Operation Manual

Diesel fuel flow sensor kit Installation and Operation Manual
21
NAVMAN
Each sensor inlet or outlet requires one or
more fittings to connect it to the fuel line. The
fuel sensor connections are all ¼ NPT taper
thread, fixed female.
The fittings required will vary with where in
the fuel lines the sensors are installed. For a
discussion of the issues involved, see section
7-3-3.
You will need threaded barrel adaptors to suit
the piping on your boat. Because there are so
many different threads and piping sizes around
the world there is no possibility of having all
the adaptors required supplied from Navman.
The Navman fuel sensors are supplied with a
standard ¼ NPT female thread for the inlets
and outlets. Any reasonable marine store,
hydraulic or diesel fitting supply house will have
a selection of threaded barrel adaptors that will
have ¼ NPT male thread on one end, and the
appropriate thread for your particular boat on the
other. It is preferable to use ¼ NPT thread, but
if necessary a ¼ BSP male threaded fitting will
fit in a ¼ NPT female thread.
There are many types of pipe and pipe fittings,
and it can get very confusing. If you are wanting
adaptors to fit a particular fitting on your boat, if
6-3 Sensor fittings
at all possible remove that fitting from the boat
and take it into the fitting store. It will save a lot
of time and doubt. Be sure to cover the exposed
ends of the pipes and fittings on your boat to
prevent dirt entering, and make allowances
for some fuel that may well drip from the pipes
while you are away at the store.
Frequently the supply line to the engine is larger
in diameter than the fuel return line. Measure
both before you go to get the fittings.
Fuel sensors are often connected to solid
copper pipe with flare joints. Each connection
requires a flare nut to fit the pipe and a barrel
union to connect the flare nut to the sensor.
For example, to connect a 3/8 inch OD pipe to
a sensor requires:
A 3/8 inch flare nut
A 3/8 inch flare to ¼ NPT taper thread
barrel union fitting
You will need to know the diameter of the fuel
pipe (see section 7-2-1). Fitting a flare joint is
described in section 7-4-1. This requires the
use of a pipe cutting tool, a flaring tool, possibly
pipe bending tools, and flare nuts.