LF Flow Meters Litre Meter Positive Displacement Flowmeters

Positive Displacement Flow Meters 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 center ‘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 the 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 that 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).

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Application Fields

Typical Applications

• Chemical Injection
• Corrosion Inhibitor
• Scale Inhibitor
• Subsea Control Fluid
• Subsea flow
• Wax Dispersant
• PIB
• Ashalphtene Dispersant

Key Features

• Compact
• No straight lengths
• Very Low Flow Measurement
• Single Moving Part
• Large Viscosity range, from methanol upwards
• Pressure independent measurement
• Measures pulsing flow accurately
• Ultra High Pressure Capability (60,000psi, 4000bar if required)
• Low Maintenance
• Tolerant of particulate up to 100+ microns
• Preserves Molecular Integrity of fluid
• Highly Durable
• Low pressure drop (<0.1 bar typical)
• Proven since 1986

Specifications

Technical Specifications LF range

Flow ranges
LF03	0-18 l/hr.
LF05	0-30 l/hr.
LF15	0-90 l/hr.
Accuracy	±1% of reading requires linearization. Provided by all Litre Meter instrumentation.
Pressure Rating	Dependent on Connection size and rating.  More detail in the CONNECTION tab
Temperature rating	-40°C - +100°C dependent on material and instrument; higher temperature possible.
Viscosity Range	0.5 - 100,000 cP or greater.  More detail in the FLOW RATE tab
Recommended Filtration	A 100-micron filter is advisable for 100% long-life serviceability. For LF03 & LF05 size 40-micron filter is recommended.
Dimensions	Refer to K0001 drawings. Link in DOWNLOADS tab

Interchangeable PBC between LF03, LF05 and LF15. Different rated chambers can be retrofitted as field demands change.

Download Datasheet: LF Flow Meters Litre Meter Positive displacement flowmeters

Reference: litremeter.com