Danfoss NRV and NRVH Check Valves
Version 2
Introduction
NRV and NRVH piston type check valves are designed for installation in commercial refrigerating systems and in residential or industrial air conditioning plants. They are used to control the unidirectional flow of refrigerant so as to prevent backflow.
Features
- Available in both straightway and angleway versions, which are easy to connect.
- Hermetic tight design for solder versions with low risk of external leakage.
- Built-in damping piston that makes the valves suitable for installation in lines where pulsation can occur, e.g., in the discharge line from the compressor.
- NRVH type check valve has a stronger spring and is recommended for use with compressors in parallel (i.e., power packs) where a higher level of pulsation and vibration is expected.
- Low pressure drop during operation.
- Oversize connections provide flexibility in use.
Functions
NRV/NRVH valves control the unidirectional flow of refrigerant to prevent backflow. For selecting the right Danfoss check valve, using Coolselector®, a Danfoss calculation and selection software, is recommended. When dimensioning and selecting Danfoss check valves for mounting into the compressor discharge line, it is important to be aware of the following:
The differential pressure across the valve must always be higher than the given minimum pressure drop at which the valve is open. This also applies to lowest capacities for compressors with capacity regulation. The NRVH type check valve, with its stronger spring, is recommended for compressors in parallel (i.e., power packs) where higher levels of pulsation and vibration are expected.
Applications
Typical applications for NRV and NRVH valves include:
- Cold room
- Heat pump
- VRF
- Chiller
Figure 1: Application Diagram Description: The diagram illustrates a typical refrigeration system. It shows a compressor, a check valve (NRV/NRVH) on the discharge line, a condenser, an expansion device, and an evaporator. Refrigerant flow is indicated by colored lines (e.g., red for high-pressure liquid, blue for low-pressure gas).
Media and Refrigerant Compatibility
Table 1: Media lists valve types, connection types, maximum working pressures, and compatible refrigerants. The valves support a wide range of refrigerants including R134a, R22, R404A/R507, R407 series, R410A, R448A, R449A/B, R450A, R452A/B, R454A/B/C, R455A, R513A, R515B, R516A, R1233zd(E), R1234ze(E), R1234yf, R290, R32, R600, and R600a. Specific notes indicate compatibility with flammable refrigerants and limitations for certain types like R32 and R1234ze.
Refrigerant Oil: POE, PAG (PVE, PAO) are suitable.
Note: For a complete list of approved refrigerants, visit store.danfoss.com. The product is approved for specific refrigerants (R290, R32, etc.) based on ignition source assessment according to EN ISO 80079-36. NRV/NRVH is not suitable for oil line applications. Flare/face seal connections are approved only for A1 and A2L refrigerants.
Product Specification
Technical Data
Table 2: Technical Data
| Max. working pressure | See ordering table |
| Media temperature range | See ordering table |
| Environmental transport/storage temperature and humidity | -40 – 65 °C / -40 – 150 °F. Air humidity: RH≤95% |
| Flow direction | Single flow |
| Serviceable | No |
Identification
Product data is available on the product and box label. Table 3 & 4 detail the content of box and product labels, including product name, code number, type, connection size, max. working pressure, manufacturing site, and temperature range.
Design and Materials
The fluid pressure opens the valve, while reverse flow closes it. A sealing disc, activated by a spring, controls the valve's open/close state. The spring force determines the differential opening pressure. When the refrigerant flow's differential pressure exceeds the minimum opening pressure, a piston compresses the spring, opening the valve. NRV/NRVH valves feature a damping piston for improved performance in lines with pulsations, such as the compressor discharge line.
Valve Configurations and Dimensions
Figure 2: Flare straightway version Description: Shows a straightway check valve with flare connections, indicating dimensions L (length) and S (spanner flats).
Table 6: Flare straightway version provides details on valve type, SAE Flare size, thread, length (L), spanner flats (S), and net weight.
Figure 3: Solder straightway version Description: Illustrates a straightway check valve with solder ODF connections, showing overall length (L) and other dimensions (L1, ØD).
Table 7: Solder straightway version lists valve type, connection size (in/mm), tolerance, dimensions (L, L1, ØD), and net weight.
Figure 4: Solder angleway connection Description: Depicts an angleway check valve with solder ODF connections, showing dimensions H, H₂, L₁, L₂, and ØD.
Table 8: Solder angleway connection provides valve type, connection size (in/mm), tolerance, dimensions (H₁, H₂, L₁, L₂, ØD), and net weight.
Connections
Standard NRV/NRVH versions are available in straightway and angleway configurations with Flare or Solder ODF connection types in various sizes. Solder versions use copper connections, while flare versions use brass connections.
Table 5: Connections details the available inlet/outlet connection types (Flare, Solder ODF) and sizes in both mm and inch formats.
Dimensions and Weights
Dimensions for major versions are provided. Downloadable dimension drawings for specific code numbers are available on the Danfoss store. Weights vary by design and are also available on the Danfoss store.
Ordering Information
NRV/NRVH code numbers are standard, made-to-stock items. Options for made-to-order include mechanical connection type and size. Multipacks contain individually packed items, while industrial packs contain multiple items not individually packed and cannot be broken down.
Table 9: Straightway Flare Version without flare nut lists valve types, SAE Flare specifications, minimum opening pressure differential (Ap), Kv, Cv, maximum working pressure, media temperature range, PED categories, and multi/industrial pack details.
Table 10: Angleway Solder ODF Version, PS = 46 bar provides similar ordering and technical data for angleway solder ODF versions.
Table 11: Angleway Solder ODF Version, PS = 49 bar details ordering and technical data for angleway solder ODF versions at 49 bar.
Table 12: Straightway Solder ODF Version presents ordering and technical data for straightway solder ODF versions.
Certificates, Declarations, and Approvals
The document lists certificates, declarations, and approvals for this product type. Individual code numbers may have varying approvals. For the most current status, check danfoss.com or contact a local Danfoss representative.
Table 13: Certificates, declarations, and approvals includes file names, document types (e.g., EAC Declaration, PED, RoHS), document topics, and approval authorities (e.g., EAC RU, Danfoss, UL).
Online Support
Danfoss offers comprehensive support, including:
- The Danfoss Product Store: A one-stop shop for product information, specs, documentation, certifications, and accessories. Browse at store.danfoss.com.
- Find technical documentation: Access data sheets, certificates, manuals, guides, 3D models, and more at www.danfoss.com/en/service-and-support/documentation/.
- Danfoss Learning: A free online platform with courses for engineers, installers, and technicians. Create an account at www.danfoss.com/en/service-and-support/learning/.
- Get local information and support: Find local Danfoss websites for product availability and regional news at www.danfoss.com/en/choose-region/.
- Coolselector®2: Software for selecting components for HVAC/R systems, allowing calculations based on operating conditions. Download for free at coolselector.danfoss.com.
Danfoss reserves the right to alter products without notice. Trademarks are property of their respective companies.
