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Precautions for Vacuuming the LOUDA Chiller System
Release Date:
2014-08-02
Before charging the refrigerant into a low-temperature refrigeration system, it is essential to perform vacuum pumping to remove air and moisture from the system. The residual absolute pressure of air must not exceed 133 Pa; otherwise, the refrigeration system may experience ice blockages, elevated condensing pressures, and corrosion of system components. There are three commonly used methods for vacuum pumping:
① Low-pressure single-side vacuum pumping
Low-pressure single-side vacuum pumping is carried out using the service port on the compressor and can also utilize the service valve connected to this port during pressure leak testing, eliminating the need for additional weld-in fittings. A drawback of low-pressure single-side vacuum pumping is that the high-pressure side—namely, the condenser—
Before charging the refrigerant into a low-temperature refrigeration system, a vacuum must first be applied to remove air and moisture from the system. The residual absolute pressure of air must not exceed 133 Pa; otherwise, the refrigeration system may experience ice blockages, elevated condensing pressures, and corrosion of system components. The three commonly used vacuum‑pumping methods are as follows.
① Low-pressure unilateral vacuum pumping
Low-pressure, single-side evacuation is performed using the service port on the compressor and can be carried out with the service valve already connected to that port during pressure leak testing, eliminating the need for an additional weld. A drawback of this method is that air from the high-pressure side—namely the condenser and the receiver‑drier—must pass through the capillary tube, the evaporator, and the compressor before being exhausted by the vacuum pump. Because the capillary tube has a small inner diameter, flow resistance is substantial; even when the low-pressure side reaches the required vacuum level, the high-pressure side often remains insufficiently evacuated. Consequently, low-pressure, single-side evacuation typically requires multiple cycles and a relatively long evacuation time. The duration of the evacuation depends on the vacuum pump’s pumping capacity; for instance, with a pump having a pumping speed of 4 L/s, evacuating for about 15 minutes usually reduces the system’s absolute pressure to below 133 Pa.
② Vacuuming on both the high- and low-pressure sides
Dual-side vacuum pumping at both high and low pressures involves welding a service valve equipped with a pressure‑vacuum gauge onto the process port of the dual‑tail dryer filter, thereby connecting it in parallel with the compressor’s process port to a single vacuum pump, or alternatively using two vacuum pumps simultaneously. This method overcomes the adverse effects of capillary resistance on the vacuum level on the high-pressure side, enabling the refrigeration system to achieve a higher degree of vacuum in a shorter time; consequently, it has been widely adopted in recent years.
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Zhejiang Loda Refrigeration Technology Co., Ltd.
Phone:0571-88587986 88543696 88543697
Address: Xiayang Village, Xiazhuhu Subdistrict, Deqing County, Huzhou City, Zhejiang Province
Fax: 0571-88526093
