Safe handling of natural refrigerants

“Climate-friendly technology alternatives to
HCFC/HFC”
Safe Handling of Natural Refrigerants
Safety Concerns in Installation and
Maintenance
Tel Aviv, Israel
27th to 28th May 2015
Rolf Huehren, GIZ Prokilma
28/05/2015
Page 1
History of Refrigeration
• Refrigeration relates to the cooling of air or liquids, thus
providing lower temperature to preserve food, cool
beverages, make ice and for many other .
• Most evidence indicate that the Chinese were the first to
store natural ice and snow to cool wine and food.
• Ancient people of India and Egypt cooled liquids in porous
earthen jars.
• In 1834, Jacob Perkins, an American, developed a closed
refrigeration system (vapour compression circuit) using
liquid expansion and then compression to maintain the
cooling effect. He used Ether as refrigerant, in a handoperated compressor, a water-cooled condenser and an
evaporator in liquid cooler. Patented 1835 as Ether-icemachine.
• Unfortunately some machines exploded because of the
formation of highly explosive Peroxide (Ether in reaction with
Oxygen)
Page 2
Harvest Ice
(ca. 1900)
Page 3
Harvest Ice and Storage (ca. 1900)
4
Page 4
Ice Transport (ca. 1900)
Page 5
„Refrigerator“ (Ice - Box) ca. 1900
6
Pictures: Eisfink Co. Germany
Page 6
Ice and Refrigeration, 1922, vol 63
Page 7
Natural Refrigerants
General Refrigerant Issues
Page 8
Potentials of Natural Refrigerants
RHPAC Applications
RHPAC = Refrigeration, Heat Pumps, Air- Conditioning
28/05/2015
Source: adapted from Mayekawa, 2012
Page 9
Natural Refrigerants Characteristics
Lower
Flammability
& Toxic
28/05/2015
Very high
pressure
Higher
Flammability
Page 10
GWP of HCFC R22
HCFC
R22
GWP 1
GWP 1810
4,5 Kg of R22 are equal to 8145 kg of CO2
Medium-class car exposes approx 0.200 Kg/Km
CO2
You can drive 40725 Km (1 x round the Earth) for
the same CO2 Emission of 4,5 Kg HCFC-R22
Page 11
General Important Demands
Think before Acting
 Pressured gas may quickly create dangerous
situations.
 With improper use, liquid gas causes severe
violation at skin, eyes and respiratory tracts
 All refrigerants displace oxygen and can
cause suffucation
 The touch of voltage-carrying operating
supplies causes life-threatening situations
Page 12
Safety Warnings
• against Electricity
• inhalation of Gases
• touch of Liquids
• working with pressured gases
Page 13
Safety Commandments
During Operation and Handling of the Equipment ALWAYS !
• Always wear safety goggles!
• Always wear safety shoes!
• Always wear working clothes!
• Always wear safety gloves!
Page 14
Safety Bans
There is a strict
smoking ban
in all work
areas!
Page 15
General
Servicing Issues
NH3
R717
CO2
R744
HCs
R290, R600a …
Weight in relation
to air
Lighter
Heavier
Heavier
99.98 % min
99,99 %
99.5 % min
Refrigerant Purity
Moisture
< 200 ppm
Moisture <
10 ppm
Moisture <
10 ppm
Gauges & Circuit
Equipment
Stainless Steel
R717 indication
High Pressure
R744 indication
As for HCFC / HFC
HC indication
Vacuum Pump
Stainless Steel
ATEX, Vent Line
Regular
Vent line
Regular
ATEX, Vent line
Charging
Scale
Scale
Pressure
Sensitive
Scale
Tubing
Carbon steel, stainless
steel
Copper
Stainless steel HP
Copper
Leak Finding
Nose, Gas detector,
Litmus paper, Sulfur
stick, Bubble test, PPE
Gas detector,
Bubble test, PPE
Gas detector
Bubble test, PPE
Pressure test
Leak Test
Nitrogen 4.0
Nitrogen 4.0
Trace Gas (N2/H2)
Nitrogen 4.0
Trace Gas (N2/H2)
Strength test
PS x 1.1
Nitrogen 4.0
Nitrogen 4.0
Nitrogen
Page 16 4.0
Think before acting
In 30 year I
have only one
accident
Safety Comes First!
Page 17
Ammonia R717
Page 18
Ammonia, NH3, R717
First commercial use in mid- 1850s. Today, 90% of NH3 use
is in developed countries, 40% of NH3 in developing countries
 Industrial food processing,
storage and chemical
processes
 Cascade systems for
supermarkets (NH3/CO2)
 Chillers for airconditioning (chilled
water)
 Marine refrigeration
 Indoor ski-loops and iceskating areas
 Deep mining AC systems
28/05/2015
Ammonia Chiller AC Installation / Basement Public Building
Page 19
Ammonia (R717) as refrigerant.



The refrigeration by ammonia is the most economic
and energy efficient method
Ammonia has excellent thermodynamic properties
and this is the reason why refrigeration and AC by
ammonia system has a lower electrical energy
consumption
It is environmentally friendly. It does not contribute
neither to depletion of the ozone layer nor to the
greenhouse effect
Page 20
Ammonia Issues
Ammonia
is natural and like water
Page 21
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Page 22
28/05/2015
Page 23
Failure mechanics of
ammonia piping and vessels
Risk
Failure Mode
Highest External corrosion
Comments
Greatest risk to loss of MI
Hydraulic shock &
hydraulic lock-up
Risk is minimized by design
and operations
Occurs @ high velocity but
Internal erosion
risk is minimized by proper
design
Risk is minimized by design,
Stress-corrosion cracking
construction, and operation
Lowest
Not a significant issue for
Internal corrosion
ammonia systems
Page 24
Our goal!
Page 25
Ammonia Issues
Targets
no Accident
no Environment Pollution
no Health Hazard
Page 26
Ammonia
putrid smell like dung
Page 27
Advantages of Ammonia
Ammonia leaks are easy to detect/Self alarming





Penetrant odor at levels less than 10 ppm
Leaks are detected and fixed before major loss
Readily absorbed in water
Lighter than air, leaks will rise away from ground
The cost of the ammonia is much lower that any
other synthetic refrigerant.
In Contrast





HCHCs and HCs are odorless
Small leaks difficult to detect
Major refrigerant loss potential before leak found
Heavier than air, displaces oxygen from ground up
Expensive
28.05.2015
Page 28
Disadvantages of Ammonia
Low concentrations toxic
 Short Term Exposure Limit 35 -50 ppm
 However self alarming at 5 ppm
 1500 ppm –instant reaction to flee
Considered flammable
 In narrow range of concentrations of 1625% by volume of air in presence of
open flames
28/05/2015
Page 29
Physiological properties NH3
noticeable limit
max. working place concentration
annoyance limit
hardly bearable limit
poisoning appearance
deadly concentration
long term effect
content in human blood
daily human production
- 5 ppm
- 50 ppm
- 250 ppm
- 500-1000 ppm
- 2500 ppm
- >5000 ppm
- non carcinogenic,
- non genotype
harmful
- 0,8- 1,7 ppm
- 1.7g= 1 mol
Page 30
Ammonia Exposure
Gaseous state
The ammonia in gaseous state reacts with the
humidity, forming a caustic solution that, in high
concentrations, irritates tissues.
Air, with 50 ppm of ammonia, produces dryness in the
nose and the throat.
Air, with over 100 ppm, produces irritation of eyes and
mucous membrane.
A lengthy exposure to air with 400 ppm ammonia can
cause the destruction of the mucous membrane.
At 700 ppm, the irritation of the eyes is evident, being
intolerable at greater concentrations.
31
Page 31
Ammonia Spill
Spill of Ammonia
Ammonia evaporates and rises up
Page 32
Ammonia Spill
Page 33
Ammonia liquid leakage
liquid
vessel
gas light
free jet
aerosol
transformation
heavy gas
transformation
Page 34
Bubbling Ammonia Vapours and
Neutralisation with Water
Emptying
gaseous
Ammonia into a
drum of water
Automatic Ammonia
Neutralisation with
“Scrubber” within the
Plant-Room
Done safely, can reduce the likelihood of
employee exposure and harm.
Reduce likelihood of offsite consequences,
and reduce potential exposure to the public.
Page 35
Ammonia Exposure
Liquid state
The most serious danger is the damage in the
eyes. If the eyes gets contact with the ammonia,
the result can be permanent damages or even
the blindness.
In contact with the skin and since it is an irritate
and corrosive product, the ammonia will
produce the destruction of the tissues with
formation of blisters and chemical burns.
In addition, thermal burns by freezing can be
produced.
Page 36
Think before acting
Liquid gas
causes violation
on technician
unprotected skin
Page 37
© IKET 2006
Verwendung nur mit
38
Page 38
© IKET 2006
Verwendung nur mit
39
Page 39
Personal Protection
Gasmasks
 The gasmasks will be used together with a special filter for
ammonia. This filter is easily recognizable since it always has a
green colour sticker and the code 87K.
 It is important to keep correctly the mask and the filters after their
use, in order to avoid scratching the crystal or plugging the filter.
 Wear the mask by using the adjustment strips, so that it is totally
watertight. It can not be used with glasses.
 To check its watertight, place the hand on the filter inlet and breath.
The air CAN NOT enter.
40
Page 40
Personal Protection
Suit and gloves
• As it was mentioned before, the ammonia
has an effect on the humid zones and the
skin, that is the reason why it is important to
protect the hands and the body. In situations
of low risk, the use of mask and nitrile rubber
gloves will be correct.
• When the situation can cause a greater leak,
it will be necessary to wear the mask and the
chemical protection suit.
• In situations, when the use of the
autonomous breathing equipment is
necessary, the use of the AMMONIA
RESISTENT protective suit will be always
required.
Page 41
Personal Protection
Protective suit with ammonia concentration < 5.000 ppm
Page 42
Personal Protection
Protective suit by ammonia concentration
> 5.000 ppm, tmin < -50°C
43
Page 43
Personal Protection
Autonomous breathing
equipment
• It is an individual
protection equipment,
used for the protection of
the respiratory tract
during the work in
contaminated
atmospheres and/or in
areas with lack of oxygen.
Page 44
Ammonia
Applications
Page 45
Ammonia Machine Rooms
Ammonia sensor
Ventilation
System
Chiller
unit
Overflow
valve
Power
panel with
ammonia
detection
system
Room
heater
Escape way
Foundation
Page 46
Carbon Dioxide R744
Page 47
Carbon dioxide, CO2, R744
The use of CO2 applications is increasing rapidly
 Industrial food processing storage
 Heat Pumps and Water Heater about 4 million worldwide
 Supermarkets
 Two- stage system (entirely CO2).
 Cascade Indirect Multiplex System with CO2 (standard
solution). Utilises NH3, HC or HFC in high stage and CO2 in
low (LT and MT) stages
 Transcritical systems moving down the climate equator
(> 1800 stores in 2013)
 Transport refrigeration and public transportation (AC)
 Marine refrigeration
 Ice skating areas
28/05/2015
Page 48
Benefits of using CO2 as a refrigerant
 CO2 is a natural refrigerant with very low global warming
potential
 ODP = 0, GWP = 1
 Non-Toxic, Non-Flammable
 CO2 is an inexpensive refrigerant compared with HCFCs and
HFCs
 CO2 has better heat transfer properties compared to
conventional HCFCs and HFCs
 More than 50% reduction in HFC refrigerant charge possible
(high volumetric cooling capacity)
 CO2 lines are typically one to two sizes smaller than
traditional DX piping systems
 Excellent material compatibility
 System energy performance equivalent or better than
traditional HFC systems in cool climates
28/05/2015
Page 49
R744 system sizing
 Higher gas density of R744 results in high volumetric
refrigeration effect compared to all other refrigerants. This
has an effect on compressor displacement and pipe sizing,
evaporators and condensers.
R404A
R744
Suction line
diameter
28 mm
12 mm
Liquid line
diameter
8 mm
6 mm
 Power consumption for a given capacity is similar to that of
HCFC (HFCs).
28.05.2015
Page 50
Basic Consideration for
Service and Design
 The critical point is the condition
at which the liquid and gas
densities are the same. Above this
point distinct liquid and gas
phases do not exist.
 The triple point is the condition at
which solid, liquid and gas coexist.
 The triple point of carbon dioxide
is high (5,2 bar / -56,6°C) and the
critical point is low (73,6 bar /
31°C) compared to other
refrigerants.
28/05/2015
Page 51
CO2 Phase Diagram
or Transcritical
The critical point is low
(73,6 bar / 31°C)
The triple point of
carbon dioxide is high
(5,2 bar / -56,6°C)
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company presentation 2012
Page 52
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Page 53
The critical point of CO2
CO2 has a critical temperature of tcrit = 31°C and a critical
pressure of
pcrit = 73,77 bar.
With an ambient temperature in summer of tambient = 35 °C
and as a result from T = 10 K the „condensing“ temperature
is tC = 45 °C.
With CO2 as refrigerant this is already transcritical.
We want to use CO2
Cascade
Solution
Transcritical refrigeration system
Page 54
Cascade system using CO2
Principle:
To remain below critical temperature (31°C for CO2) the
coolant must be well below this temperature.
If we use T = 10 K from our example, the coolant
temperature must be smaller than 21°C : tcoolant < 21°C.
This low temperature is not always available in Mediterranean
continental conditions with air cooled heat exchangers.
So a separate refrigeration system is used to cool the
condenser of the low temperature part of the refrigeration
system.
Such a system is called a cascade cooling system.
Page 55
CO2 Cascade
some aspects
• With an appropriate design of the
propane cycle, the temperature
in the CO2 condenser remains
subcritical.
• With keeping the pressures low,
the usage of standard
components for the CO2 cycle is
possible. With regard to this
aspect, systems design is
relatively simple.
• The pressure in the CO2 cycle
may become a problem if the
propane cycle is not operational
• More machinery required Second
compressor must be operational
• Typical design for low
temperature refrigeration cycles.
28/05/2015
Page 56
For higher ambient temperatures also a mechanical
sub-cooler offers good potentials,
based on components available today
Source: adapted from Carrier, 2012
28/05/2015
Page 57
What are the Hazards of CO2
The hazards of CO2 should not be underestimated.
The main safety hazards are:





Suffocation;
High pressures;
Rapid expansion of trapped liquid or gas;
Low “boiling point”;
Solidification.
28.05.2015
Page 58
Comparison of some of these hazards
to those of HFC R404
PL* is the practical limit specified in EN378 (Refrigerating systems and heat
pumps - safety and environmental requirements). It is the highest
concentration level in an occupied space which will not result in “escape
impairing effects”.
28.05.2015
Page 59
Suffocation
The practical limit of CO2 is significantly lower than HFCs/HCFC to
reflect the different physical effects CO2 has when inhaled:




3% CO2 (30,000ppm) causes hyperventilation (over breathing)
5% CO2 (50,000ppm) causes narcosis (dizziness / numbness)
Followed by hypoventilation (constant breathing in)
10% CO2 (100,000ppm) causes loss of consciousness and can
be fatal.
At 3% concentration CO2 can be “tasted” and can cause tingling in
your fingers.
CO2 is Invisible, Silent,
there is No Smell and than
it Kills
28.05.2015
Page 60
High Pressure
Comparison of typical pressures in CO2 systems to
those in R404A systems.
28.05.2015
Page 61
High coefficient of expansion
In addition to the hazard caused by the very high standstill and
operating pressures, trapped CO2 liquid or gas expands rapidly.
This causes an extremely high pressure increase.
For example, if liquid is trapped in an evaporator at -30 °C, its
pressure will rise to over 100 bar/g if its temperature rises to -20 °C.
As a rule of thumb
for every 1°C rise in
temperature, the pressure
of trapped CO2 liquid rises
by 10 bar.
28.05.2015
Page 62
Dry Ice Formation
Solid CO2 (dry ice) is formed at certain
conditions when the pressure or temperature
of CO2 is dropped.
This can occur when charging CO2 into an
evacuated system or when CO2 is vented.
The pressure drops, but when the dry ice
turns to gas (sublimes) the pressure rises
rapidly.
Dry ice has a very low surface temperature.
28.05.2015
Page 63
Avoid Suffocation with a number of measures
 Areas around CO2 systems should be very well ventilated
 If you feel any of the warning signs of suffocation (dizziness,
numbness, tingling in fingers) you should move into the fresh air
as quickly as possible.
 A personal gas detector should
be used in working areas.
 Gas detection should be located
in any area where a leak of CO2
would exceed the practical limit (0.1 kg/m3).
 This should be fitted at low level, 30cm above the floor. These
sense CO2, not oxygen deficiency, and typically alarm at 1%.
 Do not enter a room if the gas detector is alarming.
 CO2 is vented from systems rather than recovered – ensure it is
vented into a very well ventilated area or to outside.
 Wear ear defenders when venting - this is a very noisy process.
28.05.2015
Page 64
Avoid Problems Associated with High Pressure
 The equipment used to pressure test, charge, vent and
measure pressures must be suitable for the pressures of
CO2.
 A standard gauge set
must not be used.
 The equipment must not
allow refrigerant to be trapped
between closed valves.
 Take great care when accessing
a system, even if it is off.
 Ensure cylinders are secure (ideally in a suitable trolley)
and open them slowly - the pressure can de-stabilise the
cylinders if they are opened quickly.
28.05.2015
Page 65
Avoid problems associated with rapid
expansion of trapped CO2 in the
system:
 Do not allow liquid to be trapped in pipes or components
between closed valves.
 Do not weld or braze pipe work or components which contain
CO2.
 Ensure valves are open, for example by using a magnet to open
solenoid valves.
28.05.2015
Page 66
Preventing dry ice formation
 To prevent dry ice formation when charging, charge gas
until the pressure in the system is at least 4.2 bar g (i.e.
above the triple point), then charge liquid to complete the
charge.
 To prevent dry ice formation when venting the refrigerant
should be vented in the liquid state if possible.
 Be aware that if dry ice does form the pressure drops to
atmospheric pressure, and will rise again when the dry
ice sublimes.
28.05.2015
Page 67
Hydrocarbons
HCs
R290
R1270
R600a
…
Page 68
Charge Size Restrictions for HCs
e.g. Supermarkets (interior) are classified under occupancy
category A as domestic / public places
Category
Examples
Requirements
General
Anywhere
A factory sealed refrigeration system with less than 150 g HC
refrigerant can be located in any occupied space which is not a
machinery room without restrictions
•
•
< 1,5 kg per sealed system
< 5 kg in a special machinery room or in the open air for
indirect systems
B
Offices, small
•
(commercial shops, restaurants, •
/ private
places of general
manufacturing and
where people work
< 2,5 kg per sealed system
< 10 kg in a special machinery room or in the open air for
indirect systems
•
•
< 10 kg in human occupied space
< 25 kg if high pressure side (expect air cooled condenser)
is located in a special machinery room or in the open air.
No limit if all refrigerant is contained in a special machinery
room or in the open air.
A
Supermarkets,
(domestic / hotels, schools,
public)
theatres, etc.
C
Non-public areas
(industrial / of supermarkets,
restricted
cold stores, plant
rooms, dairies,
•
Page 69
Propane (R290) Chiller ODP = 0 & GWP = 3.3
ODP=1 base CFC 11, GWP 100 YR (AR4)
Machinery
room zone
classification
according to
EN60079-10
EXAMPLE
Source: Johnson Controls
Page 70
Propane (R290) Chiller ODP = 0 & GWP = 3.3
Product Regulatory Compliance – Flammability Standards
Machinery room
zone
classification
according to
EN60079-10
Distance between
electrical
components and
leakage points
according to
EN60079-10
Sensor for
flammable
gas detection
according to
EN 378-3
Total of 50 pipe joints inside a machinery room.
Non-permanent joints are potential leakage
points according to EN60079-10. Leakage rate
depending on method of detection according to
EN 1779
Emergency
ventilation
according to
EN378-3 and
EN60079-10
Page 71
R290 Chiller - Practical installation
Source: Johnson Controls
Page 72
R290 Chiller – Catalogue Data
Some data
Source: Johnson Controls
Page 73
Handling HC Refrigerants
Hydrocarbons are flammable
when mixed with air and ignited!
Page 74
Flammability Example R-290
Oxygen 0 % to 100 %
2.1 %
9.5 %
HC R-290
Refrigerant
Flammable ONLY BETWEEN 2% AND 10%
 If the concentration is below the lower flammability level
(LFL of approximately 2% by volume in air), there is not
enough HC for combustion.
 If the concentration is above the upper flammability level
(UFL of approximately 10%) there is insufficient oxygen for
combustion
Page 75
Flammability
Approximate auto ignition temperatures

R22
635 ºC

R12
750 ºC

R134a
743 ºC

R290
470 ºC

R600a
460 ºC

Oil
222 ºC

HFC-1234yf
405°C
Page 76
Flammability
 When HC’s burn they produce carbon and
steam
 When chemical refrigerants burn they ALL
produce toxic fumes.
Page 77
Potential Hazardous Situations
Note:
It is very unlikely that combustion will occur inside a
system as there will be insufficient air.
 If hydrocarbon refrigerant leaks out of
the system combustion will occur if the
correct mixture exist and there is an
ignition source.
Page 78
Ignition Sources
For combustion an ignition source is needed to ignite
the air/hydrocarbon mixture. The ignition source
must be hotter than 430°C to be able to ignite the
refrigerant.
Potential ignition sources are:
 A flame, for example from brazing torch, halide
torch leak lamp, match or lighter;
 A spark from an electrical component;
 Static electricity.
Page 79
Examples of Ignition Sources –
Electrical Devices

Light and socket switches
 Some relay / overload protectors (klixons)
 Contactors and most on / off switches
 Light starters (ballasts)
 Most pressure switches (HP, LP, oil)
 Timers, e.g. for defrosting
 Thermostats
 Some defrost heaters
Page 80
Examples of Ignition Sources –
Tools / Equipment
 Brazing equipment
 Some electronic leak testers
 Unsealed switches on equipment such as vacuum pumps
 Generator
Page 81
Electrical Safety (Challenges for Inst. &
Service
Page 82
Electrical Safety (Challenges for Inst. &
Service
Page 83
Potential Hazardous Situations
There are two potential hazardous situations:
1.
Refrigerant leaks into the air around the system and
is ignited by sufficient source e.g. sparking
electrical components
2. Refrigerant into the food compartment or any other
sealed space and is ignited by sufficient source
 Where leakage into the food compartment cannot be
prevented potential ignition sources must be
eliminated!
 Where repair takes place, only use like for like
equipment!
Page 84
HC Refrigerants DO NOT smell
 Propane and Isobutane do not smell
 Only LPG contains a stench agent which may:
• damages hermetic compressors
• blocks filters
• contaminate HC refrigerants
 Stench agent NOT used in R290 or R600a
 The advantage of Propene R1270 is a slight gassy smell
Page 85
LPG Gas Stench Additive
 Ethanethiol, commonly known as ethyl mercaptan, is a
colourless gas or clear liquid with a distinct odour. Ethanethiol
is toxic. It occurs naturally as a minor component of petroleum,
and added to otherwise odourless gaseous products such as
liquefied petroleum gas (LPG) to help warn of gas leaks. At
these concentrations, ethanethiol is not harmful.
 Ethanethiol has a strongly disagreeable odour that humans can
detect in minute concentrations. The threshold for human
detection is as low as one part in 2.8 billion parts of air. Its odour
resembles that of leeks, onions or cooked cabbage, but is
quite distinct. Ethanethiol is intentionally added to butane and
propane to impart an easily noticed smell to these normally
odourless fuels that pose the threat of fire, explosion, and
suffocation.
Page 86
General HC Safety Hazards
Liquid burns – wear
gloves and goggles
Heavier than air
Suffocating
Page 87
Tools Required
to Service
HC Refrigerant
Appliances Safely
Page 88
Access Tools for HC Technology
Piercing
pliers
Line tap
valve
Lokring
Schrader
Venting
Evacuation
Charging
Sealing













Page 89
Manifold Set
Standard 4 valve
manifold gauge
set
• R600a
• R290
• R22
Page 90
Sealing Tools – Option 1
 Lokring seals without
brazing
Page 91
Sealing Tools – Option 2
 A crimping tool seals
before brazing
Page 92
Fire Extinguisher
 Dry powder type (usually
identified with a blue
flash) or CO2 when
servicing, storing,
transporting HCs
 2 kg charge size
Page 93
Personal Protective Equipment
 Gloves and goggles for protection
against freeze burns (as with all
refrigerants)
Page 94
Cylinder Charging with HCs
 Liquid HCs have less than half the density of fluorinated refrigerants,
and therefore they take up more than twice the volume within a cylinder.
 Any recovery cylinder must be filled to a maximum of 80% of its volume.
 If the refrigerant is R22, it must only be filled to 80%; if the refrigerant is
R290, is must only be filled to 80%. However, in the case of R22, the
mass may be 10 kg, whereas with R290 the mass may only be 4 kg.
 Max fill of HC (kg) = 0.4 × max fill of HFC or HCFC (kg)
Page 95
Cylinder Transport
Follow local regulations for LPG; if none
you should at least:

Carry a dry (blue flash) power fire extinguisher
 Stow cylinders upright, capped, secure
 Ventilate and label vehicle
 No smoking
Page 96
Safe working & servicing practices
 Human behaviour has greatest influence on risk of ignition
 Business as usual as with “Safety Refrigerants” may lead to fatal
accidents
 Risk of ignition is function of
• Probability of leak; size of flammable cloud; duration of
flammable cloud; presence of sources of ignition
P *  Pleak × PFV × PFt × Psoi
 During servicing
• Higher probability of leakage (breaking into system)
• More refrigerant to leak (e.g., cylinders)
• More sources of ignition (service equipment)
• Etc.
 Overall, risk of fire 10× to 1000× higher during servicing
• Therefore, essential to focus on reducing risk whilst
installation and servicing
Page 97
Safety standards –
Installation routine
Generally, Best Refrigeration an Air- Conditioning installation
practices should be applied.
Note: Only technicians who have been trained in the safe
handling and use of hydrocarbon (HC) refrigerants should
work on this system.
 If replacing components, use like for like replacements
 With conversion, use components that do not spark or have
hot surfaces
 Take great care when brazing and unbrazing to ensure all
HC has been removed from the system.
Page 98
Having a strict work-routine in
place
General topics
• Technician activities and
refrigerant handling
• Installation of equipment
• Commissioning of
installations
• Routine maintenance
• Service and repair
• Dismantling
Page 99
Temporary Flammable Zones
 When working on systems using flammable refrigerants, the
technician should consider certain locations as “temporary
flammable zones”.
 These are normally regions where at least some emission of
refrigerant is anticipated to occur during the normal working
procedures, such as recovery, charging, and so on.
 This is typically where hoses may be connected or disconnected.
 In anticipation of the maximum quantity of refrigerant that may be
released during such a procedure (such as disconnecting a hose
whilst it is full of liquid refrigerant),
 the minimum distance from this point that should be considered
as a temporary flammable zone, is around half a metre in all
directions.
 The “Safe Working Area” around the equipment serviced is three
meter.
Page 100
Temporary Flammable Zones
Temporary
Flammable Zones
Page 101
Safety Area
 Work on this system in a well
ventilated area or outside.
3 Metres
Safety
Area
Outdoor
Unit
Indoor
Unit
 Use a local gas detector to
indicate if there is hydrocarbon
in the air around the system
before and during work on the
system (place it at low level ‐
HCs are heavier than air).
 Ensure there are no sources of
ignition (flames or sparking
electrical components)
within 2 m of your work area.
 Use refrigerant
(R290) only
grade
purity
Page 102
Sealed System Provision
“Hermetisation”
General Demand for all
Refrigerants!
Page 103
Location and Severity of Leaks
Analysed
 96% of the total refrigerant loss was through
field assembled joints
 15% of the leaks were responsible for 85% of
refrigerant loss
 21,6% of all detected leaks where flared joints –
They are responsible for close to 50% of lost
refrigerant
Page 104
Location and Severity of Leaks*
 0,16% of brazed joints had leaks
 Systems with substantial leaks over long
periods had leaks in inaccessible parts of the
system
 Very common leak-spots
at TXVs
 Detailed requirements for
safety valves (now usually blowing
to low pressure side not ambient)
Overflow Valve
(counter-pressure independent)
relief /
>
Page 105
Importance of Tubing
 Brazing
 Purging air from pipe-work with
Oxygen Free and Dry Nitrogen
(OFDN)
 Tube and components joining by
press- connectors
 Bending and perfect professional
flaring
 Use of industrial manufactured flares
 Tube supports and vibration
elimination
 Thermal insulation
Page 106
Example: Carry out thorough leak checks
– Understand how to spot them, where they normally
occur from…
Page 107
Sealed System Provision
Page 108
Installation and Leak Reduction
There is no one simple solution to leakage reduction. All the
following contribute to minimising leaks:
• If the system is provided with fixed tubing, modifications are not permitted
(extension or shortening) > intrinsic safety
• Design systems with minimal joints using components which are known
not to leak excessively
• Route, support and clamp pipe work correctly, avoid chafing
• Keep equipment and tubing protected against corrosion
• Maintain adequate vibration isolation (equipment and tubing)
• Ensure brazers are competent and qualified > e.g. ISO 13585-2012
• Pressure leak test systematic to the correct standard
• Charge systems with the correct amount of refrigerant
• Carry out planned preventative maintenance to minimise head pressure
and ensure systems are operating at the optimum level
• Carry out sufficient leak testing and repair leaks where necessary
• Improve service practices, including replacing caps after service,
tightening flanges correctly and replacing gaskets where necessary
Page 109
Flared Connections and Tightening
Flare size
Nominal outside diameter
(according to EN12735-1 & 2)
Metric series
Imperial series
(mm)
(mm)
(inch)
6
6,35
7,94
¼
5/16
9,52
⅜
12,7
½
15,88
⅝
19,06
¾
8
10
12
15
18
Minimum wall
thickness
(mm)
Tightening torque
(Nm)
0,8
0,8
0,8
0,8
0,8
0,8
0,8
0,8
0,8
0,95
1,00
1,00
14 to 18
14 to 18
33 to 42
33 to 42
33 to 42
33 to 42
50 to 62
50 to 62
63 to 77
63 to 77
90 to 110
90 to 110
NOTE: When making flared joints, care should be taken to ensure that the flare is
of the correct size and the torque used to tighten the nut is not excessive.
Care should be taken not to flare piping that has been work hardened.
Page 110
Service and Repair
All staff and others working in the local area must be instructed
on the nature of the work being carried out










The area around the workspace must be sectioned off
Obtain permit for hot work (if required), place warning signs
Working within confined spaces should be avoided
No flammable materials are stored in the work area
No ignition sources are present anywhere in the work area and
avoid sparks by static electricity
Suitable fire extinguishing equipment (CO2 or dry-powder type)
is available within the immediate are
The equipment should, whenever possible, be isolated from
the electricity supply
Ensure that all refrigerant handling and mechanical handling
equipment is available
All necessary personal protective equipment is available and
being used correctly
The area must be well ventilated or at outside area
Page 111
Service and Repair
Whilst technicians are working on systems, it can be
advisable to make use of a portable gas detector.
 Detector can be clipped to clothing or placed on the
floor within the working area.
 It should be switched on for the duration of the work,
and set to alarm at 15% of the LFL, to warn that
flammable concentration may be nearby.
 For safety reason the gas detector should not have
a “Zero Background” function
 Technicians can be alerted whenever an inadvertent
release of flammable refrigerant occurs, and can
immediately act upon the relevant emergency
procedures.
Page 112
Service and Repair
Strength (pressure) testing
 Testing of the strength and tightness of the system using pressure is
normally required after changes have been made to the system (with brazing
and repair)
 The strength (pressure) test should be conducted in the same manner as
with any other refrigerant.
In summary:
 Ensure all personnel are at a safe distance from any refrigerant containing
parts
 Charge the system with an inert gas typically OFDN
 Gradually pressurise the system to 1.1 × allowable working pressure of the
system, as prescribed on the system data plate
 Hold the pressure for several minutes and then gradually depressurise the
system
 Check all parts of the system for deformation or leakage
If the maximum working pressure is not displayed on the system, then it may be
estimated based on the saturation pressure of the refrigerant at about 55°C,
although it does depend upon the local climate conditions; if the maximum
ambient is expected to be higher, then the test pressure should Pagealso
be
113
Oxygen Free & Dry Nitrogen (OFDN)
Must have!!!
Pressure / strength test
Equipment flushing and
drying
Inert gas brazing
Page 114
Refrigerant venting and recovery
Normally, venting to a safe place is only carried out with systems
that contain a small quantity of HC refrigerant, larger quantities
should be recovered.
Outdoor
side
IDU
With removing the
refrigerant from the
system, oil should
be separated.
ODU
Diffuser
Cylinder
to collect
oil
Hose
1m
Indoor side
3m
Page 115
Refrigerant venting and recovery
When carrying out the venting,
the flow of refrigerant should be
metered using manifold gauges
to a low flow rate, so as to ensure
the refrigerant is well diluted.
Once the refrigerant has ceased
Flowing a vent-line should be
used attached to the exhaust port
of the vacuum pump to remove
HC residues
Stand
VentLine
Before final evacuation the
system should be flushed out
with OFDN
Final vacuum to 500 micron
Page 116
Evacuating the System
 Two site evacuation if
possible (LP / HP
site)
 Evacuate for at least
a min of 500 microns
 Break vacuum with
OFDN
 Check vacuum at
vacuum gauge
(preferable electronic)
 Check vacuum holds
Page 117
Vacuum Pump
• Standard vacuum pump
OK
Exhaust hose
for HC venting
to the save
environment
• Switch on remote outside
2 m area
• Do not use “home made”
vacuum pumps
Page 118
Vacuum Gauges
Page 119
Refrigerant Charging
Same charging procedures are used with HC refrigerants as with any other types
of refrigerant, except that certain considerations are particularly important:
 When connecting hoses between the refrigeration system, manifold gauges
and refrigerant cylinder, ensure that the connections are secure and there are
no potential sources of ignition within the safety area (temporarily flammable
zones).
 The use of a four-way manifold in order to avoid interchanging of hoses for the
charging process and hoses are evacuated.
 Hoses or lines should be as short as possible to minimise the amount of
refrigerant contained in them
 Typically, a balance should have an accuracy of at least ±0,5% full-scale and
resolution of 2 grams.
 Ensure that the refrigeration system is earthed prior to charging the system
with refrigerant, to
 A further leak check must be carried out prior to leaving the site
 After charging, carefully disconnect the hoses, attempting to minimise the
quantity of refrigerant emitted
 Label the system when charging is complete (if not already)
Page 120
Charging Equipment – Option 1
 Standard charging
scales OK
 Accuracy of about
2g needed
Page 121
Manifold Set
Standard 4 valve
manifold gauge
set
• R600a
• R290
• R22
Page 122
Charging Equipment – Option 2
Domestic Appliances
(small AC ≤ 1.5 TR)
Page 123
Charging Equipment – Option 3
Domestic Appliances
(small AC ≤ 1.5 TR)
Page 124
Low Pressure R600a
Low Pressure R12
Vacuum
Domestic Appliances
Page 125
Leak Finding Issues
28.05.2015
Page 126
Indirect & Direct Leakage Finding Guide
Refrigerant Tightness Testing For Leakage Inspection Procedures
- OPERATIONAL SYSTEM -
Indirect refrigerant gas detection (leakage)
Direct refrigerant gas detection (leakage)
Proceed to direct
refrigerant gas
detection methods
1. Checking
system logbook
2. Visual
inspection of
system
components
* Inspection and
analysing of
- service and
maintenance
records
- inspection
records
Inspection for…
- noise
- vibrations
- corrosion
- oil leakage and
traces
- material
damages
- component
breakdown
- sight glasses
- abnormal noise
other than
expcted
operational noise
… leading to risk
of refrigerant
leakage
* Inspection of
refrigerant hanling
reports
(recharging,
recovery etc.)
* Inspection of
system data
- design and
operating
3. Visual
inspection of
system safety
devices
Inspection of
technical
condition for …
- safety devices
- pressure limiter
(HP/LP)
- gauges
- sensors
- outlet discharge
lines
Set values
inspection for ...
- safety devices
- pressure limiter
(HP/LP)
4. Visual
inspection of
system refrigerant
charge
Inspection of
system refrigerant
charge by …
- sight glass
- level indicator
System Pressure
check …
- operating
pressure
- operating
temperature
Veriy if there is a
decrease of
refrigeration
system efficiency
5. System
tightness test for
leakage
Refrigerant
detection inspection
by …
- electronic portable
detection device,
sensitivity to be 5
gr/yr & calibration
Supplementary
checks by
- OFDN and bubble
solution
- (UV fluid)
Areas to check …
- joints
- valves/stems
- seals
- vibration areas
- seals on
replaceable filterdriers
- cones to safety
operating devices
Mandatory repair
of detected leak
6. Logbook
Update and
detailed reporting
of results on
leakage
inspection
7. Re- inspection
of repair
Mandatory reinspection within
30 days, can be
on same day at
suitable time
period
Page 127
What is Leak Detection?
+
=
Gas Detector + Inspector Gadget = Find Leak
Page 128
Gas Detection Technologies
TCD
129
Page 129
Leak finding (general demand)
Use of gas TCD
Example F-Gas Regulation - EC 842/2006:
 Service technicians must give their gas detector a formal
calibration test at least every 12 month
 Regularly check (at least every use) that the equipment is
sensitive enough to detect a refrigerant leak of a minimum
of 5 gram per year on a system.
Page 130
Electronic TCD Gas Detectors (Sniffer)
 Device must be compatible with the refrigerant that is contained in the
system undergoing leak testing.
 A technician must know his/her leak detector’s capabilities and also what
it is not capable of detecting.
 Carbon monoxide and alcohol can affect the sensitivity of some
electronic gas detectors. Be sure neither is present when leak detecting.
 The device should be checked at least once a year to ensure reliability
and accuracy.
 For most cases it is possible to use a “reference leak source” for
calibration.
 Warning: Most electronic gas detectors are not recommended to be
used in atmospheres that contain flammable or explosive vapours or
refrigerants. Sensor may operate at an extremely high temperature. If
this sensor comes in contact with a combustible gas, ignition will occur.
Page 131
Electronic TCD Gas Detectors (Sniffer)
 Recommended are electronic gas detectors (sniffer) based on Thermal
Conductivity Detection (TCD) technology
 The detector has an element in the probing tip that creates an electric
emission in the presence of a refrigerant. The electric signal is converted
in the device either to visual or an audible signal.
 The electronic gas detector enables the technician to get very close to the
leak. After finding the area in which the leak is detected, technicians can
usually decrease the sensitivity of some types of detectors to indicate the
area of the leak. The leak area is then coated with soap solution to verify
the exact point of the leak.
 Electronic leak detectors must be designed to detect a certain type of or
multiple types of refrigerant, i.e. HFC, HFCF or HC. Performance Criteria
for Electronic Refrigerant Leak detectors are set with SAE Standard 1627
 The European regulation DIN EN 14624 from 2012 addresses
“Performance of portable leak detectors and of room monitors for
halogenated refrigerants”.
Page 132
Moving the Sniffer (TCD) Sensor
0,2 cm per second around the tubes
and spots suspected for a leak!
Page 133
Leak detection (general demand)
 Understand what is being done
 Expect that there is usually not only one leak
 Repairing leaks very important
 Safety
 Performance (5% leakage,
10% higher energy consumption)
 Modern reliable “gas detectors” (TCD)
devices are sensitive to leakage ranges as
small as 3 g per year.
 Testing with a reference leak (5 grams/year)
is the only way to prove the performance of a
gas detector
Page 134
5 g / Year (HFC R-134a)
Ultrasonic Test
Leak Detection
Methods
Comparison
Bubble Test Method
Pressure Decay Test
Sniffer: Thermal Conductivity
Sniffer: Electron Capture (SF6)
Vacuum Mode
Overpressure Mode
Sniffer: 5% H2, 95% N2 Gas
Sniffer: Helium Quarz Membrane
Sniffer: Mass Spectrometer
Vacuum Mode: Helium Mass Spectrometer
103 … 100
10-1
10-2
10-3
10-4
10-5
10-6
10-7
10-8
10-9
Minimum Detectable Flow Rate in millibar · Litres / Second (mbl/s)
10-10
10-11
10-12
Page 135
Gas detector (sniffer) versus
bubble solution or pressure drop test.
Examples:
A car tyre filled to about 2.7 bar (40 PSI) air
and with a leak of 5 g per year take over 4
years to drop in pressure by 0.1 bar (1.5
PSI)
With a 5 g gas leak available, a bubble solution takes
over 20 hours to form a 1 ml bubble and a pressure
drop test would only show a change of around 0.7 mbar
(0.01 PSI) after 48 hours.
Practically, Sniffer (TCD) sensitivity less than 5gr/yr today
> Bubble Test are only accurate to 50 – 200 g/year
Page 136
Direct Leak Finding Methods with HCs
Direct Leak Finding Methods
To be used as:
Not
Must have
recommended
and do

Soapy water bubble test with refrigerant
pressure (only)
Leak Check
Using an appropriate electronic Gas2 Detector e.g. thermal conductivity detector
(TCD)
Leak Test

Tightness Test
Test pressure @ 10 bar
sufficient

1
OFDN pressurised System and soapy
3
water (Bubble Test)
N2/H2 Forming gas pressurised system and
4
Trace Gas Detector
Will be
excellent
Tightness Test
Test pressure @ 5 bar
sufficient

5 Pressurising the System with OFDN
Pressure (Strength) Test
PS x 1.1
e.g. refrigerant circuit
components are repaired or
replaced

6 Fixed refrigerant detection systems
Fixed refrigerant leakage
monitoring system. Charges
≥300 kg according to EU F-gas
regulation

Page 137
Page 138
Thank you!
28.05.2015
Page 139