DOWTHERM SR-1 and DOWFROST HD Heat Transfer Fluids In ...

DOWTHERM SR-1 and
DOWFROST HD
Heat Transfer Fluids
In Thermal Energy Storage
Application Guide

CONTENTS
Introduction
About this guide .......................................................................... 1
Types of thermal energy storage systems .................................... 1
Other literature available ............................................................ 1
Product Descriptions and Benefits
DOWTHERM SR-1 fluid ........................................................... 2
DOWFROST HD fluid ............................................................... 2
Typical product physical properties ............................................ 2
Specially formulated inhibitors prevent system corrosion ......... 2
Low freezing points prevent chiller freeze-ups............................ 2
Approved by ice storage system OEMs ....................................... 2
Backed by a comprehensive package of Dow support services... 3
Selecting the best fluid for your system ...................................... 3
System Design and Preparation
Materials of construction ............................................................ 3
Automatic water make-up .......................................................... 4
Expansion factor.......................................................................... 4
System cleaning........................................................................... 4
New systems ................................................................................ 4
Existing systems ........................................................................... 4
Preparing Solutions of DOWTHERM and DOWFROST Fluids
Dilution water quality ................................................................. 5
Solution make-up ........................................................................ 5
Introducing the fluids into your system ...................................... 5
Maintaining DOWTHERM and DOWFROST Fluids
Free analytical service ................................................................. 6
How the service works ................................................................ 6
Analytical tools for self-testing ................................................... 6
Physical Property Data
Physical properties of solutions– DOWTHERM SR-1 .............. 7
Typical freezing and boiling points – DOWTHERM SR-1 ....... 7
Pressure drop charts – DOWTHERM SR-1 ............................8-9
Physical properties of solutions – DOWFROST HD ............... 10
Typical freezing and boiling points – DOWFROST HD ......... 10
Pressure drop charts – DOWFROST HD ............................11-13

INTRODUCTION
About this guide
This guide provides general
information on the use of
DOWTHERM* SR-1 ethylene
glycol-based heat transfer fluid
and DOWFROST* HD propylene
glycol-based heat transfer fluid in
thermal energy storage systems.
Included are product descriptions
and physical property data as well
as information regarding system
design, preparation and maintenance.
If you would like additional
product information or specific
engineering or operating assistance,
call Dow toll free: 1-800-
447-4369.
Types of Thermal Energy
Storage systems
Thermal Energy Storage (TES) is
the practice of making and storing
chilled water or ice during nonpeak
electrical usage periods such
as overnight or on weekends, then
using that stored cool energy to
provide air conditioning during
peak electrical load periods during
the day. Most electric utilities
encourage this practice because
the electric chillers commonly
used to provide building air
conditioning account for a large
part of the peak electrical demand
during the summer cooling season.
In many cases the utilities provide
incentives such as cash rebates per
kilowatt hour shifted and lower
electric rates during off-peak
hours.
There are many technologies
available for TES, but in this
guide only ice storage systems are
considered. Chilled water storage
is also very popular today; however,
because these systems
generally don’t use glycol solutions,
they are beyond the scope of
this guide. The two most common
types of ice storage are “ice on
pipe” systems (also known as "ice
on coil" systems) and ice encapsulated
in plastic containers.
The ice on pipe systems consist of
*Trademark of The Dow Chemical Company
coils of plastic or metal tubing
immersed in a tank of water. A
chilled glycol and water solution is
circulated through the tubes to
build ice on the outside of the
tubes during the off-peak hours.
When air conditioning is needed
the same solution is circulated
through the tubes to melt the ice
and provide chilled glycol solution
for building cooling.
The second type of system works
in the same fashion except the
glycol solution is circulated
through a tank filled with plastic
containers of water. The ice forms
in the containers and is later
melted by the same glycol solution
when cooling is needed. For more
detailed explanations of the
different types of TES systems,
please consult the manufacturers
of the various systems.
Other literature available
■ Engineering and Operating
Guides
DOWFROST 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 HVAC
system from corrosion and high
maintenance costs" (No. 180-1263)
■ Material Safety Data Sheets
■ Engineering specifications for
closed-loop HVAC and refrigeration
systems
DOWFROST HD (No. 180-01273)
DOWTHERM SR-1 (No. 180-01274)
■ Cool Storage Ethylene Glycol
Design Guide (EPRI publication)
■ Design Guide For Cool Thermal
Storage (ASHRAE publication)
1

PRODUCT DESCRIPTIONS AND BENEFITS
DOWTHERM SR-1 fluid
DOWTHERM SR-1 heat transfer
fluid is an industrially inhibited
ethylene glycol-based heat transfer
fluid. The formulation consists of
95.4% ethylene glycol with the
balance corrosion inhibitors, water
and dye. The fluid is dyed fluorescent
pink for leak detection
purposes.
DOWFROST HD fluid
DOWFROST HD heat transfer
fluid is an industrially inhibited
propylene glycol-based heat
transfer fluid. The formulation
consists of 94% propylene glycol
with the balance corrosion inhibitors,
water and dye. The fluid is
dyed bright yellow to aid in leak
detection.
Both fluids are typically used in a
25-30% solution with water as the
heat transfer medium in ice
storage systems. Typical specifications
of these fluids are given in
Table 1.
Specially formulated inhibitors
prevent system corrosion
Dow glycol-based fluids contain
specially formulated packages of
2
industrial inhibitors that help
prevent corrosion of metal in two
ways.
First, they passivate the surface of
metals, reacting with the surface
to prevent acids from attacking it.
Unlike inhibitors used in some
other fluids, Dow inhibitors
perform this passivation process
without fouling heat transfer
surfaces.
Second, the inhibitors buffer any
acids formed as a result of glycol
oxidation. All glycols produce
organic acids as degradation
products. This degradation process
is accelerated in the presence of
oxygen and/or heat. Left in
solution, such acids lower pH and
contribute to corrosion. Properly
formulated inhibitors, such as
those in DOWTHERM and
DOWFROST fluids, neutralize
these acids.
These inhibitors are long lasting
and usually do not need supplemental
additions of other water
treatment chemicals. All the
necessary additives are already
contained in the DOWTHERM
SR-1 or DOWFROST HD fluids.
Table 1 –– Typical Product Physical Properties
Low freezing points prevent
chiller freeze-ups
DOWTHERM SR-1 and
DOWFROST HD also provide a
reduction in the freezing point of
the solution to allow the manufacture
of ice in the ice storage
system. Generally, the
DOWTHERM SR-1 or
DOWFROST HD solution is
chilled to between 20 and 26°F to
make ice. A 25% solution of
DOWTHERM SR-1 fluid has a
freezing point below 14°F, while a
similar solution of DOWFROST
HD fluid has a freezing point
below 16°F. Both provide an
adequate margin of safety below
the typical operating temperature
to prevent chiller freeze-ups.
Approved by ice storage
system OEMs
Following are some of the ice
storage system manufacturers who
have approved the use of one or
both DOWTHERM SR-1 and
DOWFROST HD heat transfer
fluids in their ice storage systems:
■ Baltimore Air Coil
■ Calmac
■ Cryogel
■ Dunham-Bush
■ Fafco
DOWTHERM SR-1 DOWFROST HD
Ethylene Glycol-Based Propylene Glycol-Based
Heat Transfer Fluid Heat Transfer Fluid
Composition (% by weight)
Glycol 95.4 94.0
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

Backed by a comprehensive
package of Dow support
services
DOWTHERM SR-1 and
DOWFROST HD heat transfer
fluids are backed by a comprehensive
package of Dow support
services. Dow technical service
personnel are available to help
with the selection of the proper
fluid for your TES installation as
well as the design, operation and
maintenance of your thermal
energy storage system for maximum
productivity and economy.
Dow also offers a free fluid analysis
service. More information on Dow
support services is provided on
page 6 of this guide.
Selecting the best Dow fluid
for your system
Since both products have a long
history of excellent performance
in closed loop heating and cooling
systems, it is sometimes difficult to
determine which fluid is best for a
particular system. There are two
major differences between ethylene
and propylene glycol fluids:
viscosity and toxicity. Ethylene
glycol-based fluids are less viscous
than propylene glycol-based fluids.
Therefore, they generally provide
superior heat transfer efficiency
and better low temperature
performance and are preferred for
most heat transfer applications.
However, in applications where
toxicity is a concern, propylene
glycol fluids are used because of
their low acute oral toxicity vs.
the moderate oral toxicity of
ethylene glycol. Examples include
applications where contact with
drinking water is possible or
applications in localities where
local, state or federal regulations
make the use of ethylene glycol
undesirable. For additional toxicity
information, see the Material
Safety Data (MSD) sheets, available
from Dow.
SYSTEM DESIGN AND PREPARATION
Following is a general discussion of
system design and other engineering
considerations related to the
use of DOWTHERM and
DOWFROST heat transfer fluids.
For information regarding a
specific system problem or question,
contact Dow’s Technical
Service and Development staff for
assistance. Call 1-800-447-4369.
Materials of construction
Standard system materials can be
used with DOWTHERM SR-1
and DOWFROST HD heat
transfer fluids. Steel, cast iron,
copper, brass, bronze, solder and
most plastic piping materials are
all generally acceptable. The use
of aluminum is not recommended
at temperatures above 150°F,
because the inhibitors will not
fully protect aluminum components
in the system. Galvanized
steel is not recommended because
the zinc will react with the
inhibitor in the fluids, causing
precipitate formation, depletion of
the inhibitor package and removal
of the protective zinc coating,
particularly above 100°F. Precipitation
can also lead to localized
corrosion.
Centrifugal pumps are commonly
used with DOWTHERM and
DOWFROST fluids. Reciprocating
pumps are necessary where
fluids must be pumped at high
head pressures. Pumps can be
made of ordinary steel or ductile
iron because the fluids are inhibited.
Piping, valves and fittings can also
be made of ordinary steel or
ductile iron. Use of gray iron
components is not recommended.
Typically, the same types of pump
packing or mechanical seals used
for water may be used with solu-
tions of DOWTHERM and
DOWFROST fluids. Packing and
seal manufacturers should be
consulted for materials appropriate
to your application and operating
temperature.
Solutions of DOWTHERM and
DOWFROST fluids are also
compatible with most plastics and
elastomers. Generally, any material
that can be use with uninhibited
glycols may be used with
DOWTHERM and DOWFROST
fluids. Before using a particular
elastomer, check with the manufacturer
to determine the suitability
of the material with ethylene
or propylene glycol over the
anticipated temperature and
pressure ranges.
If the use of a coating is desired
(for example, to protect the vapor
space of an expansion tank)
several options are available.
Suitable coatings include novolacbased
vinyl ester resins (e.g.
DERAKANE* 470-36 vinyl ester
resin), high-bake phenolic resins,
polypropylene, and polyvinylidene
fluoride. To ensure that the
coating is suitable for a particular
application and temperature, the
coating manufacturer should be
consulted.
Using dissimilar metals in a system
is not recommended because
galvanic corrosion may result.
This type of corrosion can occur
in electrolytic solutions when
dissimilar metals (referencing the
galvanic series in seawater) are in
contact with or near each other.
Aluminum directly connected to
copper is an example. Solutions of
DOWTHERM and DOWFROST
fluids are better than plain water,
but still cannot protect against
galvanic corrosion of dissimilar
metals electrically coupled in a
system. Electrical isolation eliminates
galvanic corrosion concerns.
*Trademark of The Dow Chemical Company
3

Automatic make-up water
systems
Automatic make-up water systems
should be avoided in order to
prevent undetected dilution or
loss of glycol and consequent loss
of freeze and corrosion protection.
A preferred system would be a low
level alarm on the expansion tank
to alert maintenance personnel in
case of a low fluid level condition
and prompt corrective action.
Expansion factor
Like any fluids, solutions of
DOWTHERM and DOWFROST
fluids expand as temperature
increases. Therefore, expansion
tanks must be sized appropriately.
To determine the volume of
expansion, use the following
formula:
ρ(T LOW )-ρ(T HIGH ) Expansion
_______________ x Volume =Volume
4
ρ(T HIGH )
Where,
ρ(T LOW ) = the density at the
lowest anticipated
temperature.
ρ(T HIGH ) = the density at the
highest anticipated
temperature.
Density data for DOWTHERM
SR-1 and DOWFROST HD fluids
are given in Tables 4 and 6
respectively.
One method for sizing an expansion
tank is to use the determined
expansion volume to calculate the
total size of the tank. A typical
tank size would allow the fluid to
fluctuate between the levels
associated with 15% and 80% full.
The tank size is calculated from:
Expansion Volume/0.65 = Tank Size
When using this method, ensure
that the minimum amount of fluid
in the tank will provide the NPSH
(net positive suction head) of the
pump if the tank is a portion of
the source of head.
It should also be noted that in
some ice storage systems, such as
the ice encapsulated systems,
when ice is made, the plastic
containers expand. This expansion
will cause the level of the
glycol water solution to rise and
should also be considered when
sizing the expansion tank for this
type of system. Manufacturers of
this type of ice storage system can
assist you with this calculation.
System cleaning
When preparing a system for the
addition of DOWTHERM SR-1
or DOWFROST HD heat transfer
fluid, certain procedures should be
followed. The procedure will vary
depending on whether you are
retrofitting an existing system or
filling a new system for the first
time.
New systems
New systems are typically coated
with oil, grease or a protective film
during fabrication, storage or
construction. Dirt, solder flux, and
welding and pipe scale can also
cause problems. Therefore, thorough
cleaning of new systems is
recommended. A solution of 1-2
percent trisodium phosphate can
be used with water for flushing the
system. System volume can be
calculated during this stage by
metering-in the initial fill of the
system or by chemical analysis of
cleaning chemical after known
quantities are introduced into the
system.
Existing systems
In existing systems, all lines and
materials should be cleaned and
flushed thoroughly before charging
the system with DOWTHERM
SR-1 or DOWFROST HD fluid.
This is especially important if fluid
previously in the system is
incompatible with the new
inhibited glycol fluid. A Dow
technical service representative
can help you determine the
compatibility of other fluids with
DOWTHERM and DOWFROST
fluids.
If fluid containing silicates (such
as automotive antifreeze) was
previously used, it may be necessary
to clean silicate residues from
the system.
It is also important to remove all
rust, scale and sediment in the
system. Traces of chloride should
be removed – whether from old
fluid or residue from acid cleaner –
because chlorides can contribute
to corrosion. For large systems or
systems where corrosion is already
evident, consult a professional
cleaning organization.
For heavily fouled or corroded
systems, an optimum cleaning
procedure includes the use of an
inhibited acid followed by neutralization
and phosphatization. This
procedure is quite involved and
should be done by a company
experienced in industrial cleaning.
If chemical cleaning is used, it is
important that all traces of the
cleaning agent be removed and
the system thoroughly flushed
with water.

PREPARING SOLUTIONS OF DOWTHERM AND
DOWFROST FLUIDS
Dilution water quality
Water used to dilute
DOWTHERM SR-1 or
DOWFROST HD fluids must
meet certain standards for purity.
Impurities in dilution water can
increase metal corrosion, aggravate
pitting of cast iron and steel,
reduce the effectiveness of corrosion
inhibitors, increase inhibitor
depletion rate, cause formation of
scale and other deposits on heat
transfer surfaces and cause clogging
of system components.
To assure inhibitor effectiveness,
the levels of chlorides and sulfates
in water used to dilute
DOWTHERM or DOWFROST
fluids should be less than 25 ppm
each. Total hardness should be
less than 100 ppm as CaCO 3
(Table 2). Distilled or deionized
water is recommended. If good
quality water is unavailable, prediluted
solutions of DOWTHERM
SR-1 and DOWFROST HD fluids
are available from Dow.
Table 2 –– Dilution Water
Quality Requirements
Impurity Level
Chlorides 25 ppm, max
Sulfates 25 ppm, max
Calcium 50 ppm, max
Magnesium 50 ppm, max
Solution make-up
As indicated above, good quality
water must be used for fluid makeup.
In addition, any flush water
remaining in the system should be
taken into account when introducing
and diluting
DOWTHERM or DOWFROST
fluids. In a thermal energy storage
system, it is not unusual to have
hold-up of up to 20% of the total
system volume, although 10% is
more common. It is important to
note that many of the modular ice
tank systems available will have a
certain amount of water left in the
heat transfer tubes due to pressure
testing at the manufacturing
facility. This must also be taken
into account.
These considerations are most
important when charging the
system with a pre-diluted solution
of fluid. Any water trapped in the
system will lower the final concentration
of the glycol in the system.
As a result, it may be necessary to
purchase a solution with slightly
higher glycol concentration to
achieve the desired final concentration
of glycol in the system.
Introducing the fluids into
your system
In most cases, solutions containing
glycol-based heat transfer fluid are
mixed on a volume basis. If you
wish to mix DOWTHERM SR-1
or DOWFROST HD fluids by
weight percent, use Tables 5 or 7
respectively to obtain the volumeto-weight
conversion.
Following is the mixing procedure
for installing DOWTHERM SR-1
and DOWFROST HD fluids:
1. Calculate the quantity of fluid
needed to achieve the desired
concentration. Table 3, which
provides the number of gallons per
100 feet of pipe, may be helpful in
this calculation, as may manufacturers'
information regarding the
internal capacity of the ice storage
components in the system.
2. Introduce a sufficient quantity
of water to check the system for
tightness. Pressure testing the
system at this stage can be helpful.
Pressure testing can often be
accomplished during the initial
cleaning or flushing of the system.
3. Drain enough water from the
system to provide space for the
inhibited glycol quantity as
calculated in step 1.
4. Add the correct amount of fluid
and any water needed to completely
refill the system, allowing
for liquid expansion or contraction
as needed due to the operating
temperature.
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 0.295
1/4 0.540 0.088 0.364 0.541
3/8 0.675 0.091 0.493 0.992
1/2 0.840 0.109 0.622 1.578
3/4 1.050 0.113 0.824 2.770
1 1.315 0.133 1.049 4.489
1-1/4 1.660 0.140 1.380 7.769
1-1/2 1.900 0.145 1.610 10.58
2 2.375 0.154 2.067 17.43
2-1/2 2.875 0.203 2.469 24.87
3 3.500 0.216 3.068 38.40
3-1/2 4.000 0.226 3.548 51.36
4 4.500 0.237 4.026 66.13
5 5.563 0.258 5.047 103.9
6 6.625 0.280 6.065 150.1
8 8.625 0.322 7.981 259.9
10 10.750 0.365 10.020 409.6
5

5. Circulate the system for at least
24 hours to ensure complete
mixing. Check the liquid concentration
with a refractometer or
other method to assure that the
correct mixture is obtained.
Note: If fluid mixing is a concern,
the solution can be premixed in a
separate tank before introduction
into the system, or the inhibited
glycol and the water can be added
together through a “mixing tee."
This will promote faster mixing of
the inhibited glycol and water.
6
MAINTAINING DOWTHERM AND DOWFROST FLUIDS
Free analytical service
To help ensure that corrosion and
freeze protection are maintained
in customer systems, Dow offers a
free fluid analysis service. It is
designed to assure the long term
performance of DOWTHERM
and DOWFROST fluids and help
minimize replacement fluid
requirements as well as system
maintenance and repair costs.
Typically performed on an annual
basis, the analysis includes determination
of current inhibitor and
glycol levels plus Dow’s recommendations
for maintaining
proper corrosion protection.
Dow has developed special Thermal
Fluids Sampling Kits for use
by customers participating in the
analysis program. These kits
permit easy and accurate labeling
of fluid samples and safe shipment
of samples to Dow for analysis.
Kits may be obtained by calling 1-
800-447-4369. Or write:
Thermal Fluids Testing Lab
The Dow Chemical Company
Larkin Lab
1691 North Swede Road
Midland, Michigan 48674
How the service works
After the system has been filled
and circulated for several days, an
initial four-ounce sample should
be withdrawn and sent to Dow
using one of the Thermal Fluids
Sampling Kits. After the system is
in operation, it is recommended
that samples be taken once a year.
Before withdrawing the sample,
the fluid should be well circulated
in the system so the sample is
representative. Remember to
closely follow the sampling
instructions included with the
sample kit provided by Dow.
Proper sampling is essential to
ensure meaningful assessment of
fluid condition.
Approximately three weeks after
the sample is received by Dow, a
report will be sent to you detailing
results of the analysis, discussing
unusual or troublesome conditions
(if any), and offering recommendations.
Analytical tools for selftesting
It may also be desirable to perform
some simple, on-site analysis of
your system to properly maintain
the glycol concentration. A useful
tool for this type of analysis is a
Misco Products refractometer,
model 7084VP (°F) and 7064VP
(°C). These refractometers
measure the glycol solution
concentration of DOWTHERM
and DOWFROST fluids and give
the freezing points of the fluids.
The freezing point can be translated
to glycol concentration from
the tables on pages 7 and 10. This
instrument requires only a few
drops of fluid for testing and
requires no adjustment for fluid
temperature. Diluted solutions
with concentrations from 0 to
60% glycol may be tested directly.
Stronger concentrations require a
simple dilution procedure prior to
testing. Contact Misco Products at
1-800-358-1100 and ask for the
Dow discount.

PHYSICAL PROPERTY DATA Table 4 –– Physical Properties of Solutions of DOWTHERM
SR-1 Heat Transfer Fluid
Temp. Density Viscosity Thermal Cond. Specific Heat
°F lb/ft 3 cps Btu/(hr ft 2 )(°F/ft) Btu/(lb°F)
(30 volume percent ethylene glycol)
10 65.93 6.83 0.238 0.849
20 65.85 5.38 0.243 0.853
30 65.76 4.33 0.247 0.86
40 65.66 3.54 0.251 0.861
50 65.55 2.95 0.255 0.864
60 65.43 2.49 0.259 0.868
70 65.30 2.13 0.263 0.872
80 65.17 1.84 0.266 0.876
(25 volume percent ethylene glycol)
20 65.34 4.40 0.253 0.875
30 65.26 3.59 0.258 0.879
40 65.17 2.98 0.262 0.882
50 65.06 2.50 0.267 0.886
60 64.95 2.13 0.271 0.889
70 64.83 1.84 0.275 0.892
80 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 Refractive
Ethylene Ethylene DOWTHERM DOWTHERM Freezing Point °F @ Degree Index
Glycol 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 1.3328
5.0 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 1.3428
15.0 13.6 15.7 14.2 22.2 215 9.9 1.3478
20.0 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 1.3540
22.0 20.1 23.0 21.0 15.9 216 14.3 1.3551
23.0 21.0 24.1 22.0 14.9 217 14.8 1.3561
24.0 22.0 25.1 23.0 13.7 217 15.5 1.3572
25.0 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 1.3593
27.0 24.8 28.3 26.0 10.4 218 17.3 1.3603
28.0 25.8 29.3 27.0 9.2 219 17.9 1.3614
29.0 26.7 30.4 28.0 8.0 219 18.6 1.3624
30.0 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 1.3646
32.0 29.6 33.5 31.0 4.2 220 20.4 1.3656
33.0 30.6 34.6 32.0 2.9 220 21.0 1.3667
34.0 31.6 35.6 33.1 1.4 220 21.7 1.3678
35.0 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 sugar
present 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 lowest
ambient temperature. Inhibitor levels should be adjusted for solutions of less than 25% glycol. Contact Dow for information on specific cases or for
further assistance.
7

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)
8
PRESSURE DROP, psi/100 ft of pipe
PRESSURE DROP, psi/100 ft of pipe
100
10
1.0
0.1
2
4
VELOCITY, ft/sec
10
8
1/2" 3/4" 1" 1-1/2"
6
1
2" 2-1/2" 3" 4" 6" 8" 10" 12"
SCHEDULE 40 PIPE
0.01
1 10 100
FLOW RATE, U.S. gallons per minute
1000 10,000
100
10
1.0
0.1
2
1/2"
4
VELOCITY, ft/sec
3/4"
6
1"
8
10
1
1-1/2"
2" 2-1/2"
3"
SCHEDULE 40 PIPE
4"
6"
8" 10" 12"
Factor
Factor
1.03
1.10
Temperature Correction
1.02
1.05
1.01
1.00
1.00
0.95
0.99
0.90
0.98
0.85
0.97
Multiplier Temperature Factor Correction
Multiplier Factor
0.80 15 25 35 45 55 65 75 85
15 25 35 45 55 65
Temperature, Temperature, °F °F
75
1.03
1.10
1.02
1.05
1.01
1.00
1.00
0.95
0.99
0.90
0.98
0.85
0.97
Temperature Correction
Multiplier Temperature Factor Correction
Multiplier Factor
0.80 15 25 35 45 55 65 75 85
15
25Temperature,
35 45 °F55
Temperature, °F
65
0.01
1 10 100
FLOW RATE, U.S. gallons per minute
1000 10,000
75
85
85

Figure 3 –– Pressure Drop at 25% Volume Ethylene Glycol
(Steel Tube, 25°F)
PRESSURE DROP, psi/100 ft of tube
PRESSURE DROP, psi/100 ft of tube
100
10
1.0
Figure 4 –– Pressure Drop at 30% Volume Ethylene Glycol
(Steel Tube, 25°F)
100
10
1.0
2
1/2"
2
1/2"
4
VELOCITY, ft/sec
4
3/4"
VELOCITY, ft/sec
3/4"
6
6
8
8
10
1"
STEEL TUBE
10
1"
STEEL TUBE
1-1/2"
1-1/2"
Factor Factor
1.10 1.03
1.05 1.02
1.00
1.01
0.95
1.00
0.90
0.85 0.99
Temperature Correction
Multiplier
Temperature
Factor
Correction
Multiplier Factor
Temperature, Temperature, °F °F
0.1
0.1 1.0 10
FLOW RATE, U.S. gallons per minute
100 1000
2"
2-1/2"
Factor
Factor
1.10
1.03
1.05
1.00
1.02
0.95 1.01
0.90
1.00
0.85
0.99
0.80
0.75 0.98
Temperature Temperature Correction Correction
Multiplier
Multiplier
Factor
Factor
0.70
0.9715
25 35 45 55 65
15 25 35 45 55 65 75 85
Temperature, °F
Temperature, °F
0.1
0.1 1.0 10
FLOW RATE, U.S. gallons per minute
100 1000
2"
2-1/2"
0.80
0.98
0.75
0.97
0.70
15 15 25 35 3545
45 55 65 55 756585
75
75
85
85
9

10
Table 6 – Physical Properties of Solutions of DOWFROST
HD 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 0.882
20 65.53 9.91 0.239 0.886
30 65.42 7.47 0.243 0.89
40 65.30 5.75 0.247 0.894
50 65.17 4.52 0.251 0.897
60 65.02 3.61 0.254 0.901
70 64.87 2.94 0.258 0.905
80 64.71 2.43 0.261 0.909
(20 volume % propylene glycol)
20 65.11 6.97 0.25 0.908
30 65.01 5.47 0.255 0.911
40 64.90 4.35 0.259 0.915
50 64.77 3.52 0.263 0.918
60 64.64 2.88 0.267 0.921
70 64.50 2.39 0.271 0.924
80 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 Refractive
Propylene 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 1.3328
5.0 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 1.3438
15.0 14.5 16.0 15.4 22.9 212 12.9 1.3495
20.0 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 1.3567
22.0 21.4 23.4 22.8 17.6 213 16.7 1.3579
23.0 22.4 24.5 23.8 16.6 213 17.4 1.3591
24.0 23.4 25.5 24.9 15.6 213 18.4 1.3603
25.0 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 1.3627
27.0 26.4 28.7 28.1 12.6 214 20.2 1.3639
28.0 27.4 29.8 29.1 11.5 215 20.8 1.3651
29.0 28.4 30.9 30.2 10.4 215 21.4 1.3663
30.0 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 1.3687
32.0 31.4 34.0 33.4 6.6 216 23.6 1.3698
33.0 32.4 35.1 34.5 5.3 216 24.4 1.3710
34.0 33.5 36.2 35.6 3.9 216 25.3 1.3621
35.0 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 sugar
present 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 lowest
ambient temperature. Inhibitor levels should be adjusted for solutions of less than 25% glycol. Contact Dow for information on specific cases or for
further assistance.

Figure 5 –– Pressure Drop at 25% Volume Propylene Glycol
(Schedule 40 Pipe, 25°F)
PRESSURE DROP, psi/100 ft of pipe
Figure 6 –– Pressure Drop at 30% Volume Propylene Glycol
(Schedule 40 Pipe, 25°F)
PRESSURE DROP, psi/100 ft of pipe
100
10
1.0
0.1
100
10
1.0
0.1
2
1/2"
2
1/2"
4
VELOCITY, ft/sec
3/4"
4
VELOCITY, ft/sec
3/4"
6
1"
6
1"
8
8
10
10
1
1
1-1/2"
2" 2-1/2"
1-1/2"
2" 2-1/2"
3"
3"
SCHEDULE 40 PIPE
4"
SCHEDULE 40 PIPE
4"
6"
6"
8" 10" 12"
8" 10" 12"
Factor Factor
0.97
0.80
15
15 25
35 45 4555
5565
75 65 8575
Temperature, °F °F
1.03
1.10
1.05 1.02
1.00 1.01
0.95
1.00
0.90
0.85
0.99
Temperature Correction
Multiplier
Temperature
Factor
Correction
Multiplier Factor
0.80 0.98
0.75
0.97
0.70
15 25 35 45 55 65 75 85
15 25 35 45 55 65
Temperature
Temperature, °F
0.01
1 10 100
FLOW RATE, U.S. gallons per minute
1000 10,000
Factor Factor
1.03
1.10
1.02
1.05
1.01
1.00
1.00
0.95
0.99
0.90
0.98
0.85
Temperature Correction
Multiplier Temperature Factor Correction
Multiplier Factor
0.01
1 10 100
FLOW RATE, U.S. gallons per minute
1000 10,000
75
85
85
11

Figure 7 –– Pressure Drop at 25% Volume Propylene Glycol
(Steel Tube, 25°F)
PRESSURE DROP, psi/100 ft of tube
12
100
10
1.0
2
1/2"
4
VELOCITY, ft/sec
3/4"
6
8
Factor
Factor
1.10 1.03
1.05
1.02
1.00
1.01
0.95
0.90 1.00
Temperature Temperature Correction Correction
Multiplier Multiplier Factor Factor
0.85 0.99
0.80
0.98
0.75
0.97
0.70
15
15 25 35 3545
45 55 65 55 75 65 85
Temperature, Temperature, °F °F
0.1
0.1 1.0 10
FLOW RATE, U.S. gallons per minute
100
10
1"
STEEL TUBE
1-1/2"
2"
2-1/2"
75
85

PRESSURE DROP, psi/100 ft of tube
Figure 8 –– Pressure Drop at 30% Volume Propylene Glycol
(Steel Tube, 25°F)
100
10
1.0
2
1/2"
4
VELOCITY, ft/sec
3/4"
6
8
10
1"
STEEL TUBE
1-1/2" 2"
Factor
Factor
1.10 1.03
1.05 1.02
1.00
1.01
0.95
0.90 1.00
Temperature Correction
Temperature Correction
Multiplier Multiplier Factor Factor
0.85 0.99
0.80
0.98
0.75
0.70
0.97
15
15 25 35 3545
45 55 655575 65 85
Temperature. Temperature, °F °F
0.1
0.1 1.0 10
FLOW RATE, U.S. gallons per minute
100 1000
2-1/2"
75
85
13

DOWTHERM * SR-1 and
DOWFROST * HD
Heat Transfer Fluids
In Thermal Energy Storage
Application Guide
For further information, call toll-free 1-800-447-4369
(Outside the United States and Canada, call 1-517-832-1556).
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 supersede
those given in any previous document. Because any information and recommendations furnished with reference to the proper use and disposal of these products is
provided without charge, and because use conditions and disposal are not within its control, the Seller assumes no obligation or liability for such information and
recommendations. 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 be
inferred. Because use conditions and governmental laws may differ from one location to another and may change with time, Buyer is responsible for determining whether
products and the information and recommendations in this document are appropriate for Buyer’s use, and ensuring that Buyer’s workplace and disposal practices are
in compliance with laws and other governmental enactments applicable in the jurisdiction(s) having authority over Buyer’s operations.
Printed in U.S.A. *Trademark of The Dow Chemical Company Form No. 180-01306-395 JB
McKAY32869/PO3701531
*