Suttner ST-160 Single Soap Downstream Injector
The Suttner ST-160 is the professional single-chemical downstream injector we build into our Single Soap Wash System, now sold on its own. It installs between your pressure washer and your gun and draws soap straight from your pail, drum, or tote into the water stream at a consistent dilution. There's no pre-mixing, no refilling foam cannons, and no chemical running through your pump.
It comes with 3/8" quick connects installed on both ends, so it snaps into a standard 3/8" quick-connect hose line in seconds. Use it to upgrade an existing setup, replace a worn injector, or build your own soap system for fleet washing, truck washing, detailing, or a wash bay.
Why Choose the ST-160?
- Keeps chemicals out of your pump: downstream injection adds soap after the pump, which helps protect seals and valves from harsh detergents
- Consistent dilution: the dosing nozzle meters soap at the same ratio on every wash, so you stop guessing and stop wasting chemical
- Ready to connect: a 3/8" quick-connect plug on the inlet and a 3/8" quick-connect socket on the outlet
- Built for pros: Suttner professional-grade construction rated up to 5,000 PSI (350 bar) by the manufacturer
- Works with the lance you already use: pairs with a foam lance, hi-lo wand, or low-pressure soap nozzle
- Backed by people who use it: it's the same injector we install in every Image single soap system, and we can help you set it up
Specifications
| Model | Suttner ST-160 single-chemical downstream injector |
| Water inlet | 3/8" quick-connect plug (male), installed |
| Water outlet | 3/8" quick-connect socket (female), installed |
| Chemical inlet | Hose barb for chemical pickup tubing |
| Metering | Replaceable dosing nozzle sets the soap dilution |
| Maximum pressure | 5,000 PSI / 350 bar (manufacturer rating) |
| Maximum temperature | 194°F (90°C) |
| Recommended pressure washer | 2.5 GPM minimum |
| Chemicals | One chemical at a time |
| SKU | SS-IA-1S |
How a 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. That suction pulls soap through your pickup tube, meters it through the dosing nozzle, and mixes it into the water stream. Switch to a high-pressure rinse nozzle and the suction stops, so you rinse with clean water.
That's why the nozzle matters: if the soap nozzle opening is too small, pressure stays high and the injector won't draw. Our Foaminator lance and Premium Single Barrel Hi-Lo Wand are built for use with downstream injectors.
Want the full breakdown? Read our Downstream Chemical Injectors: The Complete Guide.
How to Install and Use
- Turn off the pressure washer and release pressure from the gun.
- Connect the injector inlet plug to your pressure washer's outlet hose, then connect your wash hose to the injector's outlet socket. Follow the flow arrow on the injector.
- Push chemical pickup tubing onto the barb and drop the other end, with a strainer, into your soap container.
- Set your lance to low pressure (or use a soap nozzle) and pull the trigger. Soap will begin drawing within a few seconds.
- Switch to high pressure to rinse.
- After washing, draw clean water through the pickup tube for 30 seconds to flush the injector.
Frequently Asked Questions
What is the Suttner ST-160?
The ST-160 is a single-chemical downstream injector from Suttner. It draws one soap or chemical into the water line after your pressure washer's pump and dilutes it at a set ratio using a replaceable dosing nozzle.
Is this the same injector used in the Image Single Soap Wash System?
Yes. This is the injector from our Single Soap Wash System, sold by itself for customers who already have a lance, hose, and draw tube.
What's included?
The ST-160 injector with 3/8" quick connects installed on the inlet and outlet. A lance, soap hose, draw tube, and extra metering tips are not included; those come in our complete soap systems.
What size pressure washer do I need?
We recommend at least 2.5 GPM. The injector is rated to 5,000 PSI by the manufacturer and handles hot water up to 194°F.
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.
Can I use it with a foam cannon?
A downstream injector replaces the need for a foam cannon bottle. Pair it with a foam lance, a hi-lo wand, or a low-pressure soap nozzle instead.
Can I run two soaps?
The ST-160 draws one chemical at a time. For two-step touchless soaps, see our Dual Soap Injector System with the Suttner ST-164.
Complete Your Setup
- Single Soap Wash System with the Foaminator foam lance
- Premium Single Barrel Hi-Lo Wand for soap and rinse from one lance
- Touchless 1 & 2 truck wash soap
