Benchmark Centerstore 120 Installation And Servicing Instructions page 8

VALVE OUTLET
SIZE
G 1/2
G 3/4
G 1
Table 3: Sizing of copper discharge pipe (D2) for common temperature relief valve outlet sizes
Safety device
(e.g. Temperature
relief valve)
Fig. 5: Typical discharge pipe arrangement (extract from Building Regulation G3 Guidance section 3.9)
8
MINIMUM SIZE OF MINIMUM SIZE OF
DISCHARGE PIPE D1 DISCHARGE PIPE D2
FROM TUNDISH
15MM 22mm
28mm
35mm
22MM 28mm
35mm
42mm
28MM 35mm
42mm
54mm
Metal discharge pipe (D1) from
Temperature relief valve to tundish
500mm maximum
300mm
minimum
Discharge pipe (D2) from tundish,
with continuous fall. See Building
Regulation G3 section 3.9d i-iv,
Table 4 and worked example
RESISTANCE CREATED BY
MAXIMUM RESISTANCE
EACH ELBOW OR BEND
ALLOWED, EXPRESSED
AS A LENGTH OF
STRAIGHT PIPE (I.E. NO
ELBOWS OR BENDS
UP TO 9M 0.8M
UP TO 18M 1.0M
UP TO 27M 1.4M
UP TO 9M 1.0M
UP TO 18M 1.4M
UP TO 27M 1.7M
UP TO 9M 1.4M
UP TO 18M 1.7M
UP TO 27M 2.3M
Tundish
Discharge below
fixed grating
(Building Regulation
G3 section 3.9d gives
alternative points
of discharge)
Fixed grating
Trapped
gully