Webasto HL 90 Installation Instructions Manual page 14

6.2. Fuel lines
Only steel, copper and plastic lines of plasticised, light and temperature-sta-
bilized PA 11 or PA 12 (e.g. Mecanyl RWTL) pursuant to DIN 73378 may be
used for the fuel lines.
Since the lines normally cannot be routed with a constant rising gradient,
the internal diameter must not be allowed to exceed a certain size. Air or gas
bubbles will accumulate in lines with an internal diameter of more than 4
mm and these will cause malfunctions if the lines sag or are routed down-
wards. The diameters specified will ensure that bubbles do not form.
The lines should not be routed downwards from the metering pump to the
heater.
Unsupported fuel lines must be secured to prevent them sagging. They must
be installed in such a way that they cannot be damaged by flying road chip-
pings and high temperatures (exhaust line).
Connecting two pipes with a hose
The correct procedure for connecting fuel lines with hosing is shown in Fig-
ure 8.
Ensure that there are no leaks!
6.3. Metering pump
The metering pump is a combined delivery, metering and shut-off system
and is subject to certain installation criteria (see Figure 8).
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Right
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Figure 8: Pipe / hose connection
6.3.1. Installation location
Before installing the metering pump, ensure that the maximum pressure oc-
curring at the pickup point is no more than 0.2 bar.
It is advisable to install the metering pump in a cool place. The maximum
ambient temperature must not exceed +40 °C at any time during operation.
The metering pump and fuel lines must not be installed within range of the
radiated heat from hot vehicle parts. A heat shield must be used if necessary.
The pump should ideally be installed near the tank.
HL 90
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