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ASTM D 482 Standard Test Method for Ash from Petroleum Products

Background

Scope (1.1)

• This test method addresses the procedure for determining the ash content from

petroleum products.

o in a range of 0.001 - 0.180 mass %

o applicable to distillate and residual fuels, gas turbine fuels, crude oils, lubricating

oils, waxes, and other petroleum products

Scope (1.1)

• Any ash-forming materials present in the petroleum products are normally considered

to be undesirable impurities or contaminants.

• This test method is limited to petroleum products having no added ash-forming

additives such as phosphorus compounds.

Summary of Test Method (3.1)

• The sample contained in a suitable vessel is ignited.

• The ignited sample is allowed to burn until only ash and carbon remain.

• The carbonaceous residue is heated in a muffle furnace at 775 °C, and reduced to

ash.

• The ash is cooled and weighed.

Significance and Use (4.1)

• Determining the ash content helps to decide whether or not the product is suitable for

use in a specified application.

o ash can result from oil or water-soluble metallic compounds or extraneous solids

such as dirt and rust

Apparatus

Apparatus (5)

• Evaporating Dish or Crucible

• Electric Muffle Furnace

• Meeker Gas Burner

• Mechanical Shaker

Evaporating Dish or Crucible (5.1)

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• Made of platinum, silica, or porcelain,

• Capacity of 90 -120 mL.

Electric Muffle Furnace (5.2)

• Capable of maintaining temperature of 775 ± 25 °C.

• Has apertures at front and rear to allow slow natural draught of air to pass through.

Reagents (6)

• Propan-2-ol

• Toluene

Quality Control (QC) Samples (6.3)

• Are portions of one or more stable and representative liquid petroleum materials.

Sampling (7)

• Obtain samples in accordance with ASTM Practice D 4057 or ASTM D 4177.

• Transfer the portion of the sample to the crucible,

o after ensuring that the portion taken is representative of the larger portion

• Shake the sample vigorously.

Procedure

Procedure (8.1)

• Heat the crucible at 700-800 °C for a minimum of 10 minutes.

• Cool the crucible to room temperature in a container.

• Weigh the crucible to the nearest 0.1 mg.

Procedure (8.2)

• Mix the sample thoroughly before weighing, when the sample is sufficiently mobile.

o satisfactory mixing can be achieved in 10 minutes by manual shaking or using a

mechanical shaker

• Examine the sample for homogeneity.

• Continue mixing the sample, if it is not homogeneous.

Procedure (8.2.1, 8.2.2)

• When the sample is not homogenized after repeated mixings,

o use a non-aerating, high-speed shear mixer as per ASTM D 4928

• When the sample cannot be satisfactorily homogenized,

o reject the sample and acquire a new sample

Procedure (8.2.3)

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• When the sample is viscous or solid at room temperature,

o heat the sample until the sample is entirely liquid and mix carefully

o an oven at an appropriate temperature can be used for heating

• Mix the sample carefully by stirring rather than shaking.

Procedure (8.3)

• Select the quantity of the test specimen based on the expected ash content, as

described in Table 1.

• Select the weighing procedure based on whether the sample requires heating or not,

and whether more than one portion has to be weighed.

Note 3

• The container can be a desiccator not containing a desiccating agent.

• All weighings of the crucible should be performed immediately after cooling the

crucible.

Table 1- Test Specimen Mass versus Ash Content

Expected Ash (mass %) Test Specimen Mass (g)

Ash Mass (mg)

0.18 11 20

0.10 20 20

0.05 40 20

0.04 50 20

0.02 100 20

0.01 100 10

0.001 100 1

Procedure (8.4)

• Use a top loading balance to weigh the sufficient test specimen to the nearest 0.1 g

into the crucible.

o to yield no more than 20 mg of ash

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• Determine the mass of the test specimen at ambient temperature which is the

difference between the initial and final masses of the sample container weighed at

ambient temperatures.

Procedure (8.6)

• If one weighing is sufficient, carefully heat the crucible with the Meeker burner until

the contents are ignited by the flame.

• Maintain the crucible at the temperature sufficient to burn the sample at a uniform

and moderate rate.

o only the carbonaceous residue is left when the burning ceases

o use a hot plate for burning the sample

Procedure (8.6.1)

• The sample may contain water causing spattering effect.

o it is advisable for an operator to heat the sample cautiously by wearing personnel

protective equipment such as safety goggles and gloves

o discard the test portion when the sample escapes the confines of the crucible

due to severe spattering

Procedure (8.6.1)

• If the first test portion is discarded, add 2 ± 1 mL of flammable propan-2-ol to a

second test portion,

o while stirring the second test portion with a glass rod and warming it gently to

liquefy, if it is solid

• If this is unsuccessful, repeat the process on a third test portion using a 10 ± 1 mL

mixture of toluene and the propan-2-ol,

o each weighing 50 ± 5 % by volume

o take care since toluene is flammable and its vapor harmful

Procedure (8.6.1)

• Remove and transfer any test specimen adhering to the glass rod to the crucible

using a strip made of ashless filter paper.

• Continue burning the sample strictly under operator vigilance.

Procedure (8.8)

• Some test specimens will require extra heating after the burning has ceased.

o heavy samples such as marine fuels forming crusts over the unburned material

• The crust can be broken with the glass rod.

o remove and transfer the crust adhering on the glass rod to the crucible using the

strip

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• Burn the remaining test specimen.

Procedure (8.9)

• Avoid foaming of heavier material with considerable care.

• Avoid overheating to prevent a red hot appearance of the test specimen or the dish,

and loss of ash.

• Maintain the flame ignition level to be below the rim of the dish to avoid superheating

of the crust and sparks.

Procedure (8.10, 8.11)

• Heat the residue in the muffle furnace at 775 ± 25 °C until all carbonaceous material

has disappeared.

• Cool the dish to room temperature in the container and weigh to the nearest 0.1 mg.

• Reheat the dish for 20 min, cool and reweigh.

• Repeat the heating, cooling and weighing processes until consecutive weighings

differ by not more than 0.5 mg.

Note

• If more than one addition of test specimen is required, cool the dish to ambient

temperature before adding more samples.

Calculation

Calculation (9.1)

Calculate the mass of the ash as a percentage of the original samples using the formula,

mass % = (w/W)x100

Where,

w - mass of ash (in g)

W - mass of sample (in g)

Report (10)

• Record the value as the ash content, stating the mass of the sample taken.

Test Specimen Mass, g Report to

9.00 - 39.99 3 decimal places

≥ 40.00 3 - 4 decimal places

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Quality Control (QC)

• Confirm the performance of the instrument or the test procedure by analyzing the QC

sample.

• When QC/Quality Assurance (QA) protocols are already established in the testing

facility, confirm the reliability of the test result using the protocols.

• When there is no QC/QA protocol established in the testing facility, use Appendix X1

as described in the standard as the QC/QA system.

The End