The part number D-4400-8350 is a Johnson Controls D-4400 Series Pneumatic Damper Actuator. It is a reverse-acting actuator with a spring range of 21–103 kPa (3–15 psig), a supply pressure of 138–172 kPa (20–25 psig), a force output of 73–138 N (16–31 lbf), and a 70 mm (2.75") stroke.

Specification & Description of D-4400-8350

• Manufacturer/Brand: Johnson Controls
• Series: D-4400 Pneumatic Piston Actuators
• Type: Linear pneumatic damper actuator, reverse acting
• Spring Range: 21–103 kPa (3–15 psig)
• Supply Pressure: 138–172 kPa (20–25 psig)
• Force Output: 73–138 N (16–31 lbf)
• Stroke Length: 70 mm (2.75")
• Fail Position: Spring return ensures safe positioning during loss of air supply
• Construction:
  • Die-cast aluminum housing for durability
  • Stainless steel shaft for corrosion resistance
  • Synthetic elastomer diaphragm for long service life
  • Fully enclosed housing protects internal components from dirt and damage
• Operation:
  • Air pressure applied to the diaphragm moves the piston and shaft against spring force.
  • Reverse acting means the actuator moves in the opposite direction compared to direct-acting models (like the D-4300 series).
  • Provides precise damper positioning in HVAC systems.