Document OEV0BNm3o5JE9E2ZK50qJa5zj
American Society of Heating and Ventilating Engineers Guide, 1934
the top floor, that the length of run from the tank to the farthest fixture is 200 ft, equiva lent length of fittings 100 ft, and the pressure required at the fixture is 7 lb.
The 30-ft head is equal to a static pressure of 0.43 X 30 or 12.9 lb per square inch and to maintain a pressure of 7 lb at the highest fixtures the drop allowable in pressure is 12.9 -- 7.0 lb or 5.9 lb. As the total equivalent run is 300 ft, this is a drop per 100 ft of 1.97 lb, or practically 2 lb. Therefore, all risers and mains from the top floor back to the
v Table 4. Typical Calculation of Pipe Sizes on Down-Feed Riser with Flush Valve Water-Closets and Urinals
Riser No, 1
Floor of
Bldg.
Fixtures on
Floor
GPM PER Fext.
Max. Fixt.
GPM
Probable Use
(per cent)
Probable Fixt. GPM
Probable Allowable
Riser GPM
Drop
Lb per 100 ft
Pipe Size In.
1st
IS.S.
'4, . 4 ZOO
2nd 1S.S. 4
4 100
3rd
1 s. s.
.4
3
4th 10 Lav.
3
13
5th
4 W. C.
50
2 U. 40
6
3 Lav. 16
3
4
12 ' 30
.. .42
200 80 280
9
51
80
45
. 40
45
4. 4 4
8
10 10
19 19
112 . 22
134
30 x
. .30 '
A
*30-
K
30 1
30 2
6th
4 W.C;
50
2 Xj.
40
12 3 Lav.
3
19
200 80
560 25
9
60 42
140 25 165
30 2
7th
4 W. C.
50
2 U. 40
18 . 3 Lav. .. ...... 3
22
200 80
840 18
9
69 40
151 28 179
30 . 2M
8th . 4 W. C. . 50 2 U. 40
200 80
24 1120 15
3 Lav. - 3
9
168
25
78 40
31 199.
. :--r--
24
tank must be sized on the basis of a drop of 21b per 100 ft. Tables 4; 5, 6 and 7 showthe schedule for Risers Nos. 1, 2 and 3 with the maximum possible flow taken from Table 1, the percentage of use at the peak taken from Fig. 1 and the maximum probable flow at the peak worked out for each portion of the riser, the riser sizes being taken from Table 2 as far as possible and from Fig. 3 where the amounts exceed the values given in this table; a drop of 30 lb per 100 ft is used except on the riser from the top floor back to the tank where 2 lb per 100 ft is the allowable limit.
' : The reduction in pipe size which would occur if flush tank water-closets were used on the top floor and only 3 lb pressure used on the fixtures is given in Tables 8 and 9.
556
Chapter 39-^Water Supply Piping
tloor when a house tank is the---s-o--u--r-c--e--o--f wa..tteMr purceisusyurae.ie suDstituted'O' n the uppermost If it is now assumed that Riser No. 1 is to be fed from the bottom and the minimum
street pressure is 75 lb with the top fixture of the riser 80 ft above the main, the problem
Table 5. Typical Calculation of Pipe Sizes on Down-Feed Riser with Flush Valve Water-Closets and Urinals
Riser No. S
Floor of
Blog.
Fixture 5 on
Floor
GPM . PER Fixt.
1st
1 w. c.
50
2nd
2 W. C. 1 u.
50
40
4 1 Lav.
3
3rd
4 W. C.
50
2 U.
40
10 3 Lav.
3
4
4 W. C. ; 2 u. 16
3 Lav. 7
50
40 3
6 W. C. 22 . 4 Lav. 11
50
3
6 W. C. 28 4 Lav. 15
-___
7th 6 W. C. 34 4 Lav. 19
8th 6 W. C. 40 4 Lav.
23
50
3
50
3
50
3
Max. Fixt. GPM .-
50
100
40 190
3
200 SO
470 9
12
200 80
750 9
21
300
1050 12
33
300
1350 12
45
300 1650
12
57
300 1950
12 69
Probabl b Use (per ceni0
Probabl.b Fixt.GPM
Probabl b Allowable
Riser
Drop
. gpm
LBPBR 100 Ft
Pipe Size
Itr.
100 50 50 . 30 1%
50 95 100 3 98
.
30 141 70 8 149
30. : ix .
30 2
20 150 70 14 164
15 157 ... 48 16 173
12 162 45 20 182
10 165 .
42 24 189
9 175 40 27 202
30 2
30 2
30 2 -
30 2X
24
0.43 lb X 80 or 34.4 lb 557
per 100 ft.