Refex 134a Spec

8/12/2019 Refex 134a Spec

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Refrigerant Blends:

Composition Changes DuringRefrigerant Transfer and

Equipment Charging

Chemicals SectionJanuary 2000


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FOREWORD

Multi-component refrigerants are being used to replace several single compound refrigerants.Composition changes can occur when these mixtures are removed as liquid from containers, andthese changes may be increased if more than one transfer occurs such as in repackaging. Thecomposition changes depend on the zeotropic nature of the mixture. These handling issues areimportant to original equipment manufacturers (OEMs), as refrigerant being charged into theirequipment must be within specified tolerances.


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Table of Contents

Purpose.......................................................................................................................................1

Scope..........................................................................................................................................1

Definitions ........................... ........................... ........................... ........................... .......................1

Refrigerant Supply Chain.............................................................................................................2

Composition Change during Liquid Removal from Containers for Multi-component RefrigerantMixtures .......................... ........................... .......................... ........................... ........................... .2

Suggestions for Minimizing Composition Changes.......................................................................7

Handling of Series 400 (Zeotropic) Refrigerants...........................................................................8

Disclaimer ........................... ........................... ........................... ........................... .......................9

References..................................................................................................................................9

TABLES

Table 1. R-410A and R-407C Compositions during Liquid Removal from Containers .................3

Table 2. R-507 and R-404A Compositions during Liquid Removal from Containers...................3

FIGURES

Figure 1. OEM Storage Tank: Composition Changes during Liquid Removal and Refilling ofR-410A........................................................................................................................................4

Figure 2. OEM Storage Tank: Composition Changes during Liquid Removal and Refilling ofR-407C........................................................................................................................................4

Figure 3. OEM Storage Tank: Composition Changes during Liquid Removal and Refilling ofR-507 ......................... ........................... ........................... ........................... ........................... .....5

Figure 4. OEM Storage Tank: Composition Changes during Liquid Removal and Refilling ofR-404A........................................................................................................................................5

Figure 5. R-407C: Composition Change with Liquid Draw from Primaryand Second Containers ......................... ........................... ........................... ........................... .....6

Figure 6. R-407C: Composition Change with Liquid Draw from Primary and Second Containers .7

APPENDIX

Appendix: Summary of Liquid Draw Calculations ....................... ........................... .....................10


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Refrigerant Blends: Composition Changes During Refrigerant Transfer and Equipment Charging

1

1. Purpose

This document is intended to provide information for repackagers and users on the properhandling and repackaging of multi-component refrigerants. This is important since the refrigerantbeing charged into equipment must be within tolerances specified in ASHRAE Standard 34.

2. Scope

This document provides some general information on the fractionation of refrigerant blends andthe situations under which it will occur. It also provides guidance on how to transfer multi-component refrigerants to minimize fractionation. Information on fractionation of specific blendsduring liquid draw is included in an appendix.

3. Definitions

Azeotrope: A mixture of volatile substances whose equilibrium vapor-phase and liquid-phasecompositions are the same at a specific pressure.

Azeotropic temperature:The temperature at which the liquid and vapor phases of a blend havethe same mole fraction of each component at equilibrium for a specified pressure.

Blends: Refrigerants consisting of mixtures of two or more different chemical compounds.

Bubble point:The liquid saturation temperature of a refrigerant; the temperature at which a liquidrefrigerant first begins to boil.

Dew po int:The vapor saturation temperature of a refrigerant; the temperature at which the lastdrop of liquid refrigerant boils; also the temperature where the refrigerant just begins to condense.

Fract ionat ion: A change in composition of a blend by preferential evaporation of the morevolatile component(s) or condensation of the less volatile component(s).

Glide: The absolute value of the difference between the starting and ending temperatures of aphase-change process by a refrigerant blend, exclusive of any subcooling or superheating. Thisterm usually describes condensation or evaporation of a zeotrope. Temperature differencebetween the bubble point and dew point.

Near azeotrop e: A zeotropic blend with a temperature glide sufficiently small that it may bedisregarded without consequential error in analysis for a specific application.

Nominal composi t ion:The composition of a refrigerant blend as specified in ASHRAE 34 Table2.

Nonazeotrope: See zeotrope.

Refrigerant: Fluid used for heat transfer in a refrigeration system, which absorbs heat at a lowtemperature and a low pressure of the fluid and rejects heat at a higher temperature and a higherpressure of the fluid usually involving changes of the phase of the fluid.

Temperature glide:See gl ide

Zeotrope: A blend comprising multiple components of different volatilities that, when used inrefrigeration cycles, change composition and saturation temperatures as they evaporate (boil) orcondense at a constant pressure.


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4.Refrigerant Supply Chain

The supply of refrigerants starts from the manufacturers. The blends are mixed in large storagetanks and analyzed for purity and composition. At this point the product may be transferred intoiso-containers (18,000 liter containers that can hold ~30,000 lbs of refrigerant) in which largequantities of refrigerant are shipped either domestically or internationally for later packaging atother installations. Composition and purity are again verified in the iso-container. Another optionis tank trucks or railroad cars for bulk shipment to OEMs. However, much of the refrigerant ispackaged at the refrigerant manufacturers site into small disposable (nominally 25 to 30 lbs.) orrefillable cylinders (nominally 100 to 125 lbs.).

Currently, the most popular method for transporting refrigerant blends outside North America is touse the large iso-container. These containers are shipped overseas to Europe, Asia, and otherparts of the world. Generally, the refrigerant from the iso-containers are transferred (often at arefrigerant manufacturers remote location) into small ton tanks (900-liter vessels) where they areshipped to various distributors. At these distributor locations the product is again transferred intosmaller service cylinders (12, 26, or 60-liter vessels). Most equipment is charged from theseservice cylinders. Some large installations may utilize the ton cylinders directly. Also, largerdistributors of more popular refrigerants may receive the iso-containers directly and fill the service

cylinders without the intermediate step of filling the ton cylinders. This method of product delivery,which involves multiple transfers, offers the most challenges for composition control.

Equipment manufacturers generally receive refrigerant in bulk shipments from the refrigerantmanufacturer. They have an on-site bulk storage tank that is periodically filled from either tanktrucks or in some cases railroad cars. The refrigerant is then pumped to charging stations that fillthe air conditioning or refrigeration equipment. Although it can be controlled, there is potential forsignificant shifts of composition in this product delivery system as well.

Most of the refrigerant that is sold to the installation and service contractors in North America ispackaged at the refrigerant manufacturers plant. The refrigerant is transferred from the largestorage tanks to cylinder filling lines. This method of product delivery presents the least likelihoodof composition shifts since the composition is controlled at the manufacturers site.

5.Composition Change during Liquid Removal from Containers for MulticomponentRefrigerant Mixtures

5.1 Introduction

To understand the potential composition changes during handling processes such as liquidremoval from containers, including refilling of storage tanks, a computer model was used. Modelcalculated numbers were verified by comparison with experimental data from liquid removal tests.Examples of composition changes are shown for four refrigerant mixtures: R-410A, R-407C, R-404A, and R-507. The calculated numbers indicate that refrigerant mixtures can havecomposition changes during the handling procedures that lead to out-of-specification

compositions. Special attention is required to maintain compositions within specifications duringthe different handling procedures. A complete listing of ASHRAE designated refrigerant mixtureswith possible composition changes during liquid removal from containers is located in the

Appendix.

5.2 Liquid Removal from Containers

Tables 1 and 2 have the calculated composition changes as liquid is removed from containers ofR-410A, R-407C, R-507, and R-404A. Beginning liquid levels are at 85%, going down to 2%liquid level.


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Table 1. R-410A and R-407C Compositions during Liquid Removal from Containers

(Calculations made at 25C isothermal conditions)

R-410A (wt %) R-407C (wt %) % Liquid Level R-32 R-125 R-32 R-125 R-134a

85 50.00 50.00 23.0 25.0 52.050 49.92 50.08 22.8 24.9 52.340 49.89 50.11 22.7 24.8 52.530 49.85 50.15 22.6 24.7 52.720 49.80 50.20 22.5 24.6 52.915 49.76 50.24 22.3 24.6 53.110 49.72 50.28 22.2 24.5 53.35 49.66 50.34 22.0 24.4 53.6

2 49.61 50.39 21.9 24.2 53.9

ASHRAE composition tolerances for R-410A are +0.5,-1.5% for R-32 and +1.5,-0.5% for R-125(from the 50/50 wt% nominal composition); for R-407C the composition tolerances are +/-2% forall three components from the 23/25/52 wt% nominal composition. If we consider the lowest liquid

level at 5%, then the R-410A composition change would be 0.34% and the highest R-407Ccomposition change would be 1.6%. These changes indicate that supplying R-407C at thenominal composition could result in some refrigerant leaving the container being near the edge ofthe specification (54% R-134A). Therefore, R-407C manufacturing specification should be set atno higher than 52% R-134a. If a repackaging situation is considered such as iso-container or tontank to a smaller container such as a 100 lb cylinder or 30 lb disposable cylinder, the compositionchanges from the small containers could be higher, suggesting an even tighter manufacturingspecification for R-134a in R-407C.

Table 2. R-507 and R-404A Compositions during Liquid Removal from Containers

(Calculations made at 25C isothermal conditions)

R-507 (wt %) R-404A (wt %) % Liquid Level R125 R143a R125 R143a R134a

85 50.00 50.00 44.00 52.00 4.0050 49.96 50.04 43.95 52.01 4.0440 49.95 50.05 43.93 52.01 4.0630 49.93 50.07 43.89 52.02 4.0920 49.90 50.10 43.86 52.02 4.1215 49.88 50.12 43.84 52.03 4.1310 49.86 50.14 43.81 52.03 4.165 49.84 50.16 43.75 52.03 4.22

2 49.81 50.19 43.72 52.04 4.24

The proposed ASHRAE tolerances for R-507 are +0.5/-1.5% for R-143a and +1.5/-0.5% for R-

125. On the other hand, the UL specifications are 49.9-50.9% for R-125 and 49.1-50.1% for R-143a. This can be stated as 50.4 +/-0.5% for R125 and 49.6 +/-0.5% for R143a. For R-404A, thenominal composition is 44/52/4 wt%, with UL specifications being +/-1% for each component.

ASHRAE specifications are +/-2% for R-125 and R-134a, and +/-1% for R-143a. R-507, R-404A,and R-410A have less composition shift than R-407C as can be seen by the compositionchanges in Tables 1 and 2. However, these changes must be taken into consideration whenestablishing manufacturing specifications.


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refill refill

5.3 Storage Tank Liquid Removal and Refilling

Calculations were made for typical OEM procedures of refrigerant removal from storage tanks forcharging into equipment and storage tank refilling. We assumed an OEM storage tank of 6600gallon and a tank truck of 5000 gallon. The storage tank was operated within liquid levels of 80%to 15%. The tank truck arrived with 85% liquid level and transfers were made with vapor lineequalization. (Note: we also made calculations for transfers without vapor line equalization andfor the cases we describe in this report, there was essentially no difference - less than 0.1 wt%).

All liquid was transferred from the tank truck to the storage tank.

Figure 1 illustrates the composition changes for R-32 and R-125 in R-410A during storage tankliquid removal from 80% to 15% liquid level, followed by refilling to 80% level with refrigerant fromthe tank truck having the liquid composition of 50/50. wt% R-32/R-125.

Figure 1. OEM Storage Tank: Composition Changes during Liquid Removal andRefilling of R-410A

R-32/R-125 compositions in weight percent

The maximum change in composition is 0.3% at 15% liquid level, and the composition changestabilizes after the second refilling of the OEM storage tank. The compositions are well within the

specifications of 48.5 - 50.5% for R-32 and 49.5 - 51.5% for R-125.

Figure 2 illustrates the compositions of R-32, R-125, and R-134a in R-407C during liquid removalfrom 80% to 15% liquid level, followed by refilling to 80% level with refrigerant from the tank truckhaving a liquid composition of 23/25/52 wt% R-32/R-125/R-134a. Vapor line equalization

assumed at 25C.

Figure 2. OEM Storage Tank: Composition Changes during Liquid Removal andRefilling of R-407C

R-32/R-125/R-134a compositions in weight percent

80 % liquid level

15% liquid level

50.00/50.00

49.80/50.20

49.95/50.05

49.70/50.30

49.94/50.06

49.70/50.30

80 % liquid level

15% liquid level

23.0/25.0/52.0

22.3/24.6/53.1

22.9/24.9/52.2

22.2/24.5/53.3

22.8/24.9/52.3

22.2/24.5/53.3

refill refill


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The maximum change in composition is 1.3% R-134a at 15% liquid level, and the compositionstabilizes after the second refilling of the OEM storage tank. The compositions are within the R-407C specifications.

Figure 3 illustrates the compositions of R-125 and R-143a in R-507 during the same liquidremoval and refilling operations. The maximum change in composition is 0.14%.

Figure 3. OEM Storage Tank: Composition Changes duringLiquid Removal and Refilling of R-507

R-125/R-143a compositions in weight percent

Figure 4 illustrates the compositions of R-125, R-143a, and R-134a in R-404A during the liquidremoval and refilling operation. The maximum change in composition is 0.19% for R-125.

Figure 4. OEM Storage Tank: Composition Changes duringLiquid Removal and Refilling of R-404AR-125/R-143a/R-134a compositions in weight percent

5.4 Refrigerant Transfers to Smaller Containers

We can also illustrate graphically the composition changes that can occur when transferring liquidfrom one storage container to a second container, followed by liquid removal from the second

container. In the next figure (Figure 5), we illustrate the R-134a compositions of a primarycontainer of R-407C (initially having R-134a composition of 52.0%) which is used to fill othercontainers. The primary container liquid level has been reduced to 50% at which point transfer tothe second container begins. The second container is filled to 85% level, with the R-134aconcentration in the second container being at 52.4%. As liquid is removed from the secondcontainer, the R-134a concentration begins to increase, but staying within the maximumspecification of 54% R-134a down to 5% liquid level.

80 % liquid level

15% liquid level

50.00/50.00

49.89/50.11

49.97/50.03

49.86/50.14

49.97/50.03

49.86/50.14

refill refill

80 % liquid level

15% liquid level

44.00/52.00/4.00

43.86/52.02/4.12

43.96/52.01/4.03

43.82/52.03/4.15

43.95/52.01/4.04

43.81/52.03/4.16

refill refill


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We now describe (Figure 6) refrigerant transfers when the primary container has been reduced tolower levels of refrigerant. If liquid is taken from the primary container at the 20% level, R-134aconcentration in the second container will initially be at 53%. Refrigerant in this second containerwill be above the R-134a composition specification when refrigerant liquid has been removeddown to a liquid level of 18%. If liquid from the primary container at 5% liquid level is used to fillcontainers, the second container compositions will initially be at 53.7% R-134a, and will be abovethe R-134a specification when refrigerant liquid has been removed down to a liquid level of 50%.

FIGURE 5

R-407C: Composition Change with Liquid Draw

from Primary and Second Containers

51

51.5

52

52.5

53

53.5

54

54.5

55

0102030405060708090

% Liquid Level in Primary and Second Containers

Wt.%R-134

Primary

Container

R-134a Spec.Max.

Second Container filled to

85% level with liquid from

Primary Container at 50%

liquid level


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FIGURE 6

6.Suggestions for Minimizing Composition Changes

Fractionation of blended refrigerants can be minimized by following proper handling techniques.Initially, make sure that the system being charged is not leaking. Slow leaks, especially from thevapor phase, can cause composition changes. By careful leak checking and prompt leak repair,leaks will have a reduced effect on refrigerant composition.

The liquid and vapor phases in a container are not necessarily at the same composition. Sincethe intended composition is that of the liquid, filling should always be done from the liquid phase.This will minimize compositional changes resulting from the transfer.

Operations such as bulk transfer to storage tanks could affect the composition of zeotropic blendsdue to fractionation (see Section 5). Vapor equalization is sometimes used when refilling a tankwith a bulk delivery. Here, the refrigerant is unloaded by using a liquid pump to move the liquidproduct to a secondary tank while the top of the primary and secondary tanks are interconnectedby another hose to allow refrigerant vapor to move from one vessel to the other

1. Vapor

equalization will have minimal impact on fractionation, but care should be exercised to avoidcontamination of the delivery tank with a different refrigerant.

R-407C: Composition Change with Liquid Draw fromPrimary and Second Containers

51.5

52

52.5

53

53.5

54

54.5

55

55.5

0102030405060708090

% Liquid Level in Primary and Second Containers

Wt.%

R-134a

Primary

Container

R-134a S ec.Max.


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The ambient temperature, amount of refrigerant remaining, etc. can impact blend composition. Asalready shown in Figures 5 and 6, it may not always be possible to use all the refrigerant liquid inthe container and stay within ASHRAE composition specifications (also see Section 7.4). Ideally,analytical equipment, particularly a gas chromatograph, should be used to verify the liquidcomposition of a refrigerant blend.

Refrigerant manufacturers can assist customers with procedures for transferring refrigerantblends. The extent of composition change can be minimized by careful adherence to properprocedures.

7. Handling of Series 400 (Zeotropic) Refrigerants

7.1 System Leakage and recharging

Leaks in systems occur either while the system is operating or while the system is off. The worstcase change in refrigerant composition (fractionation) is when the leak occurs while the system isoff. In typical refrigeration systems the circulating composition of all blended refrigerants canchange from the nominal composition. Experience has shown that small changes in refrigerantcomposition have a negligible effect on performance in the vast majority of systems since

refrigerant performance is not very sensitive to changes in composition.

Recharging the system with the original composition of a zeotropic refrigerant after leakagetypically results in small changes in the composition of the refrigerant in the system. Performancechanges are usually very small, on the order of only several percent in both capacity and COP.Systems operating with minimal superheat are sensitive to refrigerant composition changes.These systems should have the superheat checked after recharging.

7.2 System Charging

When both liquid and vapor are present in a cylinder containing a series 400 refrigerant, thesaturated vapor composition can be significantly different than the liquid composition. This meansthat only liquid should be removed from the container for charging into systems. Cylinders not

fitted with dip-tubes should be inverted to allow liquid charging to take place. If vapor charging isrequired, a throttling valve or equivalent must be used on the cylinder outlet to vaporize the liquidrefrigerant before it enters the system.

7.3 Liquid and Vapor Composition in Containers

The composition of the liquid refrigerant in the cylinder changes slightly as liquid refrigerant isremoved but this is not normally significant until the cylinder is almost empty (typically in therange of 5 to 15% liquid). The composition of the vapor in the cylinder will be different from theliquid composition and should not be used to charge systems.

7.4 Liquid Filling from Container to System

Different filling procedures apply depending on the ambient temperature and the relative size ofthe filling container in combination with the refrigeration system being charged. In general terms if

the container of 400 series refrigerant remains below 85F during the charging process, thecomposition of refrigerant blend added to the system remains nearly constant as the container isemptied. The following procedures also apply;

(a) If a large container is used to fill many smaller systems most of the liquid (85 to 95%) may beused. Beyond this point, the liquid composition should be verified per ARI Standard 700. Thevapor in the container should not be used to charge a system. The refrigerant blend remaining inthe container should be returned as a heel for reclaim.


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(b) Where the size of the container and the system being charged are comparable in size, it ispossible to use all the contents of the container. As a guide, if the refrigeration system can befilled entirely from the last 20% of the cylinder contents then the composition filled into the systemwill be within specification.

(c) For large refrigeration systems, one or more full containers can be emptied completely(leaving a slight positive pressure) without any measurable change in composition.

Disclaimer

All Information contained in this document is believed to be accurate but is made withoutguaranty or warranty of any kind either express or implied. Users must satisfy themselves thatthis information is entirely suitable for their purpose and process. Users assume all responsibilitythrough use or application of the information herein. Statements concerning use of thisinformation do not grant a license under any patent and do not recommend the infringement ofany patent.

References

1- P. Pieczarka and J. Lavelle, 1996, Storage, Bulk Transfer, and In-Plant Handling ofZeotropic Refrigerant Blends, Proceedings of the 1996 International RefrigerationConference at Purdue, West Lafayette, IN, pp. 107-112.


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Refrigerant Nominal Composition Composition Change Tolerance(Wt%) @ 25

oC for 85% to 5% (Wt%)

Liquid (Wt%)

R-407C R-32: 23 -1.0 +/-2R-125: 25 -0.6 +/-2R-134a:52 +1.6 +/-2

R-407D R-32: 15 -0.53 +/-2R-125: 15 -0.45 +/-2R-134a:70 +0.98 +/-2

R-407E R-32: 25 -0.77 +/-2R-125: 15 -0.38 +/-2R-134a:60 +1.15 +/-2

R-408A R-125: 7 -0.16 +/-2R-143a:46 -0.39 +/-1R-22: 47 +0.55 +/-2

R-409A R-22: 60 -1.56 +/-2R-124: 25 +0.8 +/-2R-142b:15 +0.75 +/-1

R-409B R-22: 65 -1.46 +/-2R-124: 25 +0.9 +/-2R-142b:10 +0.55 +/-1

R-410A R-32: 50 -0.35 +0.5, -1.5R-125: 50 +0.35 +1.5, -0.5

R-411A R-1270:1.5 -0.07 +0, -1R-22: 87.5 +0.75 +2, -0

R-152a:11 -0.68 +0, -1

R-411B R-1270:3 -0.14 +0, -1R-22: 94 +0.97 +2, -0R-152a:3 -0.83 +0, -1

R-411C R-1270:3 -0.14 +0, -0.5R-22: 95.5 +0.38 +1, -0R-152a:1.5 -0.25 +0, -0.5

R-412A R-22: 70 -0.55 +/-2R-218: 5 -0.36 +/-2R-142b:25 +0.91 +/-1

R-413A R-218: 9 -0.9 +/-1R-134a:88 +1.09 +/-2R-600a:3 -0.19 +0,-1

R-414A R-22: 51 -1.48 +/-2R-124: 28.5 +0.84 +/-2R-600a:4 -0.01 +/-0.5R-142b:16.5 +0.65 +0.5, -1


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Refrigerant Nominal Composition Composition Change Tolerance(Wt%) @ 25

oC for 85% to 5% (Wt%)

Liquid (Wt%)

R-414B R-22: 50 -1.48 +/-2R-124: 39 +1.13 +/-2R-600a:1.5 -0.01 +/-0.5R-142b:9.5 +0.36 +0.5, -1

R-416A R-134a:59 -0.83 +0.5, -1R-124: 39.5 +0.88 +1, -0.5R-600: 1.5 -0.05 +0.0, -0.3

R-507*

R-125: 50 -0.17 +1.5, -0.5R-143a:50 +0.2 +0.5, -1.5

R-508A R-23: 39 -0.26 +/-2R-116: 61 +0.26 +/-2

R-508B R-23: 46 -0.33 +/-2

R-116: 54 +0.33 +/-2

R-509A R-22: 44 -0.16 +/-2R-218: 56 +0.16 +/-2

*The listed tolerances for R-507were proposed to ASHRAE and have not yet been published.

Refex 134a Spec

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