Rev. 01/11 -1.15- TFXL-X
CONNECTING THE PULSE OUTPUT
The TFXL is equipped with a circuit that outputs a pulse waveform
that varies proportionally with flow rate. The quantity of pulses per
unit volume of liquid is described by the K-factor that is recorded on
the side of the flow meter enclosure. To ensure that accurate
readings are being recorded by the receiving instrument, the TFXL
and the receiving instrument must have identical K-factor values
programmed into them.
The K-factor for TFXL transmitters utilizing small pipe transducers
(DTTS and DTTC) are fixed. These values are recorded on the side
of the TFXL enclosure.
If the TFXL is to be used on large pipes (2" and above), the K-factor
must be calculated for the particular maximum flow rate pro-
grammed into the meter. The K-factor is:
For example – the full scale flow for a 1" pipe is 15 GPM. The K-
factor would then be:
Two pulse output options are available with the TFXL:
Turbine meter simulation (SW1 ON) — This option is utilized
when a receiving instrument is capable of interfacing directly with
a turbine flow meter’s magnetic pickup. The output is a relatively
low voltage AC signal that is not ground referenced. The
minimum AC amplitude is approximately 500 mV peak-to-peak.
This option is selected by placing SW1 in the ON position. See
Figure 1.8 on page 1.16.
TTL pulse frequency (SW1 OFF) — This option is utilized when
a receiving instrument requires that the pulse voltage level be
either of a higher potential and/or referenced to DC ground. The
output is a square wave with a peak-to-peak voltage swing of 5
volts.
This option is selected by placing SW1 in the OFF position. See
Figure 1.8 on page 1.16.
PART 1 - INPUT/OUTPUT CONFIGURATION
60,000
= 3,000 pulses per gallon
15 GPM
60,000
= K-factor
Full Scale Flow
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