7218 and 7219A REGULATORS accurately maintain a constant air/gas ratio over a wide range of firing rates in both nozzle-mix and premix gas burner systems. Molded diaphragms ensure excellent tracking, repeatability, maximum flows, and superior turndown.
NOZZLE-MIX BURNERS
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 flow remains proportional to air flow at all firing rates. One regulator can be used for several burners controlled by the same air valve, but often it is better to have a separate regulator for each burner. Dual-Fuel Burners. When a dual-fuel burner’s atomizing air is left on during gas operation, the 7218 Regulator can be set to compensate for the extra air over the controlled main air by adjusting the spring for up to 1 osi “leak” with no impulse pressure.
PREMIX BURNERS
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 firing rates. (See Instructions 7218-2.) A separate regulator for each mixer is preferred to avoid interference or interaction.
7219A 7219A Regulators are modified 7218 Regulators (7218 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 field
7218 Regulators have soft seat for low flow control.
SPECIFICATIONS
Diaphragm Cover and Case: Aluminum
Body: Cast Iron
Seat: SST
Shaft: SST
Balancing Diaphragm: BUNA/Nylon (Standard) FKM/Polyester (7218-V)
Gas Diaphragm: BUNA/Nylon (Standard) FKM/Nomex (7218-V)
Maximum Inlet Pressure: 2 psi
Maximum Shock Load: 5 ps
TKLD –
Good