Standard Bus Procurement Guidelines - APTAStandards.com

Standard Bus Procurement Guidelines
Lines shall be capable of withstanding maximum system pressures. Lines within the engine
compartment shall be composed of steel tubing where practicable except in locations where flexible lines
are specifically required by the Procuring Agency in attachments to Part 5: Technical Specifications.
Flexible fuel and oil lines shall be kept at a minimum and shall be as short as practicable. Flexible lines
shall be routed or shielded so that failure of a line shall not allow fuel or oil to spray or drain onto any
component operable above the autoignition temperature of the fluid. Flexible lines shall be Teflon hoses
with braided stainless steel jackets except in applications where premium hoses are required and shall
have standard SAE or JIC brass or steel, reusable factory crimped, swivel, end fittings. Flexible hoses
and fluid lines shall not touch one another, or any part of the bus.
Hydraulic lines of the same size and with the same fittings as those on other piping systems of the bus,
but not interchangeable, shall be tagged or marked for use on the hydraulic system only.
The fuel lines forward of the engine bulkhead shall be in conformance to SAE Standard J1149 Type 1
for copper tubing, SAE Standard J526 for welded steel tubing, or SAE Standard J844 for nylon tubing
color coded orange.
Charge air pipework and fittings shall be designed to minimize air restrictions and leaks. Pipework shall
be as short as possible and the number of bends minimized. Bend elbows shall have smooth contours
with a bend radius to tube diameter ratio of no less than 2.0. The cross section of all charge air pipework
shall not be less than the cross section of the intake manifold inlet. Any changes in pipework diameter
shall be gradual to ensure a smooth passage of air and to minimize restrictions. Pipework shall be routed
away from exhaust manifolds and other heat sources, and insulated and shielded from these sources to
protect inlet air from heat radiation.
Charge air pipework shall be seamless, constructed of either stainless steel or anodized aluminum.
Pipework between the air filter and turbocharger inlet may be constructed of fiberglass. Connections
between all charge air pipework sections shall be sealed with a short section of reinforced hose and
stainless steel, constant tension clamps that provide a complete 360Ε seal.
5.2.2.3 Fuel System
5.2.2.3.1 Fuel Tank
The fuel tank(s) shall be securely mounted to the bus to prevent movement during bus maneuvers, but
shall be capable of being removed and reinstalled by a 2M mechanic for cleaning or replacement in 2.5
hours or less. Fuel tank capacity shall be (125) gallons. The fuel tank shall be equipped with an
external, hex head, brass drain plug. It shall be at least a 3/8-inch size and shall be located at the lowest
point of the tank. The tank shall have an inspection plate or easily removable filler neck to permit
cleaning and inspection of the tank without requiring its removal. The tank shall be baffled internally to
prevent fuel sloshing noise regardless of fill level. The baffles or fuel pickup location shall assure
continuous full power operation on a 6 percent upgrade for 15 minutes starting with no more than 25
gallons of fuel over the unusable amount in the tank. The underside of the tank shall be protected from
damage caused by road debris. The bus shall operate at idle on a 6 percent downgrade for 30 minutes
starting with no more than 10 gallons of fuel over the unusable amount in the tank.
5.2.2.3.2 Fuel Filler
Technical Specifications 140 10/18/07