MIDEL eN 1215

Natural ester transformer fluid

Technical Information Pack

November 2016

CONTENTS

Increased Fire Safety Page 3

Moisture Tolerance Page 4

Fluid Maintenance Guide – Distribution Transformers Page 6

Storage and Handling Guide Page 8

Safety Data Sheet Page 9

MIDEL eN 1215

Increased Fire Safety

June 2016 Page 3 of 13

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Increased Fire Safety

Transformer fires are particularly

unforgiving, spreading very quickly and

causing extensive damage, often with the

tragic loss of human life. In short,

transformer fires are an everyday

occurrence in power networks worldwide.

MIDEL eN 1215 offers the perfect solution

in terms of fire risk mitigation. With a high

fire point and certified as a less flammable

fluid, MIDEL eN 1215 joins a set of

dielectric liquids that have an impeccable

100% fire safety record since their

introduction in the 1970s.

FM Global® and Underwriters Laboratory,

two internationally recognized insurance

companies, have listed MIDEL eN 1215 as

a less flammable fluid for dielectric

purposes. This means it requires lower fire

safety measures than mineral oil. In

addition MIDEL eN 1215’s fire safe

properties allow for use in transformers

inside buildings and other critical areas

where mineral oil would not be acceptable.

Flash and Fire Point

MIDEL eN 1215 has been specifically

formulated to give a high flash and fire

point, well in excess of those required for

less flammable status and far superior to

mineral oil (Table 1).

The high fire point of MIDEL eN 1215

ensures that it will be very difficult to ignite

and that the risk of pool fires is all but

eliminated. In addition, being a listed less

flammable fluid, MIDEL eN 1215 benefits

from reduced equipment spacing

requirements, as specified in the National

Electrical Code (NFPA 70), section 450-23.

Further recommendations for less

flammable fluids can be found in the FM

Global loss prevention datasheet 5-4

‘Transformers’. By applying the FM Global

advice signficant space savings can be

made, especially for small to medium

power transformers filled with

MIDEL eN 1215.

Figure 1 shows a comparison of

transformer installations with mineral oil

and FM Approved fluid, in the volume

range 5,000-10,000gal. An additional

benefit from these recommendations would

be shorter LV cable runs and hence lower

losses.

Table 1 - Flash and Fire Points

Parameter Test Method MIDEL eN 1215 Mineral Oil

Flash Point ISO 2592 /

ASTM D92 >315°C 160°C

Fire Point ASTM D92 >350°C 170°C

Net Calorific Value ASTM D240-02 37.5MJ/kg 46.0MJ/kg

Data quoted above are typical values

Figure 1 - Example installations, mineral oil and FM Approved fluid

MIDEL eN 1215

Moisture Tolerance and Asset Life Extension

March 2016 Page 4 of 13

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Moisture Tolerance

MIDEL eN 1215 has a very high moisture

tolerance. This means it can absorb far

greater amounts of water than mineral oil

and silicone liquid without compromising its

dielectric properties. MIDEL eN 1215 can

also consume water which may slow down

cellulose ageing. In the case of mineral oil,

there is a danger that this water will be

released as condensation.

Why Moisture Tolerance is Important in

Transformers:

Dielectric strength - reduces as moisture

content increases

Rate of paper ageing - increases with

higher moisture content

Condensation during cool down - risk of

release of free water from mineral oil

Dielectric Strength

Figure 1 shows the breakdown voltage at

ambient temperature of MIDEL eN 1215,

mineral oil and silicone liquid with

increasing moisture levels. It clearly

illustrates that even a small amount of

water in mineral oil and silicone liquid

cause a rapid deterioration in breakdown

voltage. In contrast, MIDEL eN 1215

maintains a high breakdown voltage even

when moisture levels exceed 300ppm.

Paper Ageing and Asset Life

The rate of paper ageing is directly related

to water content. Various studies have

shown that the lifetime of paper reduces by

as much as a factor of ten for each extra

1% of water content in the cellulose. As the

cellulose ages it releases water, thus

accelerating the ageing process. Therefore

it is vital that cellulose is kept as dry as

possible.

Evidence from a number of studies with

natural ester has demonstrated that this

type of fluid keeps the paper drier and can

enhance lifetime. The findings are

summarized in Annex B of IEEE C57.154,

published in 2012. This includes a unit life

prediction for thermally upgraded paper

immersed in natural ester, in comparison to

mineral oil, as shown in figure 2.

By using the information in this standard,

users can either extend the lifetime of

transformers, or alternatively run at a

higher temperature while maintaining the

same life. With thermally upgraded paper

the increase in temperature can be as

much as 20°C, which in turn allows more

compact transformer designs. Another way

to use this benefit is to allow overloading of

the transformer by up to 20%.

Figure 1 - Breakdown voltage vs. moisture content at 20°C (IEC 60156 2.5mm)

Figure 2 - TUP Unit Life vs Temperature IEEE C57.154 Annex B

0.001

0.01

0.1

1

10

100

100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185

Un

it o

f N

orm

al

Pap

er

Lif

eti

me

Temperature C

TUP in Mineral Oil

TUP in Natural Ester

≈7

MIDEL eN 1215

Moisture Tolerance and Asset Life Extension

March 2016 Page 5 of 13

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Condensation During Cool Down

With mineral oil there is a potential for

water to be released when a transformer

cools from operating temperature to

ambient. This is because mineral oil has a

low moisture saturation limit, which reduces

as the temperature drops. MIDEL eN 1215

has a much higher saturation limit, which

means that it is far more difficult to reach

the saturation point.

For example if a transformer with mineral

oil and a paper water content of 1.5% was

running at 90°C the water content of the

mineral oil would be 65ppm. If the

transformer then shut down, the water

would tend to stay in the mineral oil. At

20°C the saturation limit of mineral oil is

55ppm, so the mineral oil would be 118%

saturated, releasing free water into the

transformer. The breakdown voltage of the

mineral oil will also be very low, increasing

risk of failure when restarting.

Using the same example for MIDEL eN

1215 at 90°C the water content would be

around 300ppm. The saturation limit for

MIDEL eN 1215 at 20°C is 1100ppm, so

even if all the water stays in the MIDEL eN

1215 it will only be 27% saturated. This

means there would be no free water and

still an excellent breakdown voltage.

Moisture Content Testing

Natural esters, such as MIDEL eN 1215

have a much higher affinity for water than

mineral oil and this is reflected in the

moisture content limits for the fluids. A

comparison of the standard values relating

to moisture content for new fluids are

shown in Table 1. New MIDEL eN 1215, as

delivered, is manufactured to very high

standards with a typical moisture content of

50ppm.

The different water behavior of esters has

practical implications for the interpretation

of moisture level analysis between MIDEL

eN 1215 and mineral oil in service. Users

should be careful to apply the correct limits

from guides such as IEEE C57.147. Also, if

moisture-monitoring equipment is

integrated within a transformer, it should be

calibrated for natural ester and tolerance

settings should be adjusted accordingly.

Moisture Removal

Should the moisture content rise above the

maximum recommended in-service limit,

the same methods and equipment that are

used for removing moisture from mineral oil

can also be used to remove moisture from

MIDEL eN 1215. Dissolved water can be

efficiently removed by the use of vacuum

dehydration equipment, or by the use of

molecular sieves.

For further advice on the moisture

tolerance and asset life extension benefits

of MIDEL eN 1215 please contact the

MIDEL technical team on:

mideltech@mimaterials.com.

Table 1 - Standards for moisture content in equipment at ≤69kV

Standard Moisture Content

IEEE C57.147 – Natural Ester max. 300ppm

IEEE C57.106 – Mineral Oil max. 35ppm

MIDEL eN 1215

Fluid Maintenance Guide - Distribution Transformers

April 2016 Page 6 of 13

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General

MIDEL eN 1215 is a natural ester based

fluid which is designed for long service in

sealed transformer systems. As with

mineral oil, in order to ensure that MIDEL

eN 1215 gives continued good service it is

possible to monitor a number of the fluid

parameters throughout the life of the

transformer. Testing the fluid also has the

added benefit of picking up any potential

problems with the transformer before a

failure occurs.

Generally, for distribution transformers,

sampling of the fluid is recommended

before energizing, after the first year of

service and at five year intervals thereafter.

For larger power transformers, highly

loaded or critical units, the frequency of

testing may be increased and annual

checks are commonly used.

It is important to understand some

fundamental differences between MIDEL

eN 1215 and mineral oils when carrying out

fluid testing for maintenance. Many

laboratories are now experienced in the

testing of ester based fluids, but at times a

failure can be logged against a sample

when the incorrect mineral oil limits are

applied.

Applying the limits from this guide will

ensure that the MIDEL eN 1215 fluid is in

suitable condition for continued use. Users

can also refer to the IEEE C57.147 ’IEEE

Guide for Acceptance and Maintenance of

Natural Ester Fluids in Transformers’. It

should be noted that this guide and the

IEEE standard do not apply to retrofilled

transformers, i.e. those that have been

previously filled with another fluid. If there

is any doubt about how the limits from

these guides may be applied to MIDEL eN

1215 in service, please contact the MIDEL

technical team.

Breakdown Voltage Testing

The breakdown voltage of new MIDEL eN

1215 is typically in excess of 50kV when

tested to the ASTM D 1816 2mm gap

method. Even at high moisture contents, up

300ppm at ambient temperature, testing

has shown that the breakdown voltage of

MIDEL eN 1215 will be preserved at a high

level.

There are some issues that can cause a

drop in breakdown voltage and the first is

particulate matter in the fluid. Particles can

float between the test probes and cause a

localized weakness when carrying out the

breakdown test. This can usually be

identified by erratic results when comparing

a series of breakdowns. If particles are

suspected to be causing a breakdown

issue then the fluid can be filtered through

a fine paper filter and re-tested.

Another issue that can arise is if not

enough settling time is allowed between

each breakdown test. In this case, gas

bubbles formed by the breakdown arc are

not given sufficient time to dissipate and

can cause a weak link between the probes.

Typically an average of six breakdown

tests are taken and it is recommended to

leave a minimum settling time of fifteen

minutes before the first breakdown test and

then five minutes between each

subsequent breakdown test to ensure that

gas bubbles have sufficient time to

disperse.

Kinematic Viscosity

If a natural ester fluid, such as MIDEL eN

1215, is exposed to air at elevated

temperatures, for example when there is a

leak in the transformer seal, then there will

be a gradual increase in viscosity as the

fluid reacts with oxygen. To monitor the

sealing of a transformer system it is

therefore possible to test the fluid viscosity

periodically. When measured at 40°C an

increase of more than 10% from the

original starting value of 32mm2/s should

be a trigger for further investigation.

Fire Point Testing

Fire point testing can be conducted to

determine if the MIDEL fluid has been

contaminated with another fluid with a

lower fire point, such as mineral oil.

However, fire point is less indicative of the

condition of the fluid than other tests, such

as the neutralization value. If there is no

possibility of cross contamination then fire

point testing may not be required on a

routine basis.

Table 1 - Common Test Parameters and Guidance Limits for Equipment at

≤69kV

Parameter Test Method IEEE C57.147 (2008)

Table 5

Water Content ASTM D1533 max. 540mg/kg*

Breakdown Voltage ASTM D1816 2mm min. 40kV

Fire Point ASTM D92 min.300°C

* same relative saturation as mineral oil at 20°C

MIDEL eN 1215

Fluid Maintenance Guide - Distribution Transformers

April 2016 Page 7 of 13

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DGA and Furan Analysis

Diagnosis of transformer performance by

traditional DGA and Furan analysis is still

applicable to MIDEL eN 1215 filled

transformers. The methods to diagnose

faults with DGA in mineral oil can still be

used, but adjustments need to be made to

Duval triangle boundaries and table ratios.

Guidance on DGA for ester fluids is

contained in IEEE C57.155 ‘IEEE Guide for

Interpretation of Gases Generated in

Natural Ester and Synthetic Ester-

Immersed Transformers’. For further

information regarding ester DGA and

maintenance users can also contact the

MIDEL technical department on:

mideltech@mimaterials.com.

MIDEL eN 1215

Storage & Handling Guide

January 2016 Page 8 of 13

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Introduction

MIDEL eN 1215 is a natural ester-based

dielectric fluid that is manufactured from

renewable, edible seed oil. MIDEL eN 1215

has been formulated to provide a cost

effective fluid for use in sealed

transformers under temperate climate

conditions. It is also ideally suited to indoor

installations where fire safety is a priority.

To provide excellent dielectric properties

MIDEL eN 1215 is dried and degassed

prior to filling the shipping containers. In

order to keep it in optimum condition it is

necessary to take some precautions when

handling or storing the fluid.

Receiving New MIDEL eN 1215

MIDEL eN 1215 can be delivered in 5

gallon, 55 gallon drums and 330 gallon

totes.

Totes users may notice a slight

deformation of the containers. This is due

to the degassed fluid absorbing the small

amount of air in the headspace, creating a

vacuum. This is perfectly normal and a

good indication that the seal has not been

compromised. In contrast 55 gallon drums

of MIDEL eN 1215 are not likely to deform.

This lack of deformation does not mean

that the drum seal has been compromised.

Storage

If kept in the original unopened containers

MIDEL eN 1215 has a long shelf life. Once

opened precautions should be taken to

preserve the fluid. In common with other

natural ester fluids MIDEL eN 1215 is less

oxidation stable than mineral oil, so contact

with oxygen from the air should be avoided,

especially if the fluid is heated. MIDEL eN

1215 is also hygroscopic and contact with

moist air for prolonged periods will result in

the fluid absorbing atmospheric moisture. If

a partially emptied container is necessary

for storage the head space should ideally

be back-filled with dry nitrogen to exclude

oxygen before properly resealing.

If the fluid is kept in intermediate bulk

containers the ideal location will be indoors

to avoid extremes of temperature and

exposure to the weather. Where outdoor

storage is unavoidable exposure to direct

sunlight should be prevented using a

simple covering. Storage tanks suitable for

standard mineral oil can be used for storing

MIDEL eN 1215. The tank headspace must

have a dry nitrogen blanket to keep out air

and moisture.

Pumping

MIDEL eN 1215 is an excellent lubricant,

so no specialist pumping equipment is

required. The viscosity of MIDEL eN 1215

is slightly higher than mineral oil at ambient

temperatures and this must be taken into

account when specifying pumping systems.

A higher capacity pump will be needed to

maintain the same flow rate as mineral oil

at a given temperature.

If MIDEL eN 1215 is stored outside in

ambient temperatures below 10°C it may

be necessary to heat the fluid prior to

pumping, in order to reduce the viscosity.

As with any dielectric fluid there is a

possibility of static charge build up when

MIDEL eN 1215 is flowing through the

pipes. The user should ensure that all

pumps, lines and vessels are adequately

bonded and earthed during pumping

operations.

Transformer Filling and Cellulose

Impregnation

To avoid air entrapment in the transformer

cellulose the tank should be filled from the

bottom, ideally under vacuum. In order to

aid impregnation of the cellulose it is

recommended that MIDEL eN 1215 be

heated to between 60 and 80°C when filling

and that this temperature is maintained for

the impregnation period. At 70°C the

viscosity of the fluid is very close to that of

mineral oil at 20°C, and a similar

impregnation rate has been observed in

laboratory testing.

Throughout all stages of the filling

operation it is recommended that the

introduction of air or particulate matter be

avoided. If exposure to the air is

unavoidable then the duration of this

contact should be minimized to avoid any

degradation of the fluid.

The outlet side of any pump used during

filling should be protected by a fine mesh or

paper element filter. The use of degassing

and vacuum filling is possible with MIDEL

eN 1215, using the same type of

equipment and methods employed with

mineral oil.

Thin Films of Natural Ester

Particular care should be taken to avoid

contact between the air and thin films of

natural ester based fluids, such as MIDEL

eN 1215. This is especially true if the

surface is warm, since there is a risk of

polymerization of the fluid if left for an

extended period, which would lead to

gelling and the formation of tacky surfaces.

Due to this risk of oxidation, if equipment

has been drained of MIDEL eN 1215 it is

recommended that it is filled with an inert

gas, or refilled with fluid as soon as

possible. Furthermore hot air drying is not

suitable for active parts already

impregnated with natural ester fluid.

Methods which do not expose the

impregnated parts to air, such as vapor

phase drying can be utilized.

MIDEL eN 1215

Safety Data Sheet

November 2016 Page 9 of 13

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1. Identification of the

Substance/Mixture and of the

Company/Undertaking

1.1 Product Identifier

Material Name: MIDEL eN 1215.

CAS No: 68956-68-3.

1.2 Relevant identified uses of the substance or mixture and uses advised against

Product Use: Dielectric fluid.

Uses advised against: None.

1.3 Details of the supplier of the substance or mixture

Company: M&I Materials Inc., 3675 Crestwood Parkway, Suite 400, Duluth, GA 30096,

USA.

Telephone: +1 770 817 7637.

Emergency Telephone: US Toll free: +1 844 835 4911. UK: +44 (0)161 864 5439.

Email: RussellMartin@mimaterials.com.

2. Hazards Identification This product is not classified as hazardous and therefore there is no legal requirement to

provide an SDS in Europe. This document has been compiled for information purposes, in

accordance with Regulation (EU) No 453/2010 and OSHA hazard communication

guidelines.

2.1 Classification of the substance or mixture

Regulation (EC) No 1272/2008 (CLP): Not classified.

2.2 Label elements

Regulation (EC) No 1272/2008 (CLP): No symbol or signal word.

2.3 Other hazards

None.

3. Composition/Information on

Ingredients

3.1 Substance

CAS No.: 68956-68-3. Description: Blend of natural triglyceride esters (vegetable oil). Composition:

Constituent CAS Number Contents

Blend of natural triglyceride esters

68956-68-3 >98.5%

Performance enhancing additives

Proprietary <1.5%

All constituents are listed on the TSCA inventory. Additives used in this product are a trade secret, but do not lead to classification of the substance as hazardous.

4. First Aid Measures 4.1 Description of first aid measures

Inhalation: None envisaged due to the low vapor pressure of the substance.

Skin: Wash with soap and water. Obtain medical attention if irritation develops.

Eyes: Irrigate with copious amounts of water. Obtain medical attention if irritation

develops.

Ingestion: Do not induce vomiting, obtain medical attention.

MIDEL eN 1215

Safety Data Sheet

November 2016 Page 10 of 13

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4.2 Most important symptoms and effects, both acute and delayed

No adverse effects expected.

4.3 Indication of any immediate medical attention and special treatment needed

No special treatment required.

5. Fire Fighting Measures 5.1 Extinguishing media

Carbon dioxide, dry powder, foam or water fog. Do not use water jets.

5.2 Special hazards arising from the substance or mixture

None.

5.3 Advice for fire fighters

Self-contained breathing apparatus may be required.

6. Accidental Release

Measures

6.1 Personal precautions, protective equipment and emergency procedures

Spilt product constitutes a slip hazard. Avoid contact with skin and eyes.

6.2 Environmental precautions

Do not contaminate any lakes, streams, ponds, groundwater or soil. Avoid flushing into drains. In the event of a large spillage contain product as thoroughly as possible and dispose of in accordance with local regulations.

6.3 Methods and material for containment and cleaning up

Soak up spilt material with absorbent granules for disposal.

7. Handling and Storage 7.1 Precautions for safe handling

Avoid eye and prolonged skin contact.

7.2 Conditions for safe storage, including any incompatibilities

No special precautions required.

7.3 Specific end use(s)

Exposure to air should be minimized. Opened containers should be properly resealed

8. Exposure Controls/

Personal Protection

8.1 Control parameters

No relevant control parameters.

8.2 Exposure controls

Eye washes should be available for emergency use.

Respiratory protection: None required.

Skin protection: Wear coveralls.

Hand protection: Wash hands after use. For prolonged or repeated skin contact gloves

are recommended.

Eye protection: If splashes are likely to occur wear safety glasses.

MIDEL eN 1215

Safety Data Sheet

November 2016 Page 11 of 13

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9. Physical and Chemical

Properties

9.1 Information on basic physical and chemical properties

Appearance: Pale amber liquid.

Odor: None.

pH: Not applicable.

Freezing point: -18°C.

Initial boiling point and boiling range: >300°C.

Flash point: >315°C (open cup).

Flammability (solid, gas): Nonflammable.

Upper/lower flammability or explosive limits: Data not available.

Vapor pressure: Data not available.

Vapor density: Not applicable.

Relative density: 0.92 at 20°C.

Water solubility: <1mg/l.

Solubility: Not applicable.

Partition coefficient: Data not available.

Auto-ignition temperature: No auto-ignition expected.

Decomposition temperature: Data not available.

Viscosity: 32mm2/s at 40°C.

Explosive properties: Non-explosive.

Oxidizing properties: Non-oxidizing.

9.2 Other information

Not applicable.

10. Stability and Reactivity 10.1 Reactivity

Stable under normal conditions of use.

10.2 Chemical stability

Stable under normal conditions of use.

10.3 Possibility of hazardous reactions

Data not available.

10.4 Conditions to avoid

Temperatures >250°C.

10.5 Incompatible materials

Strong oxidizing agents.

10.6 Hazardous decomposition products

None.

11. Toxicological Information 11.1 Information on toxicological effects

Likely routes of exposure: Skin and eyes are the most likely routes for exposure.

Accidental ingestion may occur. Inhalation is not expected to be a relevant route of

exposure. Product is vegetable oil based and as such non-toxic.

Acute oral toxicity: Considered to be low toxicity, vegetable oil.

MIDEL eN 1215

Safety Data Sheet

November 2016 Page 12 of 13

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Acute dermal toxicity: Considered to be low toxicity.

Acute inhalation toxicity: Low volatility makes inhalation unlikely.

Skin corrosion/irritation: Considered to be not irritating.

Eye corrosion/irritation: Considered to be not irritating.

Respiratory or skin sensitization: Considered to be not sensitizing.

Aspiration hazard: Not considered an aspiration hazard.

Carcinogenicity/mutagenicity: Not considered a mutagenic hazard or carcinogen. This

product is not considered to be a carcinogen by IARC, ACGIH, NTP or OSHA.

12. Ecological Information When used and/or disposed of as indicated no adverse environmental effects are

foreseen. Eco toxicological effects based on knowledge of similar substances.

12.1 Toxicity

Substances of this type do not pose a hazard to aquatic organisms. 12.2 Persistence and degradability

Readily biodegradable.

12.3 Bio accumulative potential

No potential for bioaccumulation.

12.4 Mobility in soil

Considered to have low mobility in soil.

12.5 Results of PBT and vPvB assessment

The product does not meet criteria for toxicity which requires further assessment. It is not

considered PBT or vPvB.

12.6 Other adverse effects

No other adverse effects envisaged.

13. Disposal Considerations 13.1 Waste treatment methods

Product and packaging must be disposed of in accordance with local and national

regulations. May be incinerated. Unused product may be returned for reclamation.

14. Transport Information Not classified as hazardous under air (ICAO/IATA), sea (IMDG), road (ADR) or rail (RID)

regulations.

14.1 UN number

Not relevant.

14.2 UN proper shipping name

Not relevant.

14.3 Transport hazard class

Not relevant.

14.4 Packing group

Not relevant.

MIDEL eN 1215

Safety Data Sheet

November 2016 Page 13 of 13

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14.5 Environmental hazards

Not relevant.

14.6 Special precautions for user

Not relevant.

15. Regulatory Information 15.1 Safety, health and environmental regulations/legislation specific for the

substance or mixture

Product is exempt from REACH registration.

All constituent substances in this product are listed in the TSCA inventory.

15.2 Chemical safety assessment

A chemical safety assessment has not been carried out for this product.

16. Other Information Compiled according to regulation 1907/EC/2006, Annex II, as amended by Regulation

(EU) No. 453/2010 and OSHA hazard communication guidelines.

16.1 Changes from last issue:

Additional regulatory information to comply with OSHA guidelines. Emergency telephone

number.

The information provided in this Safety Data Sheet is correct to our best knowledge, information and belief at the date of its publication. It

is intended to describe the product for the purposes of health, safety and environmental requirements only. It should not be construed as

guaranteeing any specific property of the product.