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Installation Guide for Danfoss NRVT Check Valve

Quick installation guide for the Danfoss NRVT check valve. Includes mounting orientation diagrams for hard and soft springs, brazing requirements, and safety specifications for R744 (CO2) systems.

Table of contents

Manual images

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Possible orientations for hard spring NRVT valves. Page 1 Risk orientations for soft spring NRVT valves. Page 1 Brazing procedure for the NRVT valve. Page 1

Important Information

The Danfoss NRVT check valve is specifically designed for use in R744 (CO2) refrigeration systems. Installation must be performed by authorized personnel only, as improper installation or closing can lead to the build-up of excessive pressure in the system.

Safety Warnings

  • Refrigerant Compatibility: This valve is UL certified for use in CO2 (R744) systems only.
  • Pressure Requirements: The design pressure must not be less than the value outlined in section 9.2 of ANSI/ASHRAE 15 for the refrigerant used in the system.
  • Authorized Personnel: Only qualified individuals are permitted to install this valve.

Mounting Orientations

The installation requirements differ based on the spring type of the valve:

Possible orientations for hard spring NRVT valves.
Possible orientations for hard spring NRVT valves.
Risk orientations for soft spring NRVT valves.
Risk orientations for soft spring NRVT valves.
  • Hard Spring: Can be mounted in vertical, horizontal, or inclined positions.
  • Soft Spring: There is a risk of internal leaks if not installed correctly. Ensure the valve is installed within a 45-degree angle from the vertical position.

Brazing Instructions

When brazing the valve into the system, follow these guidelines to prevent damage:

Brazing procedure for the NRVT valve.
Brazing procedure for the NRVT valve.
  • Material: Use a minimum of 5% silver (Ag) alloy.
  • Temperature: Do not exceed 150 °C (302 °F) during the brazing process.
  • Protection: Purge the system with Dry N2 (Nitrogen) during the brazing process to prevent oxidation.

Technical Specifications

  • Refrigerant: R744 (CO2)
  • Temperature Range (TS): -40 °C to 150 °C (-40 °F to 302 °F)
  • Max. Working Pressure (PS/MWP): 140 bar / 2031 psig

Manufacturer information

Danfoss A/S

Brand profile
Manufacturer website https://www.danfoss.com Support https://www.danfoss.com/en/service-and-support/ Manufacturer manuals https://www.danfoss.com/en/service-and-support/downloads/

Practical help

Common problems

Internal leak risk (Soft spring)

Ensure the valve is installed within a 45-degree angle from the vertical position.

Excessive pressure build-up

Installation must be performed by authorized personnel only to ensure proper system integration.

Before use

  • Verify the system uses R744 (CO2) refrigerant.
  • Confirm the design pressure meets ANSI/ASHRAE 15 section 9.2 requirements.
  • Identify if the valve is a hard spring or soft spring model.
  • Ensure brazing equipment is ready with Dry N2 for purging.

Specs in practice

Max. Working Pressure
140 bar / 2031 psig is the maximum pressure the valve can safely handle.
Temperature Range
-40 °C to 150 °C (-40 °F to 302 °F) is the operating temperature limit for the valve.
Brazing Alloy
Minimum 5% silver content is required for a secure and compliant joint.

Images and diagrams

  • Hard spring valves support vertical, horizontal, and inclined mounting.
  • Soft spring valves must be mounted within 45 degrees of the vertical axis to avoid internal leaks.
  • Brazing requires purging with Dry N2 and keeping the valve temperature below 150 °C.

Model compatibility

  • UL certified for CO2 (R744) systems only.

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David Miller

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