American Journal of Mechanical Engineering
ISSN (Print): 2328-4102 ISSN (Online): 2328-4110 Website: Editor-in-chief: Kambiz Ebrahimi, Dr. SRINIVASA VENKATESHAPPA CHIKKOL
Open Access
Journal Browser
American Journal of Mechanical Engineering. 2017, 5(4), 128-137
DOI: 10.12691/ajme-5-4-3
Open AccessArticle

Fixed Enclosure Guards and the Safety of Horizontal Screw Conveyors

Ralph L. Barnett1,

1Mechanical and Aerospace Engineering Triodyne Inc, 3054 N. Lake Terrace Glenview, IL

Pub. Date: July 03, 2017

Cite this paper:
Ralph L. Barnett. Fixed Enclosure Guards and the Safety of Horizontal Screw Conveyors. American Journal of Mechanical Engineering. 2017; 5(4):128-137. doi: 10.12691/ajme-5-4-3


One cannot overstate the value and ever growing importance of the screw conveyor and one cannot overemphasize the intrinsic danger associated with this classic monster. This danger can be controlled using fixed enclosure guards that are not only compatible with the function of screw conveyors but are anecdotally acknowledged to be the most desirable type of guard. Nevertheless, the speciality conveyor standards promulgate dangerous guarding systems with features two levels below the fixed barrier guard. This paper revisits the system of conveyor safety standards to rout out equivocal notions, expose shortcomings, and generally demonstrate that a foolish inconsistency is not the hobgoblin of small minds. Finally, this paper challenges the notion that a fixed enclosure guard is an elementary concept whose parameters are settled; e.g. a machine inside of a welded steel box. The definition of fixity and the duality of operation and maintenance are both explored.

auger CEMA fixed guard screw conveyor standard

Creative CommonsThis work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit


Figure of 14


[1]  Screw Conveyors, Conveyor Equipment Manufacturers Association, 350-1971.
[2]  Machinery Directive Harmonized Standards, Machine Building. net, July 2014.
[3]  American National Standard Performance Requirements for Safeguarding, ANSI B11.19-2010.
[4]  Code of practice for safety of machinery, BS 5304: 1988.
[5]  Japanese Industrial Standard; Safety of Machinery Principles of Risk Assessment, JIS B 9702 2000.
[6]  Japanese Industrial Standard; Safety of Machinery Prevention of Unexpected Start-up, JIS B9714: 2006.
[7]  Japanese Industrial Standard; Safety of Machinery Guards General Requirements for the Design and Construction of Fixed and Movable Guards, JIS B9716: 2006.
[8]  International Standard Organization for Standardization; Safety of Machinery Interlocking Devices Associated with Guards Principles for Design and Selection, ISO 14119.
[9]  Screw Conveyors for Bulk Materials, ANSI/CEMA 350-2009.
[10]  Conveyors, OSHA 29 CFR 1926.555.
[11]  American Society of Mechanical Engineers – Safety Code for Conveyors, Cableways and Related Equipment, ASA B20.1-1957.
[12]  American Society of Mechanical Engineers- Safety Standard for Conveyors and Related Equipment, ASME B20.1-2012.
[13]  Ralph L. Barnett, Reasonably Foreseeable Use, Triodyne Safety Brief, Vol. 14 No. 3, November, 1998.
[14]  American National Standard for Machine Tools - Safety Requirements for Construction, Care, and Use of Lathes, ANSI B11.6-1975.
[15]  American National Standard – Single –and Multiple-Spindle Automatic Bar and Chucking Machines Safety Requirements for Construction, Care and Use, ANSI B11.13-1992.
[16]  Code of Practice Safeguarding of Machinery, BS 5304:1975.
[17]  D.B. McNeil-Watson, Some Advantages of Mechanical Guarding Systems, Sheet Metal Industries V. 54, 1977.
[18]  Code of Practice for Safety of Machinery, BS EN 953: 1998.
[19]  Nicholas, Robert, Keeping Guard, Safety and Health Practioner, V. 18, n. 12, Dec. 2000.
[20]  British Safety Code for Safe Use of Machinery, PD 5304:2000.
[21]  American National Standard for Machine Tools – Safety Requirements for Machining Centers and Automatic, Numerically Controlled Milling, Drilling and Boring Machines, ANSI B11.23:2002.
[22]  American National Standard for Machines – Performance Criteria for Safeguarding, ANSI B11.19-2003.
[23]  Guarding of Machinery, CP 3004: 1964.
[24]  Principles of Guarding and Transmission Guards,' Accident Preventional Manual for Industrial Operations, 6th ed., National Safety Council, 1969.
[25]  American National Standard for Machines – Performance Criteria for Safeguarding, ANSI B11.19-2010.
[26]  American National Standard Safety Requirements for Transfer Machines, ANSI B11.24-2002.
[27]  Safety Code for Conveyors, Cableways, and Related Equipment, ANSI B20.1-1972.
[28]  Safety of machinery Guards General requirements for the design and construction of fixed and movable guards, ISO 14120:2002.
[29]  Safety of machinery -- Basic concepts, general principles for design -- Part 1: Basic terminology, methodology, ISO/TR 12100-1:1992.