CLASSES OF ENCLOSURES General The terms “dust-tight,” “semi-dust-tight,” “commercially dust-tight,” “weatherproof,” are used in specifications relating to conveyor enclosure. These are extremely broad terms and subject to many interpretations depending on individual conception and experience. It is difficult, if not impractical to attempt todefine these terms by their degree of effectiveness. Enclosure of conveyors beyond that which is necessary for the conveying function can be designed to protect most material being handled from a hazardous surrounding or to protect most surroundings from a hazardous material being conveyed. Recognizing these facts, this section establishes CEMA recommended classes of construction for conveyorenclosures—without regard to their end use or application. These several classes call for specific things to be done to a standard conveyor housing to provide several degrees of enclosure protection and will eliminate the general terms listed previously. It is recognized that other types of enclosures are sometimes practical and that additional design features can be incorporated as dictated by specificjob requirements. They are too numerous and too special to be included here. CEMA Enclosure Classifications Class IE — Class IE enclosures are those provided primarily for the protection of operating personnel or equipment, or where the enclosure forms an integral or functional part of the conveyor or structure. They are generally used where dust control is not a factor or where protection for,or against, the material being handled is not necessary—although as conveyor enclosures, a certain amount of protection is afforded. Class IIE — Class IIE enclosures employ construction which provides some measure of protection against dust, or for or against the material being handled. Class IIIE — Class IIIE enclosures employ construction which provides a higher degree of protection in theseclasses against dust, and for or against the material being handled. Class IVE — Class IVE enclosures are for outdoor applications and under normal circumstances, provide for the exclusion of water from the inside of the casing. They are not to be construed as being watertight, as this may not always be the case. When more than one method of fabrication is shown, either is acceptable.
78Chapter 5 - Materials of Construction, Classes of Enclosure, Weld Finish, Special Features and Modifications, Installation, Operation, Maintenance, Expansion
Table 5-2 Enclosure Construction
ENCLOSURE CLASSIFICATIONS COMPONENT CLASSIFICATION A. TROUGH CONSTRUCTION Formed & Angle Top Flange 1. Plate type end flange a. Continuous arc weld b. Continuous arc weld on top of end flange and trough top rail2. Trough Top Rail Angles (Angle Top Trough only) a. Staggered intermittent arc and spot weld b. Continuous arc weld on top leg of angle on inside of trough and intermittent arc weld on lower leg of angle to outside of trough c. Staggered intermittent arc weld on top leg of angle on inside of trough and intermittent arc weld on lower leg of angle to outside of trough, or spot weld when mastic isused between leg of angle and trough sheet B. COVER CONSTRUCTION 1. Plain flat a. Only butted when hanger is at cover joint b. Lapped when hanger is not at cover joint 2. Semi-Flanged a. Only butted when hanger is at cover joint b. Lapped when hanger is not at cover joint c. With buttstrap when hanger is not at cover joint 3. Flanged a. Only butted when hanger is at cover joint b. Buttstrap whenhanger is not at cover joint 4. Hip Roof a. Ends with a buttstrap connection C. COVER FASTENERS FOR STANDARD GA. COVERS 1. Spring, screw or toggle clamp fasteners or bolted construction* a. Max. spacing plain flat covers b. Max. spacing semi-flanged covers c. Max. spacing flanged and hip-roof covers *For bolted construction use: 1/4" bolts—4"-10" dia. screws—(min. dia.) 5/16" bolts—larger dia....