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General technical requirements for automatic spray control valves for hydraulic supports
"MT/T 765-1997, issued by the Ministry of Coal Industry of the People's Republic of China, was approved on December 30, 1997, and came into effect on June 1, 1998. This standard outlines the requirements for automatic spray control valves used in coal mine hydraulic supports, including testing methods, inspection rules, labeling, packaging, transportation, and storage. It applies to various types of hydraulic supports equipped with automatic spray control valves.
The standard references several national standards, such as GB 191-90 for packaging and storage pictorial signs, GB/T 6388-86 for shipping package receiving and dispatching signs, and others related to sampling procedures and quality supervision. These references are essential for ensuring consistency and compliance during testing and production.
Definitions provided in the standard clarify key terms, such as "hydraulic support with automatic spray control valve," "working fluid," and "opening pressure." These definitions ensure that all parties involved have a common understanding of the terminology used throughout the document.
The requirements section specifies that control valves must meet the standards outlined in this document and be manufactured according to approved technical documentation. Environmental conditions, appearance, interface design, strength, resistance loss, opening pressure, and service life are all specified in detail. For example, the valves must withstand pressures up to 32 MPa and maintain proper sealing after 4,000 cycles.
Testing procedures are clearly outlined, including the test system, equipment, and conditions. Each test item is described with specific methods and criteria. The inspection rules include factory and type inspections, with detailed sampling methods and quality levels. Type tests are required under certain conditions, such as when new products are introduced or major design changes occur.
Marking, packaging, transportation, and storage guidelines are also included. Each control valve must have a clearly marked nameplate, and packaging must follow established standards. Proper storage conditions, such as dry and well-ventilated environments, are emphasized to ensure product integrity over time.
This standard serves as a comprehensive guide for manufacturers, inspectors, and users of hydraulic support systems, ensuring safety, reliability, and performance in coal mining operations."
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