3065 North American Aspirators and Gas Mixers Dependable and uniform air/fuel mixtures • • • Large range of available sizes for various applications Rugged design for long life Compact design allows for simple installat

3065 Aspirator Mixers are used to create a uniform air / fuel mixture to feed premix burner nozzles. Energy from blower air passing through the 3065 venturi creates suction, which entrains a proportional flow of gas at atmospheric (zero gauge) pressure. Multiple premix burner nozzles fed by a 3065 can be controlled by a single manual or motorized air valve. Proper air/fuel ratio is initially set by adjusting the integral V-port1 valve built into the mixer. The ratio is maintained from high fire to low by an "atmospheric regulator" (zero governor) or by cross connecting the regulator (e.g., North...

3065 Aspirator Mixer Operating Principles page 3 Aspirator (air-jet) mixers generally operate with low pressure air in the 3 to 20 osi (5 to 35"w.c.) range and use the venturi effect to pull fuel into an air stream. This creates shear between the fuel and air flows that efficiently mixes them to make uniform (high quality) premix. They are often used with a zero governor (atmospheric regulator) which controls fuel/air ratio when the air flow through the mixer is adjusted. To conform to field conditions or to get lower or higher mixture pressures (with more or less suction, respectively), 3065...

Fuel/Air Ratio Control page 4 Using a zero governor (atmospheric regulator) A zero governor (atmospheric regulator) is a ratio regulator that relies on suction from an aspirator mixer to control air/fuel ratio. It is the classic way of controlling fuel air ratio in premix combustion system as it do es not require high gas pressure supply. This is very important when gas delivery systems have limited supply pressures. Zero governors work by maintaining atmospheric pressure (zero pressure) at the regulator outlet. Increasing air flow through a mixers' venturi increases suction on gas line. To maintain...

3065 Mixers can be mounted in any position convenient to the application piping. The gas adjustment cartridge assembly can be mounted in either side of the mixer. Gas inlet is perpendicular to air line. Mixers are shipped with the valve closed and with right-hand assembly as shown. Plugged pipe taps (1/8”) are provided for pressure readings. When mounting the 3065 mixer, leave clearance for removing the cap and Allen wrench adjustment of the gas valve. The cap conceals the gas adjustment, discourages tampering with the setting, and reduces the chance of gas leaks. The gas adjustment valve is...

Materials - 3065-S Mixers - Ordering Information page 6 3065-0 through -8 mixer bodies and mixing chambers are machined from iron castings. The -7 and -8 sizes have viton gaskets on flanged connections. 3065- -S Aprirator Mixers have oversized throats for higher air capacities and mixture pressures than standard mixers. Depending on the mixer size, gas cartridge assemblies are made from brass, steel and cast iron, with seals made from viton and nitril. They are useful where: — Burner capacity do es not match a standard mixer size, e.g., certain line burner assemblies and special bore nozzles....

Sizing 3065 Mixers Instructions page 7 • For Standard 4651, 4659, and 4682 premix burners: North American 4651, 4659, and 4682 premix burners share the same capacity rating system, but not every size premix burner capacity is available for every burner nozzle type, or suitable to operate at every pressure on the tables sizing tables. Consult the individual burner bulletin and sheets for details and operating stability range. — Use Table 1 to size a 3065 mixer for a single North American premix burner with zero governor control. — Use Table 2 to size a 3065 mixer for multiple North American premix...

Table 1 is used to size a single 3065 for any North American 4651, 4659, or 4682 premix burner, which all share the same capacity rating system. Mixer/burner recommendations in Table 1 maintain the required relationship between the mixer orifice size and burner port size for use with zero governor ratio control. To use this table, find burner size in the third column from the left, then read across to the mixer designation that appears to the left that matches the fuel being used. page 8 Aspirator Mixer for %" Premix Pilot Tips: The premix capacity of %" 4021 and 4027 premix pilot tips is similar...

Table 2 lists proper selection if several burners are fed from a single 3065 mixer. Burner capacity and number of premix burners (4651, 4659, or 4682) determine mixer selection. Mixer/burner recommendations in Table 2 maintain the required relationship between the mixer orifice size and burner port size for use with zero governor ratio control. Flow distribution and pressure drops should be considered carefully when designing the mixture manifold. To use this table, find burner size in left-hand column, then read across to the mixer designation that appears under the number of burners to be fed....

Sizing 3065 Aspirator Mixers - Chart 1A page 10 Chart 1A. Air Capacities for Selected Small North American 3065 Aspirator Mixers vs. Pressure Drop Across Mixer ("wc) (Differential Pressure) (see Table 3 for Data on all 3065 sizes) (for Btu/h, multiply by 100) See Table 3 for more 3065 mixers sizes Pressure Drop Across Mixer (Air Pressure - Mixer Pressure), "w.c. Flow through 3065 mixers is nearly proportional to throat area, so the capacity of an unlisted mixer-rod combination can be determined by comparing its net throat area with that of a closest known model.

Sizing 3065 Aspirator Mixers - Chart 1B page 11 Chart 1B. Air Capacities for Selected Large North American 3065 Aspirator Mixers vs. Pressure Drop Across Mixer ("wc) (Differential Pressure) (see Table 3 for Data on all 3065 sizes) (for Btu/h multiply by 100) See Table 3 for more 3065 mixers sizes Pressure Drop Across Mixer (Air Pressure - Mixer Pressure), "w.c. Flow through 3065 mixers is nearly proportional to throat area, so the capacity of an unlisted mixer-rod combination can be determined by comparing its net throat area with that of a closest known model.