Everflo EDS120, Руководство по установке

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08
EVERFLO STAINLESS uV
uNVENTEd HOT WATER CyLINdERS
The discharge pipe (d2) from the tundish should:
A) Have a vertical section of pipe at least 300mm long, below the
tundish before any elbows or bends in the pipework.
B) Be installed with a continuous fall of at least 1 in 200 thereafter.
The discharge pipe (d2) from the tundish should be of metal or
other material that have been demonstrated to be capable of
withstanding temperatures of the water discharged.
The discharge pipe (d2) should be at least one pipe size larger
than the nominal outlet size of the safety device unless its total
equivalent hydraulic resistance exceeds that of a straight pipe
9m long i.e. discharge pipes between 9m and 18m equivalent
resistance length should be at least two sizes larger than the
nominal outlet size of the safety device, between 18 and 27m at
least 3 sizes larger, and so on. Bends must be taken into account
in calculating the flow resistance. Refer to diagram 1, Table 1 and
the worked example. An alternative approach for sizing discharge
pipes would be to follow BS6700 Specification for design
installation, testing and maintenance of services supplying water
for domestic use within buildings and their curtilages.
The discharge pipe (d2) should terminate in a safe place where
there is no risk to persons in the vicinity of the discharge.
Examples of acceptable discharge arrangements are:
a. To a trapped gully with the end of the pipe below the fixed
grating and above the water seal.
b. downward discharges at a low level; i.e. up to 100mm above
external surfaces such as car parks, hard standings, grassed
areas etc. are acceptable providing that where children play or
otherwise come into contact with discharges, a wire cage or
similar guard is positioned to prevent contact whilst maintaining
visibility.
c. discharges at a high level; e.g. in to metal hopper and metal
down pipe with the end of the discharge pipe clearly visible or
onto a roof capable of withstanding high temperature discharges
of water and 3m from any plastic guttering systems that would
collect such discharges.
d. device to warn when discharge takes place.
WORKEd EXAMPLE
The example below is for 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 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 maximum 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 a straight
length of 28mm pipe (d2) from a G1/2 temperature relief valve
equates to: 14m. As the actual length is 7m, a 28mm (d2) copper
pipe will be satisfactory.
TABLE 1
Sizing of copper discharge pipe ‘d2’ for a temperature
relief valve with a G1/2 outlet size (as supplied).
Size of
discharge
pipework
Maximum length of
straight pipe
(no bends or elbows)
deduct the figure below
from the maximum length
for each bend or elbow in the
discharge pipe
22mm up to 9m 0.8m
28mm up to 18m 1m
35mm up to 27m 1.4m