In the fields of supermarket cold chain, food processing, and low-temperature logistics, **semi-hermetic piston compressors** have always been the core power unit of Freon refrigeration systems, thanks to their convenient maintenance, high resistance to liquid hammer, and wide operating pressure range. Unlike open or fully enclosed structures, the semi-hermetic design places the motor and compressor mechanism within the same housing, eliminating the risk of shaft seal leakage while facilitating on-site disassembly and maintenance.
1. Efficient valve plate and airflow optimization
The design incorporates a circular valve plate and an efficient airflow channel to reduce the clearance volume and enhance the gas transmission coefficient. Optimized for medium and low temperature refrigerants such as R404A, R507A, and R22, it delivers stable cooling output at evaporation temperatures ranging from -10℃ to -40℃, achieving an 8%-12% improvement in energy efficiency compared to traditional models.
2. Robust drive and cooling system
The built-in large-capacity oil pool, coupled with a forced oil supply system, ensures the lubrication of moving parts under high-load conditions. The motor's suction cooling technology effectively controls the temperature rise of the windings. Coupled with a PTC thermistor and an exhaust temperature protection module, it extends the equipment's trouble-free operation time.
3. Multi-cylinder structure and low vibration design
The layout of 2, 4, or 6 cylinders is optional. The crankshaft undergoes dynamic balance calibration and is paired with a mass balance block, significantly reducing the stress impact of high-frequency vibration on the pipeline system. It is particularly suitable for city distribution refrigerated vehicles or fresh food display cabinets that are sensitive to noise.
Medium-to-high temperature cold storage (0℃ ~ +10℃): Preservation of fruits and vegetables, storage of dairy products, paired with a fluorine pump liquid supply system to enhance energy efficiency.
Low-temperature freezer/quick-freezing tunnel (-18℃ ~ -35℃): used for ice cream hardening and meat quick-freezing, supporting dual-stage or parallel unit configurations.
Transport refrigeration (refrigerated containers/refrigerated vehicles): Compact design suitable for frame installation, with anti-bump performance tested on a vibration table.
Industrial process cooling (chemical/pharmaceutical): Precisely control the temperature of the reaction kettle jacket and adapt to environments with explosion-proof requirements (an explosion-proof motor can be optionally equipped).
1. **Determining the evaporation temperature range:** For medium to high temperatures (-5℃/5℃), it is recommended to use a cylinder head with high exhaust volume; for low temperatures (-30℃), it is necessary to equip with liquid spray cooling or a cylinder head fan.
2. **Refrigerant type:** The existing R22 system can be directly compatible with oil; for new projects, it is recommended to choose R404A or low GWP models such as R448A and R449A.
3. **Voltage and starting mode:** Standard 380V/3N/50Hz or customized 460V/60Hz; for motors above 7.5HP, it is recommended to equip with star-delta starter or soft starter.
Universality: Key components (valve plate, piston ring, connecting rod, shaft seal) are standardized and interchangeable with mainstream brands in the market.
Maintenance reminder: It is recommended to replace the refrigeration oil and filter after the first 500 hours of operation, and then every 4000 hours or during annual maintenance.
Common fault prediction: Equipped with an intelligent module, it can monitor oil pressure difference, exhaust overheat ratio, and motor current imbalance, preventing valve plate fracture caused by liquid hammer.
Q1: How to choose between semi-hermetic piston compressors and screw compressors in cold storage applications?
A: Piston machines have a cost-effective advantage in the refrigeration capacity range below 30 units, and they have stronger resistance to liquid hammer, making them suitable for small-scale warehouses with frequent start-stop operations. Screw machines, on the other hand, are more efficient in high refrigeration capacity and continuous operation conditions.
Q2: How to handle an emergency situation of excessively high exhaust temperature?
A: First, check the heat dissipation of the condenser (dust accumulation on air-cooled fins or scaling on water-cooled ones). Next, verify the suction superheat degree (generally recommended to be controlled between 5-8K). If necessary, install a liquid injection valve assembly under low temperature conditions.
Q3: Can old R22 piston machines be replaced?
A: Yes, it is possible. However, the compressor needs to be replaced with one that uses the corresponding POE oil, and the residual mineral oil in the system needs to be cleaned. If the original head is retained, specific compatible refrigerant oil must be used.
| Parameter | Typical Value/Range
| Displacement | 80.2 m³/h (50Hz)
|Motor power | 30 kW (40 HP)
| Applicable refrigerant | R22 / R404A / R448A
| Weight | 285 kg
| Noise | ≤ 78 dB(A)
If you are looking for a semi-hermetic piston compressor that is stable, highly maintainable, and complies with current environmental regulations, please feel free to request a selection sample or 3D drawing of the corresponding model.
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