HOSE FABRICS AND ITS APPLICATIONS AREAS AND USES

HOSE

1. HOSE FABRICS

2. Hose is a products where the fabric is reinforced in its structure to attain desirable properties. The reinforcement of any hose structure may comprise many materials or combinations of materials, dependent on the end use of the item. The reinforcement may be braided, woven, or in wound form, and it may be in single or multiple plies. The reinforcing members include both natural and man-made textiles.

3. Hose: Definition A Hose is a flexible link on pipe capable of use with gases, liquids, solids, or admixtures of such under positive or negative pressures. Factors Governing Hose Selection Pressure Temperature Fluid Compatibility Size Environment Mechanical Loads Abrasion Electrical Conductivity Hose Length

4. Hose: Construction A hose has three parts 1. Cover: It is the outermost layer of the hose. The prime function of the cover is to protect the reinforcement from damage and the environment in which the hose will be used. Covers are designed for specific applications and can be made to be resistant to oils, acids, abrasion, flexing, sunlight, ozone, etc.

5. 2. Body or carcass: It is the reinforcement supporting structure of the hose. Reinforcement can be textile, plastic, or metal, alone or in combination, built into the body of the hose to withstand internal pressures, external forces, or a combination of both.

6. 3. Tube or lining: It is the innermost element of the hose and is in contact with the material being carried. The tube may be placed over reinforcing elements. For suitable service, the tube must be resistant to the materials it is intended to convey. The characteristics of the rubber or plastic compound from which the tube is made and the thickness of the tube are based on the service for which the hose is designed.

7. Construction of hose.

8. Reinforcement and Its Functions The purpose of reinforcement is Primarily to withstand pressure To prevent under vacuum conditions for providing medium against kinking To resist against external damage To conduct electrostatic charges to the earth To increase heat resistance To enable couplings to be anchored securely

9. Fibers Used in Hose Reinforcement Cotton, asbestos, glass, polyester, nylon, rayon, high-tensile steel wires, and various stainless steels are used as hose reinforcements. Reinforcement materials are chosen depending upon service requirements and economical aspects.

10. Man-made fiber are used to give special qualities such as Higher bursting strength, Higher flex resistance, Abrasion resistance, Rot resistance, Ease of handling that may be connected with Low moisture absorption, Greater flexibility, Weight reduction due to using high-tenacity fiber.

11. bursting pressure equation, P b X D v = 3.7 C where C is T / {(1 + E/100)2 * √(Titer/ ρ)}, no unit Dv is the _reinforcement diameter (mm) E is the elongation (%) Pb is the bursting pressure (N/mm2) T is the breaking force (N) Titer is the weight per length dtex (g/1000 m) ρ is the specific weight (kg/ cu.m )

12. Yarn Structure in Hose Reinforcement Yarns are used as reinforcement in hose for reinforcing tube material to provide strength to impart the desired resistance to internal pressure or to provide resistance to deformation, or both. The basic property requirements in yarn used for hose reinforcement are Adequate strength, Acceptable heat resistance, Dynamic fatigue resistance, Satisfactory processability for the various methods of reinforcing hose.

13. Other special properties such as Stiffness, Adhesion, Conductivity may be developed depending upon the specific hose application. Yarn is available in two basic forms: staple (sometimes referred to as spun yarn) and filament.

14. Reinforcement Fabric Structures Textile fabrics used as reinforcement in hose construction provide the strength to achieve the desired resistance to internal pressure or to provide resistance to collapse, or both. Fabric properties are influenced by fiber used, yarn and fabric construction particulars, and type of weave adopted during production process. The most common weave is known as “plain weave.” This is done on a relatively simple loom. Other weaves used, though to a lesser degree, are twill, basket weave, and leno.

15. Leno weave is preferred for fabric that undergo distortion in the hose as in certain types of curved hoses. Leno fabrics also render a means for better adhesion with rubber compared to other weave patterns. The fabric is either frictioned or coated with a thin layer of rubber. Before rubberizing, some fabrics are treated with liquid adhesive.

16. Hose Components Manufacture Tube: Extruded Tubes:- The uncured rubber or thermoplastic compound ribbon or pellets are fed into the extruder, through the screw or auger with proper temperature controls, and finally forced through a pair of metal dies, where the cylindrical tube is formed. In the non continuous process, the tube is then cooled, lubricated to minimize tackiness, and stored in coils on pans, reels, or rigid mandrel poles.

17. Extrusion temperatures are typically between 200°F and 275°F for rubber compounds and 300°F–600°F for thermoplastics.

18. Wrapped Tubes For the larger diameter rigid mandrel rubber hose constructions, the wrapped tube process is utilized. Here, the rubber compound is calendered to a specific thickness and width, then spirally wrapped on the rigid mandrel with sufficient overlap to form the tube. With the wrapped process, the challenge is to provide good bonding at the tube overlap area to prevent tube de lamination.

19. Reinforcement: Types The strength component of the hose, designed to handle the entire pressure load with appropriate safety factors, is the reinforcement. Hose reinforcements are either textile, both synthetic polymeric and natural, or wire. Methods of applying these reinforcements are braid, spiral, knit, wrap, and woven. Combinations, such as spiral/knit, are available. Selection of reinforcing equipment is dependent on pressure rating, size, fitting requirements, flexibility, and crush resistance levels.

20. Braid Reinforcement Braiding is probably the most common and traditional method of reinforcing hose. Braid is a complex structure or pattern formed by intertwining three or more strands of flexible material such as textile yarns or wires. Braiding machine may be horizontal or vertical, based on the direction the tube progresses through the machine during braiding process.

21. Braided reinforcement. The major types of braiding machines are “maypole” or tubular type and rotary type.

22. Spiral Reinforcement This is similar to braiding and is used mainly for the larger bore high-pressure hoses, from 50 up to 200 mm bore diameter. Spiral reinforcement.

23. The spiral process is accomplished by wrapping a specified number of yarns through the rotating yarn guide. As the hose passes through at a controlled rate, ideally with sufficient individual yarns or wires being laid together, so that the angle of wrap, giving complete cover of the yarns, equals the neutral angle.

24. Knit Reinforcement A flexible hose with knitted reinforcement, consists of at least one inner tubular layer made of polymer material and at least one layer of knitted reinforcement. The mesh wales of the first series of yarns are superimposed on the mesh wales of the second series to define a single-layer reinforcement knitting. The yarn is fed from cone packages (usually four or eight) through a series of guides and latch-type needles onto the hose.

25. Wrap Reinforcement The multiple plies of reinforcement are wrapped spirally to a rigid mandrel hose tube with the direction of lay reversed with each succeeding ply. The tire cord is the most common fabric reinforcement used, which has strength only in the cord direction.

26. Woven Hose The reinforcement The reinforcement for woven hose is a seamless tubular textile jacket woven on a loom. This produces a strong, lightweight hose that is flexible for flat storage. Because the longitudinal warp yarns are parallel to the axis, woven hose tends to kink more easily than other hose constructions. Fire hose consists of a tube and seamless circular woven jacket or jackets, either separate or interwoven.

27. Hose: Manufacturing The principal methods used to manufacture hose will be classified as Non mandrel, Flexible mandrel, and Rigid mandrel, hich describe how the various components of the hose are supported during processing into a finished product. Hose is manufactured in the unvulcanized state by forming a cylindrical tube over which a reinforcement and cylindrical cover are applied.

28. Nonmandrel Style Nonmandrel hose is manufactured by passing long lengths of extruded tube material through a machine which adds the reinforcement in braided or spiraled layers. This manufacturing method is preferred for lower working pressure (less than 500 psi), smaller diameter (2 in. and under), textile-reinforced hoses not requiring stringent dimensional tolerances. Frequently, low-pressure air is used inside the tube for minimal support, keeping the tube from flattening during the reinforcing process. Most smooth bore thermoplastic hoses are extruded nonmandrel . The higher rigidity of most thermoplastics eliminates the need for mandrel support. Typical hose products in this category would include garden, washing machine inlet, and multipurpose air and water styles.

29. Flexible Mandrel Style Flexible mandrels are used for the hoses that require moderate tube-processing support and more accurate dimensional tolerances. The flexible mandrel method combines the long-length advantage of nonmandrel hose with the close inside diameter tolerances and high-pressure ratings of rigid mandrel hose. These mandrels are made of rubber or flexible plastic, sometimes with wire core to minimize distortion. Examples of this style product are power steering, hydraulic, wire-braided, and air-conditioning hoses.

30. Rigid Mandrel Style In larger hose sizes, where flexible mandrels become quite cumbersome to handle, working pressures are high, or stringent dimensional control is required, the rigid mandrel process is the preferred technique. Hose produced by this method is supported on a rigid metal mandrel made up of aluminum or steel.

31. HOSE CONSTRUCTION Type Booster Hose ¾- or 1-Inch (19 mm to 25 mm) Woven Jacket Hose 1- to 6-Inch (25 mm to 150 mm) Impregnated Single- Jacket Hose 1½ to 5-Inch (38 mm to 125 mm) Noncollapsible Intake Hose 2½- to 6-Inch (65 mm to 150 mm) Flexible Noncollapsible Intake Hose 2½- to 6-Inch (65 mm to 150 mm) Description Rubber Covered Rubber Lined Fabric Reinforced One or Two Woven Fabric Jackets Rubber Lined Polymer Covered Polymer Lined Rubber Covered Fabric and Wire (Helix) Reinforced Rubber Lined Rubber Covered Fabric and Plastic (Helix) Reinforced Rubber Lined