This is an extremely important safety device in the field of industrial fluid transfer.

I. Core Definition
A breakaway valve, known in English as a Breakaway Coupling or Emergency Release Coupling, is a specially designed safety valve. Its core function is to automatically and instantaneously break into two parts when the transfer hose or pipeline is accidentally over-pulled, while simultaneously sealing both disconnected sides. This effectively prevents large-scale leakage of fluids (such as petroleum products, chemicals, fuel gas, etc.), avoiding serious accidents like fires, explosions, environmental pollution, and personal injury.

Simply put, it acts like a "fuse" in an electrical circuit—when the pulling force exceeds the safety limit, it "blows" to protect the entire system.

II. Main Structure and Working Principle
Structure:
A breakaway valve typically consists of two parts, joined together by a meticulously designed mechanical connection mechanism (such as a shear ring, shear pin, locking ball, etc.).
The valve interior is equipped with a spring-loaded sealing mechanism (such as a check valve or ball valve).

Working Principle:

• Normal operating state: Under normal operating pull force, the two parts remain tightly connected, allowing fluid to pass through smoothly.

• Accidental pull state: When the hose or pipeline is subjected to an unexpected pull force exceeding the preset value (e.g., a tank truck driving away without disconnecting), this external force acts on the breakaway valve.

• Fracture and sealing: The preset mechanical connection mechanism (shear pin/ring) is precisely sheared off. After breaking, the two parts rapidly separate. At the moment of separation, the spring inside the valve immediately pushes the sealing element (such as a valve flap or steel ball) to close the channel, sealing both disconnected sides within milliseconds and preventing further fluid leakage.

III. Key Features and Advantages

• Passive safety: Fully mechanical structure, requiring no electricity, air source, or human intervention, ensuring extremely high reliability.

• Rapid response: The fracture and sealing process is extremely fast, minimizing leakage.

• Presettable breakaway force: Different breakaway pull force values can be set based on application scenarios (e.g., hose strength, fluid hazard level).

• Reusability: Most breakaway valves only require replacement of vulnerable shear components (e.g., shear pins/rings) after fracture, while the main valve body can be reassembled and reused, offering economic benefits.

IV. Main Application Scenarios
Breakaway valves are widely used in all scenarios involving hose connections for transferring hazardous fluids, particularly where there is a risk of accidental pulling:

• Petroleum loading and unloading: Unloading ports for underground oil tanks at gas stations, aircraft refueling trucks at airports, and loading/unloading arms for railway and road tankers.

• Chemical industry: Transfer of various chemicals and liquefied gases (LPG/LNG) in chemical plants, docks, and tank farms.

• Shipping industry: Fuel oil or cargo transfer arms or hoses used by ships during loading and unloading at docks.

• Other fields: Any industrial process requiring prevention of leakage due to accidental separation of fluid transfer pipelines.

V. Important Considerations

• Correct selection: The appropriate breakaway valve model must be selected based on the properties of the transferred medium (corrosiveness, pressure, temperature), flow rate, the hose’s rated working pressure, and the required breakaway force. Incorrect selection may lead to premature fracture or failure to break when needed.

• Regular inspection and maintenance: Regular checks are necessary to ensure shear components are not fatigued or corroded and sealing elements are not aged, guaranteeing functional integrity.

• Installation direction: Some breakaway valves have installation direction requirements (e.g., capable of withstanding unidirectional pull only) and must be installed strictly according to manufacturer instructions.

• Professional operation: Operators should be trained to understand the existence and role of breakaway valves to avoid accidental triggering during daily operations.

Summary
A breakaway valve is a critical industrial safety device that "sacrifices" itself at key moments to prevent catastrophic accidents, serving as a robust safety barrier in fluid transfer systems. Its mechanical and automated design philosophy makes it indispensable in complex and hazardous industrial environments.