ASTM D471 Standard Test Method for Rubber Property - Effect of Liquids
8. Apparatus
8.1 For non-volatile liquids, a glass test tube, having an outside diameter of 38 mm (1.5 in.) and an overall length of 300 mm (12 in.) fitted loosely with a stopper (see 8.2.1) shall be used. Glass beads shall be used in the liquid as a bumper and to separate the specimens.
8.2 For volatile liquids, the test tube described in 8.1 shall be tightly fitted with a stopper (see 8.2.1) and a reflux condenser. An air-cooled reflux condenser shall be used for ASTM Oils No.1 and No. 5 and for IRM 902 and IRM 903 at test temperatures of 125°C (257°F) or more. This condenser shall be a glass tube, approximately 500 mm (20 in.) or longer, in length and 15 mm (0.6 in.) in outside diameter, tightly fitted to the immersion tube by means of a stopper (see 8.2.1). The bottom of the condenser tube shall project about 12 mm (0.47 in.) below the stopper. A suitable (watercooled) reflux condenser shall be used for water or other low-boiling liquids. Glass beads shall be used as in 8.1.
8.2.1 The stopper shall not contaminate the test liquid. When in doubt, cover the stopper with aluminum foil.
8.3 Maintaining Test Temperatures - The apparatus and method chosen to maintain the specified temperature during immersion testing varies with test conditions, requirements, and circumstances. Water baths, appropriate temperature transfer oil baths, hot air ovens Note 3, or aging blocks may be used.
NOTE 3 - When hot air ovens are used, it should be noted that contamination with volatile components of the immersion liquid may occur. This can affect test results, when the same ovens are subsequently used for hot air aging.
8.3.1 The preferred method for above room temperatures is the use of aging blocks, since they have the widest temperature capability.
8.3.2 Ovens - Type IIB ovens specified in Test Method E 145 are satisfactory for use through 70°C. For higher temperatures, Type IIA ovens are necessary.
8.3.2.1 The interior size shall be as follows or of an equivalent volume:
Interior size of air oven:
min: 300 by 300 by 300 mm (12 by 12 by 12 in.)
max: 900 by 900 by 1200 mm (36 by 36 by 48 in.)
8.3.2.2 Provision shall be made for placing immersion test tubes in the oven without touching each other or the sides of the aging chamber and allowing proper air circulation around them.
8.3.2.3 The heating medium for the aging chamber shall be air circulated within it at atmospheric pressure.
8.3.2.4 The source of heat is optional but shall be located in the air supply outside of the aging chamber proper.
8.3.2.5 A recording thermometer located in the upper central portion of the chamber near the center of the aging specimens shall be provided to record the actual aging temperature.
8.3.2.6 Automatic temperature control by means of thermostatic regulation shall be used.
8.3.2.7 The following special precautions shall be taken in order that accurate, uniform heating is obtained in all parts of the aging chamber.
8.3.2.8 The heated air shall be thoroughly circulated in the oven by means of mechanical agitation. When a motor-driven fan is used, the air must not come in contact with the fan motor brush discharge because of danger of ozone formation.
8.3.2.9 Baffles shall be used as required to prevent local overheating and dead spots.
8.3.2.10 The thermostatic control device shall be so located as to give accurate temperature control of the heating medium. The preferred location is adjacent to the recording thermometer.
8.3.2.11 An actual check shall be made by means of maximum reading thermometers placed in various parts of the oven to verify the uniformity of the heating.
9. Test Specimens - Change in Mass or Volume
9.1 The standard specimen shall be rectangular, having dimensions of 25 by 50 by 2.0 +/- 0.1 mm (1 by 2 by 0.08 +/- 0.004 in.). Specimens from commercial articles shall be the thickness of the material as received when they are less than 2 mm (0.08 in.); otherwise they should be reduced to a thickness of 2.0 +/- 0.1 mm (0.08 +/- 0.004 in.). Data obtained on test specimens having different original thicknesses are not comparable.
