I. Series Overview
The LG QK/QJ/QP series consists of hermetic rotary refrigeration compressors, widely used in air conditioning systems, refrigeration equipment, and heat exchange applications. Primarily utilizing R22 refrigerant, this series covers a power range from 1.5HP to 3.0HP, serving as the core power component for small to medium-sized refrigeration and air conditioning systems.
| Series | Typical Power Range | Positioning | Main Applications |
| QK Series | 1.0–1.5 HP | Entry-level / Small | Small air conditioners, light commercial refrigeration |
| QJ Series | 1.5–2.5 HP | Mid-range / Mainstream | Residential / commercial air conditioners, refrigeration equipment |
| QP Series | 2.5–3.0 HP | High-end / High Capacity | Large air conditioners, industrial refrigeration |
Common Features: The entire series adopts rotary compression technology, single-phase 220-240V/50Hz power supply, R22 refrigerant, and features high energy efficiency (COP 3.05–3.28 W/W) and low noise characteristics.
Core Difference: The QK series is the entry-level small compressor; the QJ series is the mid-range mainstream model with the widest cooling capacity coverage; the QP series is the high-end large-displacement model, delivering the most powerful cooling capacity.
The following details six models in ascending order of power.
II. Comprehensive Parameter Comparison Table (6 Models Total)
| No. | Model | Series | Refrigerant | Power Supply | Power (HP) | Cooling Capacity (BTU/h) | Cooling Capacity (kW) | Input Power (W) | COP (W/W) | Type |
| 1 | QK125P | QK | R22 | 220-240V/50Hz | ~1.0 | 7,300 | 2.05 | 676 | ~3.05 | Rotary |
| 2 | QK208P | QK | R22 | 220-240V/50Hz | ~1.5 | — | — | — | ~3.05 | Rotary |
| 3 | QJ264P | QJ | R22 | 220-240V/50Hz | ~1.8 | — | — | — | ~3.14 | Rotary |
| 4 | QJ325P | QJ | R22 | 220-240V/50Hz | ~2.0 | — | — | — | ~3.14 | Rotary |
| 5 | QP325P | QP | R22/R410A | 220-240V/50Hz | ~2.5 | 19,200–19,500 | 5,626–5,714 | 1,773–1,856 | 3.05–3.22 | Rotary |
| 6 | QP348P | QP | R22 | 220-240V/50Hz | 3.0 | — | — | — | 3.16–3.28 | Rotary |
Note: The above parameters are sourced from public technical data and industry sources; specific values may vary depending on test conditions.
III. Detailed Explanation of Model-Specific Advantages
The following describes the unique value of each model within the QK, QJ, and QP sub-series respectively, integrating features, advantages, and benefits into a single narrative.
(A) QK Series — Entry-Level Small Rotary Compressor
The QK125P is the entry-level model in the QK series. It adopts rotary compression technology, uses R22 refrigerant, and operates on single-phase 220-240V/50Hz power. Its cooling capacity is approximately 7,300 BTU/h (2.05 kW) with an input power of 676 W. This specification makes it an ideal choice for small air conditioners and light commercial refrigeration equipment. For HVAC contractors and equipment manufacturers, the QK125P offers a cost-effective entry-level solution — while ensuring LG's consistent reliability, its moderate cooling capacity meets the refrigeration needs of small spaces (such as 10-20㎡ rooms). The COP ranges from 3.05–3.14 W/W, delivering energy efficiency superior to comparable fixed-speed small compressors.
The QK208P is the larger displacement model in the QK series, with a power rating of approximately 1.5 HP. As the upper extension of the QK series, it provides stronger cooling capacity than the QK125P while maintaining the compact structure of a rotary compressor. For applications requiring more cooling than the entry-level but with budget constraints — such as medium-sized room air conditioners or small commercial refrigeration units — the QK208P strikes a precise balance between cost and performance. It also uses R22 refrigerant and single-phase 220-240V/50Hz power, facilitating compatible replacement with existing systems.
(B) QJ Series — Mid-Range Mainstream Rotary Compressor
The QJ264P sits in the mid-range position of the QJ series, a rotary compressor with approximately 1.8 HP. Using R22 refrigerant, this model plays a "connecting" role within the series. The QJ264P achieves a COP of over 3.14 W/W, offering better energy efficiency than the QK series. For applications such as residential split air conditioners and commercial refrigeration equipment that require moderate cooling capacity and higher energy efficiency, the QJ264P delivers superior performance over the QK series while avoiding the energy waste of "an oversized compressor on a small load." Its compact rotary design also facilitates easy equipment integration.
The QJ325P belongs to the same mid-range QJ series as the QJ264P, with a power rating of approximately 2.0 HP and greater cooling capacity. Building upon the QJ264P, it further increases cooling output, covering a broad capacity range from 1.5HP to 2.5HP. For applications requiring stronger cooling but not yet reaching QP series levels — such as larger residential air conditioners, commercial display cases, or small cold rooms — the QJ325P provides "just right" cooling capacity that meets load demands without increasing equipment costs due to excess power.
(C) QP Series — High-End High-Capacity Rotary Compressor
The QP325P is the mainstay model of the QP series, with a displacement of 32.5 cc/rev and approximately 2.5 HP. It uses R22 refrigerant (some data also indicates compatibility with R410A). Its cooling capacity reaches 19,200–19,500 BTU/h (approx. 5,626–5,714 W), with an input power of 1,773–1,856 W and an EER of 10.8–11.0 Btu/W·h. The COP ranges from 3.05–3.22 W/W. For large air conditioning systems, industrial refrigeration equipment, and high-load commercial refrigeration scenarios, the QP325P delivers robust cooling power. Its maximum withstand pressure of up to 650 psi demonstrates excellent system compatibility and safety margin. Noise levels are approximately 58 dB, performing well among high-capacity compressors.
The QP348P is the most powerful model in the entire series, reaching 3.0 HP. As the top-tier product of the QP series, it adopts LG's advanced rotary compression technology, specifically engineered for applications with the highest cooling demands. The COP reaches 3.16–3.28 W/W, ranking at the leading level across the entire series. Powered by single-phase 220-240V/50Hz, for scenarios such as large commercial air conditioning, industrial water chillers, and large refrigeration equipment that demand maximum cooling capacity, the QP348P provides the ultimate solution in LG's rotary compressor lineup — delivering large displacement, high energy efficiency, and LG brand reliability to meet the most demanding refrigeration needs.
IV. Quick Selection Guide by Application Scenario
| Application Scenario | First Choice | Alternative / Upgrade |
| Small room air conditioner (10-20㎡) | QK125P | — |
| Medium room AC / Small commercial refrigeration | QK208P | QJ264P (higher efficiency) |
| Residential split AC / Medium commercial equipment | QJ264P | QJ325P (larger capacity) |
| Large residential AC / Small cold rooms | QJ325P | QP325P (industrial-grade capacity) |
| Large AC systems / Industrial refrigeration | QP325P | QP348P (maximum capacity) |
| Large commercial AC / Industrial water chillers | QP348P | — |
Quick Selection Guide:
Small space, low cost → QK125P
Medium space, cost-effective → QK208P / QJ264P
Large area, high efficiency → QJ325P
Heavy load, industrial grade → QP325P / QP348P
V. Frequently Asked Questions (FAQ)
Q1: What are the main differences between the QK, QJ, and QP series?
The main difference lies in power and cooling capacity: the QK series is entry-level (approx. 1.0–1.5 HP), the QJ series is mid-range mainstream (approx. 1.5–2.5 HP), and the QP series is high-end large-capacity (approx. 2.5–3.0 HP). Cooling capacity from smallest to largest: QK125P < QK208P < QJ264P < QJ325P < QP325P < QP348P.
Q2: Are these compressors fixed-speed or variable-speed (inverter)?
The QK/QJ/QP series consists primarily of fixed-speed compressors.
Q3: What is the difference between a rotary compressor and a reciprocating (piston) compressor?
A rotary compressor achieves compression through an eccentric rotor rotating inside the cylinder, offering advantages such as compact structure, low vibration, low noise, and fewer parts. A reciprocating compressor achieves compression through the back-and-forth motion of a piston, featuring strong adaptability to various operating conditions. The QK/QJ/QP series are all rotary compressors, suitable for air conditioning and light commercial refrigeration applications.
