Suttner ST-164 Dual Soap Downstream Injector
The Suttner ST-164 is the professional stainless steel dual chemical downstream injector we build into our Dual Soap Wash System, now sold on its own. It installs between your pressure washer and your gun and draws from two different soaps or chemicals. Flip one lever to switch from Step 1 to Step 2, with no moving pickup tubes, no pre-mixing, and no chemical running through your pump.
It comes as pictured, ready to install with 3/8" quick connects, a wall mounting bracket, and two braided chemical inlet lines with barbs. It's built for two-step touchless truck washing, fleet yards, detailers, and wash bays.
Why Choose the ST-164 from Image Wash?
- Two chemicals, one lever: run a two-step touchless soap like Touchless 1 & 2, or keep a soap and a wax or protectant connected at the same time
- Keeps chemicals out of your pump: downstream injection adds soap after the pump, which helps protect seals and valves
- Ready to mount and connect: 3/8" quick connects, wall bracket, and chemical inlet lines come installed
- Stainless steel construction: rated 1,000 to 5,000 PSI by Suttner and built for daily commercial use
- Setup help from people who use it: it's the same injector in every Image dual soap system, and our team will help you dial in your dilution
Specifications
| Model | Suttner ST-164 dual chemical downstream injector |
| Chemicals | Two, selected with an integrated lever |
| Water connections | 3/8" quick connects, installed |
| Chemical inlets | Two braided chemical lines with hose barbs |
| Metering | Replaceable injector nozzle; size must match your PSI and GPM |
| Operating pressure | 1,000 to 5,000 PSI (manufacturer rating) |
| Flow range | 1 to 18 GPM (manufacturer rating); 2.5 GPM minimum recommended |
| Maximum temperature | 212°F (100°C); best foam at 130°F or less |
| Material | Stainless steel |
| Mounting | Wall mounting bracket, included |
| SKU | SS-IA-2S |
How a Dual Downstream Injector Works
A downstream injector uses the Venturi effect. When your lance or nozzle is in low-pressure mode (a foam lance, the low side of a hi-lo wand, or a soap nozzle), water speeds up through the injector and creates suction at the chemical inlet. The ST-164 has two chemical inlets, and its lever chooses which one draws. Soap is pulled through your pickup tube, metered, and mixed into the water stream. Switch to a high-pressure rinse nozzle and the suction stops, so you rinse with clean water.
Want the full breakdown, including how to run two-step touchless soap? Read our Downstream Chemical Injectors: The Complete Guide.
How to Install and Use
- Mount the injector to a wall with the included bracket, near your pressure washer and soap containers.
- Turn off the pressure washer and release pressure from the gun.
- Connect your pressure washer's outlet hose to the injector inlet and your wash hose to the injector outlet using the 3/8" quick connects. Follow the flow arrow.
- Push pickup tubing onto both chemical line barbs and place the strainer ends in your Step 1 and Step 2 containers.
- Set the lever to Step 1, put your lance in low pressure, and apply soap from the bottom up.
- Flip the lever to Step 2 and apply over the first coat.
- Switch the lance to high pressure and rinse from the top down.
- After washing, draw clean water through both pickup tubes to flush the injector.
Frequently Asked Questions
What is the Suttner ST-164?
The ST-164 is a stainless steel dual chemical downstream injector from Suttner. It draws one of two soaps or chemicals into the water line after your pressure washer's pump, and an integrated lever selects which one.
Is this the same injector used in the Image Dual Soap Wash System?
Yes. It's the injector from our Dual Soap Wash System and Dual Soap Injector System with Hi-Lo Wash Lance, sold by itself for customers who already have a lance, hoses, and draw tubes.
What's included?
The ST-164 injector as pictured: 3/8" quick connects installed, a wall mounting bracket, and two braided chemical inlet lines with barbs. A lance, pickup tubing, draw tubes, and metering tips are not included; those come in our complete soap systems.
Does the nozzle size need to match my pressure washer?
Yes. The injector nozzle has to match your machine's flow and pressure to draw soap correctly. Call us at 616-777-7175 with your PSI and GPM and we'll confirm the right size.
Can I run Touchless 1 & 2 through it?
Yes. That's what it's built for. Connect Step 1 to one inlet and Step 2 to the other, and switch with the lever. You can pre-mix each soap 50/50 or draw the concentrate with metering tips to reach the right end dilution.
Why isn't my injector drawing soap?
The most common causes are: your lance is in high-pressure mode or your soap nozzle opening is too small; the pickup tube or strainer is clogged; there's an air leak where the tube meets the barb; the soap is too thick; or the pickup tube is too long. Check each of these, and flush the injector with clean water.
Do I need the dual injector, or will a single injector work?
A single injector like the Suttner ST-160 works if you're fine moving the pickup tube between containers. The ST-164 saves that step and keeps both soaps connected all the time.
Complete Your Setup
- Dual Soap Wash System with the Foaminator foam lance
- Dual Soap Injector System with Hi-Lo Wash Lance
- Premium Single Barrel Hi-Lo Wand for soap and rinse from one lance
- Touchless 1 & 2 truck wash soap
