L United States
Environmental Protection
Agency
EPA 430-B-11-001
The GreenChill Advanced Refrigeration Partnership
GREENCHILL
GreenChill Best Practices Guideline
Commercial Refrigeration
Leak Prevention & Repairs
U.S. Environmental Protection Agency
Stratospheric Protection Division
May 2011
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DISCLAIMER
This document does not address or assert compliance with the statutory requirements of Section
608, Title VI of the Clean Air Act, as amended in 1990. Nor does this document address or assert
compliance with the EPA Section 608 leak repair regulations, at 40 CFR Part 82, Subpart F.
The authors of this Guideline, and the companies, agencies, and organizations to which they
belong, do not assume responsibility for any omissions or errors, or assume liability for any
damages, that result from the use of this Guideline.
Always check with your equipment manufacturers for proper procedures for your equipment
before undertaking any action that may affect your equipment.
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TABLE OF CONTENTS
I. INTRODUCTION 1
Mission 1
Purpose and Scope 1
Refrigerant Leaks from Supermarket Refrigeration Systems 2
II. WHY SYSTEMS LEAK 3
Where Leaks Occur 3
Compressor Racks 3
Display Cases 4
Remote Air-Cooled Condensers 4
Walk-In Evaporators 5
Field-Installed Piping 5
Condensing Units 5
Remote Headers 5
Causes of Leaks 6
III. GETTING STARTED 9
No-Tolerance Policy 9
Tracking Leaks 9
IV. PREVENTIVE MAINTENANCE PRACTICES 10
Clean Equipment 10
Leak Detection Alarm Systems 11
Regular Leak Inspections 11
V. LEAK REPAIRS 12
Response Time 12
Thoroughness of the Check 12
Follow Up Checks and Verification 12
VI. REDUCING LEAK POTENTIAL 13
Overcharged Systems 13
System Component Upgrades 13
Additional Recommendations 13
APPENDIX A. SUPERMARKET WALK-THRU CHECKLIST 15
APPENDIX B. MONTHLY REFRIGERANT RECEIVER LEVEL CHART 2011-2012 .17
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I. Introduction
Mission
GreenChill's mission in developing this document is to assist food retailers in reducing
refrigerant leaks in their commercial refrigeration systems.
Purpose and Scope
The purpose of this Best Practices Guideline is to provide food retailers with information on best
practices for reducing refrigerant leaks from commercial refrigeration systems. The Guideline
only covers practices implemented during the design and operation of a refrigeration system and
does not discuss leak prevention practices during the installation of equipment. Information on
leak-tight installations can be found in GreenChill's Best Practices Guideline: Ensuring Leak-
Tight Installations of Refrigeration Equipment1
While GreenChill preferably encourages the adoption of advanced refrigeration as a means for
reducing refrigerant emissions, the partnership also recognizes the importance of proper
servicing and maintenance practices in refrigeration management strategies. This Guideline
document focuses on practices largely relevant to traditional centralized direct expansion (DX)
systems; however, most practices also are applicable to other system types such as distributed
systems and secondary loop systems. Specifically, the Guideline provides information on the
following:
Why systems leak;
Tracking refrigerant charges;
Preventative maintenance practices;
Responding to leaks; and
Reducing leak potential.
This Guideline document does not address compliance issues associated with EPA regulations
promulgated under Title VI of the Clean Air Act, as amended in 1990, including the regulatory
leak repair provisions under Section 608 of the Clean Air Act.
1 Available at http://www.epa.gov/greenchill/downloads/LeakGuidelines.pdf
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Refrigerant Leaks from Supermarket Refrigeration Systems
Traditionally, supermarket refrigeration systems are characterized by large refrigerant charge
sizes and potentially high leak rates, a combination that results in considerable refrigerant
emissions. EPA estimates that a centralized DX system can emit as much as 25% of its
refrigerant charge annually.2 However, through best practices and the adoption of advanced
technologies, GreenChill members have shown considerable success in reducing refrigerant leak
rates. In 2008, GreenChill partners collectively reported an average corporate-wide annual
emission rate of 12%.3 Individual partners have also shown that greater leak reduction is
possible, setting aggressive corporate emission targets of less than 7%. Furthermore, individual
stores have proven that rates less than 5% are achievable and sustainable with the adoption of
advanced refrigeration technologies in combination with best practices.
To encourage supermarkets to reduce leaks, it is first
important for supermarkets to recognize the negative
impact refrigerants have when emitted into the
atmosphere. Commonly used commercial
refrigerants such as chlorofluorocarbons (CFCs) and
hydrochlorofluorocarbons (HCFCs) contribute to
deterioration of the stratospheric ozone layer. CFCs,
HCFCs, and even the ozone-friendly
hydrofluorocarbons (HFCs) contribute to climate
change. Table 1 summarizes the ozone depletion
potential (ODP) and global warming potential
(GWP) of commonly used commercial refrigerants
Table 1: ODP and GWP of Common
Refrigerants
Refrigerant
CFC-12
R-502
HCFC-22
HFC-134a
R-404A
R-507A
R-407A
R-410A
R-744 (C02)
ODP
1
0.25
0.055
0
0
0
0
0
0
GWP
10,900
4,646
1,810
1,430
3,922
3,985
2,107
2,088
1
Source: IPCC (2007), Montreal Protocol
Seehttp://www.epa.gov/greenchill/downloads/EPASupermarketReport_PUBLIC_30Nov05.pdf
3 The GreenChill partner emission rates described here are calculated according to the methodology in GreenChill's
program guidance, which uses the ratio of emissions during one year to the system's refrigerant charge.
See http://www.epa.gov/greenchill/downloads/GreenChillStoreCertificationProgramGuidance.pdf. This differs
from the definition of leak rate in 40 CFR 82.152 used to assess compliance with EPA's regulations. The regulatory
definition expresses leak rate in terms of the percentage of an appliance's full charge that would be lost over a 12-
month period if the current rate of loss were to continue over that period.
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II. Why Systems Leak
Where Leaks Occur
Leaks can occur in a variety of locations throughout a supermarket. Figure 1 provides estimates
from one regional supermarket chain of the portion of refrigerant leaks coming from specific
sources. Each leak source is explained further below.
Figure 1: Leak Sources for a Regional Supermarket Chain
Compressor Racks, 39%
DbpldyCdbe:,, 21%
Remote Air Cooled Condensers, 12%
Field-Installed Piping, 1G%
Walk-In Evaporators, 8%
AC Urits, 4%
Condensing Units, 4%
Remote Headers, 2%
Compressor Racks
A typical supermarket in the U.S. contains 2-4 parallel compressor racks, each with a number of
rack-mounted components that are all potential leak sources. Components include 3-8
compressors; suction, liquid, and discharge manifolds; suction control valves; 3-way valves;
head pressure controls; suction filters; liquid driers and sight glasses; a liquid receiver; an oil
separator; a suction accumulator; pressure controls; and numerous shut-off valves. Prime
locations for leaks include:
Pressure controls and their control lines or cap tubes, from vibration, rub-through, or
mechanical damage;
Rack-mounted valves, including
o Brazed or mechanical fittings, flanges, and threaded pipe fittings on the
receiver;
o Valve stem packing, especially if the valve cap and/or cap seal is missing;
o Control lines, especially high-pressure lines; and
o Access ports;
Filter/drier assemblies, from deteriorated gaskets or loose flange bolts;
Manifold tee fittings that are improperly brazed from the factory and subject to vibration
from the rack;
Receiver liquid level gage ports, which leak from deteriorated gaskets;
Schrader valves, through their cores, especially if the cap is missing; and
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Steel components such as suction accumulators, suction filter shells, steel suction valves
mounted on the suction line, and even receivers mounted below a suction manifold due
to corrosion, as seen in Figure 2.
Figure 2: Excessive corrosion on rack components
Display Cases
An average-sized supermarket can contain over one hundred display cases. The potential for
leaks from display cases is great, due to the large number of leak points in the evaporators and
expansion valves. Evaporator coils are made up of small-diameter tubing and many soldered
return bends, making them susceptible to leaks.
The tubing is subject to physical abuse from thermal stress failure, improperly-brazed return
bends, metal-to-metal contact from other display case parts, and chemical reactions from food
acids, especially in service deli cases. Tubing can also be disturbed during the cleaning of a case
or de-icing of a coil by an untrained employee.
In older cases, expansion valves with flare nut connections have historically been a source of
many leaks. Flare nuts are subject to loosening, especially near the evaporator where ice is
present. Newer cases instead use brazed fittings, which have reduced - but not totally eliminated
- expansion valve leaks.
Other potential valve leak sources in a display case include check valves used in hot gas defrost
systems and solenoid valves that are used for temperature control. Each of these valves can leak
from the fittings or from the body of the valve itself.
Remote Air-Cooled Condensers
Leaks on remote condensers are most common in the finned tube area where the tubes pass
through a condenser frame member. Manufacturers have tried to eliminate this problem by
designing the tube sheet to be supported by non-refrigerant-carrying tubes or by using brass
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ferrules between the tubes and the frame. As a result of thermal expansion or improper rigging of
the condenser during installation, the brass ferrules can fall out, causing the condenser tube to
contact the condenser frame, which over time may create a leak. Brazed joints on return bends
and manifolds are also a potential source of leaks.
One major cause of significant refrigerant leaks on remote condensers is a failure of the motor
mount/fan blade assembly. Most manufacturers have improved the design of the fan motor
mounting to reduce this problem but not totally eliminate it. In many cases the motor mount
failure is preceded by a failure of the fan assembly. Fan blades are often constructed using a steel
hub assembly with multiple aluminum or steel fan blades riveted to the hub. Due to cycling of
the fan motor, over time the rivets on the individual blades may loosen or the blade itself may
begin to tear. If the fan assembly is not replaced, the blade may detach from the fan hub, causing
a major imbalance of the fan motor assembly. This extreme vibration may in turn cause the
motor support bracket to fail and the fan motor assembly to fall into the fin tube surface,
resulting in major damage to the fin tube assembly and possibly a rupture of one or more
refrigerant-carrying condenser tubes.
Receivers mounted under condensers along with liquid drier shells, head pressure valves, and
other components are subject to the same leaks as those mounted on the compressor racks. Such
leaks are just more difficult to detect due to the remote outdoor location.
Walk-In Evaporators
An average supermarket contains only about sixteen walk-in evaporator coils. The leak points in
the walk-in coil are similar to those in the refrigerated cases. Walk-in evaporators generally have
more solenoid valves and check valves than display cases, resulting in a higher leak potential.
Since walk-in evaporators are accessible and located in an enclosed space, however, leaks from
these units are more readily detected with a leak detector.
Field-Installed Piping
Field-installed piping consists of all suction, liquid, and discharge piping that connects the
compressor racks, display cases, walk-in evaporators, and remote air-cooled condensers. Leaks
can occur at any one of the hundreds of brazed connections and thousands of feet of piping in a
typical store. If care is not taken to isolate the copper piping from the steel support system,
thermal expansion or vibration can create constant movement of the soft copper tubing against
the harder steel supports, resulting in development of rub-through leaks over time.
Condensing Units
A condensing unit comprises a single compressor, an air-cooled condenser, and a receiver. Like
compressor racks, condensing units also contain valves, filter/driers, and pressure controls, all of
which are potential leak sources.
Remote Headers
Remote headers are becoming more common in supermarkets to reduce the number of piping
runs from a central point near the sales area back to the compressor room. In contrast to headers
installed on compressor racks, remote headers are able to eliminate vibrations and the attendant
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risk of leaks. While less prone to leaks, they are usually less accessible and might not be checked
as frequently as a central compressor room.
Causes of Leaks
Leaks are caused by the inevitable wear and tear on a refrigeration system as well as poor design
and improper installation,4 servicing, and maintenance practices, such as:
Poor brazing techniques. Leaks can result from improper brazing techniques such as
improper cleaning of the joint prior to brazing, using the wrong brazing alloy, and failure to
heat the joint uniformly or to the proper temperature before filling the joint with brazing alloy.
Improperly tightened fittings. Leaks occur from threaded and flared fittings either when
they are not tightened sufficiently or when they are over-tightened and crack.
Valve caps and seals missing. To reduce leaks through valve stems and Schrader cores, all
valve stems that are designed to be capped, and all access Schrader valves, must have the
proper caps in place. Figure 3 provides an example of a Schrader valve without any caps. The
caps must also have the proper seal or o-ring in place to ensure leak tightness.
3: Image of a Schrader valve with no caps
Material incompatible with oil or refrigerant Seals exposed to HCFC refrigerants swell at
a different rate than seals exposed to FIFC refrigerants. If a system is being retrofitted from an
HCFC to an HFC refrigerant, especially if it requires a change in oil from a mineral oil to a
polyolester (POE) oil, gaskets or seals in the system may need to be replaced.
4 Information specific to leak tightness during installation can be found in GreenChill's Best Practices Guideline
Ensuring Leak-Tight Installations of Refrigeration Equipment, available at
http://www.epa.gov/greenchill/downloads/LeakGuidelines.pdf.
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Vibration. Most vibrations in refrigeration systems occur on or near the compressor
discharge lines and are caused by gas pulsations. If severe, discharge line vibrations can result
in broken lines or fittings, as seen in Figure 4.
Figure 4: Image of broken clamp caused by vibrations
Thermal expansion and contraction. Refrigeration systems change temperature, resulting in
expansion and contraction of the refrigeration piping and associated components. For
example, a 100°F increase in temperature will expand a 100 foot copper line by over an inch.
This temperature change is quite common in hot gas defrost suction lines. If the line is
constrained from freely expanding, thermal stress forces on the pipe may cause it to break
fittings at the support points. Properly engineered expansion loops are required to absorb
these thermal stresses. Likewise, constant thermal expansion and contraction can, over time,
adversely affect the sealing integrity of gaskets and seals used in refrigeration components.
Corrosion. Copper evaporator coils in contact with food acids such as vinegar may corrode
over time and develop pinhole leaks, as seen in Figure 5. Corrosion leaks can also occur on
compressor rack components from condensation forming or dripping on steel rack
components. Incompatible or improperly used cleaning materials also cause corrosion.
Technicians should only use cleaning agents that are compatible with the refrigeration
componentsespecially the evaporators and associated piping.
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Figure 5: 3-year old uncoated service deli coil
Metal-to-metal contact of tubing. Copper tubing in direct contact with other tubing or
harder steel supports or concrete can rub through the tubing wall and create leaks.
Improper support of tubing. Improperly supported copper tubing will sag between supports
or at 90-degree turns, creating unwanted stress. This stress may lead to broken lines or
fittings, eventually causing leaks.
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III. Getting Started
No-Tolerance Policy
Supermarket employees manage and run their business with the goal of meeting their customers'
needs. Although most companies understand the importance of minimizing leaks, competing
responsibilities often get in the way of making refrigerant management a priority. Identifying
leaks as a high priority is an important step in ensuring proper maintenance and repair of
refrigeration systems. Companies should establish a corporate-wide no-tolerance policy for
refrigerant leaks. Establishing a no-tolerance leak policy increases store managers' and service
technicians' awareness of system maintenance and leak repair. Increased awareness reduces the
likelihood that leak checks and tests will get overlooked and helps prevent unnecessary leaks.
In supporting a no-tolerance policy, senior management must openly acknowledge and
encourage the policy in order to reinforce the message throughout the company and among its
employees.
Highlighting savings in both refrigerant and servicing costs will help senior management get on
board with a no-tolerance policy. Common commercial refrigerants cost between $6-10 per
pound of refrigerant.5 Based on these prices and assumed servicing costs, refrigerant leaks could
cost a supermarket more than $10,000 each year. Clearly, refrigerant leaks are not only harmful
for the environment but also are bad for a company's bottom line.
Tracking Leaks
In addition to making leak prevention a priority, a supermarket should incorporate a leak
tracking system into its refrigerant management program. A tracking system enables a company
to easily quantify leaks, isolate leak sources, and manage refrigerant leaks across multiple stores
and systems. It also lets a company benchmark its data against industry trends and set and meet
leak reduction goals. A tracking system also lets a company hold individual stores accountable
for their leaks and makes it possible to reward store employees, service technicians, or
contractors for good practices.
A supermarket can use either a manual leak tracking system or tracking system software.
Tracking software - depending on the type used - can help automate the tracking of refrigerant
inventories, servicing dates, system capacities, leak amounts and frequencies, and component
failures. It can also generate automatic alerts if conditions warrant.
' Range represents costs of R-22, R-404A, and R-507 on May 20, 2010 from http://www.r22.org/.
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IV. Preventive Maintenance Practices
Clean Equipment
A clean and uncluttered mechanical room provides a safe and accessible environment for service
technicians and sends a strong signal about a store's commitment to equipment maintenance and
leak reduction. Dirty refrigeration compressor racks, air-cooled condensers, remote headers, and
walk-in evaporator coils make it difficult for technicians to spot leaks and create the impression
that a store is not concerned with the maintenance of equipment. Motivation of service
technicians is key to the success of a leak reduction program. To instill a sense of pride in your
service technicians, refrigeration racks as well as the entire mechanical room should be kept as
clean as possible. Compressor racks and their components should be free of oil and dirt.
Corrosion on steel components should be removed and components painted with a rust-inhibiting
paint to help prevent future corrosion. Mechanical rooms should not be permitted to be used as
storage areas by the store personnel - besides the obvious safety concerns, the clutter reduces a
technician's productivity, adds to his or her frustration, and increases maintenance costs. As a
result, equipment and mechanical rooms should be cleaned at least annually. Oil spills and other
substantial messes should also be cleaned as they occur.
Figure 6: Clean Machine Room at a Farm Fresh Store
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Leak Detection Alarm Systems
Each store should have a refrigerant leak monitoring and alarm system to ensure a response to
major leaks that could develop between regular leak inspections. Leak detection systems are
either direct or indirect. A direct detection system directly measures the refrigerant in an air
sample taken near a refrigeration system or one of its components. An indirect system measures
changes in receiver refrigerant levels, the weight of the condenser/receiver assembly, or system
temperature. Often the first notification of a refrigerant leak comes from a temperature sensor
that actuates a temperature alarm as the rack starts to run low on refrigerant.
One low-cost alarm system that can be easily incorporated into most stores uses a system
temperature sensor that measures the temperature of the system farthest from the compressor
rack, which is the first location likely to be affected by a low refrigerant charge. This system
should be programmed with an alarm temperature as close to set point as possible without
triggering nuisance alarms. When this temperature alarm is activated, it should be treated as a
refrigerant leak alarm. Regardless of the type of system chosen, the monitoring system needs to
be tied to an alarm system that proactively notifies store management of potential leaks.
Furthermore, levels of redundancy or checks in the alarm system procedure should be in place to
ensure that the alarm is not ignored.
Unfortunately, direct central leak detection systems are not ideal in highly-vented locations due
to the rapid dilution of the refrigerant sample in the ambient air. Since remote air-cooled
condensers are located outdoors, refrigerant loss from such units can only be detected using an
indirect leak detection system or during preventative leak checks. Similarly, it can be challenging
to apply direct central refrigerant leak detection to condensing units with unit-mounted air cooled
condensers, due to the volume of air changes the condensers require. As a result, regular leak
inspections are extremely important and should not be overlooked.
Regular Leak Inspections
On a regular basis service technicians should check receiver levels, compare refrigerant levels to
data from the previous visit, and walk through the store with portable device. The GreenChill
Checklist for a Walk-Thru Leak Check of a Supermarket and the Receiver Refrigerant-Level
Chart, in Appendix A and Appendix B, respectively, should be used for this purpose. Checks
should be done every one to two months, based on the size of the system and the system type.
Large central DX systems need to be checked more frequently while secondary systems with
mechanical room refrigerant monitoring may be checked less often.
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V. Leak Repairs
Response Time
A supermarket company should establish a corporate policy for responding to a refrigerant leak
alarm. It should establish both a maximum response time and a process for finding and repairing
the leak once a service technician is on site. The response time should be as short as reasonably
possible, normally two to four hours in most areas. In the event of a major leak, large quantities
of refrigerant can leak out of a system in a short period, so a fast response time could prevent a
considerable amount of refrigerant from leaking to the atmosphere.
Under no circumstances should a leaky system be left prior to the identification and repair of the
leak. If a major component that is not readily available is leaking and needs to be replaced, that
component should be isolated from the system or given a temporary repair, if possible. Simply
adding more refrigerant to the system (i.e., topping off the system) is not considered a viable
solution to addressing a leak.
Thoroughness of the Check
In many cases the first refrigerant leak found in a leak check may not be the only leak in the
system. In fact, it might not be the leak responsible for most of a refrigerant loss. Therefore, each
technician should understand the correlation between the quantity of refrigerant charge lost and
the leak rate of the leak found. If the leak found is too small to leak the quantity of refrigerant
lost, the technician should assume there is another leak in the system and continue the leak
search.
Follow Up Checks and Verification
Once the repair is made, the system should be checked to verify it is leak-free. The verification
should include a check of the repaired area as well as the receiver level to ensure that no
additional refrigerant was lost. A drop in receiver level is an indication that there could be more
leaks in the system.
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VI. Reducing Leak Potential
Overcharged Systems
A refrigeration system may require a "winter charge," in which more refrigerant is used in the
winter to permit flooding of the condenser to maintain a minimum operating system head
pressure. This charge should be kept as small as possible by using split-condenser valves, fan
cycling, and floating head pressure control. System charges can also vary significantly if the rack
is piped to a heat recovery coil or uses a gas-type defrost. The total annual refrigerant charge is
the charge required to feed expansion valves with saturated liquid refrigerant at the time when
the system charge requirement is at its maximum, and no more. This total annual charge may
only be needed for a relatively few hours a year and is stored the rest of the time in the system's
receiver. As a result, a system could have an excess refrigerant charge in the receiver over 90%
of the time.
If a leak occurs during this 90% period, it might be possible to lose the entire receiver charge
before the refrigerant loss begins to affect case temperatures. To minimize the potential for such
loss, it is important to document the receiver levels during winter and summer conditions as well
as when the system is in defrost or heat recovery mode. These levels should be posted on the
refrigeration rack or in some other convenient location that is readily available to any service
tech who would be charging the system after a leak. It is common practice for service technicians
to charge additional refrigerant to a system as a safety buffer. This buffer refrigerant will add to
the potential loss, and a policy should be instituted to avoid this practice.
System Component Upgrades
System components should be replaced with parts that are more leak-resistant or have a reduced
number of potential leak sources. For example, discharge-piloted evaporator pressure regulating
(EPR) valves may be replaced with suction stepper valves, which eliminate the high-side control
line, provide better temperature control, and are generally more reliable. Suction and liquid
manifolds may be replaced with loop piping systems or remote manifolds to reduce the number
of fittings subject to rack vibration. During major remodels, you may also want to consider
replacing centralized DX racks with distributed systems, secondary loop systems, or CC>2
systems to further reduce leak potential.
Additional Recommendations
A store can further reduce the leak potential of its existing refrigeration system by following
these recommendations:
» Replace flared connection components with brazed connection components.
v Replace valves with bolted connections with hermetic one-piece valves with no mechanical
joints.
v Replace valves with control lines with valves that don't require control lines.
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» Ensure the proper cap is in place on all valve stems designed to be capped, as well as
access Schrader valves. The caps should also have the proper seal or o-ring in place to
ensure leak tightness.
v Replace fragile cap tube-type control lines with steel lines or armored flexible lines.
v Tighten bolts on flanges used to connect valves and filter-drier covers to the proper torque
and use a new gasket in reassembly.
v Eliminate liquid hammer by mounting a sealed vertical tee ahead of the solenoid valve.
v Use an approved thread sealant to prevent leakage from threads or from corrosion around
threads.
v Conform installations to pipe support spacing recommendations specified in the 2008
ASHRAE Handbook - HVAC Systems and Equipment.6
v Protect tubing by creating a space separation or using a cushioning material.
v Ensure equipment located in vulnerable environments has epoxy or phenolic coatings on
fin-tube surfaces, refrigerant piping, or other components that are subject to corrosion.
Vulnerable equipment may include service deli cases that are in contact with vinegar-
containing products and rooftop condensers that are located near the coastline or a
chemical plant.
v Ensure chemical compatibility of cleaning agent with components and materials.
6 2008 ASHRAE Handbook - HVAC Systems and Equipment 45.7, Table 6: Suggested Hanger Spacing and Rod
Size for Straight Horizontal Runs. Adapted from MSS Standard SP-69-2003.
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Appendix A. Supermarket Walk-Thru Checklist
This checklist should be used to routinely check your store for refrigerant leaks. To complete the leak inspection,
you will need a hand-held electronic leak detector capable of measuring refrigerant leaks of ₯2 oz per year. The leak
detector should be checked and calibrated at least once a year and preferably more often. Remember, the only way
to solve refrigerant leaks is to repair them; topping-offyour system is not a viable solution!
[. Receiver Levels: Identify and log the refrigerant level of the receiver of each
refrigeration system using the GreenChill Monthly Refrigerant Receiver Level Chart (see
Appendix B). Be sure the refrigeration systems are not in heat reclaim, gas defrost, split
condenser, or winter flooding mode, or any other condition that could affect receiver level.
Compare the current refrigerant level with levels logged during previous checks. A drop in
the receiver level from a previous reading it may indicate a leak in the system.
**REMEMBER** A significant drop in refrigerant level must be the result of a significant
leak. Do not stop at the first leak found, especially if it is a seeping connection or valve stem
leak. Continue searching until a significant leak is found.
\. Oil Seepage: Visually check the compressor racks, piping, and valves in the
mechanical room for any oil seepage. If oil seepage is identified, use soap bubbles or an
electronic leak detector to identify any refrigerant leak and pinpoint the exact location.
L Mechanical Room: Using an electronic leak detector at its most sensitive setting,
slowly move the probe over all components in the mechanical room. Temporarily turn off the
mechanical room ventilation to reduce air movement. If the detector indicates a leak within
the space, slowly reduce the sensitivity and progressively move to the leak location until
found.
I. High-Pressure Control Lines: Check the control line temperature of all high-
pressure switches about 12 inches from the compressor connection. If the temperature is
above the mechanical room ambient temperature, it may indicate a small leak in the control
line, fitting or control bellows.
Pressure Relief Valves: Check the pressure relief valves of each system for
refrigerant release. Each relief valve should have a balloon, blow-off cap, or other telltale
way to signal that a relief valve has discharged. Under normal conditions, a relief valve
should never discharge. If it has, the cause must be found and corrected and the relief valve
replaced as they are only designed for one release and may seep refrigerant if left in place.
Air-Cooled Condensers: Visually check all air-cooled condensers for oil seepage
underneath unit on finned coil surfaces. Check return bends and manifold assemblies for oil
seepage. If a view of return bends is blocked by a cover, either remove the cover to inspect or
use an electronic leak detector to probe the area under the cover. If the condenser is
suspected of leaking, the refrigeration system should be turned off temporarily along with the
condenser fans so the leak may be pinpointed using soap bubbles or an electronic leak
detector.
Condenser Fan Blades and Motor Mounts: Check condition of condenser fan
blades for cracking or tearing of the metal, especially at the point on the assembly where the
fan blade is riveted to the hub. If cracking or tearing is present, disconnect the motor and
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8.
9.
10.
11.
replace the blade as soon as possible. Check motor mounts of each fan motor assembly for
signs of deterioration and replace or repair immediately.
Sales Area: Walk through the sales area of the store with an electronic leak
detector at its most sensitive setting. Probe the entire length of the discharge air stream of
each refrigerated case. If a leak is detected, unload the case and check the evaporator coil, all
valves, connections, and interconnecting piping until the leak is pinpointed.
Refrigerated Walk-Ins & Prep Rooms: Check each walk-in cooler, freezer, and
refrigerated prep area in the store with an electronic leak detector at its most sensitive setting.
If the leak detector indicates a leak, slowly reduce the sensitivity and progressively move to
the leak location until found.
Underground Refrigerant Piping: Check sub-surface refrigeration access pits
starting with the riser pits with an electronic leak detector at its most sensitive setting. If
refrigerant is detected, reduce sensitivity to determine whether the leak is in that pit. If it is
the leak is not in that pit, move to the next pit in the underground piping network. A drop in
the leak detector reading may indicate that the leak is in the piping between the two pits. If it
increases, continue checking each pit in the piping network until the leak is pinpointed in a
pit connection or it is determined that the leak is in the interconnecting piping between two
pits. If the leak is found to be in the interconnecting piping and the piping is not accessible,
turn off each system that has lines passing though the pipe duct, one by one. This will
increase the pressure in the suction lines and should trigger an increased leak rate reading on
the electronic leak detector when the offending system is turned off. If this does not provide
positive results, the next step is to pump down each system one by one. This will decrease
the pressure in the liquid lines and should result in a decreased leak rate reading on the
electronic leak detector when the offending system is turned pumped down. If the above
steps do not yield positive results and there is a high degree of confidence that one of the
systems in the pipe duct is leaking, it will be necessary to isolate each individual line and
pressure test each to 300 psig using dry nitrogen for 24 hours. Once the leaking line is found,
it will be necessary to replace the line or reroute the line overhead.
Overhead Refrigerant Piping: Check accessible overhead refrigeration lines by
following the path of the lines using an electronic leak detector set at its most sensitive
setting. If the lines are insulated, it may be necessary to probe under the insulation to pinpoint
the leak. Be sure to properly reseal the insulation to preserve its integrity.
16
www.epa.gov/greenchill
Chillin' for the environment
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Appendix B. Monthly Refrigerant Receiver Level Chart 2011-2012
Store # Rack #
100%
90%
80%
1 70%
-
4>
Z 60%
u
4*
rt
| 50%
_
4>
W)
§ 40%
£
30%
20%
10%
J-ll F-ll M-ll A-ll M-ll J-ll J-ll A-ll S-ll O-ll N-ll D-ll J-12 F-12 M-12 A-12 M-12 J-12 J-12 A-12 S-12 O-12 N-12 D-12
17
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