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Weighfeeder Application Questionnaire 

Обзор

SITRANS weighfeeders from Siemens can improve the accuracy of processing, blend consistencies, accountability, and record keeping. All weighfeeders come standard with a belt weigh bridge and speed sensor. An integrator is required to complete the system.

Способ действия

The weighfeeder is used to deliver an accurate mass flow rate of material. In the majority of applications, material is profiled by an adjustable mechanical shear gate, which fixes the correct material bed depth for a given particle size.

The feed rate is then maintained and adjusted by varying the speed of the belt. However, in some cases the belt speed is constant with rate control (if any) done by a pre-feeding device.

The system consists of three components: weight and speed sensing, integration and control, and the mechanical conveying system. Using the belt load and the belt speed signals, small incremental totals of weight per time are measured by the integrator and then the flow rate is calculated. The measured flowrate is compared against the desired flowrate and the on-board PID controller makes necessary corrections to the belt speed.

Weighfeeder operation

Design and Applications

SITRANS WW100

The platform weigh bridge mounts directly to a corrosion-resistant platform load cell. The direct load design eliminates all intermediate mechanical suspension and allows material weight to be directly applied to the load cell.

This design minimizes zero drift normally caused by intermediary suspension components and allows for the use of a very sensitive precision platform load cell. Load cell size and construction are chosen for each specific application.

SITRANS WW200

A stainless steel platform weighdeck with a Delrin slider bar assembly mounts directly to two corrosion-resistant, sealed platform load cells. The direct load design eliminates all intermediate mechanical suspension and allows material weight to be directly applied to the load cells. The frame of the WW200 is sturdy and rigid, ensuring stable and repeatable results, maximizing resolution and weighing accuracy.

SITRANS WW300

SITRANS WW300 suspends a single weigh idler on platform load cells. Its design eliminates all moving parts in the weighing
process and subsequent maintenance and replacement problems. There are no links or flexures. Two corrosion-resistant precision strain gauge load cells provide weight sensing signals to an integrator. This design feature minimizes zero drift and maximizes
resolution and weighing accuracy.

SITRANS WW310

A modular design with external access to all bearings, speed sensors and load cells the WW310 is easy to maintain. Two corrosion resistant single point platform load cells mounted directly to a rugged idler ensure consistent weighing accuracy.

Технические данные

Criteria

SITRANS
WW100

SITRANS
WW200

SITRANS
WW300

SITRANS

WW310

Typical industries

Bulk chemicals, tobacco, food, water treatment

Bulk chemicals, tobacco, food, recycling

Cement, mineral processing, coal, mining, pulp and paper

Cement, mineral processing, coal, mining, pulp and paper

Typical applications

High-accuracy, low-capacity for minor ingredient additives

Low- to medium-capacity for minor ingredient additives

Medium- to high-capacity for macro ingredient additives

Medium- to high-capacity for macro ingredient additives

Design rate range

45 kg/h ... 18 t/h
(100 lb/h ... 20 STPH)

0.45 ... 100 t/h
(1 000 lb/h ... 110 STPH)

4.5 ... 800 t/h
(5 ... 880 STPH)

4.5 ... 270t/h

(5 ... 300 STPH)

Belt speed

0.005 ... 0.36 m/s
(1 ... 70 fpm)

0.005 ... 0.36 m/s
(1 ... 70 fpm)

0.005 ... 0.36 m/s
(1 ... 70 fpm)

0.005 ... 0.36 m/s (1 ... 70 fpm)

Accuracy1)

± 0.25 ... 0.5 %

± 0.5 % or better

± 0.5 % or better

± 0.5 % or better

Specified range

10 ... 100 % based on speed

10 ... 100 % based on speed

10 ... 100 % based on speed

10 ... 100 % based on speed

Sensing element

Long length platform weigh bridge
Single load cell

Platform weigh bridge
Dual load cells

Single idler scale
Dual load cells

Single idler scale Dual load cells

Approvals

CE, RCM
Stainless steel options meet USDA and FDA requirements for food processing

Stainless steel options meet USDA and FDA requirements for food processing

 

 


1) Accuracy subject to: On factory approved installations the weigh feeder system’s totalized weight will be within the specified accuracy when compared to a known weighed material test sample. The test rate must be within the specified range of the design capacity and held constant for the duration of the test. The minimum material test sample must be equivalent to a sample obtained at the test flow rate for three revolutions of the belt or at least ten minutes running time, whichever is greater.

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