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Product Features

The HC7Y Sulfur Hexafluoride (SF6) Gas Recovery and Charging Unit integrates a comprehensive range of functions, including recovery, charging/discharging, purification, vacuuming, storage, and cylinder filling. The system is highly comprehensive in its design; please refer to the system diagram in Appendix I. The sequencing or switching between these various functions is primarily controlled through an electrical control box and ball valves, all of which are centrally located on the unit's front panel.

The fundamental operating principle of this SF6 gas recovery and charging unit is based on the cryogenic liquefaction method. During the recovery process, the suction and compression capabilities of the compressor are utilized to draw SF6 gas—present at a specific pressure within the SF6 electrical equipment—into the compressor, where it is then compressed to a higher pressure level. Simultaneously, by leveraging the low evaporation temperature characteristics of the R22 refrigerant, the high-temperature SF6 gas is cooled to its condensation point, thereby undergoing liquefaction and subsequent storage. This continuous suction process continues—with the SF6 compressor operating in series—until the target final recovery pressure is achieved.

During the charging/discharging process, the unit's vacuum pump is first used to evacuate the SF6 electrical equipment (or gas cylinders) and the connecting pipelines. Subsequently, SF6 gas is transferred from the unit's internal storage vessel into the SF6 electrical equipment, either directly via pressure differential or by utilizing the compressor's suction capability to create the necessary pressure differential, until the required operating pressure is attained. When cylinder filling is required, the aforementioned characteristics of the R22 refrigerant are utilized to directly transfer the liquefied SF6 into the gas cylinders.

The purification function is performed concurrently with the completion of the aforementioned recovery and charging/discharging operations.

The system is equipped with three oil separators: one is installed at the outlet of the vacuum pump, and two are installed at the outlet of the compressor. These separators serve to effectively remove any oil contaminants carried by the SF6 gas.

The SF6 gas recovery and charging unit also incorporates a drying filter to ensure the purity of the SF6 entering the storage vessel and to effectively remove moisture. This filter is equipped with a heating regeneration device, allowing for thermal regeneration under vacuum conditions; this feature enables the molecular sieve medium to be reused repeatedly.

The system features reliable safety protection mechanisms. A high-pressure controller is installed at the discharge port of the SF6 compressor; should the discharge pressure exceed a preset limit, the controller automatically halts the compressor's operation, restarting it only after the pressure has subsided. Additionally, a safety valve is installed on the storage vessel; in the event of an overpressure condition, the safety valve automatically opens to vent the excess gas, closing automatically once the pressure returns to a safe level. Additionally, the Sulfur Hexafluoride (SF6) gas recovery and charging unit is equipped with a total of seven monitoring and control instruments. These include a single vacuum gauge, installed at the unit's recovery inlet, preceded by a DN8 valve that can be opened whenever a reading is required. There are five pressure gauges, positioned respectively at the recovery inlet, the SF6 compressor outlet, the suction and discharge ports of the refrigeration compressor, and on the storage vessel. Furthermore, a thermometer is installed within the refrigeration system, utilizing a thermal bulb to sense the temperature of the liquid SF6.

An electromagnetic vacuum inlet valve with an air-release function is installed at the inlet of the system's vacuum pump; this valve is wired to the same power supply as the pump. When the pump ceases operation, the valve automatically seals off the vacuum system and admits atmospheric air into the pump chamber through the inlet, thereby preventing backflow of pump oil and subsequent contamination of the vacuum system.

Within the SF6 gas recovery and charging unit, the refrigeration system's inlet and outlet pressures are regulated by high- and low-pressure controllers. Should these pressures exceed their prescribed limits, the system automatically cuts off power to the refrigeration compressor. The compressor will automatically restart once the pressure returns to within the acceptable range—specifically, after the pressure rises following a low-pressure cutoff, or after it drops following a high-pressure cutoff.

In terms of overall structure, the SF6 gas recovery and charging unit features a hand-pushed, mobile design, making it suitable for operation under normal indoor and outdoor environmental conditions. The system is relatively complex in composition, comprising a vacuum pump, an SF6 compressor, a refrigeration system, a storage vessel, interconnecting piping, various valves, instrumentation, and other ancillary components.

The electrical control cabinet, operational valves, and monitoring instruments are all centrally located on a single control panel, which also features a schematic process diagram; this arrangement ensures that the unit is both convenient and intuitive to operate.