1、 FORD LABORATORY TEST METHOD BU 001-01 Date Action Revisions 2000 11 10 Revised Editorial no technical change A. Cockman 1992 08 06 Printed copies are uncontrolled Page 1 of 2 Copyright 2000, Ford Global Technologies, Inc. MOISTURE VAPOR TRANSMISSION RATE OF WATERPROOF TAPE Application This procedur
2、e is used for the determination of the water vapor permeability of waterproof pressure sensitive tape. Description of Test A sample of tape is placed over the opening in a sm all aluminum container containing calcium chloride. The assembly is then subjected to high temperature and humidity for speci
3、fied periods. The gain in weight of the assembly due to moisture pickup by the desiccant is calculated for a definite time and r eported as the moisture vapor transmission rate. Apparatus Required Test Dishes Dishes used for this test are aluminum moisture dishes with tight fitting covers. The dishe
4、s are approximately 3 1/2 inches in diameter and 2 inches deep. An opening is cu t in the cover of the dish 3/4 inch wide and 2 inches long, over which the tape is applied. This size opening will accommodate 1 inch wide tapes, allowing 1/8 inch on each edge for a seal. Narrower tapes will require co
5、rrespondingly narrower openings. Wax Paraffin wax, U.S.P. grade, free from foreign material, is required for sealing the cover to the moisture dish. The melting point of the paraffin shall be 130 F minimum. Desiccant Calcium chloride, anhydrous, 8 -mesh, is placed in the bottom of the dish to absorb
6、 any water vapor which passes through the tape specimen. Humidity Cabinet The humidity cabinet used in the test shall provide a relative humidity of 90 +/ - 5 % at a temperature of 100 +/ - 5 F with no condensation on the test dishes or in th e space in which the dishes are placed. Laboratory Balanc
7、e A laboratory balance is required for weighing the test assembly. Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere o f 23 +/ - 2 C and 50 +/ - 5 % relative humidity for not less than 24 h prior to testing and tested under
8、 the same conditions unless otherwise specified. FORD LABORATORY TEST METHOD BU 001-01 Page 2 of 2 Copyright 20 00, Ford Global Technologies, Inc. Procedure 1. Place the cover, with the proper size opening, on the moisture dish and seal the edge wit h melted paraffin. 2. Transfer approximately 20 g
9、of calcium chloride to the moisture dish and spread evenly across the bottom. 3. Remove three turns of tape from the sample roll and discard before cutting the test specimen, which shall be 3 inches long and 1 inch wide. Note: Care must be exercised to prevent touching or otherwise defacing the adhe
10、sive side of the tape with the fingers as this will alter the test results. 4. Wipe off the cover of the can and place the tape sample over the opening in t he cover. Allow 1/8 inch overlap on all sides of the opening and press firmly in place to effect a tight seal. 5. Condition the assembly in a h
11、umidity cabinet at a relative humidity of 90 +/ - 5 % and a temperature of 100 +/ - 5 F for 24 h. 6. Remove the test dish from the cabinet and cool for 15 minutes in a room maintained at 72 +/ - 5 F with a relative humidity of 50 % and weigh (W 1 ). 7. Condition as in Step 5 with exposure periods of
12、 not less than 48 h each until the vapor transmission rate becomes constant when weighed as in Step 6. This final weight is W 2. 8. Report the vapor transmission rate in grams of moisture per 100 sq inch of tape area for 24 h. Vapor transmission rate - (W 2 - W 1) x 24 x 100 T x A Where: W 1 = weigh
13、t in grams after 24 h conditioning period W 2 = weight in grams after final exposure period T = total exposure period in hours after first 24 hour conditioning period A = area (in sq inch) of opening of aluminum dish. Chemicals, materials, parts, and equipment r eferenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities.
