Red Seal Gasfitter Class A key terms

A documented procedure for isolating all energy sources, including gas, electricity and stored pressure, before work begins. Each worker applies a personal lock and tag, and only the person who applied it removes it.

A portable instrument that measures gas concentration in air and alarms before the lower explosive limit is reached. Bump testing verifies sensor response; calibration confirms accuracy against a known reference gas.

The minimum gas concentration in air that will support combustion, expressed as a percentage by volume. Detector readings are often shown as a percentage of this limit rather than raw concentration.

Entry into a space with limited access and poor natural ventilation that is not designed for continuous occupancy. Requires hazard assessment, atmospheric testing, an attendant, and rescue provisions before entry.

Displacing flammable gas from piping or equipment with air, nitrogen or another inert medium before hot work or opening the system. Purging continues until tests confirm the atmosphere is safe.

The adopted installation code that governs gas piping, appliance installation, venting and clearance requirements in a jurisdiction. Local amendments and the authority having jurisdiction override or supplement its requirements.

The organization or official responsible for enforcing the gas code and approving installations, often a municipal or provincial inspection body. Their interpretation governs acceptance of an installation and any variance granted.

Formal authorization to install or alter gas equipment, followed by inspection before concealment or activation. Working without a permit can void insurance and exposes the contractor to penalties and rework.

The provincial body that administers gas safety legislation, licenses contractors and certified individuals, and investigates incidents. Requirements vary by province, so verify credentials and notification rules locally.

The credential issued to a tradesperson who passes the certification exam in a province or territory. It authorizes work in the trade and is subject to renewal, continuing education and code-update requirements.

A code table used to select pipe diameter from load, length, allowable pressure drop and gas type. Equivalent length adds allowances for fittings and valves to the measured run.

The measured pipe run plus an added length allowance for each fitting, valve and bend, expressed as straight pipe. It is used with sizing tables to account for friction losses in the system.

The loss of pressure caused by friction as gas flows through pipe, fittings and valves. Sizing must keep the drop within code limits so appliances still receive adequate pressure at full demand.

A compound or tape applied to male pipe threads to seal joints against gas leakage. It must be rated for the gas and compatible with the piping material, and applied so it cannot enter the pipe bore.

Steel pipe commonly used for above-ground natural gas distribution inside buildings. It is joined by threaded fittings and must be protected against corrosion where exposed to moisture or chemicals.

A fitting that separates dissimilar metals to prevent galvanic corrosion at a connection. It is commonly installed where steel gas piping meets copper or brass components.

A flexible stainless steel gas tubing supplied in coils and joined with proprietary fittings. It requires bonding to the electrical system and protection from physical damage per the manufacturer's instructions.

A wire installed alongside buried non-metallic gas piping so the route can be located later with detection equipment. It must be continuous and terminated at accessible points.

A documented layout of the lift showing load weight, centre of gravity, sling angles, equipment ratings and exclusion zones. It is prepared before hoisting and reviewed with everyone involved in the lift.

The maximum load a sling, shackle or hoist component may carry in a specific configuration. It is marked on the component and must never be exceeded, with reductions applied for sling angles.

The angle between a sling leg and the horizontal determines how much tension the leg carries. Shallower angles increase tension sharply, so wider spreads reduce stress on slings and hardware.

A lift that exceeds a set percentage of crane capacity, involves personnel, or carries unusual risk such as over occupied space. It typically requires an engineered plan and supervisory approval.

Selecting a burner orifice that delivers the correct gas input at the available manifold pressure for the appliance rating. Gas type and altitude affect the choice, and the manufacturer's chart must be followed.

The gas pressure measured at the appliance manifold, downstream of the combination gas valve. It is set to the manufacturer's rating plate value and verified with a manometer under operating flow.

A device that controls gas flow to a burner, often combining regulation, safety shutoff and manual selection in one body. Safety shutoff valves must close fully on loss of flame signal or power.

A regulator arrangement that reduces supply pressure in two steps, first to an intermediate pressure and then to appliance pressure. It provides steadier delivery than a single-stage regulator under varying load.

The minimum distance a flue or intake termination must be kept from windows, doors, corners, meters and other openings. Clearances prevent flue products from re-entering the building or contacting combustibles.

An appliance that operates with non-positive vent pressure and relies on natural draft. It requires a properly sized vertical vent and adequate dilution air to vent safely.

A device at the appliance outlet that limits draft on the flue and dilutes flue gases with room air. It stabilizes combustion and prevents excessive draft from pulling heat from the appliance.

Flue products escaping from the draft hood or relief opening into the room instead of up the vent. It signals a blocked flue, poor draft or depressurization and is a serious carbon monoxide risk.

A permanent opening sized to supply air for combustion and dilution to an appliance enclosure. Sizing depends on whether air is drawn from inside or outdoors and on the appliance input rating.

An appliance that draws combustion air from outdoors and discharges flue products outdoors through a sealed vent system. It is largely unaffected by building depressurization and requires specific termination clearances.

Measuring flue gas oxygen, carbon monoxide and temperature to calculate efficiency and confirm clean combustion. Results guide air adjustment and reveal problems such as incomplete combustion or excess air.

A method of verifying gas input by timing the meter dial over a known gas volume and comparing the result to the appliance rating plate. It confirms correct orifice sizing and manifold pressure.

A control system that proves a flame is present and shuts off gas if it is lost. Common types include thermocouples, flame rectification and ultraviolet scanners, each with specific response and testing requirements.

The sequence and allowed duration for proving ignition before the control locks out. Trial time, flame response time and purge time must match the appliance design to prevent unburned gas accumulation.

Electrical connection of gas piping to the building grounding system to prevent it from becoming energized or arcing. Required for CSST and often for metallic piping, and verified by inspection.

A documented leak test of piping or equipment at a specified pressure for a set duration using air, inert gas or gas, depending on code. Results are recorded and witnessed before the system is placed in service.

A soap-based liquid applied to joints to reveal gas bubbles during a leak check. It is used after pressure testing and at start-up, and the joint is rinsed afterward to prevent corrosion.

The structured process of verifying that installed equipment operates safely and to specification before handover. It includes start-up checks, adjustment, documentation and client instruction.