Gas revision #2

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Gas revision #2

Sometimes gas boiler heat exchangers can become blocked or obstructed with debris in the heat exchanger, what effect would this have on the combustion process?

1 point

a) Explosive ignition

b) A cosy flame effect with no real effect on the combustion process

c) Flame failure

d) Incomplete combustion because the flame is impinged

Clear selection

If an electronic gauge is used for domestic gas installation tightness testing, how often should it be calibrated?

1 point

a) Bi-annually

b) Annually

c) When the batteries require replacement

d) Once every 18 months

Clear selection

After decommissioning a gas appliance in a dwelling, the correct procedure is to:

1 point

a) purge the pipework fully safely and cap off accordingly.

b) purge the appliance only as the pipework is unaffected.

c) no purging is required when an appliance is disconnected on an existing installation.

d) cap at meter.

Clear selection

An explosive flashback in gas pipework can occur in the following situations:

1 point

a) when all appliances are running simultaneously and one appliance is firing intermittently.

b) if an electrical spark passes through a fully purged gas pipe.

c) if gas pipework is not fully purged.

d) when gas pip is full of O2.

Clear selection

In the event of a customer complaining of headaches and dizziness whenever they use their flueless single-point water heater what would you advise during a telephone conversation?

1 point

a) Ask them to remove themselves from the immediate environment and get some fresh air, and seek medical advice.

b) Ask them to call back in the morning and report any changes.

c) Ask them to always open a window when using the appliance.

d) Ask them to ask a neighbour around to see if they experience the same effects when the appliance is working.

Clear selection

BS 5440 Part 1 recommends the following when testing the integrity of the joints on a new flue block installation.

1 point

a) Use a rotating CCTY camera suspended from the terminal position.

b) Pressurise the installation to 21mb for five minutes.

c) Carry out a flue test only when the last brick has been installed and cap at the terminal with a small bag of sand.

d) Carry out a flue flow test as described in the answer C but also test each section up to each floor joist level.

Clear selection

Often, in the course of a gas pipe installation, a soldered joint must be made – therefore the most important action that must place is which of the following?

1 point

a) Turn off the meter and purge all of the pipework.

b) Disconnect the meter and cap off meter or completely remove it.

c) Disconnect all appliances attached to the pipework first.

d) Freeze the pipe at either side of the proposed point to be soldered.

Clear selection

Earth bonding of adequate CSA should be located at which point on a gas meter?

1 point

a) A minimum 600mm before the MCV and before the first tee

b) A maximum 450mm after the outlet or before the first tee

c) A maximum 600mm after the meter outlet and before the first tee, if located before that distance

d) A maximum of 1000mm after the meter outlet and after any change of direction

Clear selection

If earth bonding is found to be inadequate on a gas installation, the responsible person must be informed and a label identifying the problem should be placed by:

1 point

a) Gas Safe.

b) the installer.

c) the responsible person.

d) an approved electrical engineer.

Clear selection

A vitiation-sensing device does which of the following?

1 point

a) When there is a lack of oxygen present in a room, it automatically turns off the precision pilot and the main gas valve.

b) It reduces the gas rate to the burner until the vitiated environment improves.

c) It turns off the appliance and then reignites when the situation is safe.

d) It glows bright orange and alerts the user to the imminent danger.

Clear selection

If you carry out any type of gas related work in a dwelling or on an LPG storage vessel, the requirements must comply with is:

1 point

a) GSIUR 1998.

b) BS 6891 Part 1.

c) IGE UP IB (ed. 2).

d) HSC 2011.

Clear selection

If two metals that carry gas, such as copper and LCS, are connected, what is the preferred component to achieve this?

1 point

a) Compression union

b) Electric fusion

c) Hard soldering

d) Special push fit with yellow O-ring

Clear selection

A solenoid valve works on which of the following principles?

1 point

a) Gas pressure to the underside of the diaphragm lifts a connected push rod which in turn opens the main gas valve to the burner.

b) An open and shut valve, which is controlled via an electro magnet, which can be controlled from an electric signal from an appliance thermostat.

c) An electrical device that senses a different current when immersed in a flame.

d) An electrical device connected to a thermocouple.

Clear selection

Which of the following devices incorporates a regulator, a flame supervision device and a solenoid valve?

1 point

a) A multipoint valve

b) A cooker combination valve

c) A combination boiler valve

d) A multifunctional valve

Clear selection

A device that works on the principle of expansion of a liquid via a capillary tube to bellows, which is connected to electrical contacts, can be found on which of the following appliances?

1 point

a) Boiler

b) Gas fire

c) Multipoint water heater

d) DFE

Clear selection

A flame can conduct an electric current which in turn allows a signal to travel to a control box of an appliance, which can initiate a sequence of operation to begin. A flame rectification system incorporates this process and it is called:

1 point

a) flame derangement.

b) flame conductance.

c) signal transference.

d) heat transfer.

Clear selection

An appliance with a 27kW input net requires what size of air vent?

1 point

a) 100cm2

b) 270cm2

c) 135cm2

d) 90cm2

Clear selection

Everyone in the area of work must be informed if you are going to carry out which of the following?

1 point

a) Purge the installation.

b) Isolate an appliance.

c) Tightness test.

d) Cap the primary meter.

Clear selection

The picture below shows the C72 vertex type flue arrangement. It begins as a balanced flue, taking its air for combustion from the loft space and then changes to an open flue at the secondary part of the flue. Where is the location of the fan in this type of system?

1 point

a) Upstream of heat exchanger

b) Upstream of Draught diverter

c) Downstream of heat exchanger

d) Downstream of draught diverter

Clear selection

When working on a new building project, it is identified that one of the flue terminals from a fanned flued appliances must be located, so that it faces the wall of a premises opposite. What minimum distance is recommended in BS 5440 Part 2?

1 point

a) 1200mm

b) 2000mm

c) 300mm

d) 600mm

Clear selection

Who is allowed to remove the seal of a regulator on a primary meter?

1 point

a) Any Gas safe operative

b) The owner of the premises

c) The gas transporter

d) A responsible person

Clear selection

If a flue is terminated over the boundary line of a domestic property, what is the minimum distance it should be from that point?

1 point

a) 600mm

b) 800mm

c) 1200mm

d) 1800mm

Clear selection

A yellow floppy flame on a natural gas burner would indicate which of the following?

1 point

a) Incomplete combustion due to lack of primary air

b) Flame lift

c) Excess air

d) Complete combustion

Clear selection

A vitiation-sensing device works on which of the following principles?

1 point

a) A photo cell senses the lack of oxygen and sends a signal to the gas valve to isolate.

b) A pilot flame searches for air in the absence of oxygen and moves off the tip of a precision pilot thermocouple.

c) It automatically interrupts the thermocouple mechanism if the temperature rises in the vicinity due to lack of oxygen.

d) All of the above.

Clear selection

What is the maximum time it should take for a thermocouple to close the gas valve in the event of no flame present?

1 point

a) 90second

b) 120 seconds

c) 180 seconds

d) 60 seconds

Clear selection

What would be the volume of gas that could be passed by a 22mm copper tube which was 12m long and did not exceed 1mbar pressure drop on domestic installation?

1 point

a) 3.9 m3/h

b) 1.5 m3/h

c) 1.30 m3/h

d )1.90 m3/h

Clear selection

Which mechanical safety cut-off device would be found on which appliance?

1 point

a) Warm air unit plenum

b) Closedown lid on a cooker hot plate assembly

c) DFE link with a vitiation device

d) Cooker oven

Clear selection

Any fan-flued system boiler with flame rectification will enter a reignition sequence and will generally shut down after three attempts to relight if:

1 point

a) the programmer ends its timed sequence.

b) the electricity supply is isolated.

c) the thermostat reaches temperature.

d) the gas supply is turned off.

Clear selection

Temporary continuity bonding must be which CSA, which minimum length, and applied when?

1 point

a) 16mm2: 2 metres and when serving a combination boiler

b) 10mm2: 1 metre and when cutting a section of pipework

c) 10mm2: 1.2 metres and when isolating a primary gas meter

d) 12mm2: 1 metre and when isolating a secondary meter

Clear selection

Constant pressure of gas to an appliance from a meter is achieved by a:

1 point

a) zero-pressure governor.

b) pressure-reducing valve.

c) pressure-differential valve.

d) regulator.

Clear selection

a medium pressure meter installation has an inlet pressure ratio of

1 point

a) above 7 bar and below 10Bar

b) above 25mb but below 2Bar

c) above 75mb but below 2 bar

d) above 10mb but below 30mb

Clear selection

Sometimes there are no existing chimneys in a dwelling and a client would like an open flued space heater to be installed. Which of the options below is acceptable?

1 point

a) Attach a custom-made spigot adapter to an open flue and discharge in the normal way.

b) Install the appliances on a suitable hearth and install into a sheet metal box which conforms to BS 715 and then connect to an open-flue system.

c) Attach a fan to the flue spigot then discharge into an open area with fresh air.

d) Convert the space heater with a catalytic converter into the Type A appliance.

Clear selection

When testing a natural gas installation, which of the following is true?

1 point

a) Allow 1 minute for stabilisation and test for 2 minutes at 20–21mb.

b) Allow 1 minute for stabilisation and test for 3 minutes at 19–23mb.

c) Test for 2 minutes and then carry out a let by test at 0mb.

d) Allow 2 minutes for stabilisation and test for 3 minutes at 20mb.

Clear selection

When observing a water gauge (manometer) during a tightness test, what would be considered a perceptible movement?

1 point

a) 0.0025mb

b) 2.5mb

c) 0.25mb

d) No movement allowed whatsoever

Clear selection

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