Pressure Washer Chemical Injectors
Chemical Injector
Chemical Injector DN10 Bypass Kit
3-Way Soap Tee
Soap Filter
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How to Choose the Right Pressure Washer Chemical Injector
GPM is the first variable. The injector's orifice has to match your pump's flow or you won't get suction, no matter what tip you put on the wand. After that, you're picking between the standalone injector and the full bypass kit. And the chemical you're running matters, because some chemicals are fine for downstream injection and some will chew through brass and seals in a few months.
Match the orifice to your GPM
A downstream injector works on vacuum. Water moves past the orifice, pressure drops, and that drop is what pulls chemical up the draw line. Too small an orifice for your GPM and you choke flow. Too big and there's not enough velocity to make vacuum at all, so the chemical just sits in the jug. Sizing runs 1.8 mm for 2 to 3 GPM machines, 2.1 mm for 3 to 5 GPM, and 2.3 mm for 5 to 8 GPM. When in doubt, go smaller. A slightly undersized injector still pulls, just slower.
Standalone injector or full bypass kit
The $15 standalone injector pulls chemical when you have a low-pressure soap tip on, and stops when you swap to high pressure. That's it. The DN10 Bypass Kit is the same injector built into a stainless ball valve, stainless tees, and an 18-inch KobraJet hose rated to 4,000 PSI. The valve lets you shut off chemical draw without walking back to the gun to change tips. On long jobs with a lot of soap-and-rinse cycles, the kit gives you back real minutes.
What you're running through it
Surfactants, degreasers, and SH cut to house-wash strength all run fine through a downstream injector. Push undiluted 12.5% SH through one every day and you're replacing it inside a few months. The brass body and standard seals weren't built for that workload. If soft wash is your main service, skip the downstream injector and run a dedicated 12V or air pump with a proportioner. Different chemistry, different equipment.
Pressure Washer Chemical Injector Sizing Chart
| Pressure washer GPM | Injector orifice size |
|---|---|
| 2 to 3 GPM | 1.8 mm |
| 3 to 5 GPM | 2.1 mm |
| 5 to 8 GPM | 2.3 mm |
Related Categories
- Pressure Washer Accessories
- Pressure Washer Nozzles
- Pressure Washer Hose
- Pressure Washer Guns
- Soft Wash Proportioners
Frequently Asked Questions
How does a pressure washer chemical injector work?
It installs between your pump and your hose. When the wand has a low-pressure soap tip on, pressure drops at the injector and that drop creates suction. The suction pulls chemical from a jug through a 1/4-inch draw line and mixes it into your flow. Swap to a high-pressure tip and the suction quits. You're back to rinsing with plain water.
What size chemical injector do I need?
Match the orifice to your machine's GPM. 1.8 mm for 2 to 3 GPM. 2.1 mm for 3 to 5. 2.3 mm for 5 to 8. If you don't know your GPM off the top of your head, it's on the spec plate on the pump. Between sizes, pick the smaller orifice. A slightly small one pulls slower than ideal but still works. A slightly big one usually does nothing.
Can I run SH through a pressure washer chemical injector?
Diluted SH, fine. Full-strength 12.5% SH every day, no. These injectors are brass with standard seals. A 50/50 SH mix for occasional house washes won't bother them. But daily SH at strength chews through seals in a few months and you're shopping for a new one. If soft washing is your main service, use a 12V or air pump with a proportioner.
What's the difference between the standalone injector and the DN10 bypass kit?
The standalone injector pulls chemical anytime your tip lets vacuum form. That's all it does. The DN10 Bypass Kit puts the same injector inside a stainless ball valve, stainless tees, and a 4,000 PSI KobraJet hose. The valve shuts off chemical draw without you having to swap tips at the gun. If your jobs cycle between soaping and rinsing all day, the kit adds up to real time saved.
Why isn't my chemical injector pulling soap?
Almost always one of three things. Wrong tip on the wand, so the vacuum never forms. A clogged soap filter, or no filter at all and debris in the draw line. Or the orifice doesn't match your GPM. Check the tip first, then the filter, then the orifice. That sequence catches it about nine times out of ten.
Do I need a soap filter on my chemical injector?
Yes. A $4 soap filter at the end of your draw line catches debris, plastic flakes, and tank sediment before any of it reaches the injector. Once an injector clogs internally, replacing it is usually easier than trying to clear it. For four bucks, the filter is the cheapest insurance on the rig.
