BP MIGCS flashcards

38 cards. Read the term and the definition here. The deck at the top of this page is optional.

Authority having jurisdiction

The official or agency that enforces the adopted code and approves equipment, materials, and installations. Their adopted edition and interpretations govern the job, including permits and final inspection sign-off.

Listed vs. approved

Listed means tested and certified by a recognized testing laboratory to a published standard. Approved means acceptable to the authority having jurisdiction. Equipment generally must be both listed and approved.

Manufacturer's instructions

The installation manual shipped with a listed appliance. Codes make these instructions mandatory, covering venting configuration, clearances, gas pressures, and electrical requirements for that specific model.

Fuel gas code scope

NFPA 54/ANSI Z223.1 covers piping, appliances, venting, and combustion air for natural gas and LP-gas installations. NFPA 58 separately governs LP-gas storage and handling. Local adoption sets the enforceable edition.

Field conversion kit

A manufacturer-supplied, listed kit of orifices, springs, and labels that converts an appliance between natural gas and LP-gas. Using unlisted parts or drilling orifices voids the listing and violates code.

Permit and inspection trigger

New gas piping, appliance replacement, and alterations typically require a permit and inspection before gas is turned on. Minor repairs may be exempt, but the authority having jurisdiction decides.

Stoichiometric combustion

The exact air-to-fuel ratio for complete combustion with no excess air or fuel. Methane needs about 10 volumes of air per volume of gas; propane needs about 24.

Complete combustion equation

CH4 + 2O2 gives CO2 + 2H2O. Each volume of methane consumes two volumes of oxygen, supplied by roughly ten volumes of air at 21 percent oxygen.

Flammable limits

The gas-in-air concentration range that will ignite. Natural gas is about 4 to 15 percent; propane about 2.1 to 9.5 percent. Outside the range the mixture is too lean or too rich.

Carbon monoxide formation

CO results from incomplete combustion caused by insufficient air, flame impingement, blocked flue, or overfiring. It is colorless and odorless, so combustion analysis, not smell, detects it.

Combustion air rule of thumb

Unconfined spaces provide about 50 cubic feet per 1,000 Btu/h input. Confined spaces need two permanent openings, commonly sized at 1 square inch free area per 1,000 Btu/h each.

Gas specific gravity

Ratio of gas density to air density. Natural gas near 0.6 rises and disperses upward; propane near 1.5 sinks and pools in basements, pits, and low areas.

Odorant and odor fade

Mercaptan is added so leaks are detectable well below the flammable limit. New steel pipe and some soils can absorb odorant, causing odor fade and undetectable leaks despite odorization.

Excess air purpose

Air supplied beyond stoichiometric requirements ensures complete combustion and reduces CO. Too much excess air, however, lowers efficiency by carrying heat up the flue.

Appliance fuel match

An appliance must be listed for the gas supplied. Converting between natural gas and LP-gas requires the manufacturer's listed conversion kit with correct orifices, regulator spring, and updated rating label.

Sediment trap

A tee with a capped downward nipple at the appliance connection, installed so gas turns 90 degrees before entering the controls. It captures scale and debris that could block orifices.

Appliance connector limits

Listed flexible connectors are used for appliance connections, commonly limited to about 6 feet for movable appliances, with a shutoff valve upstream in the same room. Rigid piping is used where required.

Garage ignition elevation

Gas appliances in garages must have ignition sources elevated, commonly at least 18 inches above the floor, unless listed for garage installation, to avoid igniting heavier-than-air gasoline vapors.

Clearance to combustibles

Minimum distance from an appliance or vent to combustible material, taken from the rating plate and listing. Reductions require listed shielding or authority approval, not field-fabricated substitutes.

Service accessibility

Appliances must be reachable for inspection, cleaning, and repair, with controls and burners unobstructed and working space in front of the unit. Concealed or blocked units violate code.

Category I appliance

A non-condensing appliance that vents under negative pressure and uses Type B vent. Flue gas stays above dew point, so condensation and corrosion-resistant venting are not required.

Category IV appliance

A condensing, positive-pressure appliance requiring gas-tight, corrosion-resistant listed venting, often PVC, CPVC, polypropylene, or stainless steel, plus a condensate drain. Substituting materials is prohibited.

Vent connector slope

Natural-draft vent connectors must rise toward the chimney at least 1/4 inch per foot of horizontal run, with no sags or traps that collect condensate or block draft.

Type B vent clearance

Double-wall Type B vent uses its listed clearance to combustibles, commonly 1 inch. Single-wall connectors need greater clearance, often 6 inches, unless listed otherwise.

Oversized vent effect

A vent too large for the appliance input and height cools flue gas, weakens draft, and promotes condensation and spillage. Vent size must match the connected input and height.

Vent termination rules

Terminations must be located above the roof and at code-specified distances from operable windows, doors, air intakes, and corners. Mechanical draft vents have minimum clearance distances from openings.

Common venting risk

Multiple appliances sharing a manifold must be on the same floor with correctly sized connectors. A blocked or disconnected vent on one unit can spill flue gas into the space.

Longest-run sizing method

Select pipe size from code capacity tables using the longest equivalent length, including fitting allowances, adjusted for gas specific gravity and allowable pressure drop across the whole system.

Equivalent length

Measured pipe length plus allowances for fittings, such as about 5 feet per 90-degree elbow and 10 feet per tee branch, or values from the code table, used for sizing.

Appliance manifold pressure

Pressure at the appliance inlet, commonly 7 inches water column for natural gas and 11 for LP. It must match the rating plate and is set by the appliance regulator.

Piping pressure test

New gas piping is tested with air or inert gas, commonly at 1.5 times working pressure but not less than 3 psi for low pressure, held at least 10 minutes with no drop.

CSST bonding requirement

Corrugated stainless steel tubing requires bonding per the manufacturer and electrical code to reduce lightning-related arc damage. Bonding is separate from and additional to pressure testing.

Appliance shutoff valve

A listed gas shutoff installed within the same room or immediately adjacent to the appliance, upstream of the connector and accessible, so the unit can be isolated for service.

Piping purge procedure

Air must be removed from new piping before ignition. Purge to a safe outdoor location, never into a confined space, and never use a flame to judge purge completion.

Combustion analysis targets

Typical natural gas readings are about 8 to 9 percent CO2 or 5 to 7 percent O2, with air-free CO well under 100 ppm. Always confirm against the manufacturer's specification.

Draft hood spillage test

A smoke or flame test at the draft hood confirms flue gases are drawn up the vent rather than spilling into the room. Spillage or down-draft is a red-tag condition.

Flame safeguard test

Verify the flame sensor and safety shutoff by interrupting flame signal and confirming the gas valve closes within the manufacturer's stated time. Record the result on the commissioning sheet.

Leak detection method

Use an electronic detector or soap bubbles on joints; never an open flame. A pressure test that drops indicates a leak, which must be located, repaired, and retested before service.