The water test is applied to the roughing of all new work, unless water is not at hand or there is danger of its freezing, in which case the air test may be applied.

Plate 24 shows the plumbing system ready for testing. All openings must be closed. Lead bends, traps, and pipes must have their ends soldered, and wrought-iron pipe ends must be capped. The ends of pipes, bends, etc., should be closed when the roughing is completed, without regard to the test, in order to prevent refuse of any kind from entering the system.

Soil-pipe openings should be closed by specially devised stoppers or testing plugs, as shown in the three illustrations of Plate 25.

These openings would include the house-drain outlet, fresh-air inlet, rain leaders, floor drains, etc.

If the stacks do not end above the roof on or near the same level, the shorter stacks should have their open ends plugged.

With the plumbing system thus prepared, water is filled into the system until it overflows from the highest stack onto the roof.

The test is generally made by the plumber, in the presence of the plumbing inspector, and the water is generally required to stand for several hours before being drawn off.

This is for the purpose of exposing leaks which sometimes do not make themselves known for a time.

Defects often do not appear until the water has been standing long enough to thoroughly soak through the oakum. Water may be filled into the system through any opening, the fresh-air inlet often being a convenient point.

Testing plugs are made with a provision allowing water to pass through them, for the purpose of filling the piping. Such a plug, with its connection, is shown in the fresh-air inlet of Fig. A. Several different makes of testing plugs that do good service are now on the market, several forms of which are shown in Fig. B.

The most common form is that shown at the right-hand end. It makes tight by means of the expansion of a heavy rubber ring against the inner surface of the pipe. The ring is expanded between two iron plates brought together by a large hand nut.

Plugs of this description will not generally hold much over 50 lbs. pressure without being blown out.

A very good plug for high pressures is one which clamps around the outside of the hub, making tight by means of a rubber packing forced against the end of the hub. This testing plug is shown in Fig. B.

The same plug may be applied to the spigot end of a pipe by using a split collar against which the clamp may hold. In Fig. A the use of a double testing plug is shown.

This is a valuable device for the connection shown, and for closing the main-trap outlet.

In using this test, water should be filled into the system slowly, and as fast as defects appear they should be made tight before raising the. water higher.

There are two reasons for this. A small leak at a high point may allow water to trickle down the pipe, and thus make it difficult to locate. If the system is quickly filled, a large quantity of water may escape from some large defect before it can be drawn off.

It is sometimes necessary to test certain sections of the system as the work progresses.

In making such tests there should be a column of water at least 10 ft. in height above all parts of the work to be tested.

Very high stacks should be tested in sections of not over 75 ft. in length, as the pressure of water when such a stack is tested entire is very great, and cannot be applied with safety.

To find the pressure that is being exerted at any point on the plumbing system, multiply the vertical distance of this point from the top of the highest stack by .434, the pressure exerted by one foot of water. This will give the pressure in pounds per square inch. Thus, a point 50 ft. from the top will be under a pressure of 50 X .434 = 21.7 lbs. per sq. in.

The following table may be valuable in this connection:

Table Of Pressures Of Water

Head

Pressure per sq. in.

1 ft..

. .43 lbs.

5 " ..

. 2.16 "

10 " ..

.. 4.33 "

15 "

. 6.49 "

20 " ..

. 8.66 "

25 " .

. 10.82 "

30 " ..

.12.99 "

35

.15.16 "

40 " ..

.17.32 "

45

.19.49 "

50 " ..

.21.65 "

Head

Pressure per sq. in.

55 ft:.

.23.82 lbs.

60 "

25.99 "

65 "

.28.15 "

70 "

30.32 "

75 "

.32.48 "

80 " .

34.65 "

85 ".

.36.82 "

90 " .

..38.98 "

95 "

..41.15 "

100 " .

43.31 "

105 " .

..4548 "

Head

Pressure per sq. in.

110 ft. .

.47.64 lbs.

115 "..

.49.81 "

120 " . .

.51.98 "

125 ".

.54.15 "

130 "

56.31 "

135 "

.58.48 "

140 " .

.60.64 "

145 "

..62.81 "

150 " .

..64.97 "

155 "

..67.14 "

160 " .

..69.3I "

Head

Pressure per sq. in.

l65 ft..

. 71.47 lbs.

170 " ..

73.64 "

175 "

. 75.80 "

180 " ..

77.97 "

185 "

. 80.14 "

190 " ..

. 82.30 "

195 "

. 84.47 "

200 " ..

. 86.63 "

205 " ..

. 88.80 "

210 " ..

. 90.96 "

215 " ..

. 93.14 "

220 " ..

95.30 "

225 " ..

. 97.49

230 " ..

99.63 "

235 "

.101.79 "

Head

Pressure per sq. in.

240 ft. .

. 103.96 lbs.

245 " ..

.106.13 "

250 " . .

. 108.29 "

255 " ..

.110.46 "

260 " . .

.112.62 "

265 " . .

.114.79 "

270 " . .

.116.96 "

275 " - -

.119.12 "

280 " . .

.121.29 "

285 " ..

123.45 "

290 " . .

. 125.62 "

295 " -

. 127.78 "

300

.129.95 "

310 " ..

.134.28 "

320 " . .

. 138.62 "

Head

Pressure per sq. in.

330 ft.

.142.95 lbs.

340 . .

.147.28 "

350 " ..

.151.61 "

360 " . .

155.94 "

370 " ..

.160.27 "

380 " . .

. 164.61 "

390 " . .

. 168.94 "

400 " . .

.173.27 "

500 " . .

.216.58 "

600 " . .

.259.90 "

700 " . .

.303.22 "

800 " . .

346.54 "

900 " . .

.389.86 "

1000 " . .

433.18 "