Danfoss MT / MTZ / NTZ Compressors: Instructions

1 - Introduction

These instructions apply to Maneurop® MT, MTZ & NTZ compressors used in refrigeration systems. They cover essential safety and proper usage information for these products.

2 - Handling and Storage

Handle the compressor with care. Use the handles provided on the packaging. Use appropriate and safe lifting equipment. Store and transport the compressor in a vertical position. The storage temperature should be between -35 °C and 50 °C. Do not expose the compressor or packaging to rain or corrosive environments.

3 - Safety Precautions Before Installation

• Never operate the compressor in a flammable environment.
• The ambient temperature around the compressor must not exceed 50 °C during idle periods.
• Install the compressor on a horizontal, level surface with a tilt of less than 3°.
• Ensure the power supply matches the compressor motor specifications (refer to the nameplate).
• When installing MTZ or NTZ compressors, use equipment specifically designed for HFC refrigerants, which has never been used with CFC refrigerants.
• Use clean, dry copper tubing that meets refrigeration equipment requirements, along with silver-alloy brazing material.
• Use clean, dry system components.
• The piping connected to the compressor must be flexible in 3 directions to dampen vibration.

4 - Installation

• Slowly release the nitrogen used for filling the compressor via the Schrader valve.
• Remove seals when brazing Rotolock fittings.
• Always use new seals during installation.
• Connect the compressor to the system as quickly as possible to prevent moisture in the ambient air from contaminating the oil.
• Avoid releasing material into the system when cutting pipes. Never drill holes in locations where burrs cannot be removed.
• Brazing should be done carefully using nitrogen as a protective gas.
• Connect the necessary safety and control devices. If a Schrader valve is used for this, remove the internal needle valve.

5 - Leak Detection

• Never pressurize the circuit with oxygen or dry air. This can cause fire or explosion. ⚠️
• Do not use dye for leak detection.
• Test the entire system for leaks.
• The test pressure on the low-pressure side must not exceed 25 bar.
• If a leak is found, repair it and repeat the leak detection process.

6 - Vacuuming

• Never use the compressor for system evacuation.
• Connect the vacuum pump to both the low and high-pressure sides.
• Evacuate the system until the absolute pressure is 500 µm Hg (0.67 mbar).
• Do not use a megohmmeter or apply power to the compressor while it is under vacuum, as this can cause internal damage.

7 - Electrical Connections

Switch off and isolate the main power supply. Refer to the wiring instructions on the reverse side (not provided in OCR). The compressor is protected against overcurrent and overheating by an internal overload protector. Comply with local electrical regulations. The compressor must be grounded. All electrical components must be selected according to local standards and regulations applicable to compressors.

8 - System Filling

Keep the compressor power off. Add refrigerant in liquid form to the condenser or liquid receiver. The filling quantity should be as close as possible to the system's nominal charge to avoid the compressor operating with too low suction pressure and excessive superheat. Keep refrigerant charge below 2.5 kg per compressor cylinder if possible. If this limit is exceeded, protect the compressor from liquid by pumping down or using a liquid separator. Never leave the charging cylinder connected to the circuit, as this can lead to overfilling.

9 - To be Verified Before Commissioning

• Use safety devices such as a safety pressure switch or a mechanical relief valve that comply with both general and local regulations and safety standards. Ensure they function correctly and their settings are properly adjusted. ⚠️
• Verify that the setpoints of high-pressure switches and relief valves do not exceed the maximum operating pressure of any system component.
• A low-pressure switch is recommended to prevent vacuum operation. The minimum setting is 0.1 bar.
• Check that all electrical connections are properly secured and comply with local regulations.
• If a crankcase heater is required, it must be switched on at least 12 hours before the first start-up or after a long period of inactivity.

10 - Start-up

• All service valves must be open.
• Equalize pressures on the high and low-pressure sides.
• Apply power to the compressor. It must start quickly. If not, immediately disconnect power. Incorrect wiring in a single-phase circuit can cause a short circuit within seconds.
• If the compressor does not start, check the wiring connections and terminal voltage.
• If the internal overload protector trips, it must cool down to 60 °C before restarting. Depending on the ambient temperature, this may take several hours.

11 - Checks During Operation

• Check current and voltage.
• Check suction gas superheat, which reduces the risk of liquid slugging.
• If a sight glass is present, check the oil level at the beginning and during operation to ensure the oil level remains visible.
• Check all pipes for abnormal vibration. Movements exceeding 1.5 mm require corrective action, such as pipe clamps.
• If necessary, liquid refrigerant can be added to the system from the low-pressure side, as far as possible from the compressor. The compressor must be running during this procedure.
• Do not overfill the system.
• Never release refrigerant into the atmosphere.
• Before leaving the installation site, perform a general inspection of the assembly for cleanliness, noise level, and leaks.
• Record the type and quantity of refrigerant and the machine's operating values for future reference.

12 - Maintenance

Internal pressure and surface temperature are dangerous and can cause permanent injury. Personnel responsible for maintenance must have appropriate skills and tools. Pipe temperatures can exceed 100 °C and may cause severe burns. ⚠️

Ensure that periodic maintenance inspections are carried out on the system to guarantee its reliability and comply with local regulations.

To prevent compressor problems related to the system, we recommend the following periodic maintenance actions:

• Ensure safety devices are functioning and their settings are properly adjusted.
• Ensure the system is leak-free.
• Check compressor current.
• Verify that the system is operating in accordance with previous maintenance records and environmental conditions.
• Check that all electrical connections are still securely fastened.
• Keep the compressor clean and check its casing, pipes, and electrical connections for rust or oxidation.

13 - Warranty

Always state the model and serial number when making complaints about this product. The product warranty may be voided in the following cases:

• Missing nameplate.
• External modifications; specifically drilling, welding, broken feet, and signs of impact.
• Compressor opened or returned with open pipe connections.
• Compressor shows signs of rust, water, or leak detection fluid.
• Refrigerant or oil used is not approved by Danfoss.
• Deviation from recommended installation, operation, or maintenance instructions.
• Use in mobile applications.
• Use in potentially explosive atmospheres.
• Failure to state the model or serial number when claiming warranty compensation.

14 - Disposal

Danfoss recommends that compressors and their oil content be delivered to a suitable recycling company.

Technical Data and Diagrams

Compressor Overview and Specifications

The document shows a diagram of the Danfoss reciprocating compressor. Key specifications are labeled:

• Model No.: MTZ80HP4AVE (Example)
• Serial No.: AB1001234567 (Example)
• Refrigerant: R134a-R507A-R404A-R407C

Torque values for pipe connections are provided:

• 1": 80 Nm
• 1"1/4: 90 Nm
• 1"3/4: 110 Nm

Other labels on the diagram include:

• A: Model
• B: Serial Number
• C: Refrigerant
• D: Supply voltage, starting current & maximum current
• E: Operating pressure and temperatures
• F: Lubricant

The compressor is marked with CE and CUS certifications.

Electrical Ratings (Example from nameplate):

• 380-400V 3~50 Hz
• 460V 3~60 Hz
• MLR 80A
• 18A MAX
• THERMALLY PROTECTED
• P.E.D.
• LP side / HP side pressures: 22.6 bar / 29.4 bar
• TS max: 50 °C / 68 °C
• TS min: -35 °C / -35 °C
• Volume: 16.5 l / 0.61 l
• Lubricant: P.O.E. 160 PZ

Electrical Connection Diagrams

Diagrams illustrate typical electrical connections for compressors:

• 1~ PSC (Single-Phase Power Supply Capacitor Start): Shows connections for a 230V single-phase supply, including components labeled TH (Thermostat), RC (Running Capacitor), and IOL (Motor Protector).
• 1~ CSR (Single-Phase Capacitor Start/Run): Shows connections for a 230V single-phase supply, including components labeled TH (Thermostat), SR (Starting Relay), SC (Starting Capacitor), RC (Running Capacitor), and IOL (Motor Protector).
• 3~ (Three-Phase): Shows a general diagram for a three-phase connection, with terminals T1, T2, T3 and labels TH (Thermostat), IOL (Motor Protector).

A general warning states: "Do not operate the compressor without the terminal cover." ⚠️

Operating Range Limits

The table below details the operating limits for different compressor models and refrigerants:

Superheated gas temperature must be below 130 °C.

* When MT compressors are used with R417A, the factory-added mineral oil 160P must be replaced with polyester oil 160PZ.