The first anti-icing run of the year is a bad time to find out the truck is laying down half the rate it did last winter. Brine crystallizes in tips over summer, a rebuilt boom ends up on different spacing, and the new driver runs 30 mph where the old one ran 20. Sizing the tips takes ten minutes in October. Here's the method for TeeJet SJ3 StreamJet tips — or put your numbers into the Liquid Deicer Nozzle Selector and it will size them from what we have on the shelf.
1. Why streams, not fans
A flat-fan tip atomizes brine into droplets small enough to blow off the road, coat the truck, and land on the car behind you. The SJ3 puts the liquid down in three solid streams. Nothing atomizes, so nothing drifts, and the striped pattern leaves bare pavement between the stripes for traction while the brine spreads under traffic. Most agency specs call for streaming tips for exactly this reason. The SJ3 is an acetal body with a color-coded size, 20–60 psi working range, and it takes a standard quick-attach cap.
2. Lane-miles to GPM per tip
Road crews work in gallons per lane-mile; the tip only understands gallons per minute. The conversion:
GPM per tip = (gal per lane-mile × MPH × tip spacing in inches) ÷ (720 × lane width in feet)
Example: 40 gal/lane-mile at 25 mph, tips on 12-inch spacing, 12-foot lane = (40 × 25 × 12) ÷ (720 × 12) = 1.39 GPM per tip. The whole boom over one lane is putting out about 16.7 GPM at that speed, which is worth knowing for the pump.
For parking lots and walkways rated in gallons per 1,000 sq ft: GPM per tip = (rate × MPH × spacing × 88) ÷ 12,000. A 0.75 gal/1,000 sq ft pass at 8 mph on 12-inch spacing is 0.53 GPM per tip.
3. Correct for the weight of the brine
SJ3 charts are for water. 23% salt brine weighs about 9.8 lb/gal, 30% magnesium chloride 10.8, 32% calcium chloride 11.1, 50% potassium acetate 10.7. Heavier liquid flows slower through the same tip, so multiply your product GPM by √(lb/gal ÷ 8.34) to get the water-equivalent number you look up on the chart. For salt brine the factor is 1.08; our 1.39 GPM of brine needs a tip that flows 1.51 GPM of water. Skip this and salt brine runs about 8% light; calcium chloride runs about 13% light.
4. Pick the size and pressure
An SJ3's number is its water flow at 40 psi in tenths of a GPM, and flow scales with the square root of pressure. For 1.51 GPM the SJ3-15 (light green) lands right at 40 psi — the middle of its range, which leaves room in both directions. An SJ3-20 (black) would do it at about 23 psi, low enough that the streams start to droop. The sizes we stock and their flow at 40 psi:
- SJ3-02 yellow — 0.20 GPM
- SJ3-03 blue — 0.30
- SJ3-04 red — 0.40
- SJ3-05 brown — 0.50
- SJ3-06 gray — 0.60
- SJ3-08 white — 0.80
- SJ3-10 light blue — 1.00
- SJ3-15 light green — 1.50
- SJ3-20 black — 2.00
Each size holds a given rate over roughly a 1.7× speed range (20 to 60 psi) with a rate controller. The selector prints that speed window for each size at your rate so you can see whether one tip covers the route.
5. If the route runs 15 mph in town and 40 on the highway
No fixed tip covers a 2.7× speed swing. Either run two tip sizes with a section valve, or fit SJ3-VR variable-rate caps: the orifice opens as pressure rises (30–80 psi), so one size holds the rate across two to three times the speed range of a fixed SJ3. The selector shows the VR option next to the fixed sizes when it applies.
6. Strainers, caps, and the pre-season checklist
- Strainers: SJ3-015 takes a 100 mesh tip strainer; SJ3-02 through 06 take 50 mesh; SJ3-08 and up run without one. Brine crystals are the number-one cause of a dead stream.
- Caps: use the color-matched quick-attach cap (CP114442A series) so the size is visible from the ground. Mixed caps are how a #10 ends up in a row of #15s.
- Flush and inspect: pull every tip, soak in warm water, blow through, and hold each up to the light. Replace any with a chipped orifice; a damaged stream throws a fan and defeats the point.
- Catch test: at working pressure, catch one tip for 30 seconds and compare to the corrected target. Three or four across the boom. A whole boom running light usually means the brine is heavier than you assumed — check it with a hydrometer. One tip light is a strainer.
- Pump and pressure: confirm the pump can deliver the whole-boom GPM at 40 psi with headroom. A pump that made 40 psi last year with worn #10s may not with fresh #15s.
We stock the full SJ3 range, VR caps, strainers and quick-attach caps, and we set up deicing booms for county crews, contractors and facilities across the Inland Northwest. Run the Liquid Deicer Nozzle Selector, or call (509) 838-2209 with your truck, lane width and target rate.
Spray Center Electronics is an authorized TeeJet dealer in Spokane, WA. Application rates are typical anti-icing ranges; follow your agency's guidance and the product's data sheet. Solution weights vary with concentration and temperature — calibrate before the season.