ie-rgii-non-domestic-gas-safety flashcards

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

RGII registration requirement

Gas work in Ireland must be carried out by an installer registered with the Register of Gas Installers of Ireland holding the correct scope, including non-domestic natural gas or LPG categories.

I.S. 820 scope

The Irish standard for non-domestic gas installations, covering design, installation, commissioning, testing and documentation for commercial and industrial gas systems.

Gas Safety Act 2012

Irish legislation establishing the regulatory framework for gas safety, including the registration of gas installers and enforcement powers relating to gas works.

Warning notice purpose

A written notice attached where an immediate danger exists, stating the defect and action taken, with the supply isolated and the responsible person and RGII informed.

Natural gas relative density

Approximately 0.6, so natural gas is lighter than air, rises, and accumulates at high level, driving high-level ventilation and detector placement.

LPG vapour relative density

Approximately 1.5 to 2.0, so LPG vapour is heavier than air and collects in low areas, pits, ducts and basements, requiring low-level ventilation and detection.

Stoichiometric air requirement

The exact air volume needed for complete combustion: about 9.5 m³ air per m³ methane and about 23.8 m³ per m³ propane vapour.

Flammable limits of methane

Methane is flammable in air at roughly 5% to 15% by volume; LPG has a wider, lower range, increasing explosion risk in confined spaces.

Equivalent pipe length method

Sizing method adding measured pipe run to equivalent lengths of fittings, then selecting diameter from gas rate and allowable pressure drop tables.

Low-pressure design pressure drop

For low-pressure natural gas, pipework is commonly sized to a total pressure drop of about 1 mbar from meter outlet to appliance inlet.

Gas isolation valve location

An accessible isolation valve is required at the meter or regulator outlet and at each appliance or zone, with emergency controls clearly marked.

Medium-pressure regime

A supply pressure between about 75 mbar and 2 bar, often used on non-domestic sites with a site regulator, requiring different design and testing rules.

Type C appliance flueing

A room-sealed, balanced-flue appliance drawing combustion air from outside and discharging flue products outside, so room combustion-air openings are generally not needed.

Safety shut-off valve function

A valve that closes automatically on flame failure or unsafe condition, proved closed before light-up and on shutdown, preventing unburnt gas entering the combustion chamber.

Burner pre-purge purpose

A period of forced air flow through the combustion chamber before ignition to remove any accumulated flammable gas and prevent explosion on light-up.

Appliance data plate values

Declared gas family, nominal heat input, gas rate, burner pressure and injector size that commissioning must match and record.

Combustion air versus dilution air

Two separate ventilation requirements: air for burning the gas, and air to dilute flue products for open-flue appliances; the larger governs opening size.

Louvre free area

The actual unobstructed area of a ventilation opening after allowing for grille or louvre blockage, which must be used in ventilation calculations.

Ventilation interlock

A proven airflow device that prevents burner firing unless mechanical ventilation is running, shutting the burner down safely if airflow fails.

LPG basement ventilation

Below-ground rooms using LPG require low-level ventilation and mechanical extract at low level, interlocked with gas detection and firing controls.

CO/CO₂ ratio

An indicator of incomplete combustion calculated from flue gas analysis; around 0.004 or below is normal for natural gas, with higher values requiring investigation.

Flue draught measurement

Measurement of the pressure pulling flue products from the appliance, taken with the appliance and other appliances running under worst-case conditions.

Spillage test

A test confirming open-flue appliances clear combustion products under worst-case conditions, such as closed doors and windows with extract fans running.

Excess air from O₂ reading

Flue oxygen of about 3% to 6% for natural gas indicates correct excess air; very low O₂ risks carbon monoxide, very high O₂ wastes heat.

Tightness test medium

Air or inert gas is used for strength and tightness testing; oxygen and flammable gas must never be used as the test medium.

Purging pipework

Removing air before gas is introduced, or removing gas before opening pipework, with calculated purge volumes discharged to a safe, ignition-free location.

Commissioning sequence

Tightness test, purge, set pressures and gas rate, combustion analysis, confirm ventilation and flueing, test safety controls, then record all results.

Decommissioning steps

Isolate and lock off supply, purge the section, cap or plug pipework, make appliances safe, label the installation, and update records and the client.

LPG detector placement

Because LPG vapour is heavier than air, detectors are mounted low, typically 150 to 300 mm above floor level near potential leak points.

Gas detection alarm stages

Typically a pre-alarm near 10% of the lower flammable limit and an alarm near 20%, with the alarm stage isolating gas and shutting down burners.

Gas escape emergency actions

Eliminate ignition sources, isolate at the emergency control valve, ventilate, evacuate, and call the gas network emergency service and fire service.

Non-domestic handover pack

A record containing pipework details, tightness and purge results, appliance settings, combustion readings, ventilation and flueing details, and certificates.