Loss-in-weightLarge CabLe suspension

sCaLe sCrew Feeder

Loss-in-weight FLexure suspension sCaLe

sCrew Feeder

THAYER SCALEPROCESS MEASUREMENT & CONTROL EQUIPMENT

LOSS-IN-WEIGHT FEEDERS

Loss-in-weightsmaLL CabLe suspension

sCaLe sCrew Feeder

Loss-in-weightsmaLL CabLe suspension sCaLe vibratory Feeder

Loss-in-weightFLexure suspension sCaLe

vibratory Feeder

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 and constant flow of material.Trough 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.

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Loss-In-Weight Cable Suspension Scale Screw FeedersThayer Scale Loss-In-Weight feeders are designed to provide precision class accuracy and repeatability even in the harshest of industrial environments. They range in capacity from grams per minute to tons per hour.

These are the most versatile feeders in the industry. At the heart of each Loss-In-Weight Feeder is a THAYER scale that has been designed exclusively for the stringent requirements of Loss-In-Weight feeding.

Thayer Scale offers a powerful set of proprietary add-on accessories that are designed to defeat the problematic flow issues encountered by industry such as bridg-ing, flushing, adhesion and cohesion. Comprehensive process solutions that can only come from a company with over fifty years experience.

THAYER SCALE

Model PF-SC-S Small Cable Suspension Scale Feeder

Model PFM-SC-S Small Cable Suspension Scale Feeder

Model PF-LC-S Large Cable Suspension Scale Feeder

Sanitary Design

Trough agitator as-sures uniform mate-rial density and con-sistent filling of screw flights.

Screw overwind eliminates bridging

over screw

Progressive opening of screw chamber and feed screw design, work together to eliminate binding

AC constant speed agitator motor

“Off the shelf” gear reducers

AC Inverter Duty or DC Motor to drive feed screw

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“FMSS” CABLE SUSPENSION SYSTEMThe THAYER Cable Suspension System (patented) is the most rugged and forgiving Force Measurement Weighing System available on today’s market. It can take more physical abuse and can tolerate more foundation distortion/deflection than all other known designs.

The exclusive Thayer Scale “FMSS” (Force Measurement Suspension System) design provides extremely high sensitivity. Feeder and weigh hopper “dead load” are mass-counterbalanced so that only material weight (live load) is measured. This feature helps assure excellent control in “noisy” environments.

All of the articulate parts of the scale mechanism are supported from “axially inextensible, but laterally yieldable” suspension elements (stainless steel pre-stressed aircraft cable), which are arranged to hang freely, thereby avoiding any appreciable spring or hysteresis effect, variation in mechanical advantage, or binding due to imperfect leveling.

Because of this unique mechanical property of the force transmission system, any laterally directed forces and shock on the scale or its supported feeder can not cause destructive shear and bending stresses to develop in the elements themselves or at the load cell junction. The system, being yieldable in the lateral direction, is therefore effectively and completely protected by using laterally placed “stops” in proximity of the weighed structure.

Weight loss is measured by a highly accurate, very sensitive, high output electronic force measurement sensor. The THAYER Series LC-137 Weight Resolver is a force measuring device designed specifically for use with Thayer Scale weighing systems. It is a precision-built, heavy duty device designed for long term stability and accuracy under the most demanding applications. It is initially calibrated and installed by the factory and normally requires no routine maintenance. So rugged is the “FMSS” Scale System that the LC-137 Weigh Resolver is guaranteed for 15-years.

Features:Accurately measures load regardless of load position.Immune to support structure deflections and process vibrations.Inherently self aligning to gravity.Nulls out heavy tare loads.1,000% overload capacity.Scale may be suspended from above or supported below.Immune to shock or impact loads.Easily accessible load cell can be re-rated to meet future capacity changes without removing the feeder.

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Screw

Stub ShaftSeal

Drive Key Shear PinCam Lock

Hexagonal Drive Shaft

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The totally unique THAYER process screw has many innovative concepts. The most obvious of these is the hex shaped, eccentric cam locking, quick release screw drive shaft assembly. This allows for hassle free “no tools” screw removal.

A more subtle but equally important concept is the shaft seal and how it is integrated into the process screw for ease of maintenance. With this shaft seal design the normal wear items (namely the seals) are mounted on and removed with the quick release process screw. They can then be easily cleaned, inspected or replaced without tools or additional disassembly.The process screw is designed so that the seals do not turn with the screw, rather the screw has a special adapter mounted on it which acts as a seal gland surface. This adapter rotates with the screw and runs on the inside diameter of the non-rotating seals.

In normal service the seals are the only wear items, however if abnormal screw damage has occurred, the process screw can be disassembled. This feature allows the drive shaft as-sembly to be removed from a damaged screw and reused on the replacement screw. Also the rotating adapter and drive key can be reused or replaced in the field with a minimum amount of down time.

Seal construction is carbon fiber (graphite) reinforced PTFE with a 302 stainless steel canted-coil energizing spring.

The process screw has a round stub shaft which the adapter slides over prior to inserting into the mating hole in the screw drive shaft. This assembly along with the drive key is pinned together. This design allows for component replacement in the field. If required, the screw can be disassembled from the screw drive shaft assembly by driving the pin out. Once com-pleted the drive shaft assembly and adapter can be withdrawn off the round stub portion of the screw.

If the screw becomes jammed the spring pin will shear and protect the screw, reducer and drive motor.

SCREW & SEAL ARRANGEMENT

AUTOMATED TEST WEIGHT LIFTER (ATWL)More and more weigh feeders are being used in conjunction with statistical process control where performance records are routinely generated and delivered with the product as required by a cus-tomer’s quality assurance program. Such a record should contain a “validation of scale calibration” step to be truly meaningful as a quality assurance tool. Thayer Scale’s Automated Test Weight Lifter (“ATWL”) provides a means for automatically applying a known test load and going through a calibration sequence on computer or push-button command to check scale calibration. A “foolproof” self-checking software algorithm in the feeder control instrumentation prevents erroneous calibration.

The test weight calibration method has proven accurate and reliable over decades of in-plant use. Unlike material sampling, it is always clean, fast and safe and free from human error. Unlike electronic signal simulation, it mechanically tests the performance of critical electro-mechanical components under the full deflection range of the load cell.

Model LWF-LC-RV Large Cable Suspension Scale Feeder

with Rotary Valve

Thayer Loss-In-Weight Vibratory Feeders are designed to assure uniform, non-pulsating, accurate feeding of a wide range of materials, from free flowing to friable to cohesive.Ideal for feeding materials at very low feed rates accurately, with second to second uniformity, and without feed rate pulsations.Simple, low cost design makes it an excellent choice for feeding free flowing materials such as pellets or granules.Widely recognized as the most suitable choice for feeding delicate materials, that require gentle handling.Accurately measures load regardless of load position.Immune to support structure deflections and process vibrations.Inherently self aligning to gravity.Nulls out heavy tare loads.1,000% overload capacity.Scale may be suspended from above or supported below.Immune to shock or impact loads. Easily accessible load cell can be serviced without dismantling the feeder.

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THAYER SCALELoss-In-Weight Cable Suspension System with Vibratory Feeders

HEAVY INDUSTRY Model LWF-LC-V

Loss-In-Weight Vibratory Feeder

Model LWF-SC-V Sanitary Vibratory Feeder with SpiralatorTM

Model LWF-MC-V “Mini” Loss-In-Weight Vibratory Feeder

Model LWF-SC-V Loss-In-Weight Vibratory Feeders

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THAYER SCALE Loss-In-Weight Vibratory Feeders Special Features and Benefits

Thayer Scale has spent many years developing the Loss-In-Weight Feeder and control system for use with vibratory feeders. Since virtually all of the controllers on the market were originally designed for use with a screw feeder, it should not be surprising to find that very few of them have the versatility to cope with the special requirements of the vibratory feeder type. Without (certain) special control features, the vibratory feeder can not be controlled effectively in a volumetric mode, nor can it be controlled gravimetrically over a wide operating range without making controller adjustments to suit its non-linear characteristics.

With complete absence of motors, bearings, seals and lubricating fluids, along with the un-contested pulse free delivery “smoothness” at maximum turn down, the vibratory feeder has powerful advantages over the screw feeder in a great number of applications.

Some important differences that need to be taken into account in controlling these two fundamentally different volumetric feed devices are:

Key Features of the THAYER Loss-In-Weight Controller That Addresses “Vibratory Feeder” Control Issues

1. “OCMP” (Controller Output Compensation). This is a vibratory feeder gain compensation control block that can be programmed into the control loop between the controller output stage and the drive input stage. It represents a “characteristic” equation that permits a single controller gain setup to operate over a wide range (typically 50:1 but can go as high as 100:1) with most vibratory feeders.

2. “EFT” Excitation Tracking. A transducer physically mounted to the vibratory tray is used in conjunction with specialized circuitry to control and monitor the amplitude of the vibratory tray. During gravimetric control cycles, amplitude readings and weight readings are combined in time adjustable averaging registers for purposes of continually updating a “density” register. Thus, when a volumetric feed cycle is called for during refill, the transducer signal and the density factor are combined to provide a dynamic weight-rate signal in the control loop in place of the normal scale-derived value. Thus “closed loop” control is never discontinued, and the feeder is always responsive to changing set points. Should head pressure on the vibrating tray begin to load down its amplitude, the controller automatically responds immediately with a compensatory output change.

This parameter, which has a direct effect on the system’s front-end damping, and thus its “measurement dead time”, establishes a limit on how high the controller gain can be set without experiencing bothersome control oscillation. The combination of less front-end damping along with the higher degree of responsiveness of a magnetic drive unit (over a motor drive), reduces the overall loop time-constant dramatically making the vibratory Loss-In-Weight Feeder an excellent choice where process demand changes may occur abruptly.

1. The gain of a screw feeder is constant over its operating range. That is the in-crements of change in feed output for a given change in drive input is constant throughout its range. The “gain” of a vibratory feeder increases exponentially with its operating point. That is, the increment of change in feed output be-comes larger for a given change in drive input as the operating point increases. The consequence of this is overall gain of the control loop is lower in the low operating ranges and higher in the high operating ranges. If something is not provided to compensate for this effect, the controller gain needs to be adjusted if the set point is changed any significant amount.

2. The “volumetric” delivery of a screw feeder stays relatively constant under a constant drive input (such as during hopper refill). Under conditions of a con-stant drive input, the “volumetric” delivery is relatively independent of material’s bulk density. Variation in its “gravimetric” delivery under constant drive input is essentially determined by density changes of the material handled at the time.

3. The “volumetric” delivery of a vibratory feeder stays relatively constant pro-viding the vibration amplitude is held consistent (frequency assumed constant @ 60 hz). However, for the vibration amplitude to hold constant, the drive input must be increased or decreased to offset the loading effect on the tray itself.

4. A screw feeder can accept a refill with less material “heel” (the minimum quantity of material that is always maintained over the feeder inlet) than a vibratory feeder can, since the flights of a screw within the feed tube offers greater resistance to “flushing’ than does an open channel tray.

5. The magnetic-drive of a vibratory feeder is capable of rapidly responding to changes in controller output signal. A gear-motor drive system for a screw feeder, and the screw itself, represents considerable angular ”inertia” which simply can not be made to respond quickly to demand changes.

SPIRALATORTM

Enjoy the benefits of using a simple and reliable vibratory feeder on non-floodable materials that normally can not be reliably discharged through the small opening of a conical hopper. The benefits of using a vibratory feeder in place of a screw feeder include: higher turn-down, pulsation-free discharge, cleaning ability, and elimination of troublesome seals and bearings.

The SPIRALATORTM is a slowly rotating, non-agitating, conical wire-spiral within the hopper which counteracts the material’s tendency to pack under its own weight by virtue of its “lifting” action throughout the stored material. The resulting reduction in consolidation pressures throughout the material mass assures that the stored material will not develop sufficient strength to form stable arches that can cause erratic flow or complete flow stoppage. The combination of the unique material conditioning system and a vibrat-ing pan feeder assures that the material will be handled reliably and gently throughout the entire feeding range.

NODAL MEMBRANE VIBRATORY TRAY INSERTThis patented feeder meters material on an elastic membrane feed tray that responds uniquely to the action of the magnetic vibratory drive. A transverse multiple node standing wave is produced in the mem-brane that serves to discourage any adherence of material to its surface. The cross-sectional shape of the membrane is made up of multiple distinct curves which alternate between convexity and con-cavity so as to produce corresponding tensile and compressive surface strains in the elastomer. It is amplified and reversible surface “straining” (stretching and compressing) that creates the self- shedding action. The feeder is frequently supplied in combination with the SpiralatorTM agitator for sluggish powders.

QUICK RELEASE PANQuick release hand operated clamps permit fast removal of feed trays for cleaning and/or quick changeovers of material-dedicated trays used where cross-contamination must be avoided.

THAYER SCALELoss-In-Weight Feeder with “FMSS” Technology Flexure Plate Suspension Scale for both Screw and Vibratory feeders.

Model PF-18L-SLoss-In-Weight Screw Feeder

Model PFM-15L-SLoss-In-Weight Screw Feeder

Model LRF-801L-SLoss-In-Weight Screw Feeder

Model LWF-15L-VLoss-In-Weight Feeder with Spiralator TM

Model LWF-8-VLoss-In-Weight Feeder

Model LWF-8-V with SpiralatorTM Loss-In-Weight Feeder

THAYER Loss-In-Weight feeders come in a variety of sizes and shapes, and can incorporate various volumetric devices, depending on the material handling charac-teristics and the rates and range of rates to be encountered. Flow rates may be as low as 2 grams/min to over 100,000 pounds/hr. The most versatile feeders include the screw feeder and the vibratory pan feeder.

THAYER usually recommends one of the following feed systems: A screw feeder with horizontal helix agitator for powders, a vibratory pan feeder with steep walled conical hopper for moderately free flowing granules or flakes, or a vibratory pan and SpiralatorTM flow aid for powders requiring very smooth and steady flow. Because of the much smoother discharge of the Vibratory Pan feeder, the effective turn down ratio exceeding the usual 10:1 is possible. Vibratory feeders can operate over 50-100 to 1 range, depending on material flow characteristics.

While going against past convention, it is now possible to use many difficult to discharge powders on a vibratory pan type feeder by utilizing Thayer’s patented Spi-ralatorTM and Nodal Membrane tray insert which assures steady feeding of difficult powders. Thus, it is possible to handle powders over a typical 50:1 flow range vs. the typical 10:1 on a screw, based on accuracies over 30 seconds or so. Where second-to-second accuracy is concerned, the screw feeder is effective for only a 10:1 turndown owing to the natural pulsating flow that accompanies each revolution of the screw.

THAYER is proud of the fact that it has designed and manufac-tured some of the most accurate industrial weighing equipment in the world, based on its flexure plate and cable suspension Force Measurement Suspension Systems (FMSS’s). THAYER has supplied Defence agencies with equipment that weighs ura-nium ingots weighing as much as 600 kilograms to an accuracy of 1 gram. THAYER has supplied Loss-In-Weight feeders for critical manufacturing of liquid and dry rocket propellents, feed-ing difficult components at accuracies no other manufacturer could match.

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 “U-trough” 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 measure-ment, exceptional durability and excellent long term stability. Scale system weighs only the material, not the feeder, for second-to-second accuracy and sensitivity.

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THAYER FLEXURE PLATE SUSPENSION SCALE Laboratory Accuracy in Industrial EnvironmentsThe Basic THAYER Flexure-Plate Suspension system utilizes a series of steel flexure plates to transmit gravimetric loads vertically from the load receiving element through levers to the specifically selected controls. The combination of mass counterbalancing against tare loads, frictionless flexure-mounted levers and a high resolution transducer produces a force measuring system beyond compare. Of significance is the fact that infinite weighments may be made without maintenance or calibration, regardless of atmospheric or factory conditions. In many instances, THAYER Flexure Plate Suspension Systems placed in operation in 1950 are still working without maintenance or adjustment.

Sustained sensitivity without maintenance. Deflection less than 0.001 inch. Cancellation of horizontal force vectors. Nullification of heavy tare loads. Immunity to off-center or overhung loads. Load transducer completely isolated from overloads. Non-tilting platform design. Low mechanical resonance frequency. Load transducer utilization factor > 90%. Ability to re-rate scale capacity in field.

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Single Post ScaleThayer’s platform scale utilizes a single, vertical post, in-stead of the usual four to support the volumetric feeder from the scale platform. This unique structural arrange-ment permits the use of strategically placed top and side panels which afford direct servicing of critical scale parts without the need to first disconnect and remove the feeder from the scale platform.

Rotating Feed TroughOptional rotating trough speeds material change-out and makes cleaning even easier. Ideal for batching system use and to self-empty remaining material away from process. For both Screw and Vibratory Feeder models.

DASH POTRANGE SPRINGLVDT COUNTER WEIGHTFLEXURES

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PROCESS INSTRUMENTATIONThayer Scale manufactures a wide range of instrumentation products that can be con-figured to operate either a single or multi-feeder operation in either batch or continuous mode. Features include programmable analog and discrete I/O, multi-level password protection, RS232 and RS485 serial communications and a wide range of PLC/PC communications drivers and device level interfaces including DeviceNet, Profibus-DP, and Ethernet /IP.

High quality, professionally fabricated, custom packaging is available including feeder systems for use in hazardous areas, free standing control cabinets and fully integrated weigh feeder/PLC control systems.

Patented Differential Feed ScrewAlternative to twin screws; a forward feed helix and a reverse feed helix concentrically mounted to the same shaft.The patented differential screw feeder features a compound flight screw designed having both a forward feed helix and a reverse feed helix concentrically mounted to a common shaft. Very low vol-umetric feed rates with minimal material pulsations are achieved, while using a substantially larger diameter feed screw. This results in a more reliable and rugged industrial-service machine. The larg-er diameter screw, residing in a correspondingly wider trough, is less prone to stoppages due to material bridging across either the trough or adjacent flights. Also, the larger shaft size calls for larger bearings and seals, all leading to a much more robust design.

Where various capacity screws are needed for widely differing setup requirements, all can be supplied with the same diameter, eliminating the need to also change feed tubes.

Forward Feed Helix

Reverse Feed Helix

PRODUCTS & MARKETS SERVEDThayer Scale supplies the world with process measurement & control equipment with emphasis on solids flow weighing and metering. Our products include: Loss-In-Weight Feeder, Weigh Belt Feeders, Con-veyor Belt Scales, Measurement & Control Instrumentation and Bin & Hopper Material Flow Aids. The markets we serve include: Forest Products, Plastics, Food, Chemicals and Cement to name a few.

MAJOR PRODUCTS & TECHNOLOGIES

Patented “FMSS” Force Measurement Suspension System Cable Scales

Patented Loss-In-Weight “DifferentialTM” Screw Feeder

Patented “Nodal-Membrane” Vibratory Tray Feeders.

Patented “SpiralatorTM” Hopper Agitator

Patented “Rocking Flexure” Belt Scales

Patented “PF” Volumetric Screw Feeder

Patented “Bridge BreakerTM” Bin & Hopper Dischargers.

Low Feed Rate “Miniature” Weigh Belt & Loss-In-Weight Feeder.

“NAR” NTEP Approved commercial grade Conveyor Belt Scales

(approved for legal trade).

“SI” Insertion Weigh Belt Feeder and Scale.

“MFLI” Mass Flow Liquid Injection System.

High Capacity, Heavy Industry Weigh Belts.

Modular, Singular or Multi Feeder Continuous or Batch Control Systems.

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SUPPORT SERVICESTEST FACILITIES:Thayer Scale operates three fully equipped dry particle test centers in a dedicated wing of our Massachusetts facility. A full time staff performs product application and performance testing with user supplied materials. These facilities are de-signed to duplicate as closely as possible industrial process-ing conditions.

SERVICE:Thayer Scale has a well trained professional service depart-ment with an outstanding record of longevity, experience and achievement. Thayer’s technicians are available for start-up support, inspection, diagnosis and repair service, routine maintenance and material testing services.

TRAINING:Thayer Scale offers formal training either here at the factory in Pembroke, MA or at the customer’s plant. Each training class is tailored to the specific instrumentation and mechani-cal equipment used in their facility.

THAYER SCALE-HYER INDUSTRIES, INC.91 Schoosett St., Pembroke, MA 02359Ph: 781-826-8101 Fax: 781-826-7944

e-Mail: Sales@ThayerScale.comWEB: www.ThayerScale.com

Tote Batch Systems Heavy Duty, High Capacity Weigh Belts

Specialty Weigh Belts Low Capacity Weigh Belts

Loss-In-Weight Feeders

Process InstrumentationMaterial Flow Aids

Volumetric Feeders Conveyor Belt Scales

Thayer and the THAYER logo are Registered Trademark’s of Hyer Industries, Inc.