PGDB Certifying Gasfitter flashcards
PGDB Certifying Gasfitter · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- B149.1
- The CSA Natural Gas and Propane Installation Code used in Canada; it sets minimum requirements for installation, venting, piping, and testing of gas appliances and equipment.
- Authority having jurisdiction
- The organization or official responsible for enforcing the gas code and issuing permits and inspections. Their approval is required for field approvals and unlisted equipment.
- Listed appliance
- An appliance certified by a recognized testing agency such as CSA, ULC, UL, or Intertek. Its certified instructions and data plate govern installation and clearances.
- Methane combustion equation
- CH4 + 2O2 produces CO2 + 2H2O. Each volume of methane needs two volumes of oxygen, about 9.5 volumes of air for complete combustion.
- Propane specific gravity
- Propane vapour has a specific gravity of about 1.52, heavier than air. It settles in low areas such as basements, pits, and crawl spaces, requiring low-level ventilation and detection.
- Flammable limits
- The range of gas concentration in air that will ignite. Natural gas is about 4 to 15 percent; propane about 2.1 to 9.5 percent by volume.
- Stoichiometric air
- The exact amount of air needed for complete combustion. Propane requires about 23.8 volumes of air per volume of gas; methane about 9.5 volumes.
- Category I appliance
- A non-condensing appliance that operates with negative draft and vents with B-vent. It relies on a warm flue and adequate draft to remove products of combustion.
- Category IV appliance
- A condensing, positive-pressure appliance. It uses listed PVC, CPVC, or stainless venting per manufacturer instructions and requires condensate drainage and neutralization where specified.
- Combustion air openings
- Confined spaces need two permanent openings, high and low, sized to total input. Louvered grilles reduce free area, so metal louvers count about 75 percent free area.
- Vent connector slope
- Natural draft vent connectors must slope upward toward the chimney at least 1/4 inch per foot, about 20 mm per metre, and be as short and direct as possible.
- Equivalent length
- A method of adding fitting losses to straight pipe length for sizing. A 90-degree elbow counts about 5 feet, a 45 about 2.5 feet, and a tee branch about 10 feet.
- Pressure test requirement
- New gas piping is tested with air or inert gas at not less than 1.5 times maximum working pressure, with a minimum test pressure and duration set by code, and no pressure drop allowed.
- Sediment trap
- A drip leg installed at the appliance inlet, downstream of the shutoff valve, at least 3 inches (75 mm) deep, to catch debris before it reaches the controls.
- Appliance connector limit
- A listed flexible connector must not exceed 6 feet (1.8 m) for movable appliances and must not pass through walls, floors, or ceilings.
- Manifold pressure
- The pressure at the appliance burner manifold. Natural gas appliances typically use 3.5 inches water column; propane appliances typically 10 to 11 inches water column.
- Appliance shutoff valve
- A manual valve installed in the supply line within 6 feet (1.8 m) of the appliance, readily accessible and clearly identified, with a union to allow removal.
- Garage appliance ignition height
- For propane appliances in garages, ignition sources must be at least 18 inches (450 mm) above the floor because propane vapour is heavier than air.
- Thermocouple output
- A thermocouple generates roughly 250 to 750 millivolts open circuit from a pilot flame. That voltage energizes the safety magnet holding the gas valve open.
- Flame rectification
- A flame-sensing method where the flame conducts current between sensor and burner. The control detects microamps, typically 1 to 10, to prove flame is present.
- Hot surface igniter
- A silicon carbide or nitride igniter that glows to ignite gas. Test resistance with power off, typically 40 to 100 ohms depending on manufacturer, and inspect for cracks.
- Rollout switch
- A manual-reset safety switch that trips when flame rolls out of the combustion chamber, often from a blocked flue or dirty burner. Investigate the cause before resetting.
- Diagnostic sequence
- Verify gas supply and pressure, then electrical supply and control voltage, then ignition sequence, then flame proving, then combustion and venting. Follow the order to isolate faults.
- Soot indication
- Soot deposits indicate incomplete combustion from a rich mixture or blocked flue. Soot is a fire and carbon monoxide hazard and must be corrected, not just cleaned.
- Gas valve testing
- Check inlet and outlet pressures, confirm the valve opens on a call for heat, and verify the operator coil or diaphragm. Never disassemble a gas valve in the field.
- Carbon monoxide properties
- CO is colourless, odourless, and slightly lighter than air. It binds haemoglobin about 200 to 250 times more readily than oxygen, causing tissue hypoxia.
- CO2 max
- The maximum carbon dioxide in flue gas with perfect combustion: about 11.7 to 12 percent for natural gas and about 13.8 percent for propane.
- Excess air formula
- Excess air equals (CO2max divided by measured CO2, minus 1) times 100. Dilution air lowers measured CO2 and raises measured O2.
- Air-free CO
- A CO reading corrected for dilution air, allowing comparison between appliances. Always convert measured CO to air-free values before judging combustion quality.
- Lock out tag out
- A procedure to isolate energy before servicing. Close and lock the gas valve and electrical disconnect, tag them, and verify with a meter that power is off.
- Combustible gas detector
- An LEL meter used to check for gas leaks. Soap bubbles confirm small leaks. A flame must never be used to test for gas leaks.
- Documentation of service
- Record date, appliance model and serial, pressures, CO readings, draft, parts replaced, and tests performed. Leave a copy with the customer and retain a record.