Application Guide

DOWTHERM SR-1 andDOWFROST HDHeat Transfer FluidsIn Thermal Energy Storage

IntroductionAbout this guide .......................................................................... 1Types of thermal energy storage systems .................................... 1Other literature available ............................................................ 1

Product Descriptions and BenefitsDOWTHERM SR-1 fluid ........................................................... 2DOWFROST HD fluid ............................................................... 2Typical product physical properties ............................................ 2Specially formulated inhibitors prevent system corrosion ......... 2Low freezing points prevent chiller freeze-ups............................ 2Approved by ice storage system OEMs ....................................... 2Backed by a comprehensive package of Dow support services ... 3Selecting the best fluid for your system ...................................... 3

System Design and PreparationMaterials of construction ............................................................ 3Automatic water make-up .......................................................... 4Expansion factor .......................................................................... 4System cleaning........................................................................... 4New systems ................................................................................ 4Existing systems ........................................................................... 4

Preparing Solutions of DOWTHERM and DOWFROST FluidsDilution water quality ................................................................. 5Solution make-up ........................................................................ 5Introducing the fluids into your system ...................................... 5

Maintaining DOWTHERM and DOWFROST FluidsFree analytical service ................................................................. 6How the service works ................................................................ 6Analytical tools for self-testing ................................................... 6

Physical Property DataPhysical properties of solutions– DOWTHERM SR-1 .............. 7Typical freezing and boiling points – DOWTHERM SR-1 ....... 7Pressure drop charts – DOWTHERM SR-1 ............................8-9Physical properties of solutions – DOWFROST HD ............... 10Typical freezing and boiling points – DOWFROST HD ......... 10Pressure drop charts – DOWFROST HD ............................11-13

CONTENTS

1

INTRODUCTION coils of plastic or metal tubingimmersed in a tank of water. Achilled glycol and water solution iscirculated through the tubes tobuild ice on the outside of thetubes during the off-peak hours.When air conditioning is neededthe same solution is circulatedthrough the tubes to melt the iceand provide chilled glycol solutionfor building cooling.

The second type of system worksin the same fashion except theglycol solution is circulatedthrough a tank filled with plasticcontainers of water. The ice formsin the containers and is latermelted by the same glycol solutionwhen cooling is needed. For moredetailed explanations of thedifferent types of TES systems,please consult the manufacturersof the various systems.

Other literature available

■ Engineering and OperatingGuidesDOWFROST HD (No. 180-01286)DOWTHERM SR-1 (No. 180-201190)

■ Fluidfile Software Program(No. 176-01416)

■ Dow Product Line Guide(No. 176-01419)

■ "How to protect your HVACsystem from corrosion and highmaintenance costs" (No. 180-1263)

■ Material Safety Data Sheets

■ Engineering specifications forclosed-loop HVAC and refrig-eration systemsDOWFROST HD (No. 180-01273)DOWTHERM SR-1 (No. 180-01274)

■ Cool Storage Ethylene GlycolDesign Guide (EPRI publication)

■ Design Guide For Cool Ther-mal Storage (ASHRAE publica-tion)

About this guide

This guide provides generalinformation on the use ofDOWTHERM* SR-1 ethyleneglycol-based heat transfer fluidand DOWFROST* HD propyleneglycol-based heat transfer fluid inthermal energy storage systems.Included are product descriptionsand physical property data as wellas information regarding systemdesign, preparation and mainte-nance. If you would like additionalproduct information or specificengineering or operating assis-tance, call Dow toll free: 1-800-447-4369.

Types of Thermal EnergyStorage systems

Thermal Energy Storage (TES) isthe practice of making and storingchilled water or ice during non-peak electrical usage periods suchas overnight or on weekends, thenusing that stored cool energy toprovide air conditioning duringpeak electrical load periods duringthe day. Most electric utilitiesencourage this practice becausethe electric chillers commonlyused to provide building airconditioning account for a largepart of the peak electrical demandduring the summer cooling season.In many cases the utilities provideincentives such as cash rebates perkilowatt hour shifted and lowerelectric rates during off-peakhours.

There are many technologiesavailable for TES, but in thisguide only ice storage systems areconsidered. Chilled water storageis also very popular today; how-ever, because these systemsgenerally don’t use glycol solu-tions, they are beyond the scope ofthis guide. The two most commontypes of ice storage are “ice onpipe” systems (also known as "iceon coil" systems) and ice encapsu-lated in plastic containers.

The ice on pipe systems consist of

*Trademark of The Dow Chemical Company

2

PRODUCT DESCRIPTIONS AND BENEFITS

industrial inhibitors that helpprevent corrosion of metal in twoways.

First, they passivate the surface ofmetals, reacting with the surfaceto prevent acids from attacking it.Unlike inhibitors used in someother fluids, Dow inhibitorsperform this passivation processwithout fouling heat transfersurfaces.

Second, the inhibitors buffer anyacids formed as a result of glycoloxidation. All glycols produceorganic acids as degradationproducts. This degradation processis accelerated in the presence ofoxygen and/or heat. Left insolution, such acids lower pH andcontribute to corrosion. Properlyformulated inhibitors, such asthose in DOWTHERM andDOWFROST fluids, neutralizethese acids.

These inhibitors are long lastingand usually do not need supple-mental additions of other watertreatment chemicals. All thenecessary additives are alreadycontained in the DOWTHERMSR-1 or DOWFROST HD fluids.

Low freezing points preventchiller freeze-ups

DOWTHERM SR-1 andDOWFROST HD also provide areduction in the freezing point ofthe solution to allow the manufac-ture of ice in the ice storagesystem. Generally, theDOWTHERM SR-1 orDOWFROST HD solution ischilled to between 20 and 26°F tomake ice. A 25% solution ofDOWTHERM SR-1 fluid has afreezing point below 14°F, while asimilar solution of DOWFROSTHD fluid has a freezing pointbelow 16°F. Both provide anadequate margin of safety belowthe typical operating temperatureto prevent chiller freeze-ups.

Approved by ice storagesystem OEMs

Following are some of the icestorage system manufacturers whohave approved the use of one orboth DOWTHERM SR-1 andDOWFROST HD heat transferfluids in their ice storage systems:

■ Baltimore Air Coil■ Calmac■ Cryogel■ Dunham-Bush■ Fafco

DOWTHERM SR-1 fluid

DOWTHERM SR-1 heat transferfluid is an industrially inhibitedethylene glycol-based heat transferfluid. The formulation consists of95.4% ethylene glycol with thebalance corrosion inhibitors, waterand dye. The fluid is dyed fluores-cent pink for leak detectionpurposes.

DOWFROST HD fluid

DOWFROST HD heat transferfluid is an industrially inhibitedpropylene glycol-based heattransfer fluid. The formulationconsists of 94% propylene glycolwith the balance corrosion inhibi-tors, water and dye. The fluid isdyed bright yellow to aid in leakdetection.

Both fluids are typically used in a25-30% solution with water as theheat transfer medium in icestorage systems. Typical specifica-tions of these fluids are given inTable 1.

Specially formulated inhibi-tors prevent system corrosion

Dow glycol-based fluids containspecially formulated packages of

Table 1 –– Typical Product Physical Properties

DOWTHERM SR-1 DOWFROST HDEthylene Glycol-Based Propylene Glycol-Based

Heat Transfer Fluid Heat Transfer Fluid

Composition (% by weight) Glycol 9 5 . 4 9 4 . 0 Inhibitors & Water 4 . 6 6 . 0

Color Fluorescent Pink Bright Yellow

Specific Gravity (at 60/60°F) 1.1250 –– 1.1350 1.053 –– 1.063

pH of Solution (50% glycol) 9.0 –– 9.6 9.5 –– 10.5

Reserve Alkalinity (min.) 11.0 ml 15.0 ml

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Following is a general discussion ofsystem design and other engineer-ing considerations related to theuse of DOWTHERM andDOWFROST heat transfer fluids.For information regarding aspecific system problem or ques-tion, contact Dow’s TechnicalService and Development staff forassistance. Call 1-800-447-4369.

Materials of construction

Standard system materials can beused with DOWTHERM SR-1and DOWFROST HD heattransfer fluids. Steel, cast iron,copper, brass, bronze, solder andmost plastic piping materials areall generally acceptable. The useof aluminum is not recommendedat temperatures above 150°F,because the inhibitors will notfully protect aluminum compo-nents in the system. Galvanizedsteel is not recommended becausethe zinc will react with theinhibitor in the fluids, causingprecipitate formation, depletion ofthe inhibitor package and removalof the protective zinc coating,particularly above 100°F. Precipi-tation can also lead to localizedcorrosion.

Centrifugal pumps are commonlyused with DOWTHERM andDOWFROST fluids. Reciprocat-ing pumps are necessary wherefluids must be pumped at highhead pressures. Pumps can bemade of ordinary steel or ductileiron because the fluids are inhib-ited.

Piping, valves and fittings can alsobe made of ordinary steel orductile iron. Use of gray ironcomponents is not recommended.

Typically, the same types of pumppacking or mechanical seals usedfor water may be used with solu-

SYSTEM DESIGN AND PREPARATION

tions of DOWTHERM andDOWFROST fluids. Packing andseal manufacturers should beconsulted for materials appropriateto your application and operatingtemperature.

Solutions of DOWTHERM andDOWFROST fluids are alsocompatible with most plastics andelastomers. Generally, any mate-rial that can be use with uninhib-ited glycols may be used withDOWTHERM and DOWFROSTfluids. Before using a particularelastomer, check with the manu-facturer to determine the suitabil-ity of the material with ethyleneor propylene glycol over theanticipated temperature andpressure ranges.

If the use of a coating is desired(for example, to protect the vaporspace of an expansion tank)several options are available.Suitable coatings include novolac-based vinyl ester resins (e.g.DERAKANE* 470-36 vinyl esterresin), high-bake phenolic resins,polypropylene, and polyvinylidenefluoride. To ensure that thecoating is suitable for a particularapplication and temperature, thecoating manufacturer should beconsulted.

Using dissimilar metals in a systemis not recommended becausegalvanic corrosion may result.This type of corrosion can occurin electrolytic solutions whendissimilar metals (referencing thegalvanic series in seawater) are incontact with or near each other.Aluminum directly connected tocopper is an example. Solutions ofDOWTHERM and DOWFROSTfluids are better than plain water,but still cannot protect againstgalvanic corrosion of dissimilarmetals electrically coupled in asystem. Electrical isolation elimi-nates galvanic corrosion concerns.

*Trademark of The Dow Chemical Company

Backed by a comprehensivepackage of Dow supportservices

DOWTHERM SR-1 andDOWFROST HD heat transferfluids are backed by a comprehen-sive package of Dow supportservices. Dow technical servicepersonnel are available to helpwith the selection of the properfluid for your TES installation aswell as the design, operation andmaintenance of your thermalenergy storage system for maxi-mum productivity and economy.

Dow also offers a free fluid analysisservice. More information on Dowsupport services is provided onpage 6 of this guide.

Selecting the best Dow fluidfor your system

Since both products have a longhistory of excellent performancein closed loop heating and coolingsystems, it is sometimes difficult todetermine which fluid is best for aparticular system. There are twomajor differences between ethyl-ene and propylene glycol fluids:viscosity and toxicity. Ethyleneglycol-based fluids are less viscousthan propylene glycol-based fluids.Therefore, they generally providesuperior heat transfer efficiencyand better low temperatureperformance and are preferred formost heat transfer applications.

However, in applications wheretoxicity is a concern, propyleneglycol fluids are used because oftheir low acute oral toxicity vs.the moderate oral toxicity ofethylene glycol. Examples includeapplications where contact withdrinking water is possible orapplications in localities wherelocal, state or federal regulationsmake the use of ethylene glycolundesirable. For additional toxic-ity information, see the MaterialSafety Data (MSD) sheets, avail-able from Dow.

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(net positive suction head) of thepump if the tank is a portion ofthe source of head.

It should also be noted that insome ice storage systems, such asthe ice encapsulated systems,when ice is made, the plasticcontainers expand. This expan-sion will cause the level of theglycol water solution to rise andshould also be considered whensizing the expansion tank for thistype of system. Manufacturers ofthis type of ice storage system canassist you with this calculation.

Automatic make-up watersystems

Automatic make-up water systemsshould be avoided in order toprevent undetected dilution orloss of glycol and consequent lossof freeze and corrosion protection.A preferred system would be a lowlevel alarm on the expansion tankto alert maintenance personnel incase of a low fluid level conditionand prompt corrective action.

Expansion factor

Like any fluids, solutions ofDOWTHERM and DOWFROSTfluids expand as temperatureincreases. Therefore, expansiontanks must be sized appropriately.To determine the volume ofexpansion, use the followingformula:

ρ(TLOW)-ρ(THIGH) Expansion_______________ x Volume =

Volume ρ(THIGH)

Where,ρ(TLOW) = the density at the

lowest anticipatedtemperature.

ρ(THIGH) = the density at thehighest anticipatedtemperature.

Density data for DOWTHERMSR-1 and DOWFROST HD fluidsare given in Tables 4 and 6respectively.

One method for sizing an expan-sion tank is to use the determinedexpansion volume to calculate thetotal size of the tank. A typicaltank size would allow the fluid tofluctuate between the levelsassociated with 15% and 80% full.The tank size is calculated from:

Expansion Volume/0.65 = Tank Size

When using this method, ensurethat the minimum amount of fluidin the tank will provide the NPSH

incompatible with the newinhibited glycol fluid. A Dowtechnical service representativecan help you determine thecompatibility of other fluids withDOWTHERM and DOWFROSTfluids.

If fluid containing silicates (suchas automotive antifreeze) waspreviously used, it may be neces-sary to clean silicate residues fromthe system.

It is also important to remove allrust, scale and sediment in thesystem. Traces of chloride shouldbe removed – whether from oldfluid or residue from acid cleaner –because chlorides can contributeto corrosion. For large systems orsystems where corrosion is alreadyevident, consult a professionalcleaning organization.

For heavily fouled or corrodedsystems, an optimum cleaningprocedure includes the use of aninhibited acid followed by neutral-ization and phosphatization. Thisprocedure is quite involved andshould be done by a companyexperienced in industrial cleaning.If chemical cleaning is used, it isimportant that all traces of thecleaning agent be removed andthe system thoroughly flushedwith water.

System cleaning

When preparing a system for theaddition of DOWTHERM SR-1or DOWFROST HD heat transferfluid, certain procedures should befollowed. The procedure will varydepending on whether you areretrofitting an existing system orfilling a new system for the firsttime.

New systems

New systems are typically coatedwith oil, grease or a protective filmduring fabrication, storage orconstruction. Dirt, solder flux, andwelding and pipe scale can alsocause problems. Therefore, thor-ough cleaning of new systems isrecommended. A solution of 1-2percent trisodium phosphate canbe used with water for flushing thesystem. System volume can becalculated during this stage bymetering-in the initial fill of thesystem or by chemical analysis ofcleaning chemical after knownquantities are introduced into thesystem.

Existing systems

In existing systems, all lines andmaterials should be cleaned andflushed thoroughly before chargingthe system with DOWTHERMSR-1 or DOWFROST HD fluid.This is especially important if fluidpreviously in the system is

5

PREPARING SOLUTIONS OF DOWTHERM AND

DOWFROST FLUIDSFollowing is the mixing procedurefor installing DOWTHERM SR-1and DOWFROST HD fluids:

1. Calculate the quantity of fluidneeded to achieve the desiredconcentration. Table 3, whichprovides the number of gallons per100 feet of pipe, may be helpful inthis calculation, as may manufac-turers' information regarding theinternal capacity of the ice storagecomponents in the system.

2. Introduce a sufficient quantityof water to check the system fortightness. Pressure testing thesystem at this stage can be helpful.Pressure testing can often beaccomplished during the initialcleaning or flushing of the system.

3. Drain enough water from thesystem to provide space for theinhibited glycol quantity ascalculated in step 1.

4. Add the correct amount of fluidand any water needed to com-pletely refill the system, allowingfor liquid expansion or contrac-tion as needed due to the operat-ing temperature.

tank systems available will have acertain amount of water left in theheat transfer tubes due to pressuretesting at the manufacturingfacility. This must also be takeninto account.

These considerations are mostimportant when charging thesystem with a pre-diluted solutionof fluid. Any water trapped in thesystem will lower the final concen-tration of the glycol in the system.As a result, it may be necessary topurchase a solution with slightlyhigher glycol concentration toachieve the desired final concen-tration of glycol in the system.

Introducing the fluids intoyour system

In most cases, solutions containingglycol-based heat transfer fluid aremixed on a volume basis. If youwish to mix DOWTHERM SR-1or DOWFROST HD fluids byweight percent, use Tables 5 or 7respectively to obtain the volume-to-weight conversion.

Table 3 –– Gallons of Heat Transfer Fluid per 100 Feet Pipe(Standard Schedule 40 Iron Pipe or 40S Stainless Steel)

Nominal Outside Wall Inside Volume,Pipe Size, Diameter, Thickness, Diameter, Gallons per

Inches Inches Inches Inches 100 feet of pipe

1/8 0.405 0.068 0.269 0.2951/4 0.540 0.088 0.364 0.5413/8 0.675 0.091 0.493 0.9921/2 0.840 0.109 0.622 1.5783/4 1.050 0.113 0.824 2.7701 1.315 0.133 1.049 4.489

1-1/4 1.660 0.140 1.380 7.7691-1/2 1.900 0.145 1.610 10.58

2 2.375 0.154 2.067 17.432-1/2 2.875 0.203 2.469 24.87

3 3.500 0.216 3.068 38.403-1/2 4.000 0.226 3.548 51.36

4 4.500 0.237 4.026 66.135 5.563 0.258 5.047 103.96 6.625 0.280 6.065 150.18 8.625 0.322 7.981 259.9

10 10.750 0.365 10.020 409.6

Dilution water quality

Water used to diluteDOWTHERM SR-1 orDOWFROST HD fluids mustmeet certain standards for purity.Impurities in dilution water canincrease metal corrosion, aggra-vate pitting of cast iron and steel,reduce the effectiveness of corro-sion inhibitors, increase inhibitordepletion rate, cause formation ofscale and other deposits on heattransfer surfaces and cause clog-ging of system components.

To assure inhibitor effectiveness,the levels of chlorides and sulfatesin water used to diluteDOWTHERM or DOWFROSTfluids should be less than 25 ppmeach. Total hardness should beless than 100 ppm as CaCO3(Table 2). Distilled or deionizedwater is recommended. If goodquality water is unavailable, pre-diluted solutions of DOWTHERMSR-1 and DOWFROST HD fluidsare available from Dow.

Table 2 –– Dilution WaterQuality Requirements

Impurity Level

Chlorides 25 ppm, maxSulfates 25 ppm, maxCalcium 50 ppm, maxMagnesium 50 ppm, max

Solution make-up

As indicated above, good qualitywater must be used for fluid make-up. In addition, any flush waterremaining in the system should betaken into account when intro-ducing and dilutingDOWTHERM or DOWFROSTfluids. In a thermal energy storagesystem, it is not unusual to havehold-up of up to 20% of the totalsystem volume, although 10% ismore common. It is important tonote that many of the modular ice

6

sample kit provided by Dow.Proper sampling is essential toensure meaningful assessment offluid condition.

Approximately three weeks afterthe sample is received by Dow, areport will be sent to you detailingresults of the analysis, discussingunusual or troublesome conditions(if any), and offering recommen-dations.

Analytical tools for self-testing

It may also be desirable to performsome simple, on-site analysis ofyour system to properly maintainthe glycol concentration. A usefultool for this type of analysis is aMisco Products refractometer,model 7084VP (°F) and 7064VP(°C). These refractometersmeasure the glycol solutionconcentration of DOWTHERMand DOWFROST fluids and givethe freezing points of the fluids.The freezing point can be trans-lated to glycol concentration fromthe tables on pages 7 and 10. Thisinstrument requires only a fewdrops of fluid for testing andrequires no adjustment for fluidtemperature. Diluted solutionswith concentrations from 0 to60% glycol may be tested directly.Stronger concentrations require asimple dilution procedure prior totesting. Contact Misco Products at1-800-358-1100 and ask for theDow discount.

Free analytical service

To help ensure that corrosion andfreeze protection are maintainedin customer systems, Dow offers afree fluid analysis service. It isdesigned to assure the long termperformance of DOWTHERMand DOWFROST fluids and helpminimize replacement fluidrequirements as well as systemmaintenance and repair costs.Typically performed on an annualbasis, the analysis includes deter-mination of current inhibitor andglycol levels plus Dow’s recom-mendations for maintainingproper corrosion protection.

Dow has developed special Ther-mal Fluids Sampling Kits for useby customers participating in theanalysis program. These kitspermit easy and accurate labelingof fluid samples and safe shipmentof samples to Dow for analysis.Kits may be obtained by calling 1-800-447-4369. Or write:

Thermal Fluids Testing LabThe Dow Chemical CompanyLarkin Lab1691 North Swede RoadMidland, Michigan 48674

How the service works

After the system has been filledand circulated for several days, aninitial four-ounce sample shouldbe withdrawn and sent to Dowusing one of the Thermal FluidsSampling Kits. After the system isin operation, it is recommendedthat samples be taken once a year.Before withdrawing the sample,the fluid should be well circulatedin the system so the sample isrepresentative. Remember toclosely follow the samplinginstructions included with the

MAINTAINING DOWTHERM AND DOWFROST FLUIDS5. Circulate the system for at least24 hours to ensure completemixing. Check the liquid concen-tration with a refractometer orother method to assure that thecorrect mixture is obtained.

Note: If fluid mixing is a concern,the solution can be premixed in aseparate tank before introductioninto the system, or the inhibitedglycol and the water can be addedtogether through a “mixing tee."This will promote faster mixing ofthe inhibited glycol and water.

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PHYSICAL PROPERTY DATA Table 4 –– Physical Properties of Solutions of DOWTHERMSR-1 Heat Transfer Fluid

Temp. Density Viscosity Thermal Cond. Specific Heat°F lb/ft3 cps Btu/(hr ft2)(°F/ft) Btu/(lb°F)

(30 volume percent ethylene glycol)

10 65.93 6.83 0.238 0.84920 65.85 5.38 0.243 0.85330 65.76 4.33 0.247 0.8640 65.66 3.54 0.251 0.86150 65.55 2.95 0.255 0.86460 65.43 2.49 0.259 0.86870 65.30 2.13 0.263 0.87280 65.17 1.84 0.266 0.876

(25 volume percent ethylene glycol)

20 65.34 4.40 0.253 0.87530 65.26 3.59 0.258 0.87940 65.17 2.98 0.262 0.88250 65.06 2.50 0.267 0.88660 64.95 2.13 0.271 0.88970 64.83 1.84 0.275 0.89280 64.70 1.60 0.279 0.896

Table 5 –– Typical Freezing and Boiling Points of Aqueous Solutions of DOWTHERM SR-1†

Wt % Vol % Wt % Vol % Boiling Point RefractiveEthylene Ethylene DOWTHERM DOWTHERM Freezing Point °F @ Degree IndexGlycol Glycol SR-1 SR-1 °F 760 mm Hg Brix†† 22°C

0.0 0.0 0.0 0.0 32.0 212 0.0 1.33285.0 4.4 5.2 4.6 29.4 213 3.8 1.3378

10.0 8.9 10.5 9.3 26.2 214 6.8 1.342815.0 13.6 15.7 14.2 22.2 215 9.9 1.347820.0 18.1 20.9 19.0 17.9 216 13.0 1.3530

21.0 19.2 22.0 20.1 16.8 216 13.7 1.354022.0 20.1 23.0 21.0 15.9 216 14.3 1.355123.0 21.0 24.1 22.0 14.9 217 14.8 1.356124.0 22.0 25.1 23.0 13.7 217 15.5 1.357225.0 22.9 26.2 24.0 12.7 218 16.1 1.3582

26.0 23.9 27.2 25.0 11.4 218 16.7 1.359327.0 24.8 28.3 26.0 10.4 218 17.3 1.360328.0 25.8 29.3 27.0 9.2 219 17.9 1.361429.0 26.7 30.4 28.0 8.0 219 18.6 1.362430.0 27.7 31.4 29.0 6.7 220 19.2 1.3635

31.0 28.7 32.5 30.2 5.4 220 19.8 1.364632.0 29.6 33.5 31.0 4.2 220 20.4 1.365633.0 30.6 34.6 32.0 2.9 220 21.0 1.366734.0 31.6 35.6 33.1 1.4 220 21.7 1.367835.0 32.6 36.6 34.1 -0.2 221 22.3 1.3688

†Typical properties, not to be construed as specifications.††Degree Brix is a measure of the sugar concentration in a fluid and is important in fermentation and syrups applications. Although there is no sugarpresent in DOWTHERM heat transfer fluids, the glycol affects the refractive index of the fluid in a similar fashion.

NOTE: Generally, for an extended margin of protection, you should select a temperature in this table that is at least 5°F lower than the expected lowestambient temperature. Inhibitor levels should be adjusted for solutions of less than 25% glycol. Contact Dow for information on specific cases or forfurther assistance.

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Figure 1 –– Pressure Drop at 25% Volume Ethylene Glycol(Schedule 40 Pipe, 25°F)

Figure 2 –– Pressure Drop at 30% Volume Ethylene Glycol(Schedule 40 Pipe, 25°F)

15 25 35 45 55 65 75 850.97

0.98

0.99

1.00

1.01

1.02

1.03

Temperature, °F

Temperature Correction

Multiplier Factor

Fac

tor

100

10

1.0

0.1

0.011 10 100 1000 10,000

FLOW RATE, U.S. gallons per minute

PR

ES

SU

RE

DR

OP,

psi

/100

ft o

f pip

e

VELOCIT

Y, ft

/sec

10

SCHEDULE 40 PIPE

2-1/2"

2"

3"4"

6"8"

10" 12"

1/2"3/4"

1"

1-1/2"

8

6

4

2

1

Temperature, °F

Fac

tor

Temperature Correction Multiplier Factor

0.80

0.85

0.90

0.95

1.00

1.05

1.10

8575655545352515

8515 25 35 45 55 65 75Temperature, °F

Temperature CorrectionMultiplier Factor

Fac

tor

0.97

0.98

0.99

1.00

1.01

1.02

1.03

100

10

1.0

0.1

0.011 10 100 1000 10,000

FLOW RATE, U.S. gallons per minute

PR

ES

SU

RE

DR

OP,

psi

/100

ft o

f pip

e VELOCIT

Y, ft

/sec

2

8"10" 12"

6"

4"

3"

2-1/2"2"

1

1-1/2"

SCHEDULE 40 PIPE

1"

3/4"

1/2"

4

6

8

10

Temperature, °F

Fac

tor

Temperature Correction Multiplier Factor

0.80

0.85

0.90

0.95

1.00

1.05

1.10

8575655545352515

9

Figure 3 –– Pressure Drop at 25% Volume Ethylene Glycol(Steel Tube, 25°F)

Fac

tor

8515 25 35 45 55 65 75

0.97

0.98

0.99

1.00

1.01

1.02

1.03

Temperature, °F

Temperature CorrectionMultiplier Factor

100

10

1.0

0.10.1 1.0 10 100 1000

FLOW RATE, U.S. gallons per minute

PR

ES

SU

RE

DR

OP,

psi

/100

ft o

f tub

e VELO

CIT

Y, ft

/sec

2-1/2"

1-1/2"

2"

3/4"

1/2"

2

4

6

8

10

STEEL TUBE

1"

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

Temperature, °F

Fac

tor

Temperature CorrectionMultiplier Factor

8575655545352515

Figure 4 –– Pressure Drop at 30% Volume Ethylene Glycol(Steel Tube, 25°F)

15 25 35 45 55 65 75 85

0.97

0.98

0.99

1.00

1.01

1.02

1.03

Temperature, °F

Temperature Correction Multiplier Factor

Fac

tor

100

10

1.0

0.10.1 1.0 10 100 1000

FLOW RATE, U.S. gallons per minute

PR

ES

SU

RE

DR

OP,

psi

/100

ft o

f tub

e

VELO

CIT

Y, ft

/sec

2-1/2"

1-1/2"2"

3/4"

1/2"

2

4

6

8

10

STEEL TUBE

1"

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

Temperature, °F

Fac

tor

Temperature CorrectionMultiplier Factor

8575655545352515

10

Table 6 – Physical Properties of Solutions of DOWFROSTHD Heat Transfer Fluid

Temp. Density Viscosity Thermal Cond. Specific Heat°F lb/ft3 cps Btu/(hr ft2)(°F/ft) Btu/(lb°F)

(30 volume % propylene glycol)

10 65.64 13.44 0.235 0.88220 65.53 9.91 0.239 0.88630 65.42 7.47 0.243 0.8940 65.30 5.75 0.247 0.89450 65.17 4.52 0.251 0.89760 65.02 3.61 0.254 0.90170 64.87 2.94 0.258 0.90580 64.71 2.43 0.261 0.909

(20 volume % propylene glycol)

20 65.11 6.97 0.25 0.90830 65.01 5.47 0.255 0.91140 64.90 4.35 0.259 0.91550 64.77 3.52 0.263 0.91860 64.64 2.88 0.267 0.92170 64.50 2.39 0.271 0.92480 64.35 2.01 0.274 0.928

Table 7 –– Typical Freezing and Boiling Points of Aqueous Solutions of DOWFROST HD†

Wt % Vol % Wt % Vol % Boiling Point RefractivePropylene Propylene DOWFROST DOWFROST Freezing Point °F @ Degree Index

Glycol Glycol HD HD °F 760 mm Hg Brix†† 22°C

0.0 0.0 0.0 0.0 32.0 212 0.0 1.33285.0 4.8 5.3 5.1 29.1 212 4.8 1.3383

10.0 9.6 10.7 10.2 26.1 212 8.4 1.343815.0 14.5 16.0 15.4 22.9 212 12.9 1.349520.0 19.4 21.3 20.6 19.2 213 15.4 1.3555

21.0 20.4 22.3 21.7 18.3 213 16.0 1.356722.0 21.4 23.4 22.8 17.6 213 16.7 1.357923.0 22.4 24.5 23.8 16.6 213 17.4 1.359124.0 23.4 25.5 24.9 15.6 213 18.4 1.360325.0 24.4 26.6 26.0 14.7 214 19.0 1.3615

26.0 25.3 27.7 26.9 13.7 214 19.6 1.362727.0 26.4 28.7 28.1 12.6 214 20.2 1.363928.0 27.4 29.8 29.1 11.5 215 20.8 1.365129.0 28.4 30.9 30.2 10.4 215 21.4 1.366330.0 29.4 31.9 31.3 9.2 216 22.0 1.3675

31.0 30.4 33.0 32.3 7.9 216 22.7 1.368732.0 31.4 34.0 33.4 6.6 216 23.6 1.369833.0 32.4 35.1 34.5 5.3 216 24.4 1.371034.0 33.5 36.2 35.6 3.9 216 25.3 1.362135.0 34.4 37.2 36.6 2.4 217 26.1 1.3733

†Typical properties, not to be construed as specifications.††Degree Brix is a measure of the sugar concentration in a fluid and is important in fermentation and syrups applications. Although there is no sugarpresent in DOWFROST heat transfer fluids, the glycol affects the refractive index of the fluid in a similar fashion.

NOTE: Generally, for an extended margin of protection, you should select a temperature in this table that is at least 5°F lower than the expected lowestambient temperature. Inhibitor levels should be adjusted for solutions of less than 25% glycol. Contact Dow for information on specific cases or forfurther assistance.

11

Figure 5 –– Pressure Drop at 25% Volume Propylene Glycol(Schedule 40 Pipe, 25°F)

Figure 6 –– Pressure Drop at 30% Volume Propylene Glycol(Schedule 40 Pipe, 25°F)

15 25 35 45 55 65 75 85

0.97

0.98

0.99

1.00

1.01

1.02

1.03

Temperature

Temperature CorrectionMultiplier Factor

Fac

tor100

10

1.0

0.1

0.011 10 100 1000 10,000

FLOW RATE, U.S. gallons per minute

PR

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6

8

10

VELOCIT

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/sec

SCHEDULE 40 PIPE

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

Temperature, °F

Fac

tor

Temperature CorrectionMultiplier Factor

8575655545352515

Temperature, °F8515 25 35 45 55 65 75

0.97

0.98

0.99

1.00

1.01

1.02

1.03

Temperature CorrectionMultiplier Factor

Fac

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100

10

1.0

0.1

0.011 10 100 1000 10,000

FLOW RATE, U.S. gallons per minute

PR

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VELOCIT

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SCHEDULE 40 PIPE

Temperature, °F

Fac

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Temperature Correction Multiplier Factor

0.80

0.85

0.90

0.95

1.00

1.05

1.10

8575655545352515

12

Figure 7 –– Pressure Drop at 25% Volume Propylene Glycol(Steel Tube, 25°F)

Temperature, °F8515 25 35 45 55 65 75

0.97

0.98

0.99

1.00

1.01

1.02

1.03

Temperature CorrectionMultiplier Factor

Fac

tor

100

10

1.0

0.10.1 1.0 10 100

FLOW RATE, U.S. gallons per minute

PR

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ft/s

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4

6

8

10

STEEL TUBE

1"

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

Temperature, °F

Fac

tor

Temperature CorrectionMultiplier Factor

8575655545352515

13

Figure 8 –– Pressure Drop at 30% Volume Propylene Glycol(Steel Tube, 25°F)

15 25 35 45 55 65 75 85

0.97

0.98

0.99

1.00

1.01

1.02

1.03

Temperature. °F

Temperature CorrectionMultiplier Factor

Fac

tor

100

10

1.0

0.10.1 1.0 10 100 1000

FLOW RATE, U.S. gallons per minute

PR

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SU

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psi

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4

6

8

10

STEEL TUBE

1"

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

Temperature, °F

Fac

tor

Temperature CorrectionMultiplier Factor

8575655545352515

Printed in U.S.A. *Trademark of The Dow Chemical Company Form No. 180-01306-395 JBMcKAY32869/PO3701531

*

For further information, call toll-free 1-800-447-4369(Outside the United States and Canada, call 1-517-832-1556).

DOWTHERM* SR-1 andDOWFROST* HDHeat Transfer FluidsIn Thermal Energy Storage

Application Guide

NOTICE: The information and recommendations in this document are believed to be accurate and reliable as of March 1995 and are given in good faith and supersedethose given in any previous document. Because any information and recommendations furnished with reference to the proper use and disposal of these products isprovided without charge, and because use conditions and disposal are not within its control, the Seller assumes no obligation or liability for such information andrecommendations. Seller does not guarantee results from use of such products or other information and recommendations herein. NO WARRANTIES (INCLUDING,WITHOUT LIMITATION, IMPLIED WARRANTIES OF FITNESS OR MERCHANTABILITY) ARE MADE. No freedom from any patent owned by Dow or others is to beinferred. Because use conditions and governmental laws may differ from one location to another and may change with time, Buyer is responsible for determining whetherproducts and the information and recommendations in this document are appropriate for Buyer’s use, and ensuring that Buyer’s workplace and disposal practices arein compliance with laws and other governmental enactments applicable in the jurisdiction(s) having authority over Buyer’s operations.