various Flashcards
Give FOUR reasons why spillage from a gas appliance may occur
- High gas pressures.
- Cracked heat exchanger
- Blocked flue.
- Lack of ventilation
A fault has developed on a gas-fired, electronic continuous-flow water heater. When the
water tap is turned on, the appliance starts and the gas ignites, but the appliance shuts down after a few seconds. An error code is displayed which indicates failed ignition.
Give FOUR likely reasons this may have occurred.
- PCB Fault.
- Low gas pressure
- Faulty/dirty flame sensor probe
- Partially blocked burner or heat exchanger.
A line of soot has appeared on the front of a radiant/convector gas heater installed in an
existing fire place.
Give FOUR likely reasons this may have occurred.
- The flue is blocked causing incomplete combustion.
- The aeration for the burner could be blocked with lint.
- The mixing tube could be blocked.
- The burner ports could have enlarged or corroded.
- The gas pressure may be incorrect.
State FIVE factors that need to be specified when selecting a regulator for a gas installation.
- Type of gas being used.
- Inlet or upstream pressure.
- Outlet or downstream pressure.
- Maximum flow anticipated.
List SIX items of information that must be permanently marked on every gas appliance.
- Manufacturer.
- Model Number.
- Type of gas.
- Working pressure.
- Input rating.
- The gas safety compliance label.
A fault has developed on a gas oven. After the oven has been running for 20 minutes, it shuts the
gas off and must be manually restarted.
Give THREE likely causes for this to occur.
- The thermocouple is too far from the flame.
- The oven by-pass is set incorrectly.
- The thermostat is faulty.
A natural draught flue for a gas appliance is being designed.
State FOUR ways in which condensation in the flue can be minimised.
- Insulate flue.
- Select shortest route to atmosphere.
- avoid offsets
- avoid lateral runs
Give TWO factors that affect heat loss of a gas flue.
- Length of flue.
* Elbows or bends.
Give FOUR factors other than heat loss that determine the diameter of a gas flue.
- The spigot size
- Lateral run.
- Number of elbows and bends.
- Total length of the flue.
State THREE factors that determine the size of a rotary gas meter for an industrial boiler
- Gas inlet pressure.
- Maximum gas flow rate.
- Pipe size.
Give TWO advantages of using a rotary gas meter instead of a diaphragm gas meter.
- operate at high pressures.
* steady/smooth output.
A natural gas appliance is to be converted to operate on LPG.
List SIX items that must be checked and that may need changing in the conversion.
- Data plate.
- Aeration.
- Operating pressure.
- Regulator.
- By-passes.
- Injectors.
An installation is being converted from LPG to natural gas.
Give TWO aspects of the installation pipework that must be checked and that may need changing.
- Size/diameter.
* Labelling.
State the specific compliance document that should be used for the installation of commercial catering equipment in a catering vehicle.
AS/NZS 5601: Part 1
