Coolant Analysis

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Coolant Analysis

• Mark Mathys
• Butler Machinery Company

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Disclaimer

• The information presented here is based on the
  procedures used in Butler Machinery Companys
  Fluid Analysis Lab.
• It may or may not be fitting and proper.

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Overview

• Molybdate Testing
• Turbidity Testing
• Nitrite Calculation
• Flushing the System

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Molybdate Testing
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Why Test for Molybdate?

• Testing for moly helps identify the coolant type
  and is more reliable than depending on color.
• Coolants that contain Molybdate require lower
  levels of nitrite.
• Knowing the correct amount of additive required
  avoids overdosing.

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How Is The Test Performed?

• There are several methods that can be used.
• ICP
• Colorimeter
• Test Strips
• Well focus on the Test Strip method since it is
  the cheapest and easiest.

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Test Procedure
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Dip Strip Into Sample
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Momentarily Touch Strip to Towel
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Lay Strips on Worksheet
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Compare Color to Table
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Readings Are Accurate to /- One Color Tab

• Its OK to estimate values between color pads.

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What Levels Do We Use for Conventional Moly
Coolants?

• According to ATA RP 329
• Prediluted coolant must contain at least 1200 ppm
  nitrite (as NO2-) or
• A combined total of at least 780 ppm nitrite (as
  NO2-) plus molybdate (as MoO4-2)
• With a minimum of 300 ppm of either

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So Whats That Really Mean?

• A combined total of at least 780 ppm nitrite (as
  NO2-) plus molybdate (as MoO4-2) with a minimum
  of 300 ppm of either????
• It means the nitrite and molybdate should add up
  to 780 and both must be above 300.
• If you have nitrite at 550 and moly at 330 then
  the total would be 880 and it would meet the
  specification.

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When Do We Add Additives?

• If the levels are above those specified in RP329
  no addition is required.
• If too low we add Cat SCA additive and adjust
  nitrite to 1200. We dont try to adjust the
  molybdate level.

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Wait A Minute!

• Why dont we adjust it to a combined total of 780
  nitrite plus molybdate?
• You could certainly do this but in many cases you
  would only be adding a few ounces, which is more
  difficult to measure in the field.
• In the interest of making measurements easy we
  add a little more and then round up to the
  nearest bottle size (when possible).

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So Then, How Do We Do That?
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SCA (Nitrite) Calculations

• Note the terms SCA and Nitrite are used
  interchangeably
• SCA needed
• Snp SCA Needed (ppm)
• Stp SCA Target (ppm)
• Scp SCA Current (ppm)
• Note I have included a subscript p and q as a
  reminder of the units to use.

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SCA to Add (Quarts)
or

• Saq SCA to Add (quarts)
• Cq System Capacity (quarts)
• Stp SCA Target (ppm)
• Scp SCA Current (ppm)
• Snp SCA Needed (ppm)
• Np SCA Nitrite Level in ppm (Cat SCA is 40,000
  ppm)

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Example

• A sample from a 40-quart cooling system contains
  200 ppm nitrite and 350 ppm molybdate. We want to
  adjust this to the target level of 1200 ppm using
  Cat SCA additive.

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• Saq Quarts of SCA to add ?
• Cq System Capacity 40 quarts
• Stp SCA Target 1200 ppm
• Scp SCA Current 200 ppm
• Snp SCA Needed 1000 ppm
• Np Nitrite in Additive 40,000 ppm

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Add 1 quart of CAT SCA p/n 3P2044.
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What About ELC?

• According to the CAT literature the addition of
  ELC Extender should be done based on hours or
  miles.
• 300,000 miles for on-Highway trucks.
• 6000 hours for off-highway equipment.
• The recommended levels are 400 2000 with an
  ideal of 550

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What About ELC?

• For ELC without Moly we adjust to 1200 ppm
  nitrite using ELC Extender. This is within the
  400-2000 range and it meets RP329.
• For ELC with Moly we adjust to 800 ppm nitrite
  using ELC Extender.
• We use 800 ppm because thats the amount you
  will add if you follow Cats recommendation of
  adding 2 extender.

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• For DEAC and conventional coolants without moly
  we follow CATs recommendation
• Minimum 1400
• Target 2000
• Maximum 4000

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Other Manufacturers Recommendations

• Pencool/Penray (DDC Power Cool 3000)
• 3 - 6 by volume
• 1200 ppm - 2400 ppm
• Target 2000 PPM
• Fleetguard DCA-4
• 1.5 3.0 units (DCA-4)
• 1 Unit DCA 800 ppm nitrite
• 1200 ppm - 2400 ppm
• Target 1200 PPM

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Nitrite Targets

• Conv-Mo 1200 ppm
• Conv without Mo 2000 ppm
• New ELC with Mo 800 ppm
• Old ELC without Mo 1200 ppm

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Turbidity Testing
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What is Turbidity?

• A measure of the attenuation of a radiant flux as
  it passes through a liquid media.
• A phenomena caused by the presence of undissolved
  matter in a liquid media.
• Turbidity measures the scattering of light
  through a liquid caused by materials in
  suspension or solution.
• It is the Optical Clarity of a liquid.

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What is Turbidity?

• Turbidity is measured with nephelometer, a device
  that measures the intensity of light scattered at
  90 degrees as a beam of light passes through a
  sample.

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Why Test Turbidity?

• Quantifies the cloudiness of the coolant.
• It is less subjective than visual assessment
  because the evaluation is based on an assigned
  value
• Turbidity gt 60, "Opaque",
• Turbidity gt 25, "Cloudy",
• Turbidity gt 12, "Cloudy (Slight)",
• Turbidity gt 0, "Clear
• It is easy to spot slight changes in cloudiness
  which may indicate problems.

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Units

• The most commonly used turbidity unit is NTU, or
  nephelometric turbidity units.

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Standards

• Nephelometers are calibrated using standards
  containing formalin which is a polymer similar in
  appearance to milk.

10 NTUs
1000 NTUs
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Sample Preparation

• Sample vessels are glass containers that have
  special optical properties. They are called
  cuvettes.
• The cuvettes must be very clean and should be
  handled by the lid (when possible) to avoid
  finger prints.
• Samples are diluted 1 to 10 with distilled water
  to minimize the effects of the coolants color.

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Sample Preparation

• Dispense 18 mL of distilled water into cuvette

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Sample Preparation

• Dispense 2 mL of coolant into cuvette

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Sample Preparation

• Wipe cuvette with a soft cotton cloth to remove
  fingerprints

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Sample Preparation

• Invert cuvette gently several times

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Turbidity Measurement

• Insert cuvette into Meter

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Turbidity Measurement

• Observe reading on display

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Turbidity Measurement

• Rotate cuvette to obtain lowest reading
• Then record results.

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• The coolant program then assigns a value for
  appearance based on the turbidity reading.
• Turbidity gt 60, "Opaque",
• Turbidity gt 25, "Cloudy",
• Turbidity gt 12, "Cloudy (Slight)",
• Turbidity gt 0, "Clear

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What Can We Expect To See?

• 16357 samples with Turbidity readings
• 69 (11310) were 11 or less (clear)
• 3 (358) needed flushing
• 13 ( 2106) were 12-24 (slightly cloudy)
• 14 (298) needed flushing
• 11 (1746) were 25-59 (cloudy)
• 34 (599) needed flushing
• 7 (1188) were 60 and above (opaque)
• 87 (1029) needed flushing

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Nitrite Calculation
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Original Calculation

• NO2- (mL Titrant x 2700) - 400

New Improved Calculation
NO2- (mL Titrant - mL Blank) x 2300
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Determining the Blank

• To determine the value to use for the Blank,
  perform the titration on a blank sample (using
  distilled water instead of coolant).

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Determining the Blank

• You will probably have to determine how many
  drops of water are in 1 mL and then count drops
  to determine how many mL of titrant are required.
  
• We use 0.2 mL.

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Example

• If your titration requires 0.5 mL of ceric
  sulfate
• And you blank is 0.2
• NO2- (0.5 0.2) x 2300
• NO2- 690

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The Reaction

• 2CeSO4 NaNO2 3H2O ---gt Ce2(SO4)3 NaNO3
  2H3O 2e-
• This is a redox reaction. When the solution is
  Red (actually more orange) it is in the Reduced
  state.
• It turns Blue when the solution has been oxidized
  by adding the Ceric Sulfate.
• Oxidizable Compounds in the coolant can cause
  high readings.

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Remember

• Ceric Sulfate is light sensitive so store it
  in an amber bottle or cover it with aluminum foil.

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Flushing The System

• 12 Gallon system and we can drain 80
• 1st 12 x 80 2.4 gallons remaining
• 2nd 2.4 x 80 0.5 gallons remaining
• 3rd 0.5 x 80 0.1 gallons remaining
• 4th 0.1 x 80 0.04 gallons remaining

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Summary

• Molybdate testing helps identify coolant type and
  allows for better adjustments.
• Turbidity testing lets you quantify clarity of
  the coolant and track changes.