ACV WaterMaster 120, Installation, Operation And Maintenance Instructions For The Installer And The User

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3.63 The discharge would consist of high temperature water and steam. Asphalt, roofing
felt and non-metallic rainwater goods may be damaged by such discharges.
600mm maximum
300mm minimum
temperature relief valve to tundish
Metal discharge pipe (D2) tundish with
continuous fall. See 3.56, Table G3 and
worked example
Tundish
Discharge below fixed
grating (3.61 gives
alternative points of
discharge)
Fixed grating
Trapped gulley
Valve outlet
size
Minimum size
of discharge
pipe D1
Minimum size of
discharge pipe D2
from tundish
Maximum resistance al-
lowed, expressed as a
length of straight pipe (i.e.
no elbows or bends)
Resistance creat-
ed by each elbow
or bend.
G½ 15mm
22mm
28mm
35mm
Up to 9m
Up to 8m
Up to 27m
0.8m
1.0m
1.4m
G¾ 22mm
28mm
35mm
42mm
Up to 9m
Up to 8m
Up to 27m
1.0m
1.4m
1.7m
G1 28mm
35mm
42mm
54mm
Up to 9m
Up to 8m
Up to 27m
1.4m
1.7m
2.3m
Figure G3: Typical discharge pipe arrangement
Table G3 – Sizing of copper discharge pipe ‘D2’ for common temperature relief valve outlet sizes
UK
Worked example of discharge pipe sizing
Figure on the left shows a G1/2 temperature relief valve with a discharge pipe (D2) having 4
No. elbows and length of 7m from the tundish to the point of discharge.
From Table:
Maximum resistance allowed for a straight length of 22mm copper discharge pipe (D2) from a G1/2
temperature relief valve is 9.0m.
• Subtract the resistance for 4 No. 22mm elbows at 0.8m each = 3.2m
•
Therefore the permitted length equates to: 5.8m
• 5.8m is less than the actual length of 7m therefore calculates the next largest size.
Maximum resistance allowed for a straight length of 28mm pipe (D2) from a G1/2 temperature relief
valves equates to 18m.
• Subtract the resistance of 4 No. 28mm elbows at 1.0m each = 4.0m
•
Therefore the maximum permitted length equates to: 14m
•
As the actual length is 7m, a 28mm (D2) copper pipe will be satisfactory.
Essential recommendations for safety
• The temperature/pressure relief valve should only be replaced by a competent
person.
• No control or safety valves should be tampered with or used for any other purpose.
• The discharge pipe should not be blocked or used for any other purpose.
• The tundish should not be located adjacent to any electrical components
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WaterMaster 25 - 35 - 45 - 70 - 85 - 120 : A1006482 - 664Y7300 • D
TECHNICAL CHARACTERISTICS