Lawn and pest control spray guns may look like simple point-and-spray tools, but they is a lot going on inside the cover that allows it to deliver chemicals safely and efficiently. Understanding the key components will help you choose the right model, maintain it properly, and troubleshoot issues quickly.
Parts of a Lawn & Pest Control Spray Gun
Pesticide spray guns can be used for several tasks such as lawn care, tree spraying, spot spray, and even sealing concrete or spray painting. There are several different design variations to accommodate different flow rates and applications, but they all have the same essential design and function.
The primary parts of a spray gun:
- Cover/Housing
- Handle
- Trigger
- Hose Inlet
- Valve Assembly
- Wand Extension
- Nozzle Connection
Let’s break down these components in more detail and describe what they do.
1. Cover
The spray gun body is the main housing that holds everything together. It keeps everything aligned and protected while giving the gun its shape. Most lawn & pest guns use a two-piece polymer shell that’s chemical-resistant and light, with molded pockets that locate springs, pivots, and the valve body. Some types are made with aluminum housings.
2. Handle / Grip
The handle is the part of the housing where you grab the spray gun. A well-designed handle reduces hand fatigue, keeps the valve aligned, and helps you place product exactly where you want it.
3. Trigger
The trigger is your control valve. Squeezing it opens the internal valve to allow liquid to flow; releasing it shuts the flow off.
Some triggers have a locking feature that allow you to keep the trigger “on” and reduce hand fatigue. A spring is used inside the housing that forces the handle to the closed position when it is not being pulled.
4. Hose Inlet
The inlet is the port that connects the spray gun to your sprayer hose. Many guns feature a swivel inlet to prevent hose tangling. Typically available in 1/2″, 3/8″, or 1/4″ NPT threads.
Connecting a hose to your sprayer gun is simple. A hose barb fitting is inserted into the hose and held by a clamp. The hose barb fitting has male pipe thread and is screwed into the spray gun inlet. I always prefer to use Banjo barbed fittings as they seem to be more durable than other brands.
5. Valve Assembly
Inside the gun body you find the valve assembly. It is operated by the trigger. This is the heart of the spray gun. It starts and stops liquid flow and must seal tightly to prevent drips or leaks.
Internal Components of the Valve Assembly:
- Valve stem or poppet: Opens and closes the flow
- Valve seat: Provides the sealing surface
- Spring: Returns the valve to “closed” when released
- O-rings: Maintain a leak-free seal
Tip: Use seals compatible with your spray chemicals. Viton® O-rings are a common choice for herbicides and pesticides.
If you want to see how to rebuild a spray gun, take a look at this video and guide.
6. Wand Extension
The wand extension moves the discharge point away from your hand for better reach, ergonomics, and accuracy. Wand extensions come in several different lengths, 8–36″ are common but there are longer wands available.
7. Nozzle Connection
At the end of your spray wand is where the spray nozzle connects. This is where the fluid is discharged. The nozzle controls the flow rate, spray pattern, and droplet size. There are so many different types of spray nozzles we won’t cover them here but you can learn more in this beginner guide to spray nozzle types.
Optional Spray Gun Accessories
Extension wands or lances for tall shrubs, soffits, and hard-to-reach areas:
- Nozzle adapters for switching spray patterns quickly
- Strainers to filter debris
- Pressure Gauges for rate control
How the Spray Gun Pieces Work Together
Squeeze the trigger → the linkage pushes the valve stem off the seat (the valve assemble), opening a straight-through path from the hose inlet to the wand and out the nozzle. Release the trigger → the return spring drives the stem back onto the seat, sealing flow. The housing keeps everything in place.
Maintenance Tip
To keep a spray gun like the TeeJet AA30L in top condition:
- Flush with clean water after every use
- Inspect O-rings and valve seat if drips occur
- Lubricate the valve stem with chemical-resistant grease periodically
By understanding the anatomy of your spray gun, you can ensure longer service life, better performance, and more precise chemical application for your lawn and pest control needs.
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