6. Apparatus
6.1 The description of apparatus in this section is general in
nature and any arrangement of equipment capable of performing
the test procedure within the allowable tolerances is
permitted.
6.2 Major Components (Fig. 1):
6.2.1 Test Chamber — A test chamber or box with an opening,
a removable mounting panel, or one open side in which or
against which the specimen is installed and sealed. At least one
static pressure tap shall be provided to measure the chamber
pressure, and shall be so located that the reading is unaffected
by the velocity of the air supply to or from the chamber. The air
supply opening into the chamber shall be arranged so that the
air does not impinge directly on the test specimen with any
significant velocity. A means of access into the chamber may
be provided to facilitate adjustments and observations after the
specimen has been installed.
6.2.2 Air System — A controllable blower, compressed air
supply, exhaust system, or reversible blower designed to
provide the required maximum air-pressure difference across
the specimen. The system must provide essentially constant
airflow at a fixed pressure for the required test period.
6.2.3 Pressure - Measuring Apparatus — Adevice to measure
the test pressure difference within a tolerance of 62 % or 62.5
Pa (60.01 in. of water column), whichever is greater.
6.2.4 Water - Spray System — The water - spray system shall
deliver water uniformly against the exterior surface of the test
specimen at a minimum rate of 3.4 L/m2·min (5.0 U.S.
gal/ft2·h).
6.2.4.1 The water-spray system shall have nozzles spaced
on a uniform grid, located at a uniform distance from the test
specimen, and shall be adjustable to provide the specified
quantity of water in such a manner as to wet all of the test
specimen uniformly and to wet those areas vulnerable to water
penetration. If additional nozzles are required to provide
uniformity of water spray at the edge of the test specimen, they
shall be equally spaced around the entire spray grid.