Model PFM-15L-S Flexure Scale Loss-In-Weight Screw Feeder

Optional rotating trough & hopper
speeds material change-out
See video of Rotating Hopper

Unique THAYER® weight sensing
technology provides isolation from
all force vectors except material
weight for superior sensitivity and
accuracy.

Feed Rate: Up to 25 ft³/hr (0.70 m³/hr) at a material bulk density of 50 lbs/ft³ (0.8 gr/ cm³). Consult factory for higher feed rates.

Screw Sizes: range from 1.0 Ø. (variable pitch) to 2.0 Ø (variable pitch) solid flight or open helix with center through shaft.
Scale Type: "FMSS" Flexure Scale System (dead load is mass-counterbalanced) and LVDT Load Sensor.
Scale Capacity (live load): variable up to 500 lbs (227 kg)
Hopper Capacity: 2.25 fT³ hopper expandable to 6.75 fT³ with hopper extensions.
Accuracy: 0.25% to 1% of set rate ±2 sigma based on a minimum sample of one (1) minute, 30 revolutions of the screw or 1% of scale capacity.
Precise and reliable feeding of cohesive, easily aerated and difficult to control powders. Handles a wide range of material bulk densities at low to medium feed rates.
Patented compound flight feed screw design works in conjunction with patented Utrough feed chamber to eliminate common problems associated with feeding powders such as screw starvation and binding.

FMSS Mass counterbalanced, electronic weigh scale features high precision measurement, exceptional durability and excellent long term stability. Scale system weighs only the material, not the feeder, for minute-to-minute accuracy and sensitivity. The THAYER Model PFM-15L-S is a low to medium capacity Loss-In-Weight Feeder designed to assure uniform, non-pulsating accurate feeding of a wide range of materials, from free flowing to friable to cohesive.

Exclusive Powder Feeder Technology
Patented U-trough feed chamber with independently driven agitator assures precise, reliable delivery of material to the feed screw. Eliminates material build-up, controls material aeration and delivers a steady constant flow of material.

Optional (patented) compound flight feed screw can be used with most materials to downwardly extend the operating range of the feeder by a factor of 10 (typically).

Fast and easy to clean
The PFM-15L-S is designed for fast, easy and thorough clean out. Feeder completely disassembles in less
than one minute. High quality, rugged, stainless steel construction assures years of reliable, trouble free operation even in the most severe industrial environments.

Specialized scale design assures reliable, accurate metering.

The heart of any gravimetric feeder is its scale system. The PFM-15L-S incorporates a unique flexure suspension scale designed exclusively for use on Loss-In-Weight Feeders:

High efficiency dead load counterbalancing
Non-tilting platform design
Tolerant of shocks and overloads
Mechanical force summing to a single load sensor
Full range sensor utilization = maximum resolution
Low mechanical resonance frequency
Easily adapted to future re-rates

Conventional platform scales are NOT well suited for this service. Single point platforms are unsuitable for
supporting machinery having this degree of vertical height and elevated mass. They are very vulnerable to
side loading and other tilting disturbances. Multiple load cell platforms are unsuitable for low loading applications where forces no greater than that of an operator standing on one corner of the platform can cause damage. Finally, both types of platform scales resonate at frequencies much nearer the disturbing frequencies of other processing machinery driven by motors or vibratory drives. While electronic or software filtering may smooth out signal levels, they offer no protection to the load cells.

Exclusive trough design defeats flooding by dissipating kinetic
energy of material stream at initial fill