Page 343 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

Chapter 5 Cold water systems

● Refill the system and test for standing and running pressure at all mains
outlets using a pressure gauge.
● Check that all flow rates meet the specification and any manufacturers’
instructions, using a flow meter or a weir gauge.
● Re-check the system for leaks.

ACTIVITY ACTIVITY
Water flow rate is measured in litres per second or litres per minute. To convert Remember: water pressure
from litres per second (l/s) to litres per minute (l/m), simply multiply the l/s by is measured in bar
60. For example: pressure – 1 bar is the
equivalent of 10 m head
0.3 l/s = 0.3 × 60 = 18 l/m
of water or 100 kPa.
To convert from litres per minute (l/m) to litres per second (l/s), simply divide the Now, using the above
l/m by 60. For example: figures, calculate:

25 l/m = 25 ÷ 60 = 0.41 l/s 1 38 m in bar pressure
Now attempt the following calculations: 2 4.5 bar in kilopascals
1 30 l/m into l/s (kPa)
2 0.25 l/s into l/m 3 150 kPa in bar pressure
3 12 l/m into l/s
4 0.12 l/s into l/m

11 REPLACING OR REPAIRING

DEFECTIVE COMPONENTS:

PLANNED AND UNPLANNED

MAINTENANCE

Maintenance tasks on cold water services, appliances and valves are essential
to ensure the continuing correct operation of the system. The term used
when isolating a water supply during maintenance operations is ‘temporary
decommissioning’.
Before undertaking the repair or replacement of components, we must first
ascertain what the problem is. The customer will be able to tell you what is
happening with the component. They may not know the technical language but
they will be able to explain the problem well enough for you to understand.

IMPROVE YOUR ENGLISH
Communication is key when it comes to both resolving issues and also ensuring
that your customer feels informed and confident in your ability to complete
the job. You need to remember that most of your customers with not have the
technical vocabulary that you are accustomed to. Remember, this may be their
home, so reassure them by explaining the problem and the processes necessary
to fix (or not) the problem. Avoid overly technical terms, clearly stating the
stages of the job so they know what to expect and when.

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