_a._ A pressure gauge of the Lane double tube spring pattern with
5-inch case, must be provided with the pump, and connected near to
inboard side of air chamber, as shown in Fig. 12, by a 1/4-inch cock,
with lever handle.
The dial of this gauge should be scaled to indicate pressures up to 240
lbs. and be marked “WATER.”
This kind of gauge is used on locomotives and is the best for
withstanding the vibration which causes fire-pump gauges to be often
unreliable. Moreover, this double spring form is safer against
freezing.