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3.5.4. Gate valves (Figure 3.8) are not typically used in aircraft fueling systems. Use gate valves
for dike drains and consider their use for transfer lines where periodic pigging is required. See
MIL-HDBK-1022A for applications.
Figure 3.8. Gate Valve.
3.6. Sump Pumps. Manual or automatic sump pumps are installed in some pits to evacuate water or
fluid from the pit. Most automatic pumps are float-actuated. The float controls a single-pole, spring-
loaded switch that starts the pump at a predetermined high-liquid level and shuts the pump down when
the level drops to a set low-liquid level. All electrical components of these pumps, including switch and
motor, are explosion-proof and comply with requirements of the National Electric Code (NEC) for Class
I, Division 1, Group D locations. Maintenance includes oiling and greasing, cleaning the inlet strainer,
and inspecting the float switch and mechanism. Sump pumps are not required in lateral control pits of
Type II systems unless justified by local conditions. Discharge from sump pumps may contain fuel and
must be disposed of in accordance with governing environmental regulations.