Overview
The Karl Dungs 46020-5 air pressure switch, also designated AA-A2-6-5, is a precision-engineered SPDT (single-pole double-throw) differential pressure switch designed for critical combustion control and HVAC applications. Built to withstand demanding industrial environments, this unit monitors pressure differential and triggers control circuits with reliability and accuracy. The device features field-adjustable setpoints and integrated test button functionality for system commissioning and troubleshooting.
Key Features
- SPDT switch with independent make/break contacts for reliable circuit control
- Field-adjustable factory setting range: 2–20″ W.C. (water column)
- Integrated test button for field verification without system shutdown
- 1/4″ NPT positive and 1/8″ NPT negative connections for standard industrial plumbing
- UL, CSA, and FM approvals for North American applications
- Rated for air and non-aggressive gases in pressure, vacuum, or differential modes
Technical Specifications
- Maximum Operating Pressure: 7 PSI (500 mbar)
- Switch Type: SPDT (Single-Pole Double-Throw)
- Factory Adjustment Range: 2–20″ W.C. (50.8–508 Pa)
- Electrical Rating (AC): 5 A resistive / 3 A inductive @ 120 Vac
- Electrical Rating (DC): Min. 20 mA @ 24 Vdc; Max. 1 A @ 48 Vdc
- Contact Material: Silver (Ag)
- Operating Temperature Range: –40°F to +140°F (–40°C to +60°C)
- Positive Connection: 1/4″ NPT male
- Negative Connection: 1/8″ NPT male
- Housing Rating: NEMA Type 4
- Approvals: UL, CSA, FM
- Current Part Number: 266936
Typical Applications
The AA-A2-6-5 excels in automatic burner control systems, furnace ignition sequencing, and air-supply interlock monitoring. It is widely deployed in:
- Forced-air furnace and boiler combustion controls
- Ventilation system pressure monitoring
- Air-conditioning unit safety interlocks
- Dual-fuel burner control systems
- Makeup air damper automation
Compatibility & Replacements
Compatible With
- 24 Vdc, 48 Vdc, and 120 Vac control circuits
- Automatic burner control systems (Honeywell, Siemens, Fireye)
- HVAC and forced-air furnace control modules
- Building management systems requiring differential pressure monitoring
- Non-aggressive gas and air applications up to 7 PSI operating pressure
Replaces / Drop-In Replacement For
- Karl Dungs 46020-5 (original designation)
- Equivalent model 217-331A (legacy part number)
- Direct upgrade path to Karl Dungs 266936 (current OEM part number)
Works With
- Standard NPT male pneumatic connections (1/4″ and 1/8″)
- DC control circuits (24 Vdc, 48 Vdc minimum switching current: 20 mA)
- AC control circuits (120 Vac, 5 A resistive / 3 A inductive rated)
- Combustion control relays and sequencers with SPDT input requirements
- Field-adjustable pressure transducers and differential pressure gauges
