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G3 Tools, Instruments and Measurements: What's Tested and How to Study It

Manometers, gauges, conversions, drawings and the instruments of the trade.

Part instrument use, part arithmetic, part reading technical drawings. The conversions are the reliable marks here: they never change, and they appear every time.

What this topic covers

Manometers and reading gas pressure
Pressure conversions between PSI, inches water column and kPa
Temperature conversion between Celsius and Fahrenheit
Combustion analysers and what they report
Reading mechanical and orthographic drawings, and drawing scales
Correct tool selection

How to study it

Memorise the conversions rather than deriving them under time pressure. 1 PSI = 27.68" w.c. turns up constantly, and doing it from first principles in an exam is a waste of minutes you will want later.

Conversions and property tables →

Sample questions

Five real questions from this topic, with the answers shown. The app holds 58 in this area alone, out of 1,184 across the whole syllabus.

What two things are used to join pieces of ductwork together?

'Y' cleat only
Foil tape only
Screws only
✓ 'S' cleat and drive cleat

What are the three types of flue gas analyzers?

Tube type only
Liquid type only
Continuous sampling type only
✓ Tube, liquid, and continuous sampling

What are orthographic drawings?

drawings that show how something is related to time
drawings that compare a number of items
✓ drawings showing individual views of front, rear, sides, top, and bottom of object

What is the maximum pressure drop allowed for a propane piping system operating at 11 inches water column?

2.0 in w.c.
1.5 in w.c.
✓ 1.0 in w.c.
0.5 in w.c.

Which type of chart compares individual parts in relation to their total and displays this relationship as sectors of a circular area?

Bar chart
Flow chart
Line graph
✓ Pie chart

Practise this topic free →

The other topics

Gas Properties and Combustion318 questions Gas Code and Piping (B149.1)177 questions Electricity and Controls178 questions Appliances and Heat Transfer136 questions Safety and Workplace Practices107 questions Venting and Combustion Products77 questions Regulations and TSSA76 questions Controls and Ignition Systems57 questions