HVAC Duct Connectors: Flexible Vibration Breaks for Sound Insulation.

HVAC Duct Connectors: Flexible Vibration Breaks for Sound Insulation

Problem Statement

HVAC duct connectors require materials that simultaneously dampen vibration (NVH reduction) and maintain sealing integrity under cyclic thermal stress (120°C to -40°C). Standard EPDM compounds fail due to compression set (>40% after 1,000 hours at 100°C) and ozone cracking at flex points.

Material Science Analysis

EPDM’s saturated backbone resists ozone but lacks thermal stability above 150°C. RubberQ’s HNBR compound (hydrogenated nitrile) crosslinks with peroxides, achieving:

• Higher acrylonitrile content (34-38%) for fuel/oil resistance
• Hydrogenation removes vulnerable C=C bonds, improving thermal aging
• Silica-reinforced filler system reduces compression set to <15% (ASTM D395)

Technical Specifications

Parameter	HNBR (RubberQ-7280)	Standard EPDM	FKM (Fluoroelastomer)
Shore A Hardness	70 ±5	65 ±10	75 ±3
Tensile Strength (MPa)	18.5	12.0	16.0
Elongation at Break (%)	320	400	200
Temperature Range (°C)	-45 to +175	-50 to +150	-20 to +200
Compression Set (22h @ 150°C)	12%	35%	8%
Ozone Resistance (50pphm, 20% strain)	No cracks (1,000h)	No cracks (500h)	No cracks (5,000h)

Standard Compliance

RubberQ’s IATF 16949-certified process controls:

• Batch consistency via Mooney viscosity monitoring (ASTM D1646)
• Adhesion testing per ASTM D429 (metal inserts)
• Cleanliness validation to ISO 16232 Class 8 for duct airflow

For custom material compound development or IATF 16949 documentation, consult RubberQ’s engineering department.