest learning loop: study the sensor, run the scenario, review the debrief card.
Keep Apps in the Foreground
Keep both the Controller and Sampler in the foreground during connected exercises. Backgrounding either app may interrupt the MultipeerConnectivity session.
Works Fully Offline
The app does not require an internet connection for any feature except Live Scenarios. It is fully usable in the field, at remote training sites, or on aircraft.
Confirm Bump Test Before Deployment
Before each training deployment, confirm the bump test was performed and the calibration is current. The Bump Testing vs. Full Calibration section in the Meter Guide outlines when each is required and what documentation a confined space entry log needs.