I. Positioning
The Small-Capacity Group is Copeland's ZB series product line of compact scroll compressors designed for 2–3.5 HP medium-high temperature refrigeration applications. Covering five capacity grades—ZB15, ZB19, ZB21, ZB26, and ZB29—it offers dual oil options: KQ (mineral oil/R22) and KQE (POE ester oil/R404A/R134a). This group features a compact lightweight design, wide operating range, and high reliability, making it the ideal power choice for small cold storage, beverage display cabinets, dairy display cabinets, and other equipment.
| Feature Dimension | Description |
| Power Range | 2.0 HP – 3.5 HP |
| Refrigerant | R22 (KQ) / R404A, R134a (KQE) |
| Power Supply | Single-phase 220-240V or 3-Phase 380-420V/50Hz |
| Application Condition | Medium-high temp refrigeration, evaporation temp -25℃ to +15℃ |
| Core Positioning | Compact lightweight, preferred choice for small commercial refrigeration |
II. Full Series Parameter Comparison Table
Note: 50Hz operating condition. Cooling capacity is based on R404A (KQE) or R22 (KQ).
| No. | Model | Nominal HP | Displacement (m³/h) | Cooling Capacity @-10℃ (W) | Cooling Capacity @0℃ (W) | Oil Type | Net Weight (kg) |
| 1 | ZB15KQE | 2.0 | 5.9 | 3,550 | 6,250 | POE | 33 |
| 2 | ZB19KQ | 2.5 | 6.8 | 4,350 | 7,500 | Mineral | 33 |
| 3 | ZB19KQE | 2.5 | 6.8 | 4,350 | 7,500 | POE | 33 |
| 4 | ZB21KQ | 2.5 | 7.8 | 5,250 | 9,100 | Mineral | 33 |
| 5 | ZB21KQE | 2.5 | 7.8 | 5,250 | 9,100 | POE | 33 |
| 6 | ZB26KQ | 3.0 | 9.9 | 6,100 | 10,550 | Mineral | 38 |
| 7 | ZB26KQE | 3.0 | 9.9 | 6,100 | 10,550 | POE | 38 |
| 8 | ZB29KQ | 3.5 | 11.8 | 7,200 | 12,450 | Mineral | 38 |
| 9 | ZB29KQE | 3.5 | 11.8 | 7,200 | 12,450 | POE | 38 |
III. Detailed Explanation
Feature – Technical Characteristics
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The Small-Capacity Group adopts Copeland's patented Dual Compliant Scroll design, allowing the scrolls to separate slightly along the radial and axial directions, enabling debris or liquid to pass through the scrolls without causing damage.
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The entire ZB15 to ZB29 range is equipped with a built-in Internal Pressure Relief (IPR) valve and TOD discharge temperature protection device. The IPR valve is located between the high-pressure and low-pressure sides of the compressor. When the pressure difference exceeds 26~32 bar, it opens to divert hot discharge gas to the motor protector, triggering a protective trip.
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The compressor features a built-in mid-point protector to ensure motor safety under abnormal operating conditions.
Advantage – Technical Advantages
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This group is known for its ultra-light weight of 33 kg and compact structure. Compared with semi-hermetic compressors of the same cooling capacity, the weight reduction is significant, greatly reducing equipment integration difficulty and transportation costs.
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The scroll's "wear-in, not wear-out" design makes the compressor perform better over time. With high volumetric efficiency, its energy efficiency ratio surpasses that of traditional reciprocating compressors.
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The unloaded start technology separates the compression components after shutdown, achieving full internal pressure balance without requiring additional starting devices.
Benefit – User Benefits
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For applications such as small cold storage, beverage display cabinets, dairy display cabinets, and small ice machines, this group's compact design and flexible power compatibility reduce system integration difficulty for equipment manufacturers, while its high reliability and built-in protection systems minimize after-sales repair frequency.
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For end-users, the R404A/R134a compatibility (KQE series) enables adaptation to environmental refrigerant transition requirements, extending the equipment's lifecycle.
IV. Application Quick Selection Guide
| Application Scenario | Recommended Model | HP | Refrigerant |
| Small beverage display cabinets | ZB15KQE | 2.0 | R404A/R134a |
| Dairy display cabinets | ZB19KQ / ZB19KQE | 2.5 | R22 / R404A |
| Small refrigerated display cabinets | ZB21KQ / ZB21KQE | 2.5 | R22 / R404A |
| Small cold storage (10-20m³) | ZB26KQE | 3.0 | R404A/R134a |
| Small ice machines / Fresh-keeping storage | ZB29KQE | 3.5 | R404A/R134a |
V. Frequently Asked Questions (FAQ)
Q1: What is the difference between KQ and KQE?
A: KQ uses mineral oil and is compatible with R22 refrigerant; KQE uses POE ester oil and is compatible with HFC refrigerants such as R404A/R134a. Both share the same mechanical structure, with the only difference being the factory-filled lubricant. They cannot be used interchangeably.
Q2: What is the function of the Internal Pressure Relief (IPR) valve?
A: The IPR valve is located between the high-pressure and low-pressure sides of the compressor. When the pressure differential exceeds 26~32 bar, it opens to divert hot discharge gas to the motor protector, triggering a protective trip to prevent compressor damage.
Q3: Do the ZB15 to ZB29 series come with discharge temperature protection?
A: Yes. This group is equipped with a TOD (Discharge Temperature Protection device), which is a temperature-sensing quick-acting valve plate located at the scroll discharge port. When the discharge temperature becomes too high, it opens to allow high-temperature discharge gas to return and contact the motor protector, thereby protecting the compressor.
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V. Frequently Asked Questions (FAQ)
