Spotlight on Innovation: 5.5mm Air Bleed Orifice

Published On: December 1st, 2020
5.5mm Air Bleed Orifice

DenisDePloeg introduces the newest solution by The Lee Company for removing trapped air within a hydraulic system with our 5.5mm Air Bleed Orifice. Trapped air in hydraulic systems can cause issues with performance as air is compressible, whereas hydraulic fluid is not. Trapped air causes slower system reaction times or a “spongy feel”. The traditional way to remove trapped air from a hydraulic system has been to drill a hole, approximately Ø 0.5 mm, in the manifold allowing this air to escape back to the sump, eliminating its effect on system performance. This drilled hole also allows hydraulic fluid to flow out of the system, resulting in significant hydraulic loss, inefficient system performance, and wasted energy. In today’s environment, technology is pushing for higher system efficiencies, reduced weight and size, and increases in system pressures, which only makes reducing these system losses more critical.

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The new Air Bleed Orifice is a novel solution to removing trapped air while keeping hydraulic losses to a minimum. Utilizing a small precision flow orifice, this new Air Bleed Orifice allows trapped air to escape but is small enough to restrict most hydraulic flow, minimizing system losses. The Air Bleed Orifice also features an integrated safety screen for contamination protection. Using Lee’s Air Bleed Orifice enables system designers to optimize system component sizing, leading to improved efficiencies, reduced weight, and lower costs.

5.5mm Air Bleed Orifice - Hydraulic System's Reaction time


  • Small Precision Orifice – Removes trapped air while minimizing system losses
  • Self-Retained Design
  • Rated to 21 MPa
  • 100% Flow Tested
  • Integral Safety Screen


  • Removes trapped air in hydraulic systems
  • Automotive, Off-Road and Industrial Hydraulic Systems