Low Flow Positive Displacement Meter

0 – 90 L/Hr covered by 3 internals: LF03, LF05 and LF15
High Pressure Capability
Accuracy: ± 1.0%
Range of material options

Positive displacement flowmeters, also known as PD meters, measure volumes of fluid flowing through by counting repeatedly the filling and discharging of known fixed volumes. A typical positive displacement flowmeter comprises a chamber that obstructs the flow. Inside the chamber, a rotating/reciprocating mechanical unit is placed to create fixed-volume discrete parcels from the passing fluid.

In the VFF the rotor is basically a disc shape with an annular groove on its underside capable of holding and transporting flow from the chamber inlet to the outlet. Some fluid is also transported in a cavity formed between the rotor outside wall and the chamber wall. A centre ‘peg’ under the rotor is constrained to run in a circular groove in the body.

A web (or plate) in the body is engaged with a slot in the rotor and this modifies the rotation to that of an oscillation as flow passes. It is this oscillation that produces the compartmentation of the fluid into ‘positively displaced pockets’.

The top of the rotor is equipped with a powerful magnet directly above the ‘peg’ that is on the underside and so this also has a circular path which allows it to engage and disengage a reed switch sensor located in the top cap above.

LF03, LF05 and LF15

The LF (or Low Flow) meters are the smallest in the VFF range. LF15 was introduced as our smallest meter in 2003 and was originally rated to 1.5 l/min (hence LF15). The LF05 joined the family in 2012 and is a third of the size. The LF03 is the smallest of the LF range and is a fifth of the size. Although internally they vary, the external chamber size is identical enabling interchangeability. Flows start at 0.005 l/hr (0.00008 l/min, 0.001 GPH).