Ariston STD 100 DIRECT - Suggested Ways of Terminating Discharging Pipes Safety; Worked Example

FIG. 7
SUGGESTED WAYS OF TERMINATING
DISCHARGING PIPES SAFETY
- 21 -
FIG. 6
300L AND 500LONLY
RETURN
FLOW
DRAIN
NON-RETURN
FROM BRONZE
PUMP
SECONDARY
RETURN
- 20 -
500 mm Max.
300 mm
Min.
Temperature & pressure
relief valve
Metal discharge pipe (D1) from
temperature & pressure relief valve.
to tundish.
Metal discharge pipe (D2) from tundish
with continuous fall. See Table 2 and worked
example.
,
,
,
,
y
y
y
y
,
,
,
,
y
y
y
y
,
,
,
y
y
y
,
,
,
y
y
y
Tundish
Fixed grating
Trapped gulley
Discharge below
fixed grating.
(see page 6 for
alternative points
of discharge).
Valve outlet size Minimum size of
discharge pipe D1*
Minimum size of
discharge pipe D2*
from tundish
Maximum
resistance allowed,
expressed as a
length of pipe (i.e.
no elbow or bends)
Resistance created
by each elbow or
bend
G ½ 15 mm 22 mm
28 mm
35 mm
Up to 9 m
Up to 18 m
Up to 27 m
0.8 m
1.0 m
1.4 m
G ¾ 22 mm 28 mm
35 mm
42 mm
Up to 9 m
Up to 18 m
Up to 27 m
1.0 m
1.4 m
1.7 m
G 1 28 mm 35 mm
42 mm
54 mm
Up to 9 m
Up to 18 m
Up to 27 m
1.4 m
1.7 m
2.3 m
Table 2. Sizing of copper discharge pipe “D2” for common temperature valve outlet sizes.
WORKED EXAMPLE
The example below is for a G ½ Temperature & Pressure 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 2
Maximum resistance allowed for a straight length of 22mm copper discharge pipe (D2) from G
½ T & P valve is 9m.
Subtract the resistance for 4 no. 22mm elbows at 0.8m each = 3.2m.
Therefore the maximum permitted length equates to: 5.8m.
As 5.8m is less than the actual length of 7m therefore calculate the next largest size.
Maximum resistance allowed for a straight length of 28mm pipe (D2) from G ½ T & P valve
equates to: 18m.
Subtract the resistance for 4 no. 28mm elbow at 1.0m each = 4m.
Therefore the maximum permitted length equates to: 14m
As the actual length is 7m, a 28mm (D2) copper pipe will be satisfactory.