Field King Backpack Sprayer

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Editor’s Conclusion
Lawns, gardens, and farms have two natural enemies: weeds and pests. Having a backpack sprayer will enable even a home gardener to apply herbicides, insecticides, and fertilizer with ease and will even come in handy doing other functions around the home and yard. The Field King 190328 unit is a $75 pump type unit with a poly application wand is designed with home gardeners in mind, while the 190348 with a stainless wand is made for professionals for $15 more.

The most popular backpack sprayer is the four-gallon model, the industry standard, which weighs nearly 50 lbs. when full. Worn like a backpack, this sprayer is ergonomic as you can spread the weight between your shoulders, which is less tedious than carrying a tank or even pulling it on a cart. The shape of the unit resembles the human back.

Although there are gas and battery-powered sprayers, the most popular and cost-effective type is the pump sprayer that required that you pump the solution to build up the pressure so you can control the power of your spray. Field King offers a $170 battery-powered model that makes spraying effortless with the push of a button, but the sprayers under consideration here are the pump models.
Editor's Pros & Cons

Internal No Leak Pump design

Internal piston pump delivers up to 150 psi

Does the work of both a piston and a diaphragm backpack sprayer

Easy access pump allows changing of seals in just minutes with no tools

Premium, lockable shut off with brass components and an in-line filter

4 nozzles included: brass adjustable, 2 flat fans, and foaming nozzle. Also accepts TeeJet nozzles


Pricier than competitive models

Pump handle does not fold as advertised on 190328 which makes storage difficult

Heavy when full

Requires constant pumping to get proper pressure

Leaks can occur over time

Key Features


The housing for the Field King 190328 (and the 4-gallon other models as well) is made of molded poly plastic. Besides the chemicals to be sprayed, the tank contains internal plastic parts such as paddles activated by pump action that function as an internal agitator to mix liquid, powder, and water-soluble solutions. There is also an internal pressure chamber that helps expel the solution. To prevent chemicals from seeping out, chemical-resistant Viton seals and gaskets are used near the top cover, the bottom where the hose connects to the spray nozzle, and in the poly wand that sprays the material. On the 190348, the wand is stainless.

The handle is coated steel.

The unit weighs in at 12.6 pounds and measures 15 x 22.5 x 9.5 inches.

Notable Features

While carrying a sprayer on your back may be convenient, you want to be safe from chemical exposure. Aside from the protection offered by the seals, the unit has a one-way valve on the cover to prevent spills if the tank tips over. It also boasts a No Leak Internal Pump.

The wand has a premium, lockable shut-off with brass components and an in-line filter. Operating the unit is simple, with a trigger for easy spray. The handle helps primes the pump. The handle on the 190328 is not foldable as advertised, but the upgraded 190348 does have a foldable handle.

The spray action from the durable, 21-inch poly wand does the work of both a piston and diaphragm backpack sprayer.

The Field King may need cleaning and maintenance between uses or if the unit clogs or the seals leak. The manual that comes with the sprayer is very informative about how to fix almost any problem, and parts are readily available for replacement from the Fountainhead Group who makes it. This reliable sprayer can be kept in fine shape by the user, who can quickly change seals without tools.


The 190338 Backpack Sprayer is a diaphragm sprayer that uses a flat diaphragm held together with screws inside the housing. The type of sprayer is right for wettable powders, abrasive, or bleach solutions and allows for abrasive particles to run through the system without damaging the pump. The included pressure regulator maintains a low, continuous 25 psi, which is great for spraying herbicides and weed killers.

Where most pump sprayers can usually only pump as 60 psi. (vs. 90 psi for piston sprayers), the Field King can spray at up to 150 psi, depending on the nozzle used, and does what piston and diaphragm sprayers excel at. In general, diaphragm sprayers expel larger, more concentrated droplets of material, which is good for weed killing. Piston pumps expel smaller droplets at higher pressure, which offers better coverage at further reach. You would use lower pressure in your flower bed than for spraying trees and shrubs.

The unit comes with four nozzles to accommodate your spraying needs:

The brass adjustable nozzle is for spot spraying around flower beds; edging along fences, driveways, and walkways; killing brush such as poison ivy, poison oak, kudzu, and wild blackberry; and preparing garden beds for planting of ornamentals and vegetables.
The red high-volume fan nozzle is just right for lawn replacement. You can kill the old lawn and weeds before planting a new lawn and prepare large areas for planting ornamental and vegetable gardens.
The yellow low-volume fan nozzle is for precision spraying in confined areas such as gardens and flower beds.
The foaming nozzle is for spot spraying in flower beds, walkways, driveways, and patios, around trees and shrubs; edging along fences, driveways, and walkways; and killing brush.

The Field King sprayers also use TeeJet nozzles that fine-tune the spray pattern for both lawn and garden care according to the type of pressure desired.


When filling the sprayer, you just set it upright on the ground on the platform bottom. The opening for the chemicals is wide enough for easy filing; its built-in screen prevents debris from getting into the container. To get it to the area where you want to spray, just put it on like a backpack. Water weighs 8.34 pounds per gallon so a fully loaded unit is about 46 pounds, which makes it heavy to pick up and fling over your shoulder. Some users have suggested filling on workbench or deck rail and then backing into it and fastening the straps.


The 190328 has adjustable padded shoulder straps, waist belt, and chest cinch strap that make the unit more comfortable to use. For even more comfort, the upgraded 190348 Field King Max backpack has a deluxe padded harness with a full back pad, wide support waist belt, and chest cinch strap to keep the unit even more stable. Considering the small price differential at Amazon, the comfort alone might make it worth upgrading to the professional unit for just $15.

The handle can be adjusted for left-handed or right-handed users to make pumping convenient.


The Field King is one of many sprayer brands produced by the Fountainhead Company; Roundup, Smith, Scott, Husqvarna, and Indian are some of the others. As a result, models in the Field King line are likely to have one sold under a different brand name that does the same thing and has many of the same features. This is certainly true of the Roundup 190314 and the upgraded Roundup Pro 190413.

Other competitive brands are offered by Chapin, Oregon, Solo, Flesser, Beaugreen, and more. Offerings from Chapin and Oregon may be less expensive while offering similar features.

The Verdict

Preference goes into the brand people like and buy, but Field King backpack sprayers are the ones most purchased on Amazon, one of the biggest retailers in the world. You cannot go wrong with this brand,

While the 190328 sprayer has an MSRP of $100, Amazon’s price is $70-75, while the upgraded 190348 is $89. The features on both models are similar, but the more comfortable carrying straps and the stainless steel make the upgrade worth it.