Independent technical reference. Not affiliated with, endorsed by, or a distributor for Tokico. No product is offered; this page describes the meter's technology.
A 1-inch (DN25) rotary positive-displacement fuel meter is a small-line instrument for dispensing and light transfer of diesel and oils. This page describes the technology of a Tokico-type meter at this size.
Small-Line PD Fuel Metering
At 1 inch, a rotary PD fuel meter handles the lower flows of dispensing and small transfer duties while retaining the accuracy that makes PD the standard for fuel — around ±0.5% of reading, held steady as viscosity shifts with temperature because the fluid film seals the internal clearances. A mechanical or electronic register totalises the delivery.
Typical Build and Care
Even at small size the essentials hold: a strainer keeps grit out of the measuring element, an air eliminator prevents vapour being counted as fuel, and sizing to the real flow keeps the meter in its accurate range. A preset counter can stop delivery at a set quantity for repeatable dispensing.
Reading the Register
Small fuel meters offer either a mechanical register — a geared counter driven directly by the measuring element, needing no power and ideal in the field — or an electronic register that adds a digital display, a resettable batch total and a pulse output for automation. The mechanical option is favoured where simplicity and independence from a power supply matter most; the electronic option wins where the delivery has to feed a control system or a printed ticket. Both count the same underlying volume; the choice is about how you want to read and use it.
Where It Fits
This is the small end of the range that runs up to the 6-inch DN150 bulk meter. See the Tokico technology overview and the PD principle page for background, and the calibration page for accuracy and proving.
For vendor-neutral instrumentation practice, the International Society of Automation (ISA) is a useful reference.