for capacities at various pressure drops
(For capacities at other drops, use square root law or
Table 2 below.)
MAXIMUM WIDE OPEN
with 2 osi drop through regulator
and 2 psig inlet pressure
To size a regulator, determine required cfh of gas and pressure
drop available at high fi re. Divide required cfh by Table 2 Factor
for available pressure drop. Select smallest regulator with Table
1 (2 osi) capacity above this adjusted capacity. Never choose a
regulator capacity based on more than 16 osi drop (even if more
7218/7219A AIR/GAS RATIO REGULATORS
When used with nozzle-mix burners, the vent of a 7218 Regulator
is cross-connected to the main air line downstream of the control
valve. Regulator outlet pressure then equals air impulse pressure,
and gas fl ow remains proportional to air fl ow at all fi ring rates.
One regulator can be used for several burners controlled by the
same air valve, but oft en it is better to have a separate regulator
for each burner.
Dual-Fuel Burners. When a dual-fuel burners atomizing air is left
on during gas operation, the 7218 Regulator can be set to com-
pensate for the extra air over the controlled main air by adjust-
ing the spring for up to 1 osi "leak" with no impulse pressure.
With its vent open to atmosphere, a 7218 Regulator can be used
as an atmospheric regulator (zero governor) to supply gas to an
aspirator mixer feeding premix burners.
If burner nozzles are sealed-in and furnace pressure is other
than atmospheric, regulator vent must be connected to the
combustion chamber. Controlled gas pressure then will match
furnace pressure; this is necessary to maintain the same air/gas
ratio at all fi ring rates. (See Instructions 7218-2.)
A separate regulator for each mixer is preferred to avoid
interference or interaction.
are modifi ed
regulators have internal pressure sensing), with provision for
remote downstream pressure sensing. The 7219A is used to sense
downstream pressure at a point closer to burner or mixer. The
downstream pressure sensing connection is made in the fi eld.
7218 and 7219A Regulators
accurately maintain a constant air/
gas ratio over a wide range of fi ring rates in both nozzle-mix
and premix gas burner systems. Molded diaphragms ensure
excellent tracking, repeatability, maximum fl ows, and superior
Product Overview | Gas Ratio Regulators
Diaphragm Cover and Case:
Maximum Inlet/Outlet Pressure:
5 psi (resulting in internal parts damage)
Maximum Ambient Temperature: