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Benefits of a Flexible Screw Conveyor: Construction, Capabilities & Performance

Posted on 9th September 2016 by

flexible-screw-conveyor-helical-actionEvery year we talk to hundreds of processors around the world, and one of the first things they ask us is, ‘What are the benefits of a flexible screw conveyor?’ This is a great question because you want to make sure you choose the right conveyor that you can depend on to meet your requirements safely and reliably. And for that to happen, you’ll need to choose the right conveyor with the right specifications to do the job. We get it! This article will explain the benefits of flexible screw conveyors so that you can decide if it is the right conveyor for your application.

A Flexible Screw Conveyor can carry material in any direction from horizontal to vertical and be routed around fixed obstacles. It is ideal for lifting thousands of pounds or kilograms of materials from point A to point B but its suitability depends on your application. Just like everything else, there are pros and cons about Flexible Screw Conveyors (FSCs). Below is a comprehensive list of how a flexible screw conveyor will work best for you.

Cost Of A Flexible Screw Conveyor

The Flexible Screw Conveyor is almost always the least expensive option when compared to other mechanical conveying systems. Pricing is specifically based on the type of tubing and spiral, the length of the conveyor, the motor size, and options selected.

Flexible-Screw-Conveyor

Best Materials To Convey Using A Flexible Screw Conveyor

Flexible screw conveyors readily convey thousands of materials and mixtures from fine powders to large pellets too numerous to list. Our engineers are experts who can consult our extensive testing database and advise you on the suitability of a flexible screw conveyor for your application. They know how these conveyors perform. For example:

  • Material degradation is less than might be expected compared to other mechanical conveyors. There is moderate shear stress produced by the screw against the tube. Typically degradation is not an issue with most granular products like sugar but material testing is recommended for fragile products.
  • We recommend material tests in one of our test labs for fragile, hygroscopic, and cohesive (materials that smear) products.
  • Maintaining blends depend on densities and material characteristics of materials in a blend.
  • Moist materials, sludge, and slurries are not suitable.
  • Flex screws can transport hot and cold materials. Typical UHMWPE tubes with a steel spiral can handle material temperatures up to 180˚F (82˚C). For higher temperatures, up to 300˚F (149˚C), a steel tube is required.
  • Very fine particles that fluidize readily may require a flat spiral. In some cases, a center core may also be needed.

Speed & Capacity Of A Flexible Screw Conveyor

The conveyor’s performance is closely tied to the material it carries. Depending on a product’s flow characteristics, the bulk density of material, and layout a Flexible Screw Conveyor speeds can reach up to 1,150 RPM depending on the size of the conveyor.

The capacity of our largest FSC is typically up to 29 ft3/min (0.82m3/min). FSCs are offered in a variety of sizes which directly relate to capacities. In North America Spiroflow offers 6 models based on tube diameter: 2¼”, 2½”, 3⅛”, 4½”, 6½” and 8¾”. In Europe, our FSCs are offered in metric sizes based on the inside diameter of the tube: 37mm, 44mm, 55mm, 67mm, 80mm, 90mm, 120mm, 146mm, 196mm.

If you need higher capacities than 29 ft3/min (0.82m3/min), then you might consider an aero mechanical conveyor that can achieve capacities of up to 36 ft3/min (1m3/min). Drag conveyors typically achieve lower rates & capacities.

All of our screw conveyors can run at variable conveying rates.

flexible-screw-conveyor-outside
A Flexible Screw Conveyor transfers flour from an outdoor silo through the exterior building wall for processing inside.

Layout Constraints

Flexible screw conveyors can be approximately 40 ft (12m) on a 45˚ angle but they can be significantly longer in a different configuration. Multiple conveyors can be linked to span greater distances.

FSCs can ONLY have a single bend. If you need a conveyor with multiple bends consider an aero mechanical or tubular drag conveyor.

Standard Construction & Components

Tubes

Flexible Screw Conveyor tubing can be made from Food Grade UHMWPE for food applications, anti-static UHMWPE for explosive materials, rubber tubing for conveying abrasive materials, or metal detectable tubing, so you have many options.

Spirals

Flexible screw spirals can be made of different materials of construction namely carbon steel or stainless steel. Spirals also come in different shapes. For most applications the standard round spiral is suitable, providing a good combination of strength and flexibility. Flat section spirals are recommended for certain light or aerated products. A Proscrew beveled profile is used for conveying difficult materials. The semi-rigid construction enables steep conveying angles to be achieved without bends.

A Center Core is used for very light materials that fluidize readily and for conveyors inclined more than 60°. They are also used to prevent flooding/overfeeding of certain solids in short or horizontal conveyors.

All of our spirals are heat treated to provide greater strength and long life. Heavy duty spirals are also available for certain high density or aggressive materials.

Some applications require a polished spiral for material in the food industry. Of course, you don’t have to worry about any of this, as our engineers will recommend the type of tube and spiral based on your application.

Inlets And Outlets

Flexible Screw Conveyors can have multiple inlets and outlets and can be run will a full head of material. Vibration, air fluidizers, or agitators can be fitted to assist with poor flowing products. These conveyors are designed to be run fully charged. Inlets can be fitted with lids, hoppers, agitators, and more. Custom designs are always available.

Options

Our Flexible Screw Conveyor can be designed with options such as a flexible discharge hose, right angle gear reducer, wash down, mobile base, integral bag dump hoppers, and controls.

Hygienic options include food grade tubing and polished stainless steel spirals, a drop out inlet for quick cleaning, a sanitary seal standoff, quick release tube connections.

Explosion proof options include anti-static tubing static grounding (earthing), an explosion proof motor, anti-static tubing, purged control panels, and 7/9 (ATEX) components.

Cleanability

A Flexible Screw Conveyor can easily be cleaned. An operator simply runs it in reverse to empty material into a receptacle. It can be stripped down in a few minutes and an optional quick release and hygienic fitting are available to aid clean down. The screw can be removed from the tube so smooth surfaces can be cleaned and visually inspected.

USDA/3A designs are available for sanitary applications.

Maintenance

The Flexible Screw Conveyor requires very little maintenance. Wear typically occurs when conveying abrasive products or if the tube is excessively bent.

Installation

The Flexible Screw Conveyor has a low installation cost.

Dust Control

This type of conveyor is mechanically dust-tight. No external filters are required for operation.

Residual Material

The Flexible Screw Conveyor is not 100% self-emptying. However, running in reverse can easily empty it.

Running Empty

The conveyor can’t be run empty for extended periods without excessive noise and wear.

Starting And Stopping

Flexible Screw Conveyors can be started and stopped under load.

A Flexible Screw Conveying By Any Other Name

Depending on where you are located and when you entered the industry you may refer to a flexible screw conveyor as an auger screw, screw auger, flexible auger, screw conveyor, flex conveyor, helix or helical conveyor, flexible spiral conveyor or spiral screw conveyor.

Here at Spiroflow we help thousands of clients every year with their conveying needs. So if you need some help or advice contact us!

(1) 704-246-0900 | sales@spiroflow.com | +44 (0) 1200 422525

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Deron Seibert

Director of Sales at Spiroflow Systems, Inc
Deron has more than 20 years in the bulk material handling industry and has been with Spiroflow for more than 10 years. He has been instrumental in the execution of many of Spiroflow’s largest and most complex projects.

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