Gas System Safety Checks

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Phase 1: Initial Safety Assessment

Check for gas odor (mercaptan smell)

Use your nose - natural gas is odorized to smell like rotten eggs or sulfur

IF GAS SMELL DETECTED: Evacuate, call 911, shut off gas at meter if safe
Test for carbon monoxide presence

Use portable CO detector - test near appliances, in living spaces, near vents

Safe: <9ppm | Concern: 9-35ppm | Danger: >35ppm (evacuate)
Verify adequate ventilation/combustion air

Check for blocked vents, closed doors preventing air flow to appliances

CSA B149.1 Clause 7.2 - Combustion Air Requirements
Identify all gas appliances in building

Furnace, water heater, range, dryer, fireplace, pool heater - inventory all gas equipment
Locate main gas shut-off valve

Typically at meter - verify accessible and functional (1/4 turn to close)

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Phase 2: Gas Piping System Inspection

Visual inspection of gas piping

Check for corrosion, damage, improper support, unauthorized modifications, flexible connectors condition

CSA B149.1 Clause 6.9 - Piping Support & Protection
Check pipe sizing adequacy

Verify pipe diameter appropriate for BTU load and length - undersized = pressure drop

CSA B149.1 Clause 6.10 - Pipe Sizing Tables
Inspect all accessible joints and connections

Look for rust staining, leak sealant weeping, loose fittings, improper thread compound
Verify proper sediment trap (drip leg) installation

Required at each appliance - minimum 3" nipple extending down from tee

CSA B149.1 Clause 6.14 - Sediment Traps Required
Check gas valve operation at appliances

Manual shut-off valves should turn freely, handle perpendicular to pipe = closed

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Phase 3: Gas Leak Detection

Perform soap bubble test on all connections

Apply leak detection solution or soapy water - bubbles indicate leak

Test: Meter connections, unions, gas valves, appliance connections, caps
Use electronic leak detector on suspicious areas

Heated diode or infrared detector for detecting small leaks not visible with bubbles
Check flexible connector condition

CSST (yellow), black iron connector, or stainless flex - look for kinks, damage, corrosion

Replace if: Kinked, corroded, damaged, older uncoated CSST
Inspect gas meter for leaks

Check meter connections, regulator vent, meter body - utility responsibility but check
Test appliance gas valve connections

Where union or flare connects to appliance - common leak point

🚫 IMMEDIATE RED TAG - GAS LEAKS

Any detected gas leak requires immediate action:

Shut off gas supply to affected appliance or main if necessary
Tag appliance with red warning tag - do not operate
Notify customer in writing - explain hazards clearly
Report to TSSA if required by regulations
Do NOT restore gas service until leak is repaired and retested

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Phase 4: Gas Pressure Verification

Measure inlet gas pressure (manifold pressure)

Use manometer or digital gauge at appliance gas valve test port

Natural Gas: 3.5-5.0" W.C. | Propane: 11" W.C. inlet
Check outlet pressure at gas valve

Measure at manifold with all burners firing

Natural Gas: 3.5" W.C. | Propane: 10" W.C. typical outlet
Verify pressure drop during operation

Pressure should remain stable - excessive drop indicates undersized piping

Max pressure drop: 0.5" W.C. from meter to appliance

CSA B149.1 Clause 6.10.1 - Pressure Drop Limits
Test regulator lockup pressure (if applicable)

With all appliances off, pressure should not exceed specified maximum

✅ PASS CRITERIA

Pressure within spec range
Stable during operation
Pressure drop <0.5" W.C.
No hunting or fluctuation

❌ FAIL CONDITIONS

Pressure below minimum
Excessive pressure drop
Unstable/hunting pressure
Requires further investigation

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Phase 5: Venting System Inspection

Verify proper vent material for appliance type

Category I: B-vent | Cat II/IV: PVC/CPVC/ABS/PP | Must match manufacturer specs

CSA B149.1 Clause 7.5 - Vent Materials
Check vent pipe slope and support

Natural draft: 1/4" per foot rise | Sidewall: per manufacturer | Proper hangers every 4-6 feet

CSA B149.1 Clause 7.5.8 - Vent Slope Requirements
Inspect vent termination location and clearances

Check distances from windows, doors, air intakes, property lines, mechanical ventilation

CSA B149.1 Clause 7.5.9 - Termination Clearances (critical)
Verify vent cap/termination installed correctly

Must be manufacturer-approved cap, not damaged, proper orientation, screens intact
Check for vent blockages or restrictions

Birds nests, ice, debris - inspect with flashlight and mirror if accessible
Inspect vent pipe for deterioration or damage

Rust holes, separated joints, condensate leaking, sagging, crushed pipe
Verify proper vent sizing for appliance

Use CSA B149.1 tables - diameter and height must accommodate BTU input

CSA B149.1 Clause 7.5.7 - Vent Sizing Tables
Test draft pressure (natural draft appliances)

Should be negative (pulling) - typically -0.01 to -0.05" W.C. over fire

Positive pressure = backdrafting hazard (RED TAG)

🚫 IMMEDIATE RED TAG - VENTING DEFECTS

The following venting issues require immediate red tag and appliance shutdown:

Vent disconnected, separated, or has holes allowing spillage into building
Backdrafting observed (spillage switch tripping, products of combustion in space)
Vent termination violates clearances (too close to windows, air intakes)
Blocked or restricted vent preventing proper flow
Improper vent material causing deterioration
Inadequate vent size for appliance load

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Phase 6: Combustion & CO Testing

Perform combustion analysis in flue

Use combustion analyzer to measure CO, O2, stack temperature, efficiency

Target: CO <100ppm air-free | O2: 6-9% | CO/CO2 ratio <0.004
Test for CO in ambient air near appliance

Measure CO in room while appliance running - should be 0-9ppm

0-9ppm: Safe | 9-35ppm: Investigate source | >35ppm: Evacuate
Check for flame rollout or abnormal flame

Observe burner flames - should be blue, stable, no yellow tips, no lifting
Test spillage switch operation (if equipped)

Verify switch trips if vent blocked - some appliances have manual reset button
Inspect heat exchanger for cracks/holes

Visual inspection with flashlight - look for rust, cracks, flame distortion

Cracked heat exchanger = immediate shutdown and replacement
Verify proper air shutter adjustment

Adjust for clean blue flame - no yellow, no lifting, quiet operation

💡 COMBUSTION ANALYSIS REQUIREMENTS

While not required on every service call, combustion analysis is STRONGLY RECOMMENDED for:

New installations and modifications
Annual maintenance on commercial equipment
Customer complaints of odors or symptoms
Any suspected combustion or venting problems
After heat exchanger service or repairs

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Phase 7: Appliance-Specific Safety Checks

Verify all safety controls functioning

Flame rollout switches, high limit switches, pressure switches - test operation
Check flame sensing system operation

Flame sensor (microamps), thermocouple, thermopile - verify proves flame

Flame sensor: 2-10µA good | <0.5µA = clean or replace sensor
Test main gas valve for leakage

With appliance off, check manifold pressure - should be zero (no leak-by)
Verify pilot safety system (standing pilot)

Test that main valve closes when pilot is extinguished
Check appliance installation clearances

Verify clearances to combustibles per nameplate and code

CSA B149.1 Clause 8.4 - Appliance Clearances
Inspect burner assembly and orifices

Clean burners, check orifice size matches gas type and altitude

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Phase 8: Documentation & Customer Communication

Document all findings on work order

Record pressures, CO readings, leak test results, condition of equipment
Take photos of safety concerns

Document red tag conditions, code violations, defects - protect yourself legally
Issue red tag if required

Complete TSSA red tag form, attach to appliance, provide customer copy

Customer must sign acknowledgment - explain hazards clearly
Report to TSSA if mandatory

Some defects require reporting to Technical Standards & Safety Authority

TSSA Fuels Safety Program - Reporting Requirements
Educate customer on gas safety

How to recognize gas smell, CO symptoms, when to call for service, emergency procedures
Recommend CO alarms if not present

Required by law in most jurisdictions - one per floor, near bedrooms

Building Code requires CO alarms in residential with fuel-burning appliances

⚖️ LEGAL & PROFESSIONAL RESPONSIBILITY

As a licensed gas technician, you have legal and ethical responsibilities:

You MUST red tag dangerous appliances - customer cannot override
Document everything - your notes may be used in legal proceedings
You can be held liable for injuries if you fail to identify hazards
Your license is on the line - never compromise on safety
When in doubt, consult with senior tech or TSSA inspector