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GENERALINFORMATIONINFORMATIONGENERAL® Hose information is subject to change. For full details, visit our website or contact Customer Service. DESIGN CONSIDERATIONS SERVICE CONSIDERATIONS FOR HOSE IN In designing hose, it is customary to develop a design ratio, whichCRITICAL APPLICATIONS is a ratio between the minimum burst and the maximum working Hose is often used in locations and/or to convey materials where pressure. property damage or human injury could occur if the hose and/or Burst test data is compiled and the minimum value is established associate fittings failed while in service. by accepted statistical techniques. This is done as a check on The user must insure that the service conditions are known to theoretical calculations, based on the strength of reinforcing himself and to the hose supplier. The improper use of hose or the materials and on the characteristics of the method of fabrication. use of a hose for service applications for which it was not designed Minimum burst values are used as one factor in the establishment may result in serious consequences. of a reasonable and safe maximum working pressure. Some examples of improper uses of hoses include the following: MAXIMUM WORKING PRESSURE IS ONE OF THE ESSENTIAL water hose should not be used for chemicals or solvents; low OPERATING CHARACTERISTICS THAT A HOSE USER MUST pressure hose should not be used for high pressure service; only KNOW AND RESPECT TO ASSURE SATISFACTORY SERVICE steam hose should be used for steam service; hose for conveying AND OPTIMUM LIFE. mild chemicals should not be used for strong or concentrated acids which require special types of hose. Temperatures in or around It should be noted that design ratios are dependent on more than the hose should be known so as not to exceed supplier's the minimum burst. The hose technologist must anticipate natural recommendations, etc. decay in strength of reinforcing materials, and the accelerated decay induced by the anticipated environments in which the hose will be used and the dynamic situations that a hose might likely INFORMATION NEEDED encounter in service. Hose Dimensions Including all considerations, the following recommended design (a) I.D. ratios are given for newly manufactured hose: (b) O.D. 1. Water Hose up to 150 psi WP: 3:1 (c) Length (state whether overall length or length excluding couplings) 2. Hose for all other liquids, solid materials suspended in liquids or air, and water hose over (d) Tolerance limitations (if normal RMA tolerances 150 psi WP: 4:1 cannot be used) 3. Hose for compressed air and other gases: 4:1 Types of Service 4. Hose for liquid media that immediately changes (a) Material to be conveyed through hose into gas under standard atmospheric conditions: 5:1 1. Chemical name 5. Steam Hose: 10:1 2. Concentration * Reprinted with permission from the Rubber Manufacturers Association (RMA)3. Temperature extremes (low and high) Hose Handbook, RMA/IP-2/2003. 4. Solids, description and size (b) Working pressure (including surge) (c) Suction or vacuum requirements HOSE AND COUPLING SELECTION GUIDE (d) Velocity GENERAL (e) Flow Rate A number of hose specifications have been developed for specific Operating Conditions applications in industrial, agricultural or public service. These (a) Intermittent or continuous service specifications are based on successful performance of the hose (b) Indoor and outdoor use in the field as reported by consumers, manufacturers and governmental agencies. (c) Movement and geometry of use These may be used as procurement specifications or performance (d) Flexibility Minimum bend radius standards when the application agrees with the scope of the (e) External conditions hose specification. The RMA has published a number of hose 1. Abrasion specifications which are recommended for use. 2. Oil (Specify type) Often, additional or new requirements may be imposed on hose 3. Solvents (Specify type) because of the severity of service conditions, a change in service 4. Acid (Specify type and concentration) conditions, a change in the materials handled or in the method of handling, or the development of new uses or procedures. Hose 5. Temperature Range specifications must then be prepared with the supplier and be Normal based on all conditions affecting the expected service and Highest performance of the hose. Generally, a hose manufacturer may Lowest have types of hose or can devise new ones which may meet other requirements than those covered by published standards. 6. Ozone For best performance, a hose should be selected to meet the service conditions under which it is to be used. Before deciding on size, type, and quality of hose, complete information on the actual service requirements should be examined. 12