that is approximately coincident with the outer rim of the reflector on the heater. Take the maximum reading obtained during this lateral scan as the millivolt response of the radiometer at the 27-in distance.

Next, repeat the procedures outlined in the preceding paragraph with the probe placed 24, 21, 18, 15, 12, 9, and 6 in from the heater face, being certain in each case that the probe face is parallel to the front edge of the reflector on the heater.

After completing these measurements, convert the maximum millivolt readings obtained at each distance to temperature in F using the standard conversion tables for Chromel-Alumel thermocouples given in ASTM Procedure: E230-63. In effect, these temperatures at each distance represent a maximum flux density calibration for the radiant heater.

NOTE: These maximum temperatures are referred to later as equivalent black-panel radiometer temperatures.

NOTE: On fixtures other than bathtubs, only a part of the collimated flux may strike the test area.

Maintain the temperature of the testing laboratory at 755 °F. Store the fixture in the laboratory for at least four hours prior to testing to permit it to reach temperature equilibrium. As soon as this equilibrium has been established, position the reflector of the heater so that the front edge of the reflector is parallel to the test area and at a distance of 27 in from the fixture when measured from the outer rim of the reflector to the area to be tested. Also, adjust the height of the heater so that the collimated flux strikes approximately midway between the top and bottom of the test area.

After completing this positioning, turn on heater and expose the test area for 15 14 min to the radiant flux.

NOTE: Start timing when the heater is turned on rather than when it reaches its operating temperature. If no damage to the fixture is observed when examined within 2 min after turning off the heater, move the heater 3 in closer to the test area (24-in distance) and repeat all operations specified above.

NOTE: For the purposes of this test, damage consists of any cracking, blistering, and discoloration of the test surface as well as any distortion or buckling of the fixture.

Next, continue the testing by moving the heater three inches closer to the test area after each 15-min exposure period until a distance is reached where the 15-min treatment causes some observable damage to the fixture. The radiant-heater resistance rating of the fixture is then taken as the equivalent black-panel radiometer temperature for this distance.

NOTE: If no damage occurs at the six-inch distance, the radiant heater resistance rating is reported as greater than the equivalent radiometer temperature at six inches. Likewise, if damage is observed at the 27-in distance, the resistance rating reported is less than the equivalent radiometer temperature at 27 in.

(3) Information to be Reported

Include the following in the test report:

1. Type of radiant heater, including manufacturer's name and number;

2. Type and thickness of paint used on blackpanel radiometer probe;

3. Type of instrument used for measuring millivolt response of probe thermocouple;

4. Distance between heater and fixture at which first damage was observed;

5. Type of damage, if any, that resulted from the radiant-heater treatment;

6. Radiant-heater-resistance rating of fixture.

c. Test Results and Discussion

(1) Discussion of Existing Methods

A search of the test literature failed to reveal any earlier tests for the resistance of a fixture material to damage from radiant heaters.

(2) Test Development

The first tests were made with 4-X4-in specimens of FRPE mounted, face forward, in a small backing enclosure of 1/4-in plywood. A small wire thermocouple was cemented into a hole drilled from the back of the specimen to the gel-coat interface. The hot junction was positioned so as to be touching the gel-coat. Indicated temperatures were recorded as the specimens were moved inward toward two types of radiant heaters. Results obtained with two FRPE specimens for this type of testing are shown in figure 2.20-2. The only permanent damage observed in these tests was a discoloration (yellowing) of the specimen after exposure at 6 inches to the 650-W heater.

Because of difficulties involved in standardizing the treatment described above, and also because thermal stresses encountered in a fixture would not be duplicated in a 4- X 4-in specimen, further work on this method was terminated. Instead, emphasis was placed on the exposure of actual fixtures to the radiant flux from a commercial heater. However, since no two heaters could be depended upon to give the same radiant flux per unit area at the same distance from the heater, it was necessary to devise a simple method of calibration. The method devised is described in section 2.20 (b). Although a more sophisticated calibra

tion approach might have been used that would involve, among other things, expensive calibrated radiometers with infrared windows, such an approach was not believed justified for the radiantheater test. Results of measurements made with three different probes are given in table 2.20-1. It will be noted that the three probes are in reasonably good agreement. The maximum difference between probes was 13 °F. This occurred at the closest distance of approach to the heater.

Table 2.20-2 lists the results of radiant-heater tests made on four FRPE bathtubs. Position No. 1 is the test area specified for bathtubs in section 2.20 (b)2. Of the three tubs that could be tested in this area (PB-2, PB-4 and PD-1), two had radiant-heater-resistance ratings of greater than 215 °F while one (PB-2) showed a blister at 18 in (203 °F rating). This blister almost completely receded on cooling. Nevertheless, the bond between coating and substrate had been ruptured by the treatment and this could easily lead to later deterioration.

(3) Rationale for Test Selection

Numerous alternative approaches might be used to evaluate the radiant-heater resistance of a fixture. One might be to place a specimen cut from

the fixture into an oven and determine the temperature at which deterioration was first observed. Such a method would not be simulative, however, since when a fixture is exposed to the flux from a radiant heater, heating is from one side only. Also, the temperature reached by a given material during radiant heating is strongly dependent on its infrared absorptance and emittance while in an oven all specimens will reach the same temperature irrespective of the thermal radiation properties of the surface layer.

The particular test recommended is believed to closely simulate the conditions that exist when a portable radiant heater is placed on the floor of a bathroom in such position that it faces a bathtub. Exposure for 15 min seems a reasonable time, although longer times might have been specified. Built-in panel heaters (either gas or electric) might operate almost continuously in a bathroom during cold weather. Heaters of this type, however, are normally positioned further from the fixture and hence the flux per unit area falling on the fixture would not reach the high values encountered with the portable heaters.

d. Discussion of Performance Requirements (1) Suggested Format for a Performance Level The radiant-heater resistance rating of the fixture shall be not less than when measured by the methods and procedures specified in section 2.20 (b). This rating is the equivalent black-panel radiometer temperature for the heater distance at which first damage to the fixture is observed. (2) Rationale for a Suggested Format

In attempting to arrive at an equivalent blackpanel radiometer temperature for a performance level, one might consider a value of 215 °F. This represents the condition that exists when a typical portable heater with a power of 650 W is placed approximately 15 in from an exposed area of the fixture. This distance appears to be a reasonable

one since, if the heater was placed closer than about 15 in to one of the current FRPE fixtures, a person in the bathroom would be forewarned of impending damage to the fixture by a rather strong odor of styrene.

Long-time effects from radiant heat at lower flux densities than that represented by a 650-W heater at 15 in were not investigated because of time limitations. However, it seems unlikely that any damage from this type of treatment would be of especially serious nature.

The 15-min time period specified in section 2.20b (2) B is admittedly arbitrary. It was selected as being reasonably representative of the time that a portable heater might be left on in a bathroom.

2.21. Resistance to Thermal Shock (T304)

a. Purpose and Scope

The purpose of a thermal-shock performance test for a sanitary plumbing fixture is to evaluate the ability of the fixture to withstand (1) intermittent exposure of the finished surface to hot water, and (2) alternate exposure to hot and cold water, without exhibiting surface damage. Some degree of thermal-shock resistance is desirable in all sanitary plumbing fixtures. The need is probably least for water closets and urinals, since typical service exposure for these fixtures involves cold water at temperatures not far below normal room temperatures. The limited amount of work reported here was carried out only on a bathtub.

b. Selection of a Test Method

An apparatus was assembled for exposing a bathtub to repetitive cycles of thermal shock. This apparatus was tried out on one specimen of an enameled-steel tub. This apparatus would probably be suitable for use in thermal-shock tests with some further development and refinement, as described in paragraph 2.21e. No test method is recommended at this time, because (1) the existing published test methods reviewed impose conditions of exposure unrepresentative of service, (2) no correlation appears to have been established in the existing tests between number-of-cycles-tofailure and temperature, and (3) the limitations of the present investigation did not permit complete development of an adequate test.

A recommended test method should be relatively simple, and should effectively simulate the conditions imposed in service. Correlation between the effects produced in the test and the effects from service exposure would be needed.

c. Performance Requirements

Performance requirements cannot be stated precisely because more work is required on test development and more data are required on performance. However, it can be stated that a plumb

ing fixture should be capable of a reasonable period of service exposure, without exhibiting surface damage that can be detected by the inspection procedure described in section 2.8.

d. Test Results and Discussion

(1) Discussion of Existing Methods

A few tests involving thermal shock have been developed by other groups for use with vitreouschina and vitreous-glazed earthenware plumbing fixtures. The degree of correlation between the results obtained from these test procedures and from actual service exposure is unknown.

Among the tests referred to in existing plumbing fixture standards are the following:

1. Autoclave Test for Crazing of Vitreous Glazed Earthenware, Par. 11, CS 111-43 [7].

Flat pieces broken from a fixture (approx. 16 in2 area on one side) are subjected to 75-psi steam pressure in an autoclave for one hour, after which the pressure is released and the specimens are allowed to cool to room temperature in the autoclave. The specimens are then examined for cracking or crazing after applying a dye solution to the finished surface. Cracking or crazing after being subjected to four cycles of this treatment indicates failure.

2. Thermal Shock Test for Vitreous Glazed Earthenware, Par. 12, CS 111–43 [7].

A complete fixture is filled with boiling water which is maintained at the boiling point until the material is heated throughout, followed by rapid emptying and immediate refilling with ice water at a temperature of 38 °F. The ice water is maintained at 38 °F by addition of ice until the fixture material is thoroughly cooled, after which the fixture is quickly emptied and the cycle repeated. Visible injury of the specimens upon exposure to 25 cycles of this treatment indicates failure.

3. Crazing Test for Vitreous China, Par. 6.4 of CS 20-63 [6] and Par. 10.11.4 of FS WW-P541b(4), 1962 [3].

Test specimen 4 to 5 in2 is suspended in a solution of anhydrous calcium chloride and water (equal portions by weight) and boiled for 12 hr. Then the specimen is removed and immediately plunged into an ice-water bath and allowed to cool. Following this, the specimen is soaked for 12 hr in a concentrated solution of methylene-blue dye, and finally examined for craze lines. Visible evidence of crazing after this treatment indicates failure.

(2) Test Development

Apparatus was constructed and tried out which subjected the inside surface of a bathtub to thermal shock with a differential in water temperature approximating 160 °F. Figure 2.21-1 is a schematic representation of the apparatus. The bathtub was filled with hot or cold water to the overflow outlet in about three minutes, and emptied in about four