b Acid resistant, class AA, dry process specimen obtained from manufacturer of sanitary plumbing fixtures.

• Laboratory specimen from gel-coat producer.

Tests at low temperatures require long testing times. However, there was at least an indication from the data that low-temperature performance might be predicted from high-temperature data. The possible existence of an exponential relationship between water temperature and time-tofailure was indicated from the results of tests on three bathtubs of the same make, one specimen at each of the three temperatures. If this correlation could be satisfactorily established, a test temperature greater than 120° could be selected so that test duration could be reduced. However, there are not sufficient data at this time to recommend the higher test temperature.

(3) Rationale for Test Selection

An exposure test of the entire bathtub (inside surface below over-flow-outlet level) is recommended for two reasons:

1. The detection of susceptibility to deterioration on exposure to hot water is more certain with the use of a whole fixture than if only a few small specimens cut from the fixture were tested.

2. Any possible effects of unequal stress distributions and other characteristics that might be associated with curved surfaces in whole fixtures probably cannot be detected in hot-water tests of small flat specimens.

It is recognized that the recommended test involves a prolonged exposure, whereas in service the exposure is typically intermittent. Thus, the recommended test does not incorporate thermal shock, nor does it allow for possible effects caused by alternate wetting and drying. Some consideration was given to the desirability of combining both termal-shock and hot-water resistance into a single test. A discussion of this possibility appears in section 2.21. However, this will require further development work.

d. Comments on Performance Requirements (1) Suggested Format for Performance Level The bathtub shall withstand exposure of the interior surface to water at a test temperature of 120 °F for hr without blistering, cracking, loss of bond between surface coating and base material, or other damage as detected by the surface-inspection test of section 2.8. In addition, residual deflection after hr of exposure when measured 30 min after emptying bathtub shall not exceed .in.

(2) Rationale for Suggested Format

The requirement of the appearance of no defects in a bathtub surface after a given exposure to water at 120 °F is believed to be a reasonable requirement. A bathtub is meant for bathing and if blisters and cracks or other defects that seriously affect its usability appear after only short

periods of service, the fixture is not performing the function for which it was intended. It was assumed that a total of 400 hr of exposure might occcur in eight years of service. However, since most baths are probably taken at water temperatures appreciably less than 120 °F, and since timeto-failure appears from the test results to be lengthened by lowering the temperature, 400 hr of exposure at 120 °F could represent a normal service hot-water exposure of much longer than eight years. Hence, 400 hr without the appearance of defects might be considered as a fairly reasonable test requirement.

It should be pointed out that the blisters that first appeared in the tests were not of a type that would have made the tubs immediately unusable in service, although their presence would have been undesirable. The observed tendency of these blisters to recede on cooling, however, does not suggest that their appearance is of no significance. When a blister occurs the original bond of the coating to the substrate is destroyed, and for this reason the coating may be subject to spalling at these blister points during later service. In fact, it is even possible that the small spalls observed on some of the older tubs in the field inspection of FRPE fixtures could have originated from this

cause.

A possible limit on center deflection of the sump 30 min after draining the hot water from the bathtub would be 1/8 in. This value is based on the following considerations:

1. A center deflection of % in that uniformly diminishes with distance from the center should not present a drainability problem in bathtubs with bottom slopes comparable to those of current production. The deflection limit recommended may include an inherent safety factor, since the intermittent loading occurring during use would tend to cause less sump deflection in some materials than continuous hot-water loading for the same period of exposure, and also because many polymeric materials (such as FRPE) will continue to recover for much longer periods than the 30 min specified in paragraph 2.18c.

2. Field information on bathtubs did not show a significant incidence of drainability problems; hence, it may be inferred that sump-bottom deflection from hot-water exposure has not been a problem with the current materials. The FRPE bathtubs tested pass the suggestion deflection requirement. Because of their particular properties, porcelain-enameled metal bathtubs are not subject to permanent deflection from exposure to hot water. However, the same sort of a deflection limit is proposed as both necessary and desirable so as to prevent possible future use of materials that may have permanent deflections sufficiently high to affect adversely their drainability.

2.19. Cigarette-Burn Resistance (T303)

a. Purpose and Scope

The purpose of this test is to evaluate the ease of removal of chars or stains caused by lighted cigarettes that are left in contact with a flat surface of a sanitary fixture.

b. Recommended Test Method

(1) Test Procedure

Maintain the temperature of the testing laboratory at 75 ± 5 °F. Store the fixture in the laboratory at least 4 hours prior to testing to permit it to reach temperature equilibrium.

Select any three contemporary but popular brands of cigarettes and designate them Brands A, B, and C, respectively. Remove three cigarettes from a freshly opened package of Brand A, light each one, and immediately after lighting, place each burning cigarette on any flat horizontal surface of the fixture, with the burning end in contact with the surface and not less than 1/4 in from a fixture edge. If the fixture has no suitable flat, horizontal areas, the fixture may be tilted so that a flat area will be horizontal, or alternatively, flat specimens may be cut from the fixture.

Separate the burning ends of the cigarettes during test by a distance of at least 6 inches. After 2 min (2 sec), remove each cigarette from the fixture and allow the tested area to cool to room temperature. Repeat the same operations and procedures with three cigarettes of Brand B, placing each one on an area of the fixture adjacent to the earlier test areas. Finally, repeat the same operations and procedures with cigarettes of Brand C.

After all test areas have cooled to room temperature, assign a burn rating to each test area on the basis of the rating method shown in table 2.19-1.

To evaluate burn ratings of 80 and lower, use a 1/4-in wide strip of 220-mesh abrasive paper (6/0) fastened to a rigid backing strip to abrade away the coating at the test areas until a depth is reached where no more than a faint trace of discoloration remains. Measure thickness of coating removed with a depth gage that can be read to 0.2 mils (0.0002 in). Record these readings and, in addition, on any three of the test spots, continue to abrade the coating until the substrate becomes visible. Measure these depths and designate the average as the coating thickness. Compute for each spot the percent of the coating thickness that must be removed to a point where only a faint trace of the discoloration remains.

After burn-resistance ratings have been assigned to each test area in accordance with the rating method, add all of the nine burn-resistance ratings and divide the sum by nine to obtain the burnresistance rating of the fixture.

80

70

60

50

40

30

20

10

0

For molded fixtures with no coating, burn ratings of 70 and lower are based on measured char depths only. If, for these fixtures, the stain is eliminated by removal of not more than 2 mils of material from the surface, the burn resistance is 70; by not more than 4 mils, 60; by not more than 6 mils, 50; by not

(2) Information to be Reported

Include the following in the test report:

1. The three brands of cigarettes that were selected for testing;

2. Total thickness of coating;

3. Depth of coating removed at each test spot and average of the three depth measurements for each of three cigarette brands. Do not identify test data with cigarette brand names.

4. The assigned cigarette-burn-resistance rating for the fixture.

c. Test Results and Discussion

(1) Discussion of Existing Methods

A search of the literature disclosed only one test method for cigarette-burn resistance. This appeared as one part of ASTM D 1300-53T [11]. This particular test uses a calibrated automobile cigarette lighter with a controlled wattage input placed 0.313 ± 0.003 in from the surface of the specimen. Heating of the surface is by radiation. Failure is defined as evidence of blistering, permanent discoloration, or charring after 110 sec of exposure for the standard grade of material and 10 min for the cigarette-proof grade.

(2) Test Development

Consideration of the aforementioned ASTM test procedure indicated that (a) it might be unnecessarily complex and involved as a test for sanitary ware, and (b) the small cigarette-lighter source might not simulate an actual burning cigarette since the heating of the test surface is almost entirely by radiation, whereas, when a lighted cigarette is placed on a surface, some of the heating is by conduction. As a result of these considerations the development of a new cigarette-burn test was initiated which led to the recommended test method described in paragraph 2.19 (b).

(a) Effect of time of contact

Figure 2.19-1 shows the results of a series of tests made on one FRPE specimen with a gelcoat thickness of 22 mils. It can be seen that char

more than 8 mils, 40; by not more than 10 mils, 30; by not more than 12 mils, 20; and by not more than 14 mils, 10. If the stain is not eliminated by removal of 14 mils from the surface, the burn rating is zero.

depth goes up rapidly with the time of contact. Partly on the basis of these results, but mostly from considerations of the average time of contact that might be expected in service, a contact time of 2 min was proposed for the standard condition.

(b) Effect of cigarette brand

Four cigarette brands were tested on the same specimen. The results are summarized in table 2.19-2.

The differences in the char-depth averages for the various brands are not statistically significant at the 0.05-probability level except for Brand D, which gave significantly lower char-depth than Brand A and Brand C. The burn-test rating of the specimen for all four brands, however, was 60.

(c) Burn ratings of porcelain enamels and vitreous china

Burn ratings of both porcelain on steel and cast iron, and of the glaze on vitreous china were 100 when measured according to the system outlined in the table. This rating might drop for abraded surface since condensed tars would undoubtedly be more difficult to remove from the roughened finishes.

(d) Effect of gel-coat thickness

Although not studied systematically, there was some evidence that char-depth increases with gelcoat thickness. A char-depth of 4.6 mils was measured with Brand A cigarettes for a 22-mil thick gel-coat as against a char-depth of 1.9 mils for what was presumably the same gel-coat with a thickness of 10.2 mils. The burn-resistance ratings of the two specimens would, according to table 2.19-1, be 50 and 60, respectively.

(e) Comparison of char-depths determined by two operators

Two different operators evaluated the burn resistance of a 4- by 4-in FRPE specimen with a 10-mil thick gel-coat. Brand A cigarettes were used. The results follow:

(g) Burn-resistance ratings of FRPE fixtures

The burn-resistance ratings were obtained on two FRPE bathtubs. No difficulties were encountered in performing the tests. Both units gave a burn-resistance rating of 70.

(3) Rational for Test Selection

Admittedly, the proposed test tends to be somewhat qualitative, especially with respect to the end point, which depends both on the judgment and visual acuity of the observer. However, since nine. burned areas are evaluated, and since char depths obtained over a relatively wide range of percentage loss in thickness yield the same burn-resistance rating, high scatter in results among the observers would not be expected. One desirable feature of the test is that it exactly simulates the service exposure involved in this performance characteristic.

d. Comments on Performance Requirements

(1) Suggested Format for a Performance Level The burn-resistance rating of the fixture shall be not less than when measured as prescribed

in paragraph 2.19 (b).

(2) Rationale for Suggested Format

Lighted cigarettes are occasionally placed on the flat ledges of bathtubs. The field survey made near the beginning of the project showed that burns from this practice were not uncommon on bathtubs with organic finishes. At the same time, however, it was found that once a burn had occurred, a polyester gel-coat could be restored to almost its original appearance without the need for an expensive or complex repair operation or of the removal of an excessive amount of coating material. Other future organic finishes might not have this property. Therefore, it would seem desirable to require that the cigarette-burn resistance be approximately as great as the currently produced polyester gel-coat. A burn-resisting rating of not less than 50 would accomplish this purpose.

2.20. Radiant-Heater Resistance (T303A) a. Purpose and Scope

The purpose of this test is to evaluate the resistance of a sanitary plumbing fixture to permanent damage caused by a radiant heater placed near the fixture.

b. Recommended Test Method

(1) Apparatus

Radiant Heater. The radiant heater to be used shall be a 650-watt 120-volt heater. The heating element shall be a wire-wound annulus of conical shape that operates in an air atmosphere. A 10-in bright metal parabolic mirror placed behind the heating element collimates the radiant flux. The

front safety grill of the heater shall be removed prior to testing. Also, the heater shall be operated at the same voltage to ±2 volts for all tests described herein. In addition, the reflector shall be cleaned of accumulated dust and dirt prior to each use. The heater used in the present test was a Sears Roebuck Model 135. 71600.

Black-Panel Radiometer. A black-panel radiometer is required. This shall be constructed as specified in figure 2.20-1 (Part A). A null-type potentiometer (or a millivoltmeter) readable to 0.1 mV is required to measure the response of the radiometer thermocouple.

Figure 2.20-1 specifies that a flat black paint shall be applied at a thickness of 0.002 in to the sensing area of the radiometer probe. This paint film may blister if the temperature of the probe is raised too rapidly during the first heat-up. Therefore, the paint film shall be cured prior to the test by moving the probe very slowly toward the radiant heater until a probe temperature of 250 °F is indicated. The probe shall then be maintained at this temperature for 15 min to complete the curing, after which the painted surface shall be inspected for the presence of blisters. If blisters are present, the probe shall be repainted, and the paint film cured with a slower heating cycle. In no case shall the probe be used for the testing described herein unless the paint film is completely free of blisters.

The paint used as the probe coating shall be 3M Brand Black Velvet Coating (101-C10 Black), or equivalent. This is available in 6-oz spray cans from the Reflective Products Division, 3M Co., St. Paul, Minn. The required 0.002 in thickness is achieved with this paint by spraying as two coats but without permitting complete drying between the two applications. Film thickness can be determined by micrometer measurements before and after application.

(2) Test Procedure

A. Calibration of Radiant-Heater Response with Black-Panel Radiometer: Mount the heater and radiometer on a flat, horizontal surface using an arrangement such as that suggested in figure 2.20-1 (Part B). Then, with the temperature in the test room at 75 ± 3 °F, place the probe at a distance of 27 in from the face of the heater. Position the probe with the painted surface facing the heater and also, with the center of the probe at the same height as the center of the reflector, and, in addition, center the probe with respect to the horizontal axis of the heater.

After positioning the heater, turn on the heating element and, after 5 min, measure the millivolt response from the probe thermocouple. Then, without turning off the heater, move the probe 12 in in a lateral direction and after 2 min, again measure the millivolt response. Repeat this operation moving the probe 1/2 in in a lateral direction after each measurement until a position is reached