ASTM D2570 Test Method for Simulated Service Corrosion Testing of Engine Coolants
5. Apparatus
5.1 Reservoir - An assembly drawing of this component is shown in Fig. 1. The material ofconstruction, representing that ofthe engine cylinder block, shall be SAE G3500 Gray Iron for Automotive Castings. Install a right angle fitting on the top of the reservoir for attachment of an air line. Install a shutoff valve in the air line to avoid backing up the solution into the pressure hose.

5.2 Automotive Components - These shall be those normally used with a 4, 6, or 8-cylinder automobile engine used in current automobiles in the United States, in the 1.6 to 5.0-L (98 to 305-in.) range of piston displacement. General characteristics shall be as follows:
5.2.1 Radiator - Brass, GM part No. 3056740 (cross flow), with coolant recovery tank. An aluminum radiator, GM part No. 3093506, may be used subject to mutual agreement of the parties involved.

5.2.2 Radiator Pressure Cap - Normally open 12 to 15 psi (80 to 100 kPa), GM part No. 6410427.

5.2.3 Coolant Pump - GM part No. 14033483 (aluminum matching front end cover). GM part No. 14033526 (aluminum provides back cover), coolant discharge parts and mounting for pump.

5.2.4 Coolant Outlet - GM part No. 14033198 (aluminum).

5.2.5 Hoses - Reinforced elastomer, meeting the requirements of SAE J20e.

5.2.6 Hose Clamps - Preferably worm-screw type (constant tension may be used).

5.2.7 Hose Sight Tube - A borosilicate glass sight tube shall be installed in the top radiator hose. The tube should have a slight bead on each end. (The primary purpose of the sight tube is to see that there is entrained air in the system.)

5.3 Pipe Fittings - The preferred material for the fittings required in the hose connections between pump discharge ports and reservoir inlet is malleable cast iron. A satisfactory alternative is steel.

5.4 Electric Motor - 1 1/2 hp (1.1 kW) or larger, drip-proof or explosion-proof in accordance with local safety regulations.

5.5 Pulleys and Drive Belt - Sized to drive the pump at aspeed that will produce a flow rate of 20 to 25 gal/min (1.3 to 1.6 L/s) for the General Motors 173-in. (2.8-L) V-6 engine. The flow rate may be determined by a flow measurement device located between pump discharge and reservoir inlet, as indicated in Fig. 2. The pressure drop between pump discharge and reservoir inlet, measured by the pressure gages shown in Fig. 2, must be maintained when the flow measurement device is removed from the system. This can be done by substituting for the flow measurement device a variable-flow restriction, such as a valve, which can be adjusted to produce the same pressure drop as that measured across the flow measurement device at the specified flow rate.

5.6 Electric Heater - About 2000 W, either a hot plate installed under the reservoir or a circumferential, metal-clad heater band around the reservoir.

5.7 Thermoregulator - A suitable temperature regulator shall be used to maintain the coolant temperature between the limits specified by 9.3. The sensing unit of the regulator shall be installed in an opening on the reservoir cover.

5.8 Temperature Measuring Device - An instrument capable of indicating coolant temperature to the nearest 1°F or 1°C shall be installed in an opening on the reservoir cover.

5.9 Framework - A suitable framework shall be used to mount all the components as a unit.

6. Safety Precautions
6.1 Reservoir - Protection against bursting shall be provided, either by a pressure-relief valve on the cover or by a safety enclosure.

6.2 Pump Drive - A safety guard for the coolant pump drive belt and pulleys shall be provided.

6.3 Electrical - Electrical circuits required for operation of motor, heater, and thermoregulator shall be installed with suitable precautions against electrical shock to operating personnel in the event of accidental spills of electrically conductive liquids.

6.4 Thermal - Protection of operating personnel against burns from exposed metal surfaces, especially those of the heater, shall be provided.

6.5 Plumbing - Protection of operating personnel against burns or scalds from hot fluid escaping from burst hoses or failed plumbing connections shall be provided.

7. Metal Test Specimens
NOTE 1 - The specimens prescribed for this test method have been accepted by automobile manufacturers and are required for Specifications D3306 and D4985 qualification. Current production vehicles may have differing alloy. Therefore, specimens other than those designated in this test method may be used by mutual agreement of the parties involved.

7.1 The description, specification, preparation, cleaning, and weighing of the metal test specimens to be used in this test method are given in detail in Test Method D1384. However, the solid solder specimen allowed as an alternative in Test Method D1384 shall not be used in this test method, as it has been known to bend and contact an adjoining specimen. Specimens containing high lead solder, or low lead solder, or both, may be used subject to mutual agreement of the parties involved.

NOTE 2 - The procedure for the cleaning of aluminum alloy coupons was changed in 1995 to eliminate the use of chromic acid, a recognized health hazard.

7.2 Arrangement - The metal test specimens shall be drilled through the center with a 17/64 -in. (6.8-mm) drill to accommodate a 2 1/2 -in. (65-mm) 10 - 24 brass machine screw covered with a thin-walled insulating sleeve. Polytetrafluoroethylene tubing with a 1/4 -in. (6.4-mm) outside diameter and a wall thickness of 1/64 in. (0.4 mm) is satisfactory. The standard test "bundle" shall be assembled on the insulated screw with the specimens in the following order, starting from the screw head: copper, solder, brass, steel, cast iron, and cast aluminum. The specimens shall be separated by 3/16 -in. (5-mm) thick solid metal and insulating spacers having a 17/64 -in (6.8-mm) inside diameter and a 7.16-in. (11-mm) outside diameter. Brass spacers shall be used between the copper, solder, and brass specimens, and steel spacers between the steel, cast iron, and cast aluminum specimens. Insulating spacers made from polytetrafluoroethylene shall be used between the screw head and the copper specimen, between the brass and steel specimens, and between the cast aluminum specimen and a brass nut. The nut shall be tightened firmly to ensure good electrical contact between the test specimens in each section of the bundle. As shown in Fig. 3, each bundle shall be positioned on a bracket mounted on the cap of the reservoir and fastened in place with another brass nut; the 2-in. (50-mm) dimensions of the test specimens shall be horizontal when inserted into the reservoir.

8. Test Solution
8.1 The coolant to be tested shall be a 44 % by volume glycol-based coolant prepared with corrosive water (Note 3). The corrosive water shall contain 100 ppm each of sulfate, chloride, and bicarbonate ions introduced as the sodium salts. Preparation of the sample shall be done in accordance with Section 6 ofTest Method D1176, with corrosive water used for dilution. Thus, any insoluble materials will be included in the representative sample.

NOTE 3 - The specified corrosive water can be prepared by dissolving the following amounts of anhydrous sodium salts in a quantity of distilled or deionized water:
Sodium sulfate: 148 mg
Sodium chloride: 165 mg
Sodium bicarbonate: 138 mg

The resulting solution should be made up to a volume of 1 L with distilled or deionized water at 20°C.

If relatively large amounts of corrosive water are needed for testing, a concentrate may be prepared by dissolving ten times the above amounts of the three chemicals, in distilled or deionized water, and adjusting the total volume to 1 L by further additions of distilled or deionized water. When needed, the corrosive water concentrate is diluted to the ratio of one part by volume of concentrate to nine parts of distilled or deionized water.

NOTE 4 - The test solution concentration of 44 % by volume was selected to improve the precision of the test method. Previously, the concentration had been 33 % by volume. The precision of the test, both intra-laboratory and inter-laboratory, improved at the higher concentration. Using this test at concentrations lower than the 44 % will result in a decrease in precision, with a corresponding need to evaluate any test limits selected for use in a specification.