_a._ A pressure gauge of the Lane double tube spring pattern with 5
inch case must be provided and attached to the steam chest inside the
throttle valve.
The dial of gauge should be scaled to indicate pressures up to 120 lbs.
and be marked “STEAM.”
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 is safer against freezing.