"
Boiler Fittings.
[Illustration: FIG. 89.-Safety valve.]
Safety Valves.--The best all-round type is that shown in Fig. 89. There
is no danger of the setting being accidentally altered, as is very possible
with a lever and sliding weight. The valve should be set by the steam
gauge. Screw it down, and raise steam to the point at which you wish the
safety valve to act, and then slacken off the regulating nuts until steam
issues freely. The lock nuts under the cross-bar should then be tightened
up. In the case of a boiler with a large heating surface, which makes steam
quickly, it is important that the safety-valve should be large enough to
master the steam. If the valve is too small, the pressure may rise to a
dangerous height, even with the steam coming out as fast as the valve can
pass it.
[Illustration: FIG. 90.-Steam gauge and siphon.]
Steam Gauges.--The steam gauge should register pressures considerably
higher than that to be used, so that there may be no danger of the boiler
being forced unwittingly beyond the limit registered. A siphon piece should
be interposed between boiler and gauge (Fig.
Pages:
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182