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9.1 Fuel Pressure miniDaqu — Manual
9.1 Fuel Pressure
In most cases, ECUs do not have fuel pressure information. In order to get
it, a fuel pressure sensors must be connected to Daqu.
Rotax iS is a bit special here and it is explained in a separate section 9.2.
9.1.1 Sensor Type Selection
Often, a sensor of given range appears in different type regarding reference
pressure. In principle there are three basic options:
ˆ
Absolute type works like a barometer. The sensor has a membrane
and a chamber. The chamber has pure vacuum inside, which serves as
the reference. On one side of the membrane is vacuum and on the other
side is applied pressure. The sensor measures deflection of the membrane
against vacuum chamber and then translates this to an absolute pressure
reading.
ˆ
In vented gage type, the measuring pressure is applied on one side of the
membrane and on the other side is atmospheric (or better said surround-
ing) pressure, (hence term vented). This surrounding pressure serves as
reference. This is what you usually need to measure oil or fuel pressure.
You get the pressure relative to the surroundings.
ˆ
Sealed gage type is similar to absolute sensor in principle. However, it
does not have vacuum inside the chamber, but some known reference
pressure. So, the membrane deflection will be zero if the applied pressure
is the same as the reference pressure inside the chamber.
IMPORTANT: Daqu supports mostly vented gage type pressure sensors. Ab-
solute types can be also used in specail cases.
9.1.2 Installation
Try to use sensors, which can be disconnected close to the sensor head. This
reduces the problems with sensor installation – sensor is installed first and
then connected.
During installation, always respect the limiting torque and other details from
the engine installation or maintenance manual. Sensors with NPT threads
require application of special sealant.
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Kanardia 2019-2022
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