Document NGQXXBBvz7G4M1065jXxZwnXD
American Society of Heating and Ventilating Engineers Guide, 1935
Table 8. Typical Calculation of Pipe Sizes on Down-Feed Risers with Flush Tank Water-Closets and Urinals on Top Floor Only`(See Fig 4)
Floor of
Bldg.
Fixtures on
Floor
GPM
PER
Frxr.
Max. Fixt. GPM
Probable Use
(per cent)
Probable Use
cpm
Probable Riser GPM
7thand 12 W-C. below 6 U.
18 19 Lav. 3 S. S.
22
0 W. C.
ou.
18 4 W. C. 2 U. 3 Lav.
31
-5040
3 4
00 00
18 18 3
Riser No. 1
600 240
840 57 12
69 40
000 000
840 72 36 9
186
2K b3.3
7th and below
29 W. C. 5 U.
34 19 Lav.
8th 0 W. C. 0 U.
34 6W.C. 4 Lav.
29
50 40
3
00 00
18 3
Riser No.
1450 200
1650 57
000 000
1650 ' 108
12
177
10 42
10 38
165 24 189
'-------165
67 ..
232
30 3.3
2M4
7th and below
6 W. C-
5 S. S. 4 Lav.
9
8th 0W. C.
6 1 S. S.
10
50 4 3
00 4 ;
Riser No. 8
300 20 12 . 32
000 300
4 36
40 50
40 48
120
16
120 17
~-----
612
136 137
30 2H 3.3 3
Chapter 35--Water Supply Piping
The last method is usually the most satisfactory. (See Fig. 6.) In the first instance the up-feed riser maybe sized for the same pressure drop as used for the cold water riser and, from the top of the riser just below the top fixture connection, a return circulation line may be carried back to the main return line in the basement and connected through a check valve, set on a 45-deg angle, and a gate valve; these return circu lation lines should never be less than % in., and on the farther half of the riisens, not less than 1 in. to favor circulation in the far end. Typical top and bottom connections for such risers are shown in Fig. 7.__ ___ ___
4W.C.-F.V. 2U.-F.V. 8th 3 Lav.
. 4W.C.-F.V. 2i 2U.-F.V. t * 3 Lav.. 7th
4W.C-F.V. 2\ 2U.-F.V.
3 Lav. t . 6th
.. 4W.C.-F.V. 24 2 U.-F.-V. . * 3 Lav. 5th -
y 10 uv. 4th.
3* . 1 S. S. 3rd.
3` i a a 2nd.
3V iaa 1st
? 3'Main. 1
(1) Fig. 5. Up-Feed
System
For the second arrangement of hot water risers, circulation lines are run back from the last fixture supplied to the main return circulation line in the same, manner as just described, using % in. for the near risers and 1 in. for the far risers. The'sizing is much.more difficult, as it is necessary to start at the bottom floor of the return riser and work back to the top of this riser and then carry the maximum flow across onto .the top of the corresponding supply riser and work down on this riser from the top floor' to the bottom. Naturally this gives a much greater flow in the supply riser and aids circulation by reducing pipe friction. The allowable loss per 100 ft in such lines must be made about half that used for the cold
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