For hydraulic system design engineers in equipment manufacturing, determining pressure ratings, hose sizes, and product consistency across different industries can be complex. The ISO 18752 standard simplifies this process by classifying hoses based on pressure ratings and impulse performance. Its key advantage is that all hose sizes within the same pressure rating share a uniform maximum working pressure, making selection much easier during system design.
For example, if a hydraulic system requires a maximum pressure of 21.0 MPa, engineers can select hoses from the 21.0 MPa constant pressure series across all diameters. ISO 18752 testing standards are more stringent, ensuring hoses meet higher impulse performance criteria, which extends their service life. This is why many industries are increasingly adopting ISO-certified hydraulic hoses.
The ISO 18752 standard also enhances hose identification, helping engineers and end users quickly determine the appropriate hose for specific equipment or machinery.
For instance, if your hydraulic hose operates under high-frequency pressure cycles over long periods, a Class C or Class D hose assembly would be the ideal choice. The key benefit of ISO standards is their global recognition, ensuring that hoses are manufactured, tested, and sold under the same rigorous requirements worldwide. This consistency makes ISO 18752 the preferred choice for many industries.
Comprehensive Overview of ISO 18752
Standard Name
ISO 18752: This international Standard specifies requirements for ten classes, four grades and seven types of steel wire hydraulic hoses or textile-reinforced hydraulic hoses and hose assemblies of nominal sizes ranging from 5 to 102.
Each class has a single maximum working pressure for all sizes, Such hoses are suitable for use with hydraulic fluids HH, HL, HM, HR and HV as defined in IS0 6743-4 at temperatures ranging from -40 °C to +100 °Cfor types AS, AC, BS and BC and -40 °C to +120 °C for types CS, CC and DC.
This International Standard does not include requirements for the connection ends. it is limited to the performance of hoses and hose assemblies. The hose assembly's maximum working pressure is governed by the lowest maximum working pressure of the components.
NOTE : It is the responsibility of the user, in consultation with the hose manufacturer, to establish the compatibility of the hose with the fluid to be used.
Working Pressure Ratings
The ISO 18752 standard is based on ten maximum working pressure levels, ranging from 3.5 MPa to 56.0 MPa. Each pressure rating applies to the entire range of hose sizes, ensuring consistency across different diameters.
Ten classes of hose are specified, distinguished by their maximum working pressure, as shown in Table 1. Each class may be manufactured in up to 14 nominal sizes.
Unlike traditional DIN and SAE standards, which classify hoses based on construction, ISO 18752 simplifies the selection process by providing a universal specification for both size and performance. This approach makes it easier for equipment designers to choose the appropriate hose for hydraulic systems.
| Class | 35 | 70 | 140 | 210 | 250 | 280 | 350 | 420 | 490 | 560 |
| MWPa(MPa) | 3.5 | 7 | 14 | 21 | 25 | 28 | 35 | 42 | 49 | 56 |
| MWPa(bar) | 35 | 70 | 140 | 210 | 250 | 280 | 350 | 420 | 490 | 560 |
| Nominal size | ||||||||||
| 5 | X | X | X | X | X | X | X | X | N/A | N/A |
| 6.3 | X | X | X | X | X | X | X | X | N/A | N/A |
| 8 | X | X | X | X | X | X | X | X | N/A | N/A |
| 10 | X | X | X | X | X | X | X | X | N/A | N/A |
| 12.5 | X | X | X | X | X | X | X | X | N/A | N/A |
| 16 | X | X | X | X | X | X | X | X | X | X |
| 19 | X | X | X | X | X | X | X | X | X | X |
| 25 | X | X | X | X | X | X | X | X | X | X |
| 31.5 | X | X | X | X | X | X | X | X | X | X |
| 38 | X | X | X | X | X | X | X | X | N/A | N/A |
| 51 | X | X | X | X | X | X | X | X | N/A | N/A |
| 63 | X | X | X | X | X | X | X | N/A | N/A | N/A |
| 76 | X | X | X | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| 102 | X | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
| NOTE X=Applicable;N/A=Notapplicable. Maximum working pressure. |
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Table 1-Classes and nominal sizes
Resistance To Impulse Grade
Hoses are classified into four grades according to their resistance to impulse: A, B, C and D.
Each gradeis classified by outside diameter into standard types (AS, BS and CS) and compact types (AC, BC, CC andDC), as shown in Table 2.
| Grade | Type (a) | Resistance To Impulse | ||
| Temperature℃ | Impulse pressure mwp%(b) | Minimum number of cycles | ||
| A | AS | 100 | 133% | 200000 |
| AC | ||||
| B | BS | 100 | 133% | 500000 |
| BC | ||||
| C | CS | 120 | 133% and 120 %(c) | 500000 |
| CC | ||||
| D | DC | 120 | 133% | 1000000 |
| a. Standard or compact, e.g. CS is grade C and standard type. Standard types have larger outside diameters and larger bend radii and compact types have smaller outside diameters and smaller bend radii. b. Maximum working pressure. c. 120 % of the MWP shall be used for classes 350, 420, 490, and 560 instead of 133 %. |
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Table 2 - Grades and types
Each class includes one of each type or both as shown in Table 3
| Class | 35 | 70 | 140 | 210 | 250 | 280 | 350 | 420 | 490 | 560 | |
| MWPa(MPa) | 3,5 | 7 | 14 | 21 | 25 | 28 | 35 | 42 | 49 | 56 | |
| MWPa(bar) | 35 | 70 | 140 | 210 | 250 | 280 | 350 | 420 | 490 | 560 | |
| Grade | Type | ||||||||||
| A | AS | X | X | X | X | X | X | X | X | N/A | N/A |
| AC | X | X | X | X | X | X | X | X | N/A | N/A | |
| B | BS | X | X | X | X | X | X | X | X | N/A | N/A |
| BC | X | X | X | X | X | X | X | X | N/A | N/A | |
| C | CS | N/A | N/A | N/A | X | X | X | X | X | N/A | N/A |
| cC | N/A | N/A | N/A | X | X | X | X | X | X | X | |
| D | DC | N/A | N/A | N/A | X | X | X | X | X | N/A | N/A |
| NOTE
X=Applicable; N/A=Not applicable. In the table, "NA" indicates that this product series cannot reach the specified working pressure, while "X" indicates that the product in this specification meets the required working pressure. Maximum working pressure. |
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Table 3-Type and maximum working pressure
Additionally, the ISO 18752 standard specifies detailed requirements for inner and outer diameters, concentricity, minimum bend radius, oil resistance, low-temperature flexibility, impulse performance, abrasion resistance, and ozone resistance for hoses of different pressure and impulse ratings. These aspects are not elaborated here.
For more information about the ISO 18752 standard, please contact Sinopulse's sales team, and you will receive the most professional guidance.
To meet customer needs, Sinopulse has specifically developed the ISO 18752 series hoses, making system selection more convenient. Our hoses are designed, manufactured, and tested to fully comply with ISO 18752 specifications, covering all pressure and impulse levels.
If you have any requirements, we can provide the most precise and professional products to suit your needs.
| No. | Resistance To Impulse Grades | Related Standards |
| 1 | AS, AC, BS and BC | SAE R1AT, R2AT, SAE R16, R17, R19 |
| 2 | CS, CC and DC | SAE R16, R17, R19
EN853 1SN, 2SN EN857 1SC, 2SC SAE R12, R13, R15 |
To meet ISO 18752 standard requirements and various customer application needs, Sinopulse has developed a range of hydraulic hoses in different performance levels.
The table below provides a reference for selecting Sinopulse hoses, showing the corresponding ISO 18752 classifications for our products.
| Standard | Temperature℃ | Resistance To Impulse |
| IS018752 DC | 120-125 | spiral 1000000+ cycles |
| IS018752 CS | 120-125 | spiral 500000+ cycles |
| ISO 18752 CC | 120-125 | spiral 500000+ cycles |
| ISO18752 BC | 100-110 | braided 500000+ cycles |
| IS018752 BC | 100-110 | spiral 500000+ cycles |
| ISO 18752 AC | 100 | braided 200000+ cycles |
Hydraulic Hose Testing Methods and Evaluation Standards
For decades, SAE J517 has established guidelines for hydraulic hose series 100R1 to 100R19.
These manufacturer-driven SAE standards are based on design, construction, and pressure ratings, ensuring that hydraulic hoses meet structural requirements.
SAE standards define minimum pressure ratings for various hose inner diameters (ID). Over time, the standards have been revised to include constant pressure hoses, such as R13, R15, R17, and R19, which maintain a consistent pressure rating across the same category.
The ISO 18752 standard classifies hydraulic hoses into nine pressure class, with maximum working pressures ranging from 500 to 8,000 psi.
Hydraulic hoses that comply with ISO 18752 are categorized into four performance grades: A, B, C, and D, based on impulse pressure resistance. Each grade must undergo a specified number of impulse cycles under defined temperature and impulse pressure conditions to meet the standard.
SAE J517 Standard
Hydraulic hose specifications provide reliability and confidence when selecting hoses. One of the most widely used standards in North America is SAE J517, which defines universal size and performance specifications for the most common hydraulic hoses used in mobile and stationary equipment.
The most recognized SAE J517 standards, such as 100R1 and 100R2, describe single-wire and double-wire braided hydraulic hoses, which are widely used in North America. While the standard leaves little room for variation in materials and manufacturing techniques, it ensures that hoses meet pressure ratings, bend radius, and temperature range requirements.
In most cases, maximum working pressure is based on safety factors derived from proof pressure and burst pressure tests:
- Proof pressure is twice the working pressure and represents the minimum pressure before permanent fatigue occurs.
- Burst pressure is at least four times the working pressure, ensuring high safety margins.
- In practice, a well-manufactured hose can exceed these ratings rather than operate at the limits.
Currently, SAE J517 includes 19 classifications, though some have been phased out while others have gained popularity due to versatility and specific applications.
- 100R7 is a non-conductive hose designed for utility applications to reduce the risk of electrical hazards.
- 100R17 is a highly versatile solution with a 3,000 psi working pressure across all sizes, making it a preferred choice for many applications.
ISO 18752 Standard
Unlike SAE J517, the ISO 18752 standard does not classify hoses based on construction type. Instead, it categorizes hoses based on hydraulic system pressure and flow requirements.
After the initial pressure classification, hoses are further classified based on:
- Impulse pressure resistance
- Compactness and bend radius
- Temperature rating
For example, a 2-inch hydraulic hose must meet the same pressure rating as a ¼-inch hose, ensuring consistent reliability across all diameters—without requiring identical construction methods.
Production Testing Descriptions under ISO 18752 Standard
1. Burst Test
Test Method:
The burst test is a destructive test typically performed on newly assembled hydraulic hose assemblies within 30 days of crimping. Pressure is uniformly increased to four times the maximum working pressure (MWP) to determine the minimum burst pressure of the assembly.
Evaluation Criteria:
If the hose assembly exhibits leakage, bulging, fitting ejection, or rupture at a pressure below the specified minimum burst pressure, the assembly is deemed non-compliant.
2. Cold Bend Test
Test Method:
The cold bend test involves placing the hose assembly in a low-temperature chamber set to the hose’s specified minimum operating temperature (e.g., –40°C). The hose is kept straight for 24 hours. Subsequently, it is bent around a mandrel with a diameter twice the hose’s minimum bend radius. After bending, the hose is allowed to return to ambient temperature. If no cracks are observed visually, a proof pressure test is conducted.
Note:
Standard hydraulic hoses are rated for a minimum temperature of –40°C. Sinopulse’s ultra-low-temperature single-wire braided, fabric-covered hydraulic rubber hoses can withstand temperatures as low as –55°C.
3. Impulse Test
Test Method:
The impulse test predicts the service life of hydraulic hoses. The procedure is as follows:
- Bend the hose assembly into a 90° or 180° configuration and install it on the test rig.
- Circulate the test medium through the assembly. For high-temperature tests, maintain the medium temperature at 100±3°C.
- Apply cyclic impulse pressure to the hose assembly at 100%, 125%, or 133% of its maximum working pressure (MWP), with a frequency range of 0.5–1.3 Hz. The test concludes after completing the number of cycles specified by the standard.
Upgraded Version – Flexing Impulse Test:
In this test, one end of the hose assembly is fixed, while the other end is connected to a horizontal reciprocating mechanism. During testing, the movable end oscillates at a defined frequency to simulate dynamic bending under pressure.
Sinopulse was established in 2001 and is a modern, comprehensive international enterprise specializing in the research, development, manufacturing, and sales of engineering rubber hose products.
With strong technical capabilities, Sinopulse is a professional hydraulic hose factory located in Handan, China. The company has a rubber hose engineering technology research and development center, and its products have been awarded multiple invention and utility model patents.
The company currently produces a range of high-pressure hoses, including steel wire spiral hoses, steel wire braided hoses, and fiber-reinforced hoses, as well as hose assemblies, hose fittings, and hose crimping.
Certified by authoritative organizations, the hoses are known for their oil resistance, high-pressure resistance, high-temperature resistance, flexibility, excellent pulse performance, minimal pressure deformation, fixed length, and ease of use and maintenance. As a result, they are widely used in industries such as construction machinery, coal mining, petrochemicals, metallurgy, construction, and transportation.
To make it easier for customers to choose the right hose, Sinopulse produces hydraulic hoses based on ISO 18752. These hoses are manufactured according to the pressure range specified by customers and their intended use, rather than just the structure, providing simple and powerful hydraulic hose solutions that can withstand harsh working conditions.
Global hoses comply with the ISO 18752 standard and are tested at twice the standard level to ensure high performance in demanding environments and high-impact applications.
For global customers, ISO standards are crucial. Customers prefer not to use traditional regional standards to regulate hydraulic hoses because their equipment is manufactured, used, and maintained worldwide.
The ISO 18752 standard helps address these issues by simplifying hydraulic hose specifications for various applications, markets, and locations.
FAQ of ISO18752 standard
What is ISO 18752?
ISO 18752 is an international standard for rubber hoses and hose assemblies used in hydraulic applications. It specifies requirements for wire- or textile-reinforced single-pressure hoses based on their maximum working pressure (MWP) rather than structural design.
Key Features of ISO 18752:
- Pressure-Based Classification
- Unlike standards such as SAE 100R2 (which defines hoses by structural layers, e.g., "two steel wire braids"), ISO 18752 categorizes hoses into nine pressure classes:
3.5, 7.0, 14.0, 21.0, 25.0, 28.0, 35.0, 42.0, and 56.0 MPa. - Each class maintains the same MWP across all sizes. For example, a hose in the 21 MPa class will have a consistent 21 MPa rating regardless of its diameter.
- Unlike standards such as SAE 100R2 (which defines hoses by structural layers, e.g., "two steel wire braids"), ISO 18752 categorizes hoses into nine pressure classes:
- Simplified Pressure Tracking
- Traditional standards (e.g., SAE 100R2) often see reduced working pressure as hose size increases due to structural limitations.
- ISO 18752 eliminates this complexity by fixing the MWP for each class, ensuring uniform performance across all sizes.
- Global Compatibility
- Originally proposed by Japan, ISO 18752 addresses the need for a universal hydraulic hose standard to replace region-specific specifications.
- It simplifies hose selection for global industries, as equipment manufacturers and users no longer need to navigate conflicting regional standards.
Why ISO 18752 Matters:
- Consistency: Ensures predictable performance in harsh environments (e.g., high pressure, extreme temperatures).
- Ease of Use: Users select hoses based on required pressure, not structural details.
- Global Adoption: Aligns with international equipment manufacturing, maintenance, and safety practices.
For example, a 21 MPa ISO 18752 hose will deliver the same pressure rating whether installed in construction machinery in Europe or mining equipment in Asia, streamlining global supply chains and maintenance workflows.
Why should rubber hoses comply with ISO 18752?
The ISO 18752 standard is easy to understand and makes choosing a hose for your application straightforward. If you know the working pressure level required for your application, you can easily select the right hose.
Using an international specification such as ISO means that the specification is understood and used throughout the world, not just in one region.
For example, the SAE standard is primarily a North American specification, so if your equipment containing SAE-compliant hose is shipped to Asia, it will be difficult for them to understand and replace the hose with one that meets the standard!
What do AC, AS, BC, CC, and DC stand for in ISO 18752?
The ISO 18752 standard contains different classes and forms of hoses.
The first digit represents the class of the hose, which indicates the number of pulses, the ratio of test pressures and the temperature at which the hose is to be tested.
The second digit indicates whether the hose is of standard (S) or compact (C) construction.
Do all hose manufacturers use the ISO 18752 standard?
Not all hose manufacturers have adopted the ISO standard. Many hose manufacturers still use regional standards to design and manufacture their products, and Sinopulse, as an advanced hose manufacturer, can manufacture your hose to any standard, including ISO 18752 hose.
In short, SAE specs revolve around hose construction. In contrast, ISO 18752 specs center around the design practices of engineers who typically design hydraulic systems. They center around performance and pressure rating.
The working pressure of SAE rated ‘conventional’ hoses (R9, R10, R11, and R12) varies by size. The smaller the inside diameter of the hose, the higher the working pressure of the hose. Typically, these hoses are made with the same number of reinforcements in all sizes. The reinforcement is usually a wire braid or wire helix, but can also be fibre.
The newer SAE rated hoses (R13, R15, R17, and R19) have constant working pressure ratings for all hose sizes. Smaller hose sizes can use one layer of reinforcement, and larger sizes can use two or more layers of steel wire reinforcement to maintain the same pressure rating for all sizes.
Today, the ISO standard is becoming increasingly popular for hose products. Engineers are increasingly using the standard to identify what equipment the hose should be used on, such as hydraulic machinery, equipment or tools.
The ISO 18752 standard makes it easy to identify which hose should be used on a machine. The stringent testing requirements allow users to know exactly what the hose is rated for and how it should behave on hydraulic equipment. Hoses tested to higher impulse standards are likely to have longer hose life, which is why many users are turning to ISO standards. For example, if you need a hydraulic hose for a demanding application that involves many repetitive pressure cycles in a short period of time and long periods of continuous use, you may choose a Class C or Class D hose assembly. However, this choice is based on whether the hose is properly installed and protected from harsh environments.
Another important aspect of ISO standards is that they are accepted globally, meaning that no matter where your hose is manufactured or purchased, you know it will be tested to the same standards. Global manufacturing standards are critical to many OEMs.
In response to the market trend for high-pressure hose, hose manufacturers have developed a range of constant-pressure hoses that meet or exceed the ISO 18752 specification. For example, Sinopulse produces hoses that include 1,000, 3,000, 4,000, 5,000 and 6,000 psi. Each line of constant pressure hose has colour-coded laylines based on pressure ratings and is available in different covers to meet application requirements. These hoses meet the minimum 1 million impulse cycles test required by ISO 18752 Class D DC types and have a smaller bend radius than required by code.
Although SAE J517 and ISO 18752 do not require pressure pulse testing while the hose is in motion, Sinopulse and other manufacturers do so to further ensure hose life. The hose will flex during randomly applied pulse pressure cycles to positively demonstrate hose performance and service life.
Hydraulic hoses conforming to ISO 18752 are specified by the following performance definitions. These ISO definitions determine the grade and type of hose required for different applications based on criteria such as temperature, pulse pressure, or cycle rating.
Get started today by contacting Sinopulse to select the standard hose for your application!