Characteristics of combustion

what is the most common cause of incomplete combustion of an open flued appliance

• the primary ports become blocked with a build up of lint, fibres

• the secondary ports become blocked due to lint, fibres etc

• the burner injector becomes enlarged

• the burner is damaged due to corrosion or heat stress

An obvious sign of incomplete combustion of an open flued central heating boiler is

• explosive ignition

• yellow flames at the burner

• carbon monoxide alarm activating

• signs of spillage at the draught diverter

The process of stoichiometric combustion is shown in which following chemical equation

• CH4+2O2 = CO2+2H2O

• 2CH4+3O2 = 2CO+4H2O

• CH4+O2 = C+2H2O

• 2CH4+5O2=2CO2 +4H2O

In reality oxygen is not supplied neat, but is supplied by the provision of air. Air is generally taken to consist of

• 20% Nitrogen and 80% oxygen.

• 20.9% Oxygen and 79.1% Nitrogen

• 20.9% Nitrogen and 79.1% Oxygen

• 20% Oxygen and 80% Nitrogen

Battery and mains powered carbon monoxide detectors are now manufactured to which standard

• BS 7860

• BS 5440-1

• BS EN 50291

• BS 5440-2

If CO poisoning is suspected, any person affected must be

• Given medical advice over the phone

• removed from any room containing a gas appliance and relocated to another room

• advised that gas appliances should be serviced immediately

• removed from the area and relocated to the open air immediately

what level of CO could cause a carbon monoxide alarm to go off within 3 minutes

• 35 ppm

• 50ppm

• 100ppm

• 300ppm

What type of sensors are fitted within a typical flue gas analyser?

• carbon dioxide and oxygen

• carbon monoxide

• oxygen

• carbon monoxide and oxygen

Which of the following is likely to cause vitiation of a room sealed balanced, fanned draught combi boiler?

• Room air supply is contaminated

• incorrectly assembled flue

• partially blocked injectors

• fan failure

when sufficient oxygen is mixed with gas and complete combustion occurs the main constituents produced are

• carbon monoxide and hydrogen

• carbon dioxide, carbon monoxide and hydrogen

• carbon dioxide and water vapour

• carbon monoxide and water vapour