SCREW CONVEYOR

DESIGN DATANo machinery design is complete without considering its usage. A conveyorthat will be used intermittently for two hours a day does not have to be builtas heavily as one that will operate twenty-four hours per day. Likewise, shockloads will affect the consideration given on gauge of steel used as well as driveequipment. Treatment of these factors and their affect on conveyor design arenot discussed here in sufficient detail to prescribe. As mentioned previously, ourengineers are available to assist you in every way possible to determine yourbest conveyor design.Since the Screw Conveyor selected is based on a maximum volume controlof material to be handled, surge loads, overloads and choke feeding must beaccounted for in the conveyor design. Screw feeders are popularly used for thiscontrol and are discussed in other pages of this catalog.CLASSIFY YOUR MATERIALMaterials are classified in table No. 6 on pages 12, 13 and 14. If your materialis not listed, it can be classified by comparing it with similar materials that doappear in the table. If necessary, your material can be classified by referring totable No. 4 “Material Classifications”, page 11.ESTABLISH REQUIRED DIAMETER AND SPEEDKnowing your material classification and required capacity, refer to the CapacityChart, page 15. Your material classification indicates which trough loadingapplies. Select the size for your capacity using the smallest diameter conveyorthat is below the maximum recommended speed. After size is determined thenexact conveyor speed is determined by dividing the required capacity in cubicfeet per hour by cubic feet per hour at 1 revolution per minute.Note: If handling a material with hard lumps [lumps that will not break up in theScrew Conveyor] refer below to Table No. 1, “Size of Lumps to Diameter”. If therequired diameter (as found above] is smaller than the recommended size givenin the Lump Chart, use the conveyor diameter from the chart Table #1 and thendetermine the RPM from Table #7.TABLE NO. 1 MAXIMUM SIZE OF LUMPS, INCHESRATIOLumpsto TotalVolumeDiameter of Conveyor, Inches4691012141620241.52.52.53.03.54.0 4.5 5.06.0Lump 20%to 25%0.5 0.751.51.52.02.53.0 3.0 3.5 3.75All Lumps0.30.75 0.75 1.0 1.25 1.5 2.0 2.0Lumps 10%1.0or less.0.5182.5COMPONENT GROUP CLASSIFICATIONAs shown in the Material table No. 6, pages 12, 13, and 14 each material isassigned to a Component Group. These groups take into account the material’sphysical characteristics and then match these with the proper conveyorcomponents. A description of these components in each group can be found onpage 11, table No. 5.Please note that Babbitted bearings are considered standard where contaminationfrom the required lubricants is not a factor. Oil impregnated wood or nylonbearings are often recommended where lubricant contamination is a factor. Ballbearings are not recommended for use in conveying gritty or very fine materialswhich might penetrate the oil seal. For abrasive or applications involving hightemperatures, hard iron bearings are normally used. Other types of bearingmaterials furnished upon request.ESTABLISH THE “D” FACTORThe “D” Factor is a constant applied to the particular Component Group of agiven conveyor. To establish the “D” Factor, locate your conveyor diameter andbearing material in table No. 2. The figure appearing at this intersection is to beused as “D” in the horsepower formula.TABLE NO. 2EngineeringTABLE OF FACTORS “D”TYPE OF HANGER BEARINGSSize ofConveyor,InchesBall orRollerWood, Babbitt,Nylon or MoldedFabricSelfLubricatingBronzeWhite Iron orManganese 10690355080130160250350480600700950ESTABLISH THE REQUIRED HORSEPOWERThe formula stated below gives the horsepower (HP) required at the conveyordrive shaft for a standard conveyor.Additional power will be required for starting under load, overcoming chokeloads or other unusual conditions. There is also a loss of power through thedrive machinery of from 10% to 15%. To compensate for these factors, theformula for the required motor horsepower is divided by .90. Step No. 1H [(D x S Q x F)]1,000,000WhereL Overall length in feetD Bearing Factor (see “D” Factor table) (Table No. 2)S Speed in RPM (see Capacity Chart)Q Quantity of material being conveyed in lbs./hr.F Horsepower factor “F” (see Material Tables)Step No. 2Motor Horsepower H x PP 2 when H is less than 1P 1.5 when H is between 1 and 2P 1.25 when H is between 2 and 4P 1.1 when H is between 4 and 5P 1 when H is greater than 5Step No. 3HP Minimum Recommended Horsepower.90CONVEYOR HORSEPOWER RATINGSOne of the factors that must be considered now is to check the requiredhorsepower from the above formula against the torque and horsepower capacitylimitation for each conveyor pipe and shaft size.Use table 3, page 10 which shows the maximum allowable horsepower at variousconveyor speeds.Example: a 9" conveyor mounted on 2" standard pipe, bushed for 1 1/2"diameter couplings, is limited to a maximum of 5 HP at 100 RPM. If, in a givenapplication, a larger motor is required, it is then necessary to use a 9" conveyormounted on 2 1/2" pipe, bushed for 2" diameter couplings. You will see that thisarrangement is rated at 12 HP at 100 RPM or 6 HP at 50 RPM. These ratingsare on the basis of two coupling bolts at each end of the conveyor pipe. In somesizes three bolts can be used to increase the drive limitation shown. Consult ourEngineering Department for specific recommendations if in doubt.9

EngineeringTABLE NO. 3DESIGN DATAHORSEPOWER RATINGSAdditional Screw Conveyor specifications for indoor operation will be:Size ofPipeMax, HP Max, HP Max, HP Max, HPCouplingConveyor, Size@125@100@ 75@ 50Dia.InchesInchesRPMRPMRPMRPM6, 9, and 102.01 1/26.255.03.752.59, 10, and 122.52.015.012.09.06.012 and 143.02 7/1618.7515.011.257.512,14,16,18 and 203.53.030.7524.618.5012.320 and 244.03 7/1643.7535.026.2517.5SAMPLE PROBLEMEstablish the conveyor size, speed, horsepower and other specificationsnecessary for conveying 1,800 bushels of dry, clean wheat per hour for adistance of 50 feet.SOLUTIONRefer to the Material table No. 6, pages 12, 13 and 14.Note: Average weight/cu. ft. of wheat is 45–48 Ibs.The material classification is 47C½25NThe recommended types of conveyors are 1A, IB, 1CThe “F” Factor is .4The material classification, C½25N indicates the material is granular — 1/2"inch and under, very free flowing — angle of repose up to 30 , non-abrasiveand contains explosive dust. The recommended types of conveyors, lA, 1B, 1Cindicate the group that is designed for normal service. (See table 5, page 11 andCapacity table 7, page 15.)Convert the given capacity from bushels per hour to cubic feet per hour. Known:there are 1.25 cubic feet in a bushel of wheat. Therefore, 1,800 x 1.25 equals2,250 cubic feet per hour. Now, 2,250 cu. ft. per hour x 48 Ibs. equals 108,000lbs./hr. This will be assumed to be the maximum desired capacity. Turn to theCapacity Chart table No. 7, page 15 and establish the conveyor diameter andproper speed. As you will note C25 material class has a 45% recommendedtrough loading and 2,250 cu. ft./hr. requires a 12" diameter screw conveyoroperating at 116 RPM (EXAMPLE: 2,250/19.4 115.9 or 116 RPM.) Remember,do not exceed the maximum recommended speed without first consulting withour staff engineers. If hard lumps had been present, we would now consult tableNo. 1, page 9.We now know that:L 50 feetD 96 (see “D” Factor table, table No. 2) 12" conveyorwith wood bearings)S 116 RPM (see Capacity Chart)Q 108,000 lbs./hr.F .4 (see Material Tables)Now, inserting these figures in the formula:H 50(96 x 116 108.000 x .4)1,000,000Therefore: H 2.8Motor Horsepower equals H x P (see value of P under formula)Therefore: 2.8 x 1.25 3.5To be assured of having sufficient power, divide the HP by .90. This gives you aminimum recommended horsepower of 3.9. Your minimum choice of motor sizewould, therefore, be 5 HP.Now, refer to the Torque Capacity table No. 3 and note the minimum pipe sizefor a 12" conveyor is 2 1/2". Maximum allowable horsepower for this conveyor’sspecifications is 15 HP. Since this figure is in excess of our requirements, wecan use the computed 5 HP motor.10Group Classification: 1AConveyor Size and Speed: 12" at 120 RPMConveyor Screw: 12" Standard HelicoidConveyor Trough: 12" No. 12 gauge steel, Double FlangeConstruction, Flanged Cover and Barron ClampsType of hanger bearings: 12" x 2" bore, intermediatehanger with babbitted bearingsRefer to page 17 for additional Layout Data and Details.SPECIAL APPLICATIONS AND SPECIFICATIONSThe selection procedure, outlined above, takes into account the material’sphysical characteristics, provides for the proper cross-section loading of aconveyor and specifies, through the component tables, the type of conveyorcomponents to be used. Some material’s physical characteristics will requireadditional special features.ABRASIVE MATERIALSAbrasive materials tend to cause excessive wear on Screw Conveyorcomponents and should be carried at low cross-sectional loads and at relativelyslow conveyor speeds. For conveyors which will handle extremely abrasivematerials or will be subjected to heavy or continuous service, heavy-dutycomponents should be specified. Heavier than standard, surface-hardenedor abrasive resistant steels are available for this application.There are also some materials that are normally considered abrasive whichmay easily become aerated, thus reflecting a minimum density and greaterflowability. Here it is possible to use higher speeds and in some cases, highercross-sectional loads. Judgment and experience, however, will dictate theconditions when this can occur.CONTAMINABLE MATERIALSWhen handling easily contaminable materials, such as food products orsome chemicals, it is possible to specify components and other features ofconstruction which were not necessarily included and made a part of theconveyor selection process. These features would include non-lubricating typeintermediate hanger bearings, seals under the end bearings, easily removabletrough covers and, possibly, drop bottom conveyor trough construction.Accessibility to the internal parts of the conveyor through the use of some ofthese features means the conveyor can be easily inspected and cleaned out.Conveyor Flighting may be continuously welded to the conveyor pipe on either/or both sides of the flight. Grinding and cleaning of the welds can remove scaleand/or roughness that could contribute to contamination.CORROSIVE MATERIALSWhen handling bulk materials which are corrosive, conveyor componentsmanufactured from stainless steel, aluminum or other special alloys areavailable, also hot dipped galvanized carbon steel components may be used innon-abrasive applications.DEGRADABLE MATERIALSMaterials which tend to break or separate easily, affecting quality, may behandled in larger diameter, slower turning Screw Conveyors to reduce agitation.EXTREME TEMPERATURESMaterials may be heated or cooled while being conveyed in a jacketed conveyor.When handling materials in extreme temperatures, specify Screw Conveyorcomponents of metal alloys designed to meet these conditions.FLUIDIZING MATERIALSWhen agitated, some materials tend to “aerate” and react similar to a liquid.When handling these materials, it is important to know the aerated density sothat conveyor size and speed will be based on the larger aerated volume. Whena volumetric type feeder is used, the horsepower should he based on the designvolume and maximum material density.

EngineeringDESIGN DATAMIXING MATERIALSIf the materials are to be mixed or agitated while being conveyed, ribbonflights, cut flights, cut and folded flight or one of the above in combination withpaddles, may be used.TABLE NO. 5 COMPONENT GROUP SPECIFICATIONSScrew SizeInches69Occasionally, materials tend to pack under pressure and become hard in theclearance between the conveyor screw and trough. Some of these materials canthen be conveyed satisfactory if the Screw Conveyor is operated at low speedsand the edge of the flight is used as a cutting edge.1214HYGROSCOPIC MATERIALSMaterials which readily absorb moisture are hygroscopic. Such materialsbecome less free flowing as they absorb moisture. This factor must betaken into account when determining conveyor size, HP and speed. Somehygroscopic materials can, as they absorb moisture, change in density andangle of repose and thus, effect the material classification number.16182024VISCOUS OR STICKY MATERIALSViscous materials can best be handled by Ribbon Conveyors because theyusually have a tendency to stick and adhere to the joint of the conveyor pipeand flight on a standard conveyor.Component group 2CoComponent group 2Ds69ClassDesignationFlowabilityVery Free FlowingFree FlowingAverage FlowabilitySluggishFlow Function 10Flow Function 4 But 10Flow Function 2 But 4Flow Function 21234AbrasivenessMildly AbrasiveModerately AbrasiveExtremely AbrasiveIndex 1–17Index 18–67Index 68–416567MiscellaneousProperties OrHazardsBuilds Up and HardensGenerates Static ElectricityDecomposes — Deteriorates in StorageFlammabilityBecomes Plastic or Tends to SoftenVery DustyAerates and Becomes FluidExplosivenessStickiness-AdhesionContaminable. Affecting UseDegradable, Affecting UseGives Off Harmful or Toxic Gas or FumesHighly CorrosiveMildly CorrosiveHygroscopicInterlocks, Mats or AgglomeratesOils PresentPacks Under PressureVery Light and Fluffy — May Be WindsweptElevated TemperatureFGHJKLMNOPQRSTUVWXYZSizeComponent group 2Boheavy troughheavy flightsTABLE NO. 4 MATERIAL nessCoverThickness121416182024extra-heavy troughextra-heavy flights69121416182024 418S61620S61624S71614 ga.10 ga.10 ga.3/163/163/163/163/163/163/163/163/1616 ga.14 ga.14 ga.14 ga.14 ga.14 ga.14 ga.14 ga.14 ga.12 ga.12 ga.12 ga. babbitted bearing hangerscold rolled steel couplings wood bearing hangerscold rolled steel couplings ball bearing hangerscold rolled steel couplings hard iron bearing hangers coldhardened steel couplings1½1½222 7/1632 7/1633333 7/16Extra Heavy ServiceComponent group 3A Component group 3D E babbitted bearing hangers wood bearing hangers ball bearing hangers1 1/21 1/2222 7/1632 7/1633333 7/16Heavy ServiceoComponent group 2ATOXIC MATERIALSIf harmful vapors or dust are released by agitation and conveying, the systemshould be of sealed construction. No. 200 Sieve (.0029") And UnderVery Fine No. 100 Sieve (.0059") And Under No. 40 Sieve (.016") And UnderFine No. 6 Sieve (.132") And Under1/2" And UnderGranular3" And Under7" And Under16" And Under*LumpyOver 16" to Be SpecifiedX — Actual Maximum SizeIrregular Stringy, Fibrous, Cylindrical, Slabs, EtcScrewNumber Normal ServiceComponent group 1AComponent group 1BComponent group 1Cregular troughregular flightscold rolled steel couplingsMATERIALS WHICH PACK AND RESIST DIGGINGSome materials have very strong resistance lo digging which means that itis difficult, and in some cases, impossible to shear a pile of the material orto penetrate it with a sharp edge such as in a conveyor flight. Offsetting theconveyor screw and placement of an angle inside the trough on the carryingside will enable some of these materials to be handled.Material CharacteristicsCoupling 51214H61416H61418S61620S61624S71614 ga.10 ga.10 ga.3/163/163/163/163/163/163/163/163/1616 ga.14 ga.14 ga.14 ga.14 ga.14 ga.14 ga.14 ga.14 ga.12 ga.12 ga.12 ga. babbitted bearing hangers cold rolled steel couplings hard iron bearing hangers cold hardenedsteel couplings1 1/21 1/2222 7/16333333 8S62420S62424S72410 ga.3/163/161/41/41/41/41/41/41/41/416 ga.14 ga.14 ga.14 ga.14 ga.14 ga.14 ga.14 ga.12 ga.12 ga.12 ga.For use with non-abrasive materials.For use with nonabrasive irregular materialor lumpy material containing lumps over 1/2"o sFor use with mildly abrasive material. For use with mildly corrosive materials. For use with very abrasive materials.11

EngineeringMATERIAL TABLETABLE NO. 6WEIGHTLBS. PERCU. FT.Adipic Acid45Alfalfa Meal14-22Alfalfa Pellets41-43Alfalfa Seed10-15Almonds, Broken27-30Almonds, Whole Shelled28-30Alum, Fine45-50Alum, Lumpy50-60Alumina55-65Alumina Fines35Alumina Sized or Briquette65Aluminate Gel (Aluminate Hydroxide) 45Aluminum Chips, Dry7-15Aluminum Chips, Oily7-15Aluminum Hydrate13-20Aluminum Ore (See Bauxite)-Aluminum Oxide60-120Aluminum Silicate (Andalusite)49Aluminum Sulfate45-58Ammonium Chloride, Crystalline45-52Ammonium Nitrate45-62Ammonium Sulfate45-58Antimony PowderApple Pomace, Dry15Arsenic of Lead (See Lead Arsenate)-Arsenic Oxide (Arsenolite)*100-120Arsenic Pulverized30Asbestos-Rock (Ore)81Asbestos-Shredded20-40Ash, Black Ground105Ashes, Coal, Dry-1/2"35-45Ashes, Coal, Dry-3"35-40Ashes, Coal, Wet -1/2"45-50Ashes, Coal, Wet -3"45-50Ashes, Fly (See Fly Ash)-Asphalt, Crushed -1/2"45Bagasse7-10Bakelite, Fine30-45Baking Powder40-55Baking Soda (Sodium Bicarbonate)40-55Barite (Barium Sulphate) 1/2"-3"120-180Barite, Powder120-180Barium Carbonate72Bark, Wood, Refuse10-20Barley, Fine, Ground24-38Barley, Malted31Barley, Meal28Barley, Whole36-48Basalt80-105Bauxite, Dry, Ground68Bauxite, Crushed - 3"75-85Beans, Castor, Meal35-40Beans, Castor, Whole Shelled36Beans, Navy, Dry48Beans, Navy, Steeped60Bentonite, Crude34-40Bentonite-100 Mesh50-60Benzene Hexachloride56Bicarbonate of Soda (Baking Soda)-Blood, Dried35-45Blood, Ground, Dried30Bone Ash (Tricalcium 50-60Bones, Whole*35-50Bones, Crushed35-50Bones, Ground50Borate of Lime60Borax, Fine45-55Borax, Screening-1/2"55-60Borax, 1 1/2"-2" Lump55-60Borax, 2"-3" Lump60-70Boric Acid, Fine55Boron75Bran, Rice-Rye-Wheat16-20Braunite (Manganese Oxide)120Bread Crumbs20-25Brewer’s Grain, Spent, Dry14-30Brewer’s Grain, Spent, Wet55-60Brick, Ground-1/8"100-120MATERIAL12MATERIAL MATERIALFACTOR 1.820.810.520.60.50.82.2COMPONENTGROUPWEIGHTLBS. PERCU.

The Screw-Lift does an efficient elevating job as part of a complete Screw Conveyor system. The Screw-Lift illustrates the compact arrangement possible when space is a concern. Screw Conveyor system and SCC Bucket Elevators being used for speed grain handling in a large facility. Two screw c