five to seven drops per minute should be fed. Air pumps in freight
service where the brake pipe is in moderately good condition can usually
be run with one or two drops per minute when handling long trains of
cars equipped with air brakes.

81. Q. Will any bad results ensue from filling the lubricator full of
cold oil?

A. Yes; when the oil gets hot it will expand and may break the glass or
bulge or burst the lubricator.

82. Q. If a sight feed gets stopped up, how could you clean it out?

A. Close the water valve and the regulating valves to the other feeds.
Open drain cock and draw out a small quantity of water so as to bring
the oil in top part of lubricator below the top end of oil pipe leading
to feed arm, then open wide the regulating valve to feed that is stopped
up and the pressure from the equalizing tube will force the obstruction
out of the feed nozzle and up into the body of the lubricator. Next,
close this regulating valve until the feed glass fills with water, then
open water valve and start feeds.

83. Q. How would you clean out chokes?

A. First, shut off boiler pressure and condenser valve; next, remove
feed valve bonnet, then open main throttle valve, when the steam from
steam chest will blow back through the choke plug, clearing it of any
obstruction.

84. Q. What is superheated steam?