Karl Dungs FRG Ratio Regulator and Zero Governor

Karl Dungs FRG Ratio Regulator and Zero Governor

  • Max. Operating pressure: 7 PSI / 5 PSI
  • Nominal diameter: NPT 1/2 – NPT3
  • Optional Low fire bypass for 1/2 in. NPT to 2 in. NPT models
  • Connection for air impulse line
  • Inlet and outlet 1/4 in. NPT test ports on each side
  • Factory installed vent limiter
  • Approvals: ANSI Z21.18 / CSA 6.3


The FRG ratio regulator/zero governor has an adjustable setpoint spring and nonadjustable counterspring. The FRG is recommended for industrial and commercial heating applications. It is suitable for dry natural gas, propane, butane, air and inert gases. Suitable for up to 0.1% by volume, dry H2S.

Application for Ratio Regulator:
Holds a constant gas/air ratio during turndown by varying gas flow to the burner in proportion to combustion air flow. Adjustable ratio for excess gas or air operation.

Application for Zero Governor:
Controls fuel by reducing incoming gas pressure to zero or adjustable to slightly above or below atmospheric pressure.

Technical Documentation

FRG Ratio Regulator and Zero Governor Technical Documentation