Find technical information on refrigeration, air conditioning and heat pumps

Looking for previously purchased publications?

Search publications 1899-2013 in our archives

Safety Code of Practice Flammable Lower Toxicity Refrigerants (Groups A2L, A2 and A3) HFO & Hydrocarbon

IOR report flammable front

Non-member price: £48.00

Member price: Free

Safety Code of Practice Flammable Lower Toxicity Refrigerants (Groups A2L, A2 and A3) HFO & Hydrocarbon

This publication provides essential industry guidance for owners, designers, installers and operators of vapour compression refrigerating systems that use flammable refrigerant. This includes Group A2, A2L or A3 – otherwise known as hydrocarbon and HFO refrigerant.

It covers properties of refrigerants, decommissioning, testing and maintenance as well as design issues with useful appendices such as typical schedules for inspection and maintenance, system register details, machinery rooms, definitions and an updated list of relevant standards. The Code has been prepared by the IOR Technical Committee as a reference source and guide to interpretation of current safety standards such as BS EN378:2016 and legal requirements such as PED, PSSR and PUWER.  

The IOR publishes four Safety Codes of Practice specific to refrigerant type.  

  • Non Flammable, Lower Toxicity Refrigerants Group A1 
  • Flammable Lower Toxicity Refrigerants Group A2L, A2 and A3 
  • Carbon Dioxide R744 
  • Ammonia R717

This Code is supplied as a 114 page PDF.


Addendum added May 2019 - Section 11: CLP and DSEAR

August 2019 - Minor text changes to Appendix F, section 4.1

Members - you must be signed in to download this publication for free

Not a member? Find out how you can join at

Non members - either click on the basket to purchase this item (prices include VAT) or become a member and receive this and other publications for free.


Section 1 –Scope & LIMITATIONS

Section 2 – Relevant Properties of Refrigerants

2.1 Physical Properties

2.2 Chemical Properties and Potential Hazards

Section 3 – Design of Components

3.1 General

3.2 Component Design and Test Pressures

3.3 Compressors

3.3.1 General

3.3.2 Design Criteria

3.3.3 Pressure Testing

3.3.4 Nameplate Data

3.4 Pressure Vessels and Heat Exchangers

3.4.1 General

3.4.2 Design pressures

3.4.3 Test pressures

3.4.4 Nameplate data

3.4.5 Pressure Vessels

3.4.6 Shell and Tube Heat Exchangers

3.4.7 Coil or Grid Exchangers

3.4.8 Plate and Plate & Shell Heat Exchangers

3.5 Liquid Refrigerant Pumps

3.5.1 Design Criteria

3.5.2 Test Pressures

3.5.3 Nameplate Data

3.6 Refrigerant Control Valves and Sensing Devices

3.6.1 General

3.6.2 Design Pressure and Temperature

3.6.3 Manufacturing Tests

3.6.4 Nameplate Data

3.6.5 Shut-Off Valves

3.6.6 Liquid level indication

Section 4 – System Design and Installation

4.1 General

4.2 Material Selection

4.3 Steel Piping Systems

4.3.1 Pipe Materials

4.3.2 Pipe Connections

4.3.3 Pipe Supports and Hangers

4.4 Copper Pipework Systems

4.4.1 Material

4.4.2 Pipe Connections

4.4.3 Pipe Supports and Hangers

4.5 Location and Arrangement of Piping

4.6 Arrangement of Isolating Valves

4.7 Instrumentation

4.7.1 General

4.7.2 Arrangement of Pressure Indicators

4.7.3 Level Indicators on refrigerant receivers

4.7.4 Liquid level glasses

4.8. Protection against Excess Pressure

4.9 Protection against Environmental Effects

4.10 Notification to Local Authorities

4.11 Refrigerant Detection

4.12 System Labelling

4.13 Allowable Refrigerant Charge

4.14 Electrical components

4.14.1 General

4.14.2 Hot surfaces

4.14.3 Precautions against electrical sources of ignition

4.14.4 Non-switching components

4.15 Protection for indirect circuits

4.16 Equipment enclosure or casing

Section 5 – System Testing

5.1 General

5.2 Strength Test Procedure

5.3 Tightness Test Procedure

5.4 Test Certificates

5.5 Leak Simulation Tests for potential sources of ignition

5.5.1 Equipment requirements

5.5.2 Testing Environment

5.5.3 Leakage Simulation

Section 6 – Commissioning of New Installations

6.1 General

6.2 Evacuation and dehydration

6.3 Charging

6.4 Protection devices

Section 7 - Inspection and Maintenance

7.1 General

7.2 System Log

7.3 Routine inspection

7.3.1 General

7.3.2 Logging system performance

7.3.3 Pipework

7.3.4 Compressors

7.3.5 Condensers and evaporators

7.3.6 Liquid pumps

7.3.7 Pressure relief devices and pressure controls

7.4 Major inspection

7.4.1 System

7.4.2 Pipework

7.4.3 Compressors

7.4.4 Pressure Vessels and Heat Exchangers

7.4.5 Refrigerant Pumps

7.4.6 Stop Valves, Safety Valves and Control Devices

7.5 Pressure System Examination

7.5.1 General

7.5.2 Uninsulated vessels and heat exchangers

7.5.3 Insulated vessels and Heat Exchangers

7.5.4 Extended surface heat exchanger and grid coils

7.5.5 Plate heat exchangers

7.5.6 Piping

7.5.7 Pressure test for strength

7.5.8 Extent of tightness test

Section 8 - Documentation

8.1 General

8.2 Risk Assessment

8.3 Health and Safety File

8.4 Written Scheme of Examination and Records

8.5 Commissioning records

8.6 Refrigerant Inventory and F Gas Regulation Requirements

8.7 Contingency Provisions

8.8 The System Register

8.9 System Log

8.10 Instruction Manual

Section 9 - Decommissioning

9.1 General

9.2 Recovered Refrigerant

9.2.1 General

9.2.2 Refrigerant Recovery

9.2.3 Recovery for recycling to another system

9.2.4 Recovery for reprocessing or disposal

Section 10 – References, Standards and Legislation (all refrigerants)

Section 11 – Addendum: CLP and DSEAR

Appendix A - Definitions (Applies to all refrigerants)

Appendix B – Maximum Allowable Pressure and Strength Test Procedure

Appendix C – Pneumatic Strength Pressure Test Procedure

Appendix D – Marking and Name Plate Data

Appendix E - Handling, Transport and Storage of Refrigerant Cylinders

Appendix F – Commissioning of New Installations

Appendix G – Machinery Rooms and Auxiliary Safety Equipment

Appendix H – Typical Schedule for Inspection and Maintenance

Appendix I - Sample details for Register

Appendix J – Sample Compressor Operating Data and System Log

Appendix K – IOR Policy on refrigerant choice

Appendix L - Guidelines for repairs of equipment containing A2L, A2 or A3 refrigerants

Appendix M - Dangerous Substances and Explosive Atmospheres Regulations (DSEAR)

Appendix N – Examples of Maximum Charge Size Calculations