elco Thision EVO WH 250-120, Operation And Installation Manual

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Valve outlet size Minimum sizeof
discharge pipe D2
Minimum sizeof
from tundish
Maximum
res is tance
allowed,
expressed as a
length of straight
pipe (i.e. no.
elbowsor bends)
created by each
elbow or bend
G1/2 15mm
22mm
28mm
35mm
up to 9m
up to 18m
up to 27m
0.8m
1.0m
1.4m
G3/4 22mm
28mm
35mm
42mm
up to 9m
up to 18m
up to 27m
1.0m
1.4m
1.7m
G1 28mm
35mm
42mm
54mm
up to 9m
up to 18m
up to 27m
1.4m
1.7m
2.3m
Fixed grating
Discharge below
fixed grating
(Building Regulation
G3 section 3.9d gives
alternative points
of discha rge )
Trapped
gully
Discharge pipe (D2) from t undish,
with continuous fall. See Building
Regulation G3 section 3.9d i-iv,
Table 4 and worked example
300mm
minimum
500mm maximum
Metal discharge pipe (D1) from
Temperature relief valve to tundish
Tundish
Safety device
(e.g. Temperature
relief valve)
Sizing of copper discharge pipe (D2) for common T&P relief valve sizes
Schematic discharge pipe arrangement
Unvented Applications
Worked example of discharge pipe sizing.
The example below is for 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 1:
Maximum resistance allowed for a straight lenght of 22mm copper discharge pipe (D2) from a G1/2 temperature relief
valve is 9.0m.
Subtract resistance of 4 No. 22mm elbows at 0.8m each = 3.2m
Therefore permitted length equates to 5.8m.
5.8m is less than the actual length of 7m therefore calculate the next largest size.
Maximum resistance allowed for straight lenght of 28mm copper discharge pipe (D2) from a G1/2 temperature relief
valve equates to 18m.
Subtract resistance of 4 No. 28mm elbows at 1.0m each = 4.0m
Therefore the maximum permitted length equates to 14m.
As the actually length is 7m, a 28mm (D2) copper pipe will be satisfactory.
15
Resistance
discharge pipe D2