Mixer Installation - 8666 TESTIPS
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 perpendic- ular 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 not designed for tight shut off, use a suitable shut off valve upstream of the 3065 gas inlet.
When using a cross-connected regulator an impulse line can be taken off the tap provided on the 3065 mixer or use a tap location in a straight section of air piping. Taps in piping should come off from the side or top of a pipe to prevent condensate or dirt from entering it. Small impulse lines are easily plugged by dirt. Avoid sharp edges and abrupt changes of flow direction. Any burrs or nipples projecting into the pipe cause the air in the pipe will increase velocity. Any change in velocity gives a false pressure reading. Avoid dips in the impulse lines where condensed water could collect. If possible pitch impulse lines so water will run back to the air line and not to the regulator, where it could collect on the diaphragm and "fool" the regulator. Leave the connection at the regulator end of an impulse line till last; and blow out the impulse line from the regulator end until you can feel air coming through the tapped pipe. 8666 TESTIPS Flames often are not easily visible when sealed-in nozzles are used. An 8666 Testip facilitates setting desired air/fuel mixture. The Testip is installed in mixture line per diagram below; it is lit with a manual torch after main flame has been lit. Air/gas ratio is adjusted in the mixer until Testip flame seems appropriate: — A purple tinge indicates lean ratio. — A greenish-blue inner cone denotes a rich flame. — Compare testip flame with correct burner ratio setting. Testips are turned off after ratio setting has been set. They should be removed (and the hole plugged) when not in use. Do not use an 8666 Testip for final settings with mixers smaller than 1 ½ ", its capacity would represent too high a percentage of total capacity to allow accurate main flame settings. Use extra caution with 8666 Testips outdoors, the flame can be difficult to see in direct sunlight.
L.H.
R.H.
L.H.
R.H.
Gas Cartridge Assembly (self-contained) Turn gas adjustment plug clockwise to decrease gas
Right-hand assembly of cartridge furnished unless otherwise speci fi ed
Remove packing cap to make gas adjustment
Figure 4. Gas Cartridge detail of 3065 Aspirator Mixer
Installing elbows directly at the outlet of a 3065 mixer or using a short nipple between the 3065 mixer and burner can cause combustion instability, or require narrowly held air/fuel ratio settings. It can require the mixture pressure to be held lower than desired to avoid flame lift-off, and nuisance outages of flame supervisory devices. To help avoid these problems install straight unobstructed pipe with a minimum length of 5 L/D between the mixer and pre-mix burner nozzle. If space is limited, then mixer can be connected to the burner with two long nipples and an elbow (see sketch). Allow at least 4 pipe diameters on each side of the elbow. For additional information see: Handbook Supplement 14 "Straight Pipe Run Requirements".
Allow 6" minimum flame clearance
1⁄8 NPT
5 L/D (Min)
Burner
Mixer
5⁄8
4 11⁄16 "
Burner
5 L/D (Min)
Burner
Mixer
Burner
4 L/D (Min)
5 pipe dia.
5 pipe dia.
Figure 5. Minimum recommended straight pipe runs
Bulletin 3065 page 5
Figure 6. 8666 Testip
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