Blaze EMS-2 Operating Manual
Page 57
downwards. Another possible problem is the fuel sender jet. When you install it, do not damage it. Use a drill bit of
suitable diameter (5.5mm) to push the jet all the way, the opening of the jet must be just in front of the impeller.
YOU NEED TO APPLY SOME FORCE TO INSERT THE JET ALL THE WAY (about 24mm). THE JET MUST BE
LOCATED RIGHT IN FRONT OF THE IMPELLOR. YOU CANNOT PUSH THE JET TOO FAR.
Using other Flow Senders
It is quite possible to use flow senders other than the MGL Avionics fuel flow sender. In this case ensure that the sender
outputs a 5V TTL square wave or a similar signal. The EMS-2 interface electronics will adapt to a variety of different
voltages and pulse shapes as it contains a Schmitt-trigger input stage. The calibration factor can be entered in a wide
range making the unit particularly suited to other flow senders. The supply output terminal for the sender provides a
positive, regulated 5 volt output. This may be used to power the flow sender provided the sender will not draw more than
40 mA of current. Should your sender require a higher voltage or more current, you must supply the sender from a
different power source. Exceeding the rating on the MGL Avionics fuel flow sender supply terminal can affect the
operation on the unit negatively or even damage it. Some senders require a pull-up resistor to the 12V supply line. We
find most installations of these senders require a 4K7 pull-up resistor.
Recommended Calibration Factors for the MGL Avionics dual range flow sender:
With jet installed = 7000. Recommended for flow rates below 30 Litres/hour maximum
Without jet installed = 1330. Recommended for flow rates above 30 Litres/hour
Please refer to the leaflet included with the flow sender for information on pressure drop versus flow rate, wetted materials
etc.
It is your responsibility to ensure that the flow sender used is compatible with the fuels you
intend using. We have found the MGL Avionics fuel flow sender to be very compatible with
automotive fuels used in South Africa, many of which contain methanol. 100LL AVGAS also
appears not to harm the sender in any way. We have exposed a sender continuously to our
automotive fuels for the duration of two years without any noticeable ill effect on the sender.
However, despite this MGL Avionics or its appointed agents cannot assume responsibility for
any incident or damage, even loss of life by whatsoever cause connected with the fuel flow
sender or the EMS-2 instrument. Usage of this or other senders is your own sole
responsibility.
If you do not agree with the above statement you must not use the fuel flow sender.
Note to Pilots:
(Even though this is the installation manual)
You must always have a visual indication of the fuel level available, either by means of a sight glass, direct tank
observation or a known, reliable secondary fuel level gauge. As pilot in command of an aircraft it is your responsibility to
ensure that you have sufficient fuel to reach your intended destination. Always ensure that you have a generous amount
of reserve fuel and never use your reserve fuel except in an emergency if it is unavoidable.