Section 5: Equipment
Anchor: #i1022354Model 85 Spray Unit (GSD Issue)
The Model 85, which was initially produced within the General Services Division shops in 1985, is the spray unit predominantly used today.
The Model 85 Spray Unit uses an electrically activated spray head called a Flex-Five spray head to spray wide areas of the right of way.
As shown in Figure 3-11, the Flex-Five spray head consists of five independently operated nozzle groups.
Figure 3-11. Flex-5 Spray Head configuration.
Nozzle Group 2 includes two 6520G nozzles. Nozzle Group 3 has one 2520G nozzle. Nozzle Group 4 includes one 2520G nozzle and two 1520G nozzles. Nozzle Groups 5 and 6 both include three 0020 nozzles.
Example of nozzle sizes: Nozzle number 6520 directs the spray pattern at a 65 degree angle and distributes two gallons of solution per minute.
The spray pattern adjusts vertically through an electric cylinder operated from the control panel in the vehicle. This adjustment permits the applicator to maintain a constant spray width even on sloping terrain. Although wind affects all spray patterns, the flex-five spray head is designed to be able to spray wide areas (approximately 36-40 feet), as seen in Figure 3-12.
Figure 3-12. Flex-5 spray patterns
Figure 3-13. Flex-5 spray head.
As seen in Figure 3-14, this unit is distinguished by a spray head system that includes a 50-mesh in-line filter, followed by the main pressure gauge and a series of six in-line electric solenoids. On the downstream side of each of the electric solenoids are flow regulators and pressure gauges.
At the downstream side of the last in-line electric solenoid is the by-pass pressure regulator which permits return of excess fluid to the main tank during spraying operations.
Figure 3-14. Model 85 (Original) spray head valving.
Figure 3-15. Flex-5 spray head in operation.
As illustrated in Figure 3-16, the main difference between the modified Model ’85 unit and the original unit is that the solenoids and flow regulators have been switched. This helps with the repair and replacement of the solenoids, which need to be checked on a regular basis. Also on the modified Model ’85 unit, the return hose and pressure relief valve have been eliminated.
Figure 3-16. Model 85 (modified) spray head configuration.
Anchor: #i1022431Fixture Operations
The fixture operation does not use an electrically or hydraulically operated boom system, but includes an arrangement of nozzles for spraying:
- outside the guardrails
- under guardrails
- inside, middle and edge of pavement on right or left hand sides of the vehicle.
These units were fabricated within the General Services Division shops.
As seen in Figure 3-17, the fixture spray operation is capable of spraying with the inside, middle, edge and outside nozzle, depending on need. Use an 8008 nozzle for both the inside and middle, a 6508 nozzle for edge work, two OC08s for guardrail work, and a 6508 and 2508 for outside spraying around shoulders, guardrails, delineators, signs, etc.
The fixture nozzles are not used to spray wide areas of the right of way.
Spray pressures should be set on 35 psi to ensure proper operation of the diaphragm check valves. See Figure 3-19, below.
Figure 3-17. Fixture operations.
Figure 3-18. Flex-5 spray head in operation.
Figure 3-19. Fixture boom nozzles.
Anchor: #i1022491Turbodrop Nozzles
Turbodrop nozzles are an optional nozzle type that replace the edge 6508 and the two 8008s below and are used for the edge of pavement, inside and middle nozzle positions. When installed, driving speed can be increased from five mph to 10 mph, cutting application time in half. Calibration for these nozzles is the same except speed should be calculated at 10 mph instead of five mph. These nozzles cannot be ordered at this time through TxDOT warehouses, but must be ordered from outside distributors. Please call the Vegetation Management Section for details concerning these nozzles.
Anchor: #i1022501Wick Applicator
Rope-wicks are generally used for thin stands of undesirable vegetation. When an undesirable stand of vegetation exceeds 35 percent of the ground surface, use the overspray operations of the herbicide spray unit. Before using the rope-wick, check to make sure all of the ropes are wetting. Check possible sources of obstructions in the lines from tank to rope. The ropes used on the rope-wick should be polyester over acrylic.
The herbicide mixture rate is two parts water to one part Roundup Pro. For tougher to control weed species, a mixture rate of one part water to one part Roundup Pro may be used.
CAUTION: Do not wipe desirable vegetation.
Figure 3-20. Wick applicator.