An Alternative Standard for Hydraulic Hoses

    Many industry professionals are already aware that the ISO 18752 standard can streamline design and improve productivity. After all, there are several aspects of this global standard that could have direct financial and operational impacts on a business. More importantly however, switching from traditional standards could help hydraulic system designers boost efficiency, improve uptime, and streamline the selection process for products globally.

    By Kyri McDonough, Global eBusiness Marketing Manager, Parker

    Adopting ISO18752

    Hydraulic hoses can be found in countless applications across industries and markets around the world. There are many complex standards developed and augmented by organizations regionally and globally that regulate the construction and performance specifications for these hydraulic hoses. While standards are constantly evolving with the progression of technology to meet industry demands, many companies, manufacturers, and end customers stand to benefit greatly from improved standards, such as the newer global ISO 18752 hydraulic hose specification.

    Traditionally, OEMs of hydraulically driven equipment, such as material handlers and other types of mobile equipment, have specified their hydraulic hoses using engineering standards common to the region where those machines were being manufactured.
    For example, North American builders of mobile equipment like tractors and excavators have long used SAE standards, created by the U.S.-based standards organization SAE International (traditionally known as the Society of Automotive Engineers), to provide general, dimensional, and performance specifications for hydraulic hoses.
    Another common group of standards used for specifications are the collection of ISO standards, written by the International Organization for Standardization. This global organization has created several standards relating to hydraulic hoses used in various industries and applications. These standards support the technology used by OEMs and end users, and consistently ensure the quality and proper usage of materials and products across markets.

    Traditional Hydraulic Hose Standards

    North American hydraulic system designers have most commonly used the SAE standards for specification. Originally published in 1968, the SAE standard has been revised more than 20 times. SAE J517 currently contains more than a dozen sub-standards, such as 100R1, 100R2, and 100R19. Each of these sub-standards describes a specific type of hydraulic hose for a given application. For example, different standards apply to hydraulic hoses with a one-wire braid reinforced construction, two-wire braid reinforced construction, or a four-wire spiral construction. Pressure classes for many of the sub-standards vary by hose size, as the traditional SAE standards do not generally apply to hydraulic hoses capable of handling constant working pressures across sizes.

    Hoses rated to SAE standards meet specified dimensional and performance criteria as determined by SAE, ensuring similarity between products from different participating manufacturers aligned to SAE standards. Likewise, hoses rated to different regional standards or older ISO standards specify different criteria related to construction and performance that hoses must meet.

    Limitations and Concerns

    While the SAE sub-standards have been useful for defining hydraulic hose pressure classes, sizes, and constructions, traditional hydraulic industry standards are unable to maintain relevance when competing with new, updated standards for many OEMs and customers on the global scale. The legacy standards define varying pressure ranges for each size. That means the smaller diameter hoses are generally made to handle higher pressures, while larger diameter hoses are built for lower pressures within the same product family.
    The vast range of products and applications makes specification and product selection complex, especially considering most applications have systems operating at a single pressure, and designers may need hoses with different diameters that are capable of handling the same pressures. With traditional standards such as the SAE 100R1 and 100R2, the pressure rating, degrades as hose diameters increase.

    In addition to construction types, traditional SAE and ISO standards also require products to withstand defined temperature ranges. However, with the wide range of hose styles and applications on the market, the temperature criteria vary by substandard, with maximum working temperatures ranging from 212°F (100°C) to 257°F (125°C).

    While SAE standards have evolved over the years to cover different hose styles and applications, sorting through the different criteria and specifications can be confusing and over-complicated because of the vast number of sub-standards associated with the J517 standard for hydraulic hose. A separate issue that arises when equipment designers use certain regional or manufacturer-based standards, such as SAE, is that it is difficult to switch hoses from one region to another, where a different prevailing hydraulic hose standard may be the norm.

    While standards and specifications differ between regions, their purpose is universal: provide products that ensure quality and performance for their designated application. Machines and equipment sold locally are expected to conform to locally accepted standards. Not only does this ensure availability of the correct replacement parts, it also guarantees that customers are receiving equipment made to the quality and performance specifications required by their application and promised by their manufacturer.
    However, if a piece of equipment is manufactured in a different geographic region, and thus aligned to a different hose standard, it will be difficult for the manufacturer to find the same parts locally. For instance, U.S.-based manufacturers may specify hoses with the SAE standard, while European counterparts are using the EN standard to select their hoses. That means that not only will finding an exact product match be difficult between regions, but there will be differences between the hydraulic hoses manufactured in each area, and the different regional specs will have different qualifications.

    The Global ISO 18752 Standard

    The newer ISO 18752 standard for hydraulic hoses solves many of the issues concerning pressure classes, hose sizes, and product uniformity in different regions. Introduced in 2006, ISO 18752 centers around 10 maximum working pressure classes, ranging from 500 psi to 8,000 psi.

    With the introduction of this standard, ISO is helping large global OEMs and their customers to apply the same specifications to their systems, no matter where in the world they are made or sold. That means manufacturers can be assured of receiving the same hydraulic hoses, tested to the same specifications, to meet the needs of their applications globally.

    Under ISO 18752, hoses are identified by pressure class, and each pressure class accommodates an entire range of hose diameters. This is in contrast to traditional SAE standards, which provide general, dimensional, and performance specifications for the most common hoses used in hydraulic systems based on hose construction.

    In addition to requiring constant working pressure performance ratings in each pressure class for different hose sizes, the ISO 18752 standard introduces four different classes of service, A through D, which correlate with each class’s resistance to impulse pressure. In order to be rated to the ISO 18752 standard, hydraulic hoses undergo rigorous testing for durability and performance to ensure products possess the high quality necessary to meet the demands of tough applications.

    For each grade of hose, every ISO 18752 hose for a single pressure class must test to high impulses, extended cycles, and higher pressure and temperature criteria to be rated to the new global standard. Additionally, each grade is classified further by its outside diameter (O.D.) as either standard (AS, BS, CS) or compact (AC, BC, CC, DC). Compact hose types have a smaller O.D. and tighter bend radius than the standard types.

    Another benefit of hoses made to the ISO 18752 standard is establishing uniformity between locations. Written by the global standards organization, ISO engineers around the world can use this standard in place of their regional standard to designate hoses by size and pressure class for their application.

    Why to Make the Switch

    OEMs who decide to adopt and use ISO 18752 standards can expect to gain numerous benefits financially as well as reduce engineering complexity. Moving to the ISO 18752 standard allows OEMs and distributors to benefit in terms of inventory reduction because ISO 18752 hoses are classified by pressure class rather than construction. Stocking hoses rated for a single pressure class in numerous sizes decreases inventory needs and simplifies the selection process. Hoses made to the ISO 18752 standard meet all the same requirements as SAE hoses, but require fewer types of hose to do so.

    Having the ISO-rated hoses also helps OEMs remain relevant in the global marketplace. End users, particularly those with global operations, expect to have access to products regardless of their location and to be able to purchase readily available equipment designed and tested to the latest standards.

    Dependability and high performance are uniform qualities of hoses rated to the ISO 18752 standard, since hoses conforming to this standard have had to undergo rigorous testing to meet the spec. In that way, having an ISO 18752 designation for their hydraulic hoses helps the end customer to feel confident about the quality of the product they receive.

    In conclusion, anytime an OEM is securing quotes for a new platform, such as a new tractor, using the ISO 18752 standard to find and quote parts can be a time- and money-saving way to move to the new standard.

    ABOUT THE AUTHOR

    Kyri McDonough has been a digital marketing professional for a variety of B2B and B2C companies for the last twenty-five years. She is currently the Global eBusiness Marketing Manager for Parker Hannifin, one of the world’s leading diversified manufacturers of motion and control technologies and systems.

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