Introduction to Types and Installation Requirements for Loading Arm Emergency Breakaway Valves

1. Types of Emergency Breakaway Valves

Emergency Breakaway Valves (EBVs), also known as Emergency Release Systems (ERS) or breakaway couplings, are critical safety devices installed on loading arms. They are primarily categorized based on their actuation mechanism:

• Mechanical Breakaway Valves: The most common type.

  • Working Principle: The valve body is held together by a mechanical system (e.g., ball bearings, locking lugs, a split collar) designed to disengage at a pre-set tensile force. Upon separation, internal springs instantly drive shut-off valves (e.g., ball or poppet valves) on both sides to seal the flow path.

  • Characteristics:

    • Advantages: Simple design, proven reliability, self-contained (no external power required), easier maintenance.

    • Disadvantage: Typically a single-use device. The entire valve assembly or specific rupture components must be replaced after an activation.

• Hydraulic Breakaway Valves: A more advanced type, often used for high-frequency operations or critical applications where minimal product loss is mandatory.

  • Working Principle: The connection is maintained by an internal or external hydraulic system. A shear pin in the hydraulic circuit breaks when excessive force is applied, causing a loss of hydraulic pressure which triggers the immediate closure of the valves.

  • Characteristics:

    • Advantage: Reusable. After activation, usually only the inexpensive shear pin and hydraulic fluid need replacement, reducing long-term costs.

    • Disadvantages: More complex design, higher initial investment, requires regular inspection and maintenance of the hydraulic system.

2. Key Installation Requirements

Proper installation is crucial for the reliable operation of the breakaway valve.

• Installation Location: Must be installed between the loading arm (swivel joint) and the hose or end connection that attaches to the truck's manifold. This ensures it will activate before the hose or arm itself is damaged.

• Orientation: Must be installed in the correct orientation, often indicated by an arrow showing the direction of flow. Incorrect installation can hinder its operation.

• Alignment: Must be installed without introducing excessive torsion, bending, or compressive stress on the valve body. Misalignment can alter the activation force and cause premature failure.

• Activation Force: The breakaway force must be set appropriately. It should be:

  • Lower than the ultimate strength of the hose and other weakest links in the system.

  • Higher than the forces expected during normal operation (e.g., hose weight, pressure thrust, routine movement).

• Support: The hose assembly might require proper support (e.g., a hose loop) to prevent its own weight from acting on the valve and to ensure a clean, straight pull in the event of a drive-away.

• Inspection and Testing: After installation, a functional check (according to the manufacturer's guidelines, which might involve a tension test rig) should be performed to verify correct operation without actually activating the valve. Regular visual inspections for damage, corrosion, or leaks are also mandatory.