ASTM D2271 Test Method for Preliminary Examination of Hydraulic Fluids (Wear Test)
6. Sampling
6.1 The sample of new fluid shall be thoroughly representative of the material in question and the portion used for the test shall be thoroughly representative of the sample itself.

7. Preparation of Apparatus
7.1 Cleaning and Flushing of Test System - Proper cleaning and flushing of the entire test system is extremely important in order to prevent cross-contamination of test fluids.
7.1.1 Open all drain valves and the petcocks at all low areas to permit removal of the used test fluid.

7.1.2 Remove the used pump cartridge, if not already done.

7.1.3 Clean the pump housing with an appropriate solvent (use Stoddard Solvent (Warning - see Combustible. Health hazard.) for petroleum and synthetic fluids; hot water for water glycol and other water-based fluids).

7.1.4 Visually examine the pump head and the interior of the pump body. Replace when evidence of deterioration is observed.

7.1.5 Inspect the pump drive shaft, shaft seal, and bearings after every run. If these parts appear to have wear or damage, replace any suspect part prior to starting the next test.

7.1.6 Insert a good used pump cartridge into the pump housing to circulate the flushing fluid.

7.1.7 Check pump alignment.

7.1.8 Remove the used filter element, clean the filter housing, and install a new filter element.

7.1.9 Remove, clean, and reinstall the 60-mesh screen in the reservoir outlet.

7.1.10 Close the reservoir outlet valve and pour 60 % of a full charge (3.2) of the appropriate cleaning solvent (7.1.3) into the reservoir.

7.1.11 Close all drain valves and petcocks and open the reservoir outlet valve to allow the flushing fluid to fill the pump and the lower lines of the system.

7.1.12 Reduce the setting of the pressure control valve, if not already done.

7.1.13 Jog the pump drive motor ON and OFF switches to remove the air from the test system. Continue until the fluid returning to the reservoir is visually free of air.

NOTE 5 - If fluid cannot be visually observed in the reservoir, the lack of pump noise is an acceptable indication that the fluid is suitably deaerated.

7.1.14 Circulate the flushing fluid through the system for 1/2 h at 1200 r/min (use a pressure of 1.40 MPa (200 psig) when using water or 3.45 MPa (500 psig) when using Stoddard Solvent). Maintain a temperature between 30 and 49°C (100 and 120°F).

NOTE 6 - One flush of this petroleum solvent is usually sufficient to clean a system in which an oil was run. Other solvents can be used when oxidized oil has coated the reservoir and lines. Repeat the flush if the first flush is cloudy or opaque. In some cases, hot water can be suitable for flushing the system.

7.1.15 Drain the flushing fluid.

7.1.16 Remove the filter element, clean the filter housing, and reinstall the same filter element.

7.1.17 Repeat 7.1.10-7.1.13 full charge (3.2) of new test fluid with the pressure increased to 3.45 MPa (500 psig) for 2 h.

7.1.18 Completely drain the test system of all fluid.

7.1.19 Remove, clean, and reinstall the 60 mesh-screen in the reservoir outlet.

7.1.20 Remove the filter element, clean the filter housing, and install a new filter element.

7.1.21 Remove the pump cartridge used for flushing from the pump housing.

7.1.22 Close the reservoir outlet valve.

7.1.23 Put a full charge (3.3) of new test fluid into the reservoir.

7.2 Preparation of New Test Pump Cartridge:
7.2.1 Inspect all pump cartridge components for manufacturing or material irregularities. A completely new pump cartridge must be used for each test. Do not reuse any cartridge components.

7.2.2 Remove the sharp edges and burrs from all steel pump cartridge parts with an oil stone.

7.2.3 Inspect the rotor for cracks and make sure the rotation arrows on it and the bushings are correct.

NOTE 7 - Some laboratories have found it useful to lap the terminal holes at the base of the vane slots in the rotor in an attempt to minimize the possibility of rotor segment breakage. To do this, each hole is lapped for several minutes using a 3/32-in. (2.38-mm) diameter drill rod with lapping compound or with a slurry of carborundum powder and oil.

NOTE 8 - Some laboratories have found it useful to polish both sides of the rotor. To do this, the rotor is installed on a used pump shaft, and the small end of the shaft is placed in a drill press. Both sides of the rotor are polished with 400 wet paper and oil and then finish polished with 600 wet paper and oil.

Vigorous lapping might have a detrimental effect on the rotor strength. Depending on how the lapping is done, this could cause an imbalance in the compressive residual stresses on the surface of the metal. These stresses are induced by the carburizing and hardening process and are a major factor in developing the rotor fatigue strength.

NOTE 9 - Some laboratories have found it useful to minimize internal pump leakage at elevated pressures and temperatures. This polishing is done on a piece of crocus cloth or 400 wet paper with plate glass or a surface plate under it. The polishing (circular motion) is continued until the outer 6 mm (1/4 in.) of the inner surface of the bushing shows evidence of polishing. The use of Prussian blue dye before polishing will aid in determining whether that portion of the bushing is flat.

7.2.4 Clean the cartridge parts in Stoddard Solvent, rinse with precipitation naphtha (Warning - Flammable. Health hazard.) and air dry.

7.2.5 Measure the rotor width between each vane slot and the ring width at twelve places equally spaced around the ring. Measure the width of each vane at the top and bottom. Record all measurements. Both the top and bottom vane widths must be 2.5 to 15.2 µm (0.001 to 0.0006 in.) less than the average rotor width, and the average rotor width must be 17.8 to 35.6 µm (0.0007 to 0.0014 in.) less than the average ring width.

7.2.6 Weigh (separately) the cam ring and the complete set of twelve vanes. Determine these two weights to the nearest milligram and record these values. The vanes should be checked to see if they have been magnetized. They must not be magnetized when weighing before or after the test. Vanes may be demagnetized with a degausser.

7.2.7 Assemble the test pump cartridge, wetting all parts with a film of test fluid. Verify proper vane insertion into the rotor. Verify correct assembly of the rotor, inner and outer bushing, and cam ring direction and alignment (see Fig. 2). The vanes should be checked for free movement in rotor slots when assembling.

NOTE 10 - Tight vanes will often fit freely in another slot.

7.2.8 Insert and bottom the assembly alignment pin, only about 3 mm (1/8 in.) of the large end should be visible above the outer bushing surface.

7.3 Installation of Test Pump Cartridge: (See Fig. 3).
7.3.1 Insert a properly prepared test pump cartridge into the pump housing, being careful to completely seat it using the guide pin hole for right-hand rotation (small hole near inlet of pump housing).

7.3.2 Install pump housing head and gasket.

NOTE 11 - The following torque sequence has been found satisfactory. Use a torque wrench to tighten the eight head bolts. 1100 N-mm (10 in./lb) at a time, using the following sequence: top (1), bottom (5), right side (3), left side (7), then bolts (2), (6), (4), and (8). Slowly rotate the pump shaft by hand while tightening the bolts. Tighten bolts until binding is felt. Then, loosen the head bolts until the shaft is completely free and re-torque 1100 N-mm (10 in./lb) at a time to 1100 N-mm (10 in./lb) less than the above binding point. Record the final level of torque (usually about 11 300 to 17 000 N-mm (100 to 140 in./lb)). The pump should rotate with a slight drag on the shaft but there should be no binding.

NOTE 12 - Some laboratories disconnect the pump to the motor shaft coupling during torquing to eliminate the drag of the motor while rotating the pump shaft.

NOTE 13 - Bind is characterized by: (a) catch or tight spot in an otherwise smooth shaft rotation, (b) a smooth revolving pump shaft with immediate stoppage after turning effort is stopped, or (c) complete seizure or stoppage requiring abnormal hand effort to turn the shaft, or all of these.

NOTE 14 - If binding occurs at less than 5600 N-mm (50 in./lb) there probably is a misalignment within the pump and it should be disassembled.