1. Gas and Maintenance Safety in HVACR
Dr Jason Shilliday
Mr Nicolas Abry

2. Refrigerant and Maintenance Safety in HVACR
Refrigerant Safety and Regulations in HVAC Design
Fall Protection Systems and Standards for HVAC Access
Gas Detection Technologies for Buildings

3. Refrigerant Safety and Regulations in HVAC Design
Dr Jason Shilliday

4. Refrigerants Industry Standards Common Applications
Content
Refrigerants
Industry Standards
Common Applications
Technology Overview
Recommended features

5. Refrigerants
Refrigerants are natural or synthetic chemicals with the correct pressure / temperature relationships to be used in a vapor compression cycle to generate a cooling effect.
Refrigerants have poor warning properties, no smell.
An uncontrolled refrigerant leak in an enclosed space can result in an immediately dangerous to life or health (IDLH) low-oxygen atmosphere. 
Costly implications with loss of refrigerant and regulatory fines. 

6. Refrigerant History Time Fluorocarbons Natural Refrigerants
Ozone Depletion
(Montreal Protocol)
1990
Non- Ozone Depletion
(Kyoto Protocol)
2006
High ODP
CFC’s
High ODP
HCFC’s
High GWP
Lower GWP
HFC
HFO
R11
R12
R500
R22
R123
R134a
R410a
R407C
R32
R1234yf
R1234ze
R290 Propane
R717 Ammonia
R744 CO2
R600 Butane
Water
ODP
GWP
Flammable
Toxic
Energy Efficiency
Gas Price
GWP – Global Warming Potential
ODP – Ozone Depletion Potential

7. Refrigerant Classification
Classified in ASHRAE
Designation and Safety Classification of Refrigerants
Flammability (when tested at 140°F (60°C) and 14.7 psia (101.3 kPa)
1 – No flame propagation
2L – Lower flammability
2 – Flammable
3 – Higher Flammability
Toxicity
Class A – OEL of 400ppm or greater ADD GAS EXAMPLES
Class B – OEL of less then 400ppm ADD RCL
OEL (Occupational exposure limit)

8. Refrigerant Leaks Refrigerant Leaks
2011 – Charlestown, USA – 1 person dead, 3 injured. Engineers where removing in the AC units from a confined space.
2013 – Washington DC – 1 person died in a hospital due to leak from AC system into a confined space.
2015 – Hammington, USA – Eight people injured due to refrigerant leak from AC system into a business premises.
2016 – Victoria, Australia – 2 men died in an explosion caused by the flammable refrigerant in an AC system.
2018 – Chennai, India – Family of 3 die of asphyxiation due to leak from AC system

9. Refrigerant Refrigerants prices can range from $15 - $100 per kg
On average, two chillers per office building, chillers can hold 1000 kg. of R134a each. Leak costs, $ $100,000.
The loss of refrigerant + recovery process = loss in productivity and cooling for the end user.
Damage to frozen foods or pharmaceutical drug stores can be very costly due to shut-down.

10. Refrigerant

11. Design Guidelines and Regulations

12. Design guidelines and regulations
ASHRAE 15
ASHRAE 34
EN 378

13. ASHRAE 15 – Safety standard for Refrigeration Systems
ASHRAE Standard 15 is directed toward the safety of persons and property on or near the premises where refrigeration facilities are located. Personal injury and property damage from inadequate precautions may occur from a number of origins, such as
rupture of a part with risk from flying debris;
fire resulting from or intensified by burning or deflagration of escaping refrigerant or lubricant.
Personal injury resulting from the accidental release of refrigerants may also occur from
suffocation from heavier-than-air refrigerants in inadequately ventilated spaces;
narcotic and cardiac sensitization effects

14. ASHRAE 15 – Safety standard for Refrigeration Systems
Occupancy Classification
Institutional / Public Assembly / Residential / Commercial
Refrigerant System Classification
Direct / Indirect / Closed systems
Refrigerant Safety Classification
ASHRAE 34

15. ASHRAE 15 – Safety standard for Refrigeration Systems
Restrictions on Refrigerant Use
Refrigerant Concentration Limits (RCL)
The concentration of refrigerant in a complete discharge of each independent circuit of high-probability systems shall not exceed the amounts shown in ASHRAE Standard 34
Exceptions – Institutional occupancies – 50% of RCL
Exceptions – Refrigerant detectors are installed
Exceptions – Self Contained systems
ASHRAE 34 Designation and safety classification of refrigerants

16. ASHRAE 15 – Safety standard for Refrigeration Systems
Restrictions on Refrigerant Use
Volume Calculations
Group A2L refrigerant for Human Comfort (2019)
Refrigerant detector when refrigerant charge exceeds (0.212 x LFL)
When occupancy classification is intuitional
Installation Restrictions
Machinery Room General Requirements
Each refrigerating machinery room shall contain a detector, located in an area where refrigerant from a leak will concentrate.
Airflow – No airflow from or to an occupied space from a machinery room
Further restrictions on A2L, B2L and Ammonia (R717)
Details on Ventilation rates due to leakage.

17. ASHRAE 15 – Safety standard for Refrigeration Systems
Design and Construction
Design pressures
Pressure relief devices
Pressure vessels
Refrigerant discharge relief locations

18. ASHRAE 34 ASHRAE Standard 34 describes a shorthand way of naming
refrigerants and assigns safety classifications and refrigerant
concentration limits based on toxicity and flammability data.

19. ASHRAE 34
Refrigerant numbers / OEL / RCL Safety Group

20. Refrigerant Classification
Classified in ASHRAE
Designation and Safety Classification of Refrigerants
Flammability (when tested at 140°F (60°C) and 14.7 psia (101.3 kPa)
1 – No flame propagation
2L – Lower flammability
2 – Flammable
3 – Higher Flammability
Toxicity
Class A – OEL of 400ppm or greater ADD GAS EXAMPLES
Class B – OEL of less then 400ppm ADD RCL
OEL (Occupational exposure limit)

21. EN378

22. EN378 – Refrigerating systems and heat pumps
Part 1 – Basic requirements, definitions, classification and selection criteria
Part 2 – Design, construction, testing, marking and documentation
Part 3 – Installation site and personal protection
Part 4 – Operation, maintenance, repair and recovery

23. EN378 – Refrigerating systems and heat pumps
Part 1 – Basic requirements, definitions, classification and selection criteria
Access Categories – a – General access – Hotels, schools, home
b – Supervised access – Business offices
c – Authorized access – Manufacturing
Location Classification – Class I – Equipment in occupied space
Class II – Compressors in machine room / open air
Class III – Machinery room / Open air
Class IV – Ventilated Enclosure

24. EN378 – Refrigerating systems and heat pumps
Part 1 – Basic requirements, definitions, classification and selection criteria
Allowable Charge -

25. EN378 – Refrigerating systems and heat pumps
Part 1 – Basic requirements, definitions, classification and selection criteria
Alternative for risk management of refrigerating systems in occupied spaces
If the value of the total charge divided by the room volume exceeds the QLMV appropriate measures shall be taken:
Gas detection device
Safety shut off valves and safety alarm
Ventilation (natural or Mechanical)

26. Applications

27. Application – Hotel, Schools, Offices
Example:
Hotel room with ducted indoor unit attached to a DX/VRF/VRV system with R410A
Rooms size: 7.5m x 4m x 2.2m
Room Volume = 66 m3
QLMV= 0.42 kg/m3 (EN378)
RCL = 0.42 kg/m3 (ASHRAE 34)
Max system charge =
66 x 0.42 = kg
If the VRF/VRV system has a total refrigerant charge above kg then a gas detector should be installed

28. Application – Hotels, Schools, Offices
Example:
Hotel room with ducted indoor unit attached to a DX/VRF/VRV system with R32 (A2L)
Rooms size: 7.5m x 4m x 2.2m
Room Volume = 66 m3, room size is irrelevant
ASHRAE 34 (2019)
A refrigerant detector provided when refrigerant charge exceeds 6 x LFL (kg) where LFL is in kg/m3 = 6 x 0.3 = 1.8 kg
EN378 (2016)
Alternative provisions in conjunction with gas detector
When greater than m1xLFLx1.5, (m1 = 4) = 4 x 0.3 x1.5 = 1.8kg

29. Application – Hotels, Schools, Offices

30. Application – Hotels, Schools, Offices

31. Application – Hotels, Schools, Offices

32. Application – Machine Rooms
A gas detector should be located in the machinery room where a leak could concentrate.
The gas detector must activate an audible and visual alarm inside the machinery room and outside each entrance to the machinery room.
The gas detector must activate the mechanical ventilation system.
The activation of the audible and visual alarm and the mechanical ventilation system is to he triggered at a gas value not greater than the corresponding TLV-TWA of the particular refrigerant.

33. Application – Machine Rooms

34. Application – Machine Rooms

35. Technology

36. Technology – System Type
Passive Diffusion
Process whereby particles of liquids, gases, or solids intermingle as the result of spontaneous movement caused by thermal agitation and in dissolved substances move from a region of higher to one of lower concentration.
Diffusion Point Sensors
PPM, %LEL, % O2
Diffusion Open Path Infrared for
ppm meters, %LEL

37. Technology – System Type
Sample Draw
Central Monitoring Station. Air pump draws sample to the monitor and continually repeats the sequence

38. Technology – Detection type
MOS – Metal Oxide Semi-Conductor
MOS sensors detect concentration of gases by measuring the resistance change of the metal oxide due to adsorption of gases. Atmospheric oxygen residing on the MOS surface is reduced by the target gases, allowing more electrons in the conduction band of the metal oxide material.
Thermistor
Electrodes
Substrate
Film
O2 O O O2
Heater
e e e e -
e e e e -
H2S O H2S O2
e - e - e - e - e - e - e -
e - e - e - e - e - e e -

39. Technology – Detection type
MOS – Electrochemical
Target gas is absorbed through the capillary diffusion barrier. A gas permeable membrane reacts at the surface of the sensing electrode. The number of electrons given off is proportional to the gas concentration
Electrolyte
Reservoir
Counter Electrode
Reference Electrode
Sensing Electrode
(with catalysts)
O-Ring
Seal
Gas Permeable
Membrane
Gaseous
Diffusion
Barrier

40. Technology – NDIR – Non-dispersive infrared
When using an absorptive infrared monitor, a gas sample is introduced into the monitor’s measurement chamber and is exposed to infrared light. The detector compares the amount of light transmitted through the sample and reference cells. The monitor can determine the gas concentration that is present in the sample by the ratio of light that is transmitted by the sample gas to the light that is transmitted by the reference gas.

41. Technology – PAIR – Photo Acoustic Infrared
When using a photoacoustic infrared instrument, a gas sample is introduced into the monitor’s measurement chamber and the sample is exposed to a specific wavelength of infrared light. If the sample contains the gas of interest, that sample will absorb an amount of infrared light proportional to the gas concentration that is present in the sample.
A highly sensitive microphone is located inside the photoacoustic infrared monitor to detect even the smallest of pressure pulses, enabling detection of even the lowest gas levels.

42. Technology – PAIR – Photo Acoustic Infrared

43. Recommended features Refrigerant Leak Detection Systems
Infra-red Technology – Long sensor life
PAIR – Stability and no downtime due to comparative sample
Low Level Detection - 1ppm for Machine room / 50ppm others.
Full communication outputs – Modbus / Bacnet / Analogue
Cloud Connectivity – Remote monitor multiple sites / Alarms
Sample system for Machine Rooms – Early detection
Dispersive for VRF
Annual Calibrations and Bump tests to check detectors are working

44. QUESTIONS ?