I. Positioning
The Danfoss Maneurop® MT series is a line of fully hermetic reciprocating compressors optimized for R22 refrigerant, covering six capacity levels: MT45HJ, MT51HK, MT57HL, MT65HM, MT73HN, and MT81HP, with a power range of 4 HP to 7 HP. Positioned for medium-to-high temperature refrigeration applications, the evaporation temperature range covers -25°C to +15°C, with cooling capacities from approximately 10.8 kW to 20.3 kW. Suitable for cold storage, food retail, milk cooling, process cooling, and food service equipment. The MT series comes standard with mineral oil (160P), making it an economical, reliable, and plug-and-play compressor choice for R22 systems.
| Feature Dimension | Description |
| Power Range | 4 HP – 7 HP |
| Refrigerant | R22 |
| Lubricant | Mineral oil (160P) |
| Application Temperature | Medium-to-high temp., evaporation -25°C to +15°C |
| Core Positioning | R22 system maintenance & replacement, economical & reliable |
II. Full Series Parameter Comparison Table
| No. | Model | Nominal HP | Cooling Capacity (R22, 50Hz) | Input Power | Current | COP | Displacement (cm³/rev) | Cylinders |
| 1 | MT45HJ | 4 | 10,786 W | 3.62 kW | 6.86 A | 2.98 | 76.22 | 2 |
| 2 | MT51HK | 4.5 | 12,300 W | 4.01 kW | 7.86 A | 3.07 | 85.64 | 2 |
| 3 | MT57HL | 5 | 13,711 W | 4.54 kW | 9.24 A | 3.02 | 96.13 | 2 |
| 4 | MT65HM | 5.5 | 15,763 W | 5.23 kW | 8.81 A | 3.01 | 107.71 | 2 |
| 5 | MT73HN | 6 | 17,863 W | 5.98 kW | 9.99 A | 2.99 | 120.94 | 4 |
| 6 | MT81HP | 7 | 20,298 W | 6.94 kW | 11.27 A | 2.93 | 135.78 | 4 |
50Hz operating condition, R22 refrigerant. MT73HN and MT81HP feature 4-cylinder design; all other models are 2-cylinder.
III. Core Technical Advantages
Feature: The MT series adopts a fully hermetic reciprocating structure, with the motor and pistons sealed in a single welded housing. All models are completely suction-gas cooled—the motor is cooled by low-temperature suction gas, eliminating the need for an external cooling fan. Equipped with high-efficiency ring valves and high-torque motors, combined with an internal motor protection device, these compressors lay the foundation for high quality and long service life. Factory-charged with mineral oil (160P) and dry nitrogen holding charge, featuring Rotalock connections for easy installation and maintenance. A large internal free volume effectively resists liquid slugging risks.
Advantage:
Native R22 Compatibility: Designed exclusively for R22 with perfect mineral oil lubrication matching. No oil change needed for direct use in R22 systems—the most economical and reliable native solution for existing R22 stock markets.
High Efficiency: COP reaches 2.93–3.07 (MT51HK peaks at 3.07). Optimized piston clearances achieve 92% volumetric efficiency. Patented valve plate design reduces airflow resistance, with EER reaching 3.2–3.5 W/W.
Liquid Slug Resistance: Large internal free volume tolerates occasional liquid refrigerant return without catastrophic damage.
Wide Operating Range: Evaporation temperature from -40°C to +10°C, max condensing temperature 60°C, ambient range -30°C to +45°C. Noise below 65 dB(A).
Benefit: For R22 maintenance and replacement markets, MT means true plug-and-play—no oil changes, no piping modifications, no re-commissioning. For cost-sensitive contractors and OEMs, the mature design means lower failure rates and reduced service costs. For end users, COP 2.93–3.07 controls electricity expenses while triple-seal protection ensures long-term stability. Standardized Rotalock interfaces enable quick changeover.
IV. Application Scenario Quick-Selection Guide
| Application Scenario | Recommended Model | HP | Key Advantage |
| Small cold storage, milk tanks, beverage coolers | MT45HJ | 4 | 10.8kW, COP 2.98 |
| Medium cold storage, food retail | MT51HK | 4.5 | 12.3kW, COP 3.07 (highest) |
| Medium cold storage, process cooling | MT57HL | 5 | 13.7kW, 96.13cc displacement |
| Medium cold storage, ice machines | MT65HM | 5.5 | 15.8kW, 107.71cc displacement |
| Large cold storage, food processing | MT73HN | 6 | 17.9kW, 4-cyl smooth operation |
| Large cold storage, industrial cooling | MT81HP | 7 | 20.3kW, 4-cyl max capacity |
Selection Tip: For R22 systems, choose MT series from MT45HJ (4 HP) to MT81HP (7 HP) in ascending order. Small capacity: 45/51; medium: 57/65; large: 73/81.
V. Frequently Asked Questions (FAQ)
Q1: What refrigerant and lubricant does the MT series use?
The MT series is designed exclusively for R22 refrigerant, factory-charged with mineral oil (160P). R22 systems must use mineral or alkylbenzene oil—do NOT mix with POE ester oil.
Q2: Can MT series compressors replace MTZ series?
Direct replacement is NOT possible. While mechanically identical, the difference lies in factory lubricant—MT uses mineral oil (R22), MTZ uses POE ester oil (HFC refrigerants). Interchanging requires a complete oil change; failure to do so will cause lubrication failure and compressor damage.
Q3: What is the maximum working pressure of MT series compressors?
Maximum high-side working pressure is 29.4 bar (27.8 bar for some smaller models); low-side is 22.6 bar (model-dependent).
Q4: What is the operating temperature range of the MT series?
Evaporation temperature range: -40°C to +10°C. Maximum condensing temperature: 60°C. Ambient temperature range: -30°C to +45°C.
Q5: Why do MT73HN and MT81HP feature 4-cylinder design?
MT73HN (6 HP) and MT81HP (7 HP) use 4-cylinder design for smoother operation, lower vibration and noise compared to 2-cylinder models—ideal for large cold storage and industrial cooling where operational quality matters.
The R22 System Buyer's Checklist: 5 Reasons the Danfoss Maneurop® MT Series Should Be Your Next Compressor
Specifying a replacement or new-build compressor for R22 systems shouldn't be a guessing game. Use this quick checklist to see if the MT series aligns with your requirements:
☐ You need true plug-and-play replacement. No oil changes, no piping mods, no re-commissioning. Factory-charged mineral oil (160P) means the MT drops into existing R22 systems exactly as-is.
☐ Your application demands 4–7 HP with proven reliability. From walk-in coolers to milk tanks to process chillers, the MT series covers 10.8–20.3 kW with COPs up to 3.07. Decades of field-proven operation in commercial refrigeration.
☐ Liquid slugging is a concern in your system. Large internal free volume design tolerates liquid refrigerant return—no catastrophic failure from the occasional slug.
☐ You operate in extreme ambient conditions. With an evaporation range of -40°C to +10°C and ambient tolerance from -30°C to +45°C, the MT keeps running where others stall.
☐ Noise matters in your installation environment. At under 65 dB(A), these units won't disrupt customer-facing retail or food service spaces.
Checked 3 or more? The MT series is your answer.
Should you require a model cross-reference chart, volume pricing, or delivery lead-time confirmation, please feel free to contact us at any time. Upon receiving your inquiry, our Application Engineering team will respond with the utmost priority, providing you with precise selection support and tailored commercial solutions. We look forward to establishing a long-term partnership with you.
III. Core Technical Advantages
