Why do we allow a wall to be classified as firewalls when it is significantly different from the tested configuration?
Typical, Metal Stud Assembly Description
"1-1/4 in. wide by min 3-5/8 in. deep fabricated from min 0.020 in. (25-gauge) thick galv steel, attached to floor and ceiling with fasteners spaced 24 in. OC max." (With 5/8 Type X gypsum wallboard both sides etc.)
At the 1800-degree temperature attained during ASTM-E119, Thermal Expansion causes metal stud to expand 1/4 inch per foot. That three inches of expansion, on a twelve foot stud causes the stud to bow laterally twelve inches.
How can they say that a wall constructed with 3-5/8", 16-gauge CSJ (1-5/8 inch) studs placed 16 inches on center will respond the same in ASTM E119 fire test, Actually they don’t.
The following was copied from UL description of ASTM-E119
Significance and Use
These test methods are intended to evaluate the duration for which the types of building elements noted in 1.1 contain a fire, retain their structural integrity, or exhibit both properties during a predetermined test exposure.
The test exposes a test specimen to a standard fire controlled to achieve specified temperatures throughout a specified time period. When required, the fire exposure is followed by the application of a specified standard fire hose stream applied in accordance with Practice E2226. The test provides a relative measure of the fire-test-response of comparable building elements under these fire exposure conditions. The exposure is not representative of all fire conditions because conditions vary with changes in the amount, nature and distribution of fire loading, ventilation, compartment size and configuration, and heat sink characteristics of the compartment. Variation from the test conditions or test specimen construction, such as size, materials, method of assembly, also affects the fire-test-response. For these reasons, evaluation of the variation is required for application to construction in the field.