Pressure Relief HD 3530-18X18 past 12 months back blades parallel to the

back blades parallel to the shortest dimension Extruded aluminum surface mount frame with signature line marks Provides 4-way air flow on one plane Nylon bushings on adj

Options * MAR - Mounting Angle Ring (sold in pairs - 2 needed

080") Aluminum Construction 1/8" GA (

Opposed Blade Damper standard on 4" widths

52h * Interlocking steel roll-formed blade (3) with roll-formed frames (1) * Blade lock (5) * Damper manufactured from corrosion tested galvanized mild steel (G-90) * Self locking corner (4) * 165° replaceable fusible link (2) h3

Pressure Relief HD 3530-18X18 past 12 months back blades parallel to theh3. Standard Features * 3510 Vertical mount * 3520 Horizontal mount air up * 3530 Horizontal mount air down * Designed to open with negative or positive pressures for intake or exhaust air * Felt edge blades to hold noise to a minimum * Aluminum construction * Blade to blade linkage * 1 4" pivot pins in nylon busings * Maximum size 24 x 24 * Mill finish h3. Options * Sleeve variations * Mounting flange * Adjustable counter balance to adjust various