ASTM D1176 Standard Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
4. Sampling Concentrated Liquid Products
4.1 When received, the material will preferably be in a sealed, marked container. Allow the container to stand at room temperature (not below 20°C) before attempting to obtain a sample. The container and its contents shall be shaken well before sampling (see Note 3). Any signs of solution separation should be noted and appropriate samples obtained by using a decanting or pipeting technique. Some samples that contain multiple phases may require the use of a separatory funnel to isolate a particular liquid layer or solids.

NOTE 3 - In the case of larger containers such as those with a nominal volume of 20 or 200 L (5 or 55 gal), the contents should be mixed thoroughly with a stirrer for at least 5 min to ensure a homogeneous mixture. The stirrer should be capable of dispersing any separated solids and supernatant phases without drawing air into the mixture.

4.2 Remove a representative sample by pipeting or siphoning.

5. Separation of Multiphase Products
5.1 If the product contains separated solids or liquids, place a representative sample obtained as described in Section 4 in a separatory funnel. Stopper the funnel and allow to stand for at least 16 h. Separate the various phases as follows:
5.1.1 Remove settled liquids or solids, if present, by allowing them to drain out together with a minimum amount of the major liquid phase.

5.1.2 Then drain the major liquid phase into a suitable container, taking care not to include any supernatant liquid phase.

5.1.3 Finally, drain the supernatant phase into a separate container.

5.1.4 If the solids will not drain out from the separatory funnel, siphon off the various liquid phases in sequence from the top of the funnel.

5.1.5 Ifthe solid does not separate from the liquid phase but remains in suspension, separate by passing a representative sample ofthe product through an appropriate filter paper, using suction, and transfer the liquid to a storage container.

6. Preparation of Aqueous Solutions
6.1 Concentration is generally expressed as the percentage by volume of the product at a specified temperature, usually 20°C (68°F).

6.2 Gravimetric Procedure (Weight/Volume %):
6.2.1 Determine the relative density of the product at 20/20°C (68/68°F) to the nearest 0.0005 in accordance with Test Method D1122 or D5931.

6.2.2 Calculate the weight of the product required to give the volume at 20°C (68°F).

NOTE 4 - Example - For a 30 % solution and a final volume of 100 mL, a product that has a relative density of 1.0149 at 20/20°C (68/68°F) would require that the following amount be weighed:
0.30 x 100 x (1.0149 x 0.99715) = 30.360 g of product
0.99715 = the density of water at 20°C (68°F).

6.2.3 Weigh the sample in a clean, dry container on a balance at room temperature. The sample shall be weighed to an accuracy of +/- 0.02 %. Record the weight and transfer the sample to a clean, dry volumetric flask. Care should be taken to ensure that all of the sample is transferred from the weight container by rinsing with Specification D1193, Type IV water (or ASTM corrosive water, if required by the test). Fill to just below the mark.

6.2.4 Mix the contents of the volumetric flask and bring to 20°C (68°F) by placing the flask in a constant temperature bath set at 20 +/- 0.1°C. Adjust the volume to the mark using the specified water when the contents have had a chance to come to temperature. Transfer the solution to the test vessel or storage container.

6.3 Volumetric Procedure (Volume %):
6.3.1 For many applications, sufficient accuracy can be obtained by measuring the sample in a graduated cylinder. Measure the required volume of engine coolant or antirust into a graduated cylinder. Add water of the type to be used for the test to just below the final volume. Mix the solution well. Add enough water of the type to be used for the test to bring the contents of the graduated cylinder to the final volume and mix well again. The test concentration shall be expressed as the ratio of the initial volume of the product to the final volume of the mixture of the product and water, both measured at 20°C.

6.3.2 More accurate concentrations can be prepared by the following procedure: Suspend the sample in a constant temperature water bath set at 20 +/- 0.1°C. Allow 15 to 30 min for the sample to equilibrate to this temperature. When the sample has reached bath temperature, transfer the required volume by pipet (see Note 5) to a clean, dry volumetric flask calibrated at 20 +/- 0.1°C.

NOTE 5 - The pipet should be calibrated using the test solution at 20 +/- 0.1°C. Bring the level in the flask almost to the graduated mark with the type water to be used for the test. Mix the contents of the flask by inverting several times, taking care to avoid loss of solution through the stopper. Proceed as directed in 6.2.4.

7. Preparation of Test Solutions that Contain Solids or Liquid Mixtures, or Both, in the Sample to be Tested
7.1 It is difficult to handle and obtain accurate specific gravity measurements on samples containing solids and separated layers. They are generally handled best by following the recommendation outlined in 4.1.

8. Treatment of Mixtures Resulting from Separation of Secondary Phases on Dilution of Product with Water
8.1 If a representative portion of the mixture is desired, proceed as directed in 4.1 before a portion is removed by pipeting or siphoning. Stirring should be continued during removal of the sample.

8.2 If secondary phases are to be separated, proceed as directed in 5.1.

9. Keywords
9.1 antirust; aqueous solutions; engine coolant; gravimetric procedure; sampling; solutions; volumetric procedure