I. Positioning
The DH Series Fixed-Speed is Hitachi's fixed-speed scroll compressor product line optimized for R22 refrigerant, covering two capacity grades: 503DH and 603DH. With a power range of 6–8 HP, high reliability, and cost-effectiveness as its core features, this series is a classic power choice for commercial air conditioning, water chiller units, and industrial refrigeration systems.
| Feature Dimension | Description |
| Technology Type | Hermetic scroll, Fixed-Speed |
| Power Range | 6 HP – 8 HP |
| Refrigerant | R22 |
| Power Supply | 3φ, 380-415V/50Hz |
| Core Positioning | High reliability, economical & practical, fixed-speed classic |
II. Full Series Parameter Comparison Table
| No. | Model | Nominal HP | Displacement (cm³/rev) | Cooling Capacity (kW) | Cooling Capacity (Btu/h) | Input Power (kW) |
| 1 | 503DH-80C1 | 6 | 80 | 14.9 | 50,800 | 4.4 |
| 2 | 503DH-83C1 | 6.5 | 83 | 15.4 | 52,510 | — |
| 3 | 603DH-90C1 | 6 | 90 | 16.8 | 57,290 | 5.1 |
III. Detailed Analysis
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Feature: The DH Series Fixed-Speed adopts a hermetic scroll structure, optimized specifically for R22 fixed-speed applications. The compressor features a simple structure with fewer moving parts, resulting in low vibration and low noise. The scroll wraps are precision-machined to minimize gas leakage and enhance compression efficiency. The entire series operates on a three-phase power supply of 380-415V/50Hz, compatible with global mainstream industrial power standards.
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Advantage: This series centers on high reliability and cost-effectiveness. The 503DH-80C1 delivers a cooling capacity of 14.9 kW, while the 603DH-90C1 delivers 16.8 kW with an input power of 5.1 kW. Fixed-speed scroll compressors feature a mature design with low failure rates and minimal maintenance costs. The 603DH-90C1 is rated for a maximum of 6 starts per hour, with a maximum crankcase oil temperature of 80°C and a maximum ambient temperature of 43°C, ensuring stable operation even under demanding conditions.
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Benefit: For commercial air conditioning and water chiller manufacturers, the DH Series Fixed-Speed precisely matches the 6–8 HP system requirements with cooling capacities ranging from 14.9 kW to 16.8 kW. For the maintenance, repair, and replacement (MRR) market of existing R22 systems, this series provides a plug-and-play replacement solution—eliminating the need to replace refrigeration oil or modify system piping. For end users, the mature structure and long-life design of fixed-speed scroll compressors reduce the total lifecycle operating cost while ensuring reliable cooling performance.
IV. Quick Selection Guide by Application Scenario
| Application Scenario | Recommended Model | HP | Key Advantage |
| 6 HP Commercial A/C | 503DH-80C1 | 6 | 14.9 kW, economical & reliable |
| 6.5 HP Commercial A/C | 503DH-83C1 | 6.5 | 15.4 kW |
| 6 HP Large Commercial A/C | 603DH-90C1 | 6 | 16.8 kW, 90 cc displacement |
Selection Mnemonic: For 6 HP, choose 503DH-80C1 or 603DH-90C1; for 6.5 HP, choose 503DH-83C1.
V. Frequently Asked Questions (FAQ)
Q1: What are the cooling capacity and input power of 503DH-80C1?
503DH-80C1 is a 6 HP fixed-speed scroll compressor with a displacement of 80 cm³/rev, cooling capacity of 14.9 kW (50,800 Btu/h), and input power of 4.4 kW.
Q2: What are the technical specifications of 603DH-90C1?
603DH-90C1 is a 6 HP fixed-speed scroll compressor with a displacement of 90 cm³/rev, cooling capacity of 16.8 kW (57,290 Btu/h), and input power of 5.1 kW. Maximum starts: 6 times per hour; maximum crankcase oil temperature: 80°C; maximum ambient temperature: 43°C.
Q3: What refrigerant and refrigeration oil does the DH Series Fixed-Speed use?
It uses R22 refrigerant and mineral oil. R22 systems must use mineral oil or alkylbenzene oil; do not mix with POE ester oil.
To sum up: The DH Series fixed-speed scroll compressors are the classic power choice for 6–8 HP R22 commercial A/C and water chiller systems. With a simple structure, low failure rate, and virtually negligible maintenance costs, they deliver exceptional cost-effectiveness over the entire lifecycle. If you're currently in the selection phase or need a sample unit, just let me know anytime for a quote or technical datasheets!
III. Detailed Analysis
