It is best to have two seperate sprayers, one for herbicides and one for insecticides. If this is not possible, you will need to triple rinse the entire sprayer, tubing, tank etc after each and every use. Never leave mixed solution in your sprayer, as this can cause damage to your equiptment.
The extra wand length on the B&G Sprayer 1 Gallon 18 in. Wand (N124-S-18) vs the 9 inch wand would just make applications easier by you not having to bend down as far to apply products. The 18 inch is generally the more popular sprayer for this reason.
The B&G Sprayer 1 Gallon 18 in Wand (N124-S-18) would be great for indoor and outdoor perimeter use for general pest control. To reach the height of 30 feet, you would want to use the Chapin Slide Pump Sprayer which will reach up to 30 ft.
Unfortunately, the B&G Sprayer 1 Gallon 18 in. Wand (N124-S-18) does come with a pressure relief valve. It is located in the actual wand itself.
The B&G Sprayer 1 Gallon 18 in. Wand (N124-S-18) should be triple rinsed after use and the wand flushed with just water to ensure any residual product is removed and allowed to dry before storing. Be sure to keep out of freezing temperatures so that the brass wand is not damaged.
There is some assembly required when you receive the B&G Sprayer 1 Gallon 18 in. Wand (N124-S-18). The hose and wand will need to be attached. The sprayer comes with a 4 way tip that features 2 sizes of pin-stream and 2 sizes of fan spray patterns
If you drilled the holes 12 inches apart, then you would have 10 holes over 10 feet that you are trying to fill with 4 gallons. This works out to be a little less than half a gallon per hole. To fill these I would recommend using the one gallon sprayer on a "pin stream" setting so you can force the liquid down the hole and not splash it everywhere. You could use the B&G 1 Gallon Sprayer N124-S-18. You can also use a funnel and pour the termiticide down the holes. For more information on treating for termites, please click the link below.
In order to install the line in your B&G Sprayer 1 Gallon 18 in. Wand (N124-S-18), please refer to Extenda-Ban Valve Repair and Maintenance on page 2 of the B&G product manual. If you have further questions you can reach B&G at 1-800-544-8811.
The B&G Sprayer 1 Gallon 18 in. Wand & Extenda-Ban Valve (N124-S-18) comes with a 4-way C&C tip which includes, a fine or coarse fan, pin stream, and a crack and crevice setting, along with the crack and crevice straw. They will have the same effectiveness whether larger or smaller droplets depending on the product you use. Also, their durability will be a lot longer than your Chapin Polyethylene tank sprayers as well.
The B&G 1 Gallon Sprayer + 18-inch wand - N124-S-18 will spray about 10 feet. We do carry a sprayer for reaching high areas normal sprayers will not and for treating large trees. It is called a Chapin slide pump sprayer. We do have a video that shows the sprayer in action on the Chapin Slide Pump Sprayer page. https://www.youtube.com/watch?v=1MGro7AtRpE&t=187s