DAF - EXHAUST DISCHARGE POSITION
Possible positions of the exhaust discharge
Horizontal or vertical discharge?
The exhaust discharges from the SCR (Selective Catalytic
Traditionally, vehicles operating in dusty environments, such
Reductor) unit, which is part of the engine exhaust
as those found in construction and agricultural applications,
aftertreatment system.
are equipped with a vertical exhaust discharge to prevent
dust blow-up by the exhaust.
Depending on the vehicle type, various exhaust layouts are
possible:
Prior to Euro 6 this certainly was the right choice: otherwise
• SCR unit located at the right-hand or left-hand side of the
clouds of dust might be blown around that would seriously
chassis. Horizontal discharge to below the chassis, via an
hamper working in the immediate vicinity of the vehicle.
exhaust diffuser below the SCR unit.
• SCR unit located at the right-hand or left-hand side of
DAF Euro 6 vehicles
the chassis. Exhaust discharge via a vertical tailpipe with
The choice between horizontal or vertical discharge of the
diffuser behind the cab.
exhaust gases is completely different for Euro 6 vehicles with
• Vertical SCR unit with exhaust discharge behind the cab,
an exhaust diffuser.
used for some 4-axle vehicle types.
Due to the very low exit velocity of the gases for DAF Euro 6
The function of the exhaust diffuser
vehicles, the dust blow-up with horizontal diffuser at 1,500
In order to reduce the temperature of the exhaust gases,
engine rpm is less than the dust blow-up at idle speed for a
particularly during a stationary regeneration, an exhaust
Euro 5 vehicle with low level exhaust discharge.
diffuser is mounted in which the hot gases are mixed with
ambient air to dissipate the heat.
In many cases this would eliminate the need for a high level,
vertical exhaust discharge, leaving the benefits of discharge
This not only lowers the exit temperature but, with the
directly beneath the SCR unit intact:
exhaust diffuser design used by DAF also considerably
• Efficient use of space around the chassis by the absence
lowers the exit velocity of the exhaust gases.
of additional piping
• No loss of space behind the cab
• Lower weight – higher payload
• Reduced overall vehicle price
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DAF - EXHAUST DISCHARGE POSITION