Industrial Hose Selection Guide    Industrial Hose Selection Guide       Industrial Hose Selection Guide

Image Credit: Grainger Industrial Supply | CEJN Industrial Corporation | Novaflex Group

 

A hose is a flexible and often reinforced vessel used to transfer fluids from one location to another. Industrial hose covers the broad spectrum of fluid transfer lines, including flow lines for fluids and gases in pneumatic, hydraulic, or process applications, as well as specialized uses in heavy industry such as mining, geotechnical, and construction. Industrial hose is usually application-specific; consultation with hose manufacturers regarding specific applications is typical.

 

Construction

Hoses are constructed using three basic parts:

  • A plastic or rubber tube or inner lining which makes contact with the fluid.
  • A textile, plastic, or metal body or carcass which reinforces the structure of the hose to withstand internal and external pressures.
  • A rubber, plastic, metal, or textile cover which protects against damage due to wear, abrasion, and the environment.

Although there are innumerable specific hose designs for different applications, there are four basic types of hose construction found in industry:

  • Vertical braided hose - the entire hose length is cured in one operation for good flexibility, high kinking resistance, and excellent tensile strength.
  • Spiral hose - the hose is built by machine with wire reinforcement so that each ply is laid at a given angle. This allows for extreme flexibility, high strength, and maximum dimensional stability.
  • Hand built spiraled ply hose - the hose is built by hand and cured under pressure applied from outside. These hoses are built to specific requirements, with wide variations in sizes, constructions, and materials.
  • Knitted hose - the hose consists of a seamless tube with a seamless woven textile jacket for reinforcement. These hoses are very flexible, lightweight, crush and kink resistant, and do not change length under pressure. 

Size

Sizing is the most basic and essential factor in industrial hose selection. Sizing specifications for industrial hose include inner diameter, outer diameter, and length.

 

Inner Diameter

Inner diameter (I.D.) is the span of the empty space in a circular hose cross section. It is the most important factor in hose sizing because it affects the flow velocity of the fluid within the hose. A hose with an oversized I.D. will result in sluggish system performance, while an undersized I.D. can cause excessive pressure drops, leaks, and system damage. Hose and fitting sizes are designated using dash numbers or dash sizes. The dash number designates the size in sixteenths of an inch (i.e. -03 is 3/16"), except for SAE 100R5 transportation and refrigerant hose. The chart below provides a reference for dash numbers and their corresponding hose sizes in inches.

 

Image Credit: Parker

 

 

All except Transportation and Refrigerant Hoses

Transportation and Refrigerant Hoses

Dash No.

Inches

Millimeters

Inches

Millimeters

-3

3/16

5

-

-

-4

1/4

6.3

3/16

5

-5

5/16

8

1/4

6.3

-6

3/8

10

5/16

8

-8

1/2

12.5

13/32

10

-10

5/8

16

1/2

12.5

-12

3/4

19

5/8

16

-16

1

25

7/8

22

-20

1-1/4

31.5

1-1/8

29

-24

1-1/2

38

1-3/8

35

-32

2

51

1-13/16

46

-40

2-1/2

63

2-3/8

60

-48

-

-

3

76

Sizing chart for hose I.D. Table Data Credit: Parker

 

Outer Diameter

Outer diameter (O.D.) measures the entire span of the hose cross section, including the inner tube, reinforcement, and outer cover. The difference between the O.D. and I.D. reveals the thickness of the hose wall. Outer diameter is important for sizing industrial hose to appropriate fittings and system components.

 

Length

The length of industrial hose defines its maximum reach between end-points. Increasing length can also increase pressure drop in the system, since hose length is a function of head loss due to friction. 

 

Performance Specifications

The most crucial performance specifications for industrial hose selection are temperature rating and pressure rating.

 

Temperature

When determining the required temperature rating, consider both the media temperature (the temperature of the media conveyed inside the hose) and the ambient temperature (the temperature of the environment outside the hose). The temperature rating of the hose should meet or exceed both of these temperatures. Operating a hose at temperatures above or below its rated range can reduce its service life and have a number of other adverse effects on performance (e.g. loss of flexibility, cracking). The type of media being conveyed should also be considered, since different fluids can increase or decrease the effects of temperature variation on the hose. Because of this, some manufacturers specify different temperature ratings for different fluids.

 

Pressure

The pressure rating defines the force per unit area that can be exerted on the hose or vessel during operation, typically measured in pounds per square inch (psi). The required maximum working pressure of the hose should be determined based on both the system working pressure and any surge pressures and spikes. The hose's published maximum working pressure should be equal to or greater than the maximum system pressure and any surge pressures or peak transient pressures in the system. Often the maximum working pressure is rated based on a design safety factor (e.g. 2:1, 4:1) to ensure reliability and safe operation. 

 

Selection Tip: The maximum working pressure of a hose assembly system is rated based on the pressure rating of the weakest component in the system. For example, if the hose has a pressure rating of 7,500 psi but a quick-coupler fitting has a pressure rating of only 4,200 psi , the pressure rating for the assembly is 4,200 psi.

 

Vacuum hose and hose assemblies may also have ratings for minimum pressure or maximum vacuum. These define the minimum vacuum pressure that can be maintained within the hose during vacuum applications.

 

Media Compatibility

For effective performance, it is important to ensure the hose is compatible with the media that is being conveyed. This includes compatibility with the inner tube, cover, hose fittings, and o-rings of the hose assembly. Incompatibility can result in corrosion, abrasion, contamination, and other problems which reduce the performance, safety, and service life of the hose. Chemical resistance charts can be used as guides to determine the compatibility of hose materials with different fluids and chemicals. Certain media have specific characteristics that make them suitable for a particular type of hose design or material.

  • Air - Hoses often require abrasion resistance for fine particles in the air, and wall linings that resist oil mist if present.
  • Adhesives, sealants, or coatings - Hoses that carry adhesives, sealants, or coatings often must be able to withstand temperature changes (heating) during flow because of the thick and viscous nature of the fluids.
  • Chemicals - Hoses that carry reactive, alkaline, or acidic chemicals must be made of corrosion resistant materials.
  • Coolant or refrigerant - Hoses that carry coolants or refrigerants must be able to handle high or low temperatures without sustaining damage or permanent defects such as cracking or stiffness. It may also be important for these hoses to be relatively insulated.
  • Oil and fuel - Hoses that carry volatile substances like oils and fuels should be gas-tight, explosion-proof, and flame resistant to reduce the chance of ignition.
  • Solids and particulate - Hoses that transport solid and particulate slurries or dry solids must be resistant to abrasion.
  • Steam - Hoses that transport steam must be able to handle high temperatures. The structure of all types of rubber hose can be severely affected by steam at elevated temperatures, so the operating temperature rating must be carefully considered when selecting the appropriate hose. It may also be important for these hoses to be relatively insulated.
  • Water - Hoses that carry water must be resistant to rust corrosion.

Application Features

Often industrial hose is rated or constructed for a specific application. Some standard hose types for specific applications include:

  • Air or pneumatic hose - These hoses are used in pneumatic systems and controls, or as supply lines for pneumatic devices and tools. Pneumatic hoses must be able to operate at high pressures and remain gas-tight under these conditions.
  • Hydraulic hose - These hoses are used in a variety of industrial hydraulic systems. Hydraulic hoses have very high pressure ratings needed for high-powered hydraulic tooling and equipment.

For other, less standard uses, hoses should be selected based on the features needed for the application.

 

Construction Options

Hoses may be constructed in a number of different ways, each of which provides suitability for different applications.

  • Articulated - Rigid hose sections are often constructed with "joints" that can be swiveled, positioned, or articulated. These products are often used in cases where the hose discharge must be aimed, such as coolant delivery to a workpiece.
  • Coiled - Hose is coiled for flexibility and elasticity, making it expandable and relatively easy to store.
  • Corrugated - Hose contains corrugations, pleats, or spiral convolutions to increase flexibility and the capacity for compression and elongation.
  • Crush-proof - Hoses are designed to resist crushing or collapse caused by exterior forces. This is important for applications where flow interruption or kinking cannot be tolerated.
  • Lay-flat - Lay-flat hose is designed to default to a flat, collapsed (not rigid) structure when not filled with fluid. This feature makes hose easier to store, and more flexible and forgiving while in service.
  • Reinforced - Reinforced hoses are constructed with some type of reinforcement that provides additional strength. Reinforcement styles include textile braid, wire braid, wire helix, and many other designs in ply or layer configurations.

Features

Hoses may possess design features which are essential for certain applications.

  • Anti-static - Hoses are conductive or semi-conductive to prevent the buildup of static electricity.
  • Flame resistant - Hoses are constructed to maintain their integrity in the presence of flame or fire.
  • Explosion proof - Explosion-proof hoses are constructed to withstand internal explosion of a specified gas, vapor or dust. Several explosion-proof ratings are governed by Underwriter's Laboratories (UL).

Standards

A wide variety of industry standards exist which set specific requirements for the construction and performance properties of hoses used in their corresponding fields. Standards include SAE (Society of Automotive Engineers), EN (European Norm), DIN (Deutsche Institute fur Normung), ISO (International Standards Organization).

 

References

 

Basic Hose Construction - JGB Enterprises, Inc.

 

How to Select the Right Hose - JGB Enterprises, Inc.

 

Selecting The Proper Hose for Your Application - Hose & Fittings, Etc.

 

Selecting the Right Hose - Parker (pdf)

 

Tube Dash Size - Ryco (pdf)

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