allow tub to drain until continual dripping ceases, at which time replace the drain plug.

Refill bathtub with tangent-depth volume of water, empty receiving vessel and replace in marked position, remove drain plug, and measure time duration of discharge required to bring water level in receiving vessel up to the mark corresponding to 98 percent of the tangent-depth volume.

Replace drain plug immediately after cessation of continual dripping, and collect water clinging to inside surface of bathtub bottom with a flexible, non-absorbent squeegee. By use of the graduated cylinder, determine volume of water collected.

Repeat the three last-mentioned steps, obtaining measurements in triplicate for drainage time and retained water. Compute average values from the measurements in triplicate.

In using the graduated cylinder, wet inside surface immediately before using, shake out and discard excess water. If repeated uses of cylinder are necessary to determine marking level on receiving vessel or to fill bathtub to tangent depth, shake inside surface water into receiving vessel or bathtub, as appropriate, after each such use. Immediately before each use of the receiving vessel, first wet inside surface and then, holding upside down, shake vigorously, so as to dislodge excess water or foreign matter clinging to inside surface of vessel.

(3) Information to be Reported

Include the following in the test report:

1. Tangent-depth volume;

(2) Test Development

In developing a test, measurements were first made to determine the nature of the discharge curve near the end of the period of drainage for a bathtub (the last 3 gal). In addition, the effect of bottom slope on the amount of water retained after cessation of dripping was investigated. These data are shown in figures 2.17-2 and 2.17-3. From these data it was concluded that a bottom of near zero slope, a slope away from the drain, or a wavy or warped bottom could be detected by measuring the water retained after cessation of dripping.

In further development work, five bathtubs were tested using the procedure prescribed under section 2.17b (2), and the data are shown in table 2.17-1. In these tests, specimen SC-1 retained somewhat less water after dripping than shown in figure 2.17-2: this was apparently because it was not thoroughly cleaned before the test represented in the figure. The data of table 2.17-1 show reasonably good repeatability and agreement between results by different observers.

2. Time for discharge of 98 percent of tan

FRPE (PB-2).......

11,840 ml ADDED TO WETTED TUB. APPROXIMATELY 120ml RETAINED AFTER END OF DRIPPING

REGIME 2, FILM FLOW

The test on specimen PB-3 yielded a value of retained surface water slightly in excess of 100 ml. This was not surprising in view of the appearance of the test specimen which had previously been subjected to a 100-hr boil test. Apparently some permanent warping of the bottom had occurred, and the surface was roughened with many blisters. These conditions probably contributed to the retention of excessive water.

(3) Rationale for Test Selection

Since important properties to be evaluated by this test are duration of drainage near the end of the discharge period and retention of water on the bottom after cessation of continuous dripping, it was considered sufficient to base the tests on the quantity of water required to barely cover the bottom surface, referred to as the tangent-depth volume. By measuring the quantity of water retained after dripping, the "pooling" that might result from improper design or manufacturing errors can be detected. As a practical indication of the duration of time for the discharge of the tangentdepth volume, the time for discharge of 98 percent of the tangent-depth volume was used. While this percentage value was somewhat arbitrary, it was about the maximum value at which good repeatability could be obtained in the measurement of the time values and yet gave a meaningful comparative indication of duration of discharge for the amount of water required to cover the bottom of a bathtub. The requirement that the tests be made with a rim slope of 0°30' opposite to the drain end of a bathtub is based on field measurements of rim slope of installed fixtures. In these measurements the maximum deviation of rim slope from the horizontal approximated 0°30', although most fixtures were set very nearly horizontal. A

rim slope opposite to the drain end of the fixture was selected for test purposes since this condition imposes a more critical requirement than a slope toward the drain.

d. Comments on Performance Requirements (1) Suggested Format for a Performance Level

The maximum allowable time for discharge of 98 percent of tangent-depth volume shall be sec (average of three measurements), as determined in accordance with the procedure in section 2.17b (2). In addition, the maximum allowable quantity of water retained on the fixture surface below the tangent-depth plane shall not exceed ml (average of three measurements), as determined in accordance with the procedure in section 2.17b (b).

(2) Rationale for Suggested Format

All bathtubs which were tested for drainability discharged 98 percent of the tangent-depth volume in less than one minute, and when new retained less than 100 ml of water on the surface below the tangent-depth plane. A limitation on drainage time is of interest to the user since many persons prefer to scrub and rinse a bathtub immediately after bathing. Likewise, excessive retention of water on the surface due to surface irregularities and puddling makes cleansing and rinsing more difficult and time consuming, and may be aesthetically objectionable.

2.18. Hot-Water Resistance (Bathtub) (T302)

a. Purpose and Scope

The purpose of this test is to evaluate the ability of a bathtub to withstand exposure of the interior

a bathtub filled to the overflow outlet with water, and that will allow clearance under the bottom of the bathtub for deflection measurements with a dial gage. The bathtub shall be secured to the supporting structure as specified in section 2.2. In addition, a drain-fitting assembly shall be installed complete with overflow fitting and stopper. A flat surface shall be provided on the under-surface of the central point at the sump determined as specified in section 2.2, paragraph b(3), so that center deflections of the sump can be measured normal to bottom.

(3) Test Procedure

Clean the inside surfaces of the bathtub with water and mild soap or synthetic detergent, rinse with water, dry, and then inspect for surface defects using the procedure described in section 2.8. Fill the fixture to the overflow outlet with water at cold-water supply temperature, drain and within 10 min after emptying determine the dial-gage reading representing the elevation of the center of the underside of the sump. This reading constitutes the zero reference for subsequent deflections. Next, fill the bathtub to the overflow outlet with clean tap water, set temperature control to 120 °F, turn on heat source and start temperature recorder and hot-water circulating pump. After water temperature stabilizes, adjust thermostat so that temperature of the water at recorder sensor (point B in fig. 2.18-1) as measured with a calibrated thermometer is maintained at 120 °F within range of ±2°F. Temperature measured with the thermometer approximately 1 in from the fixture surface at eight points (two points near the bottom at approximately the third points of the longitudinal centerline, also two points each near front and rear walls and one point near each end wall at approximately halfway depth) shall not vary from 120 °F by more than ± 5°F.

NOTE: Nonuniform temperature distribution may be corrected by adjusting circulating-pump discharge rate or position of free ends of suction and/or discharge lines.

Stop the test at intervals of 100 hr, drain the tub, and inspect the fixture for damage in accordance with the procedure described in section 2.8. Also, 30 min after draining, determine the center deflection of the sump. After the final 100-hr interval of exposure terminate the test, inspect the fixture for the final time, and make the final dial-gage reading. NOTE: The test may be terminated after any test interval if the inspection shows that the fixture has failed the requirements specified in paragraph 2.18c.

(3) Information to be Reported

Include the following in the test report:

1. Specimen identification, including overall dimensions

2. Description of test frame and method of fastening tub to frame

3. Results of visual inspections at beginning of test and at each successive inspection interval

4. Deflection of center of sump 30 min after draining, at each 100-hr interval

c. Test Results and Discussion

(1) Discussion of Existing Methods

Hot-water exposure tests have been prescribed for several sanitary plumbing fixture materials. Among these are the 100-hr boil test for small specimens of FRPE materials described in the proposed revision of CS221-59 [1], and the total immersion test of a complete fixture in boiling water described for vitreous-glazed earthware in CS11143 [7]. Hot-water exposure of small specimens by total immersion is involved in the tests of thermal shock and water absorption for vitreous china described in CS20-63 [6] and FS WW-P-541b-54 [3]. However, none of these tests subjects the fixture to the type of exposure encountered in service; i.e., partially filling the fixture with hot water.

(2) Test Development

Three FRPE bathtubs were tested first as described in section 2.18b, with the test temperature maintained at 200-212 °F. The tests were terminated after an aggregate of 100 hr of exposure. The data are shown in table 2.18-1. Blistering occurred in all three tests at exposure times of 25 hr or less. Cracking was observed in two of the three tests at 50 and 75 hr. Subsequently boil tests for 100 hr as prescribed in the proposed revision of CS221-59 were made using specimens, 4 in sq, prepared by cutting from the undamaged areas of the tested fixtures; i.e., from above the water line. The results of these tests are shown in table 2.18-2. Blistering, but not cracking, was observed with these specimens. The relatively early blistering observed on specimens PB-3(1) and PB-3 (2) indicates that the thermal insulation provided by backing materials may reduce the resistance of gel-coats to blistering. This increased thermal insulation could easily result in a higher temperature in the coating as well as at the coating-substrate interface.

Deflections of the bathtub sumps due to prolonged exposure to water at or near the boiling point are summarized in table 2.18-1. In all three tests appreciable deflection recovery occurred upon empting the bathtub, and recovery continued for some time afterwards. However, some residual deflection existed after periods of up to 72 hr. In one test, the lower rear wall of the sump assumed a noticeable permanent rearward set. This particular area was not supported by a reinforcement backing.

In preliminary development work, a porcelainenameled-steel bathtub was tested at a temperature approaching the boiling point for 53 hr, including 50 hr of exposure essentially as described in section 2.18b, and the balance from the hot-water phase of 25 cycles of the thermal-shock test described in section 2.21. No noticeable effects were

observed aside from a very slight dulling of the finish.

Two additional tests using whole FRPE bathtubs were made, one exposed to 160 °F (±5 °F) water and one to 120 °F (±5 °F). The results of the 160° test are shown in table 2.18-1. As in the tests at the higher temperature, deflection recovery in the 160° test continued for at least 90 hr after emptying the tub. Blistering, however, did not appear until the 74-hr inspection.

In the 120° test (specimen PC-2), inspections were made at the beginning, and at 74, 146, 241, 355, 500, 600, 796, and 1000 hr of exposure to 120 °F (±5 °F) water. Blisters were not observed until the 500-hr inspection. At that time, the defects comprised less than half a dozen slightly raised areas of circular (up to 1% in diam) or needle shape (up to 34 in long). As in the earlier tests at higher temperatures, the blisters were less prominent after the bathtub had cooled. The 600hr inspection showed little if any further change in the surface condition. However at 796 hr, fiber and blister prominence had increased, and a number of new raised areas were observed. Still further deterioration was noted at 1000 hr. As before, some degree of recession was noted after cooling. Residual sump deflections taken immediately after draining the tub at the various inspection intervals ranged up to approximately 0.11 in, with some characteristic deflection recovery after remaining empty for a period of hours at room temperature.

In short-time load tests on FRPE bathtubs with 150 lb of water at approximately 115 °F on which was superimposed a 150-lb concentrated load at the center of the sump bottom, maximum deflections of the sumps did not exceed approximately 0.05 in. These data are presented in section 2.13.

While these trials showed that the particular FRPE bathtubs furnished for test were incapable of withstanding exposure to hot water for long periods at temperatures of 160 °F, or higher, without exhibiting surface defects, bathtubs in service are probably only rarely exposed to such temperatures and then probably for very short intervals of time.

Two series of 100-hr boiling water tests were performed on 4-in × 4-in flat specimens provided by manufacturers or specially prepared in the laboratory. Equipment was used conforming to that specified under paragraph 6.1.1 of the proposed revision of CS 221-59 [1]. The results of the first series of tests are summarized as follows: Appearance After Boiling

Material

.055 A number of blisters in diam, especially in area of front radius. Longitudinal cracks in rear radius on both sides of overflow opening.

Greater number of blisters, ranging up to 4 in diam. Largest blisters in corners.
Blisters tended to recede upon cooling. Fiber impressions evident. Additional
cracks especially at ends, some in branching pattern.

More blisters than at 75 hr, some up to 16 in across. Recede somewhat on
cooling. Bottom warped outward near edge of reinforcement at back of sump.
Cracking worse than at 75 hr, length of cracks ranging up to approx. 12 in
No defects.

Two small blisters near center of bottom.

A number of additional bisters.

Co (Hot Tub)

.024

.106

. 027

. 101

0

25

.109

40 4

A B

45 6

Co (Hot Tub)

0

C° (Cold Tub)

C° (Cold Tub) 0

811

No defects.

(Hot Tub) (Cold Tub)

Many large blisters just below water line. Size diminished on cooling.

Two hours after draining, blister counts of 20 to 80 were obtained from randomly spaced 6-in circular areas on sidewalls, ranging up to 316 in diam (up to in on bottom). Needle-shaped raised areas approx. 1⁄2 to in long, particularly on sidewalls. Two small areas on lower sidewall contained numerous short, parallel cracks.

Surface below water line covered with numerous tiny blisters, except in front

corners.

Blisters increased in number (8 in tog in) All areas below water line blistered, many blisters joined with adjacent blisters.

100

. 143

18

b. 034

.034 b. 048

021

.021

. 010

No defects.

155

.266

Blisters flattened out considerably, many having burst open.

No defects.

Approx. 20 blisters on finished surface of tub bottom, ranging from 1⁄4 in to in diam. Blister prominence decreased upon cooling.

Blisters noticeably less prominent. Three new blisters approx. 4 in diam on concave surface of an inside corner slightly below water line. Outlines of numerous filaments of fiberglass.

¡ Measured after tub had been empty for 42 hr. Measured after tub had been empty for 72 hr.

1 Measured after tub had been empty for 2 hr. Measured after tub had been empty for 25 hr.

n Measured after tub had been empty for 90 hr.

• Designations A, B, and C identify 6-in circular areas on longitudinal centerline of finished surface of bottom of bathtub. A was at mid-point, C adjacent to drain, and B at opposite end of tub. Numbers indicate blister counts in the respective areas.