Page 2-2
Document Ref 942175-001 Rev 3
TQM for Fuel Dispensers
Component Technical Manual
2
PRODUCT INFORMATION
2.1
Functional Description
The TQM consists of two parts as follows:
•
The piston meter - transforms the delivered volume into a rotation of the shaft
•
The pulser
(MP-T1(CW), MPE-EC, MPE-TC, MPL or MPC-TC) - converts this rotation
into pulses for the calculator
The following diagram shows the parts of the measurement transducer:-
2.2
The Piston Meter
The TQM is a twin piston meter. The pistons are activated by the flow of fuel from the
pumping unit (suction or submersible type) and are mounted in parallel cylinder bores.
Both pistons transmit their reciprocating movement to separate crank shafts mounted
perpendicular to the piston stroke. The two crank shafts are linked through a set of gears
to a common drive shaft, onto which the electronic subsystem (the pulser) is mounted.
The pulser is integrated in the top cover of the meter. The pulser converts the rotational
movement of the drive shaft into a highly precise stream of electronic signals, allowing
subsequent calculation of the exact volume of fuel displaced through the TQM.
Fuel entering the TQM flows alternately into one or two chambers (to the front and back
of each piston). The flows are carried out through a sequence of four phases piloted by
the control valve mounted on the drive shaft.
Each of the four chambers has a capacity of 125 millilitres. The
TQM delivers 500 ml per cycle. A PTFE lip seal on each piston prevents leakage between
opposite chambers. Calibration of the volume measurement of the TQM is possible by
equal adjustment to both of the calibration screws. These screws are sealed following
calibration by Weights and Measures officials.
Pulser
Volume
Meter
888888
888888
8888
Fuel flow
