Bulletin 8699 Page 2
INSTALLATION Gas flow is controlled into the manifold by:
CONSTRUCTION In ½ " through 2" pipe sizes, Balancing Orifices are threaded unions. 2 ½ ", 3" and 4" pipe sizes are flanged unions. Threaded 8699 units are specially machined malleable iron unions with jig-drilled stainless steel orifice plate and rubber gasket. An 8699 cast iron flange union has a bored, tabbed stainless orifice plate and two gaskets and hardware. Accuracy is 5% in all standard Balancing Orifices. Special drillings are available at extra cost, but accuracy cannot be guaranteed when quantity required is 10 or less.
1. a single limiting orifice valve downstream of a cross-con- nected ratio egulator, or
2. a manual or motorized adjustable port or other type of gas control valve, or
3. a cross-connected regulator with a controlled impulse,usually via a manual or motorized bleed arrange- ment. Figure 2 shows system #1 above: The limiting orifice valve is set for desired air/fuel ratio. All burners get the same cfh of gas because pressure drops through downstream pipe, fittings, cocks, etc. are insignificant relative to the drop across each individual Balancing Orifice. For best results, install the 8699 unit in a straight run with at least 5 pipe diameters upstream, 2 diameters downstream of any valve or fitting.
RATINGS
max. pressure: 50 psi max. temperature:
250°F standard, 750°F with special construction
furnace, oven, or kiln
gas burner
zone air control valve
Balancing Orifi ces
zone air metering orifi ce (optional)
limiting orifice valve (adjustable)
zone gas metering orifice (optional)
gas manifold
turbo blower
gas supply
air/gas ratio regulator (cross-connected)
Figure 2. A properly sized Balancing Orifice in each burner's gas line assures an equal flow to every burner off the manifold, despite uneven pipe lengths and/or inconsistent welding or pipe- fitting practice. (Note: Schematic dœs not show all items required in air and gas pipes.)
The 8699-01 ( ½ ") Balancing Orifice has a third standard drilling: 0.073", which is used in the cross connection line of a bled-impulse control system; it is too small for use as a balancing orifice.
DIMENSIONS SHOWN ARE SUBJECT TO CHANGE. PLEASE OBTAIN CERTIFIED PRINTS FROM FIVES NORTH AMERICAN COMBUSTION, INC. IF SPACE LIMITATIONS OR OTHER CONSIDERATIONS MAKE EXACT DIMENSION(S) CRITICAL .
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