UFC 3-460-03
21 JANUARY 2003
Chapter 6
CONSTANT-PRESSURE HYDRANT FUELING SYSTEM, TYPE III (PHILLIPS)
6.1. General Information. The constant-pressure hydrant fueling system is the newest system used by
the Air Force. It was conceived by the Phillips Petroleum Company in the mid-1950s to refuel military
transports and bombers, and has come into extended use since the mid-1980s. The standard Type III
system is designed for a maximum of 9085 liters per minute (2400 gallons per minute). Earlier systems
were designed as large as 22,712 liters per minute (6000 gallons per minute), but large pipe sizes, low
normal flows, and surge problems made these systems impractical. There have been some alterations to
this system design, but current standards are in DoD Standard Design 78-24-28-88-AF, Pressurized
Hydrant Fueling Systems Type III, available for download or in hard copy from the Corps of Engineers,
Huntsville Center (http://www.hnd.usace.army.mil). This system is constantly under pressure when
energized, and responds automatically to refueling and defueling requirements. Supervision is not
required at the pumphouse during the automatic mode if a "pump run" light and emergency shut-off
switch are provided at the RCC. Any number of aircraft parked along the fueling loop can receive fuel
simultaneously up to the flow capacity of the system. Additionally, aircraft can be defueled while others
are refueling. Because the system relies on pneumatically operated valves at the hydrants, the electrical
problems encountered with Type I and Type II systems do not exist. The heart of the Type III system is
the computer or microprocessor in the pumphouse control room, which controls the component
operation. A product recovery tank is provided to collect liquids from pressure reliefs, strainer drains,
F/S automatic drains (when used), low point drains, and the operating storage tank water draw-off
system. The Type III system has many components similar to those covered in the preceding chapters
under the Type I and Type II systems. The system includes filtration, aboveground operating storage, a
pumphouse, a control room, hydrant loop, a hydrant servicing vehicle (HSV) check-out stand, and
sometimes a fill stand. The pumphouse components include API Std 610 pumps, API horizontal F/Ss,
issue and return venturis, both direct-pressure and differential-pressure transmitters (DPT), and
automatic control valves. The loop also includes a hydrant control valve (HCV) at each hydrant. A
HSV is typically used between the hydrant outlet and the aircraft. Where filtration is not required at the
skin of the aircraft, a pantograph is acceptable.
6.2. Piping. As aircraft become more sophisticated, it is increasingly important to maintain fuel
quality, especially thermal stability. Contact with iron and steel degrades thermal stability; therefore,
the use of non-ferrous and coated materials is emphasized. For piping from the receipt F/S to the issue
F/S, only coated carbon steel, stainless steel, or aluminum (if not buried) may be used. For hydrant
systems, use stainless steel pipe downstream of the issue F/Ss. The F/S removes fuel degradation
products and degraded coating particles before they enter the loop. Stainless steel prevents fuel
deterioration and protects thermal stability. NOTE: All underground metal piping must be protected by
exterior coating and cathodic protection. In making pipeline repairs, take care when replacing or
repairing coatings. Even the most minuscule break in a coating can be a starting point for corrosion. Be
aware that buried stainless steel corrodes faster than carbon steel and must be treated carefully.
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