Danfoss NRVT Data sheet

Data Sheet

Check valve

Type NRVT

For high pressure CO2 application

NRVT piston type check valves is designed for installation in discharge line to prevent refrigerant migration to protect compressor and enable the pressure equalization of rotary compressor before startup. In the meanwhile this valve can be used in other installation positions of CO2 systems such as hot gas and

suction lines.

Features:

• Stable operation covering full map of compressor

• Ful•lls high temperature and pressure requirements for the discharge lines used in Transcritical CO2 systems

◦ Rupture proof, optimized TIG welding

◦ Specially-selected sealing material for CO2

refrigerant

• Hermetic brass body design

• Compatible to connect both copper/stainless steel tubes

• In compliance to PED & UL regulations

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Check valve, type NRVT

Applications

Typical applications for NRVT valves are:

•CO2 MiniPack

•CO2 CDU BLDC

Pressure Equalization/ Relief

•To start rotary BLDC compressors, it is necessary to equilize pressure between discharge and suction line.

•In single compressor solution it is possible to manage equalization via high pressure valve and bypass valve

•In system with parallel mounted compressors, It is necessary to install on each compressor check valve in discharge line and solenoid valve to bypass high pressure to suction line

Figure 1: Pressure Equalization/ Relief

CCMT Light

CCMT Light

NRVT

EVT

AKVP

NRVT

EVT

AKVP

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Check valve, type NRVT

Discharge line – compressors mounted in parallel

•If using an individual oil separator for each compressor – for protection against back condensation of refrigerantin the separator with the compressor shut-o„.

•If the cylinder heads of the compressors can cool down below the condensing temperature at standstill

•Check valve for a common oil separator (installation position towards the condenser):

–If there is a danger of back condensation from the condenser or liquid receiver

–Systems with long shut-o„ periods

Figure 2: A diagram of Discharge line – compressors mounted in parallel

CCMT

NRVT

CCMT

NRVT

AKVP

NRVT

AKVP

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Check valve, type NRVT

Hot Gas Defrost

Figure 3: A diagram of Hot Gas Defrost

Liquid line

Suction line

Hot Gas line

Defrost drain line

Low Pressure lift Multi Ejector / cold & warm ambient temperature

Optimal solution for smaller commercial refrigeration systems

•In colder ambient conditions system operates as a standard booster system

•Ejector is simply controlling the high pressure as a high pressure valve according to the optimal COP Gas Cooler pressure algorithm

•Pressure in the receiver as pressure di„erence between the receiver and Po-MT evaporator suction pressure

•Receiver pressure controlled by •rst gas by-pass valve CCMT#1, second gas by-pass valve CCMT#2 is closed

•Check valve on MT evaporator suction line is open

•In warmer ambient conditions temperature out of the gas cooler is high and corresponding optimal pressure in gas cooler is high too, so ejector can lift all gas mass flow from MT evaporators through the ejector to the receiver

•Check valve in suction line between compressors and MT evaporators is closed due to pressure difference

•The pressure in the receiver is result of the ejector performance.

•Both gas by-pass valves CCMT#1 & CCMT#2 are open to minimize pressure loses

•MT compressors are controlled based on Po-MT pressure sensor and Psuc-MT is protection

© Danfoss | Climate Solutions | 2022.02

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