Series AS-MB Micro Bubble Air Separator

Eliminate all that Banging and Hammering!

Hydronic heating systems can sometimes be objectionably noisy. Trapped air and bubbles are often the cause, even when the system is operating normally. Say goodbye to all the noise with the Series AS-MB Micro Bubble Air Separator. Fully serviceable and easily installed, the patent-pending Series AS-MB has the high capacity and high temperature rating to quiet the heaviest hydronic vocalizing.


  • Requires no minimum inlet/outlet piping length for proper operation
  • Coalescing media withstands petroleum based cleaners, glycol antifreeze and temperatures up to 240° F (116°C)
  • Air vent assembly is ideal for use with glycol systems or as an anti-vacuum device
  • Fully serviceable - can be disassembled for inspection and cleaning

Pressure – Temperature

  • Maximum Working Pressure: 150psi (10.3 bar)
  • Maximum Operating Temperature: 240°F (116°C)


  • Body: Brass

Cv Ratings

  • ¾ in. (20mm) = 12.5 GPM
  • 1 in. (25mm) = 14.5 GPM
  • 1¼ in. (32mm) thread and flange = 19.0 GPM
  • Durable forged brass body construction in flanged, ¾ in., 1 in. and 1¼ in. FPT sizes
  • Rugged, corrosion-resistant polyphenylsulfone coalescing media
  • DuoVent Air vent assembly has a high capacity and high temperature rating
  • ½ in. FPT bottom tapping for use with Series RBFF Residential Boiler Fill Fitting
  • AS-MB FL flanged model can be used with Series PIPF Isolation Pump Flanges with Purge Port & Swivel Flange to create a compact purge/air elimination module (can also be used with standard circulator flanges)

Speedy Water; Noisy Air

Hydronic heating systems use circulators that whip water around pretty quickly, in and out of a normal size room in just seconds. And with that water there is also air. Noisy air. The air is in solution when cold water is introduced to the system. It comes out of solution when the water is heated, sometimes getting trapped at the far ends where it stops the flow of heat entirely.

Slow and Release

Catching that air before it has a chance to get out into the system is where the Series AS-MB Micro Bubble Air Separator comes in. The AS-MB’s DuoVent Air vent assembly slows the air-laden water just enough to release the air bubbles and the coalescing media captures the bubbles and automatically vents the air out of the system.

An Air Separator that’s Easy to Install

Our patent-pending Series AS-MB is a unique product that will be of interest to all heating professionals who install and service residential and light commercial hydronic heating systems. As the trend in newer installations is for smaller boilers in smaller spaces, we’ve created an air separator product that allows the installer to follow the manufacturer’s guidelines for correct boiler piping.

The AS-MB is properly installed on the boiler supply header in a vertical position with the vents facing up. The DuoVent Air vent assembly can be unscrewed and removed for easy servicing. The ½ in. (15mm) bottom tapping allows for direct connection to an expansion tank if desired. No minimum inlet/outlet piping length is required for proper operation.

A separate Model AS-MB FL is equipped with flanged inlet and outlet connections. This model’s fixed inlet flange is intended for use with our Series PIPF Isolation Pump Flange to create a compact system purge/air separation module.



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