A. Test Mode
When your instrument is first turned on, it is in Test mode and ready to perform fuel test #1 (FT1). This is
the mode where all the fuel tests are performed.
The displayed outputs of both fuel test 1 and 2 are non-linear scales which give very sensitive readings near
zero and then expand to lower resolution as the number gets larger. This allows a large range to be covered
while maintaining good sensitivity in the main area of interest. The DT-47FT and the DT-15 (Digatron’s
former fuel tester) have the same calibration from 0 to 600.
Fuel Test 1: FT1 tests admittivity, which is the dielectric constant if conductivity is zero. FT1 is the same
test as performed by Digatron’s DT-15 fuel tester. The number 1 will be on the left side of the display,
signifying that this is test 1.
When checking fuel at the track, it is important that the temperature of the fuel being tested and the
temperature of the Cyclohexane be within five degrees of each other. It is also important to keep the
temperature of the DT-47FT fairly constant (be sure to keep it out of direct sunlight). Recalibration should
be done every 10 minutes to avoid errors (see B. Calibration Mode).
Draw a sample of the fuel to be tested and put it in a plastic sample container. Insert the sensor into the
fuel and observe the reading on the instrument. Be sure that the sensor is completely covered by the fuel.
The displayed number is the result for FT1. If you are using the standard base number of –75 and the
reading is zero or a negative number, the fuel is legal. A reading above zero (a positive number) indicates
that the fuel may contain an illegal additive. The more positive the number, the greater the possibility that
the fuel contains illegal additives. Illegal or disputed test results should be confirmed by laboratory
analysis.
If a fuel sample tests illegal, the following procedure should be used:
A. Clean the fuel tester sensor in fresh gasoline or aerosol brake cleaner. Allow the sensor to dry for
at least 30 seconds.
B. Check the reading of the instrument in Cyclohexane. It should read –75, if you are using the
standard base number. If it does not read –75, go to Calibration Mode and recalibrate the
instrument.
C. Allow the fuel sample to stabilize to the same temperature as the Cyclohexane and then repeat the
test.
While testing, the instrument’s Cyclohexane reading should be checked every 10 – 30 minutes. With
current commercial pump gasoline, the instrument should read -75. For the greatest accuracy, keep the
temperature of the Cyclohexane close to the temperature of the fuel in the vehicles coming off of the track.
To check the temperatures, press and hold the Temp button.
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