The Chemical Injector is a 3/8" fixed downstream injector. It pulls your mix into the water stream after the pump, so SH never runs through your seals. Rated to 3,600 PSI and 300°F, with a stainless ball, seat, and spring.
Key Features
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Downstream injection: Sits after the pump and unloader, so corrosive SH never runs through your pump. That's the job.
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Stainless ball, seat, and spring: Hold up to SH better than plated-steel internals, so the check ball keeps seating clean under daily use.
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Two fixed orifices: 2.1mm draws for 3-5 GPM machines, 2.3mm for 5-8 GPM. Match the orifice to your flow.
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Up to 20% chemical draw: Pulls a strong, fixed mix. Real-world draw lands around 12-18% once your hose and fittings add restriction.
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3/8" male NPT both ends: Drops into a standard rig. Add quick-connect couplers to run it on QCs.
Specifications
| Brand / origin |
MTM Hydro (Veloci), made in Italy |
| Type |
Fixed downstream injector, high-draw |
| Wetted internals |
Stainless steel ball, seat, and spring |
| Max pressure |
3,600 PSI |
| Max temperature |
300°F |
| Inlet / outlet |
3/8" male NPT x 3/8" male NPT |
| Orifice / flow |
2.1mm (3-5 GPM) or 2.3mm (5-8 GPM) |
| Max chemical draw |
Up to 20% |
| SKUs |
22.0352 (3-5 GPM) / 22.0353 (5-8 GPM) |
| How sold |
Individually, injector body only |
What's Included
- One chemical injector body. No nozzle, chem line, filter, or couplers included.
Installs downstream, after the pump and unloader, with the body arrow pointing in the direction of flow. It needs a low-pressure soap nozzle to draw. A high-pressure tip keeps the check ball seated and nothing pulls. It won't work upstream, and it isn't rated for potable water. Long hose runs or high lift can stall the draw, usually once you're past 100 to 150 feet. For roof mixes, downstreaming tops out around 0.8 to 1% SH, so run an X-Jet or a 12V system instead.
How It Works
A downstream injector is a Venturi. Water speeds up through the fixed orifice, pressure drops, and the vacuum pulls your pre-mixed chemical past the stainless check ball into the stream. Under full pressure the ball stays seated and nothing draws. Fit a low-pressure soap nozzle, pressure falls about 30%, the ball lifts, and chemical flows.
Because injection happens after the pump, your SH never touches the seals. Flush a couple gallons of clean water through after every job. The ball, seat, and spring are wear parts, so keep a rebuild on hand if you're running daily SH.
Pairs Well With
Frequently Asked Questions
Is this a General Pump injector made in the USA?
No. This is an MTM Hydro (Veloci) injector made in Italy, rated to 3,600 PSI and 300°F, with a stainless ball, seat, and spring. If you've seen it listed as a 4,500 PSI General Pump unit, that spec belongs to a different injector.
Why won't my chemical injector draw soap?
Almost always the nozzle. A high-pressure tip won't drop pressure enough to open the check ball, so swap to a low-pressure soap nozzle. Too much hose, too much lift, or the wrong orifice for your GPM will also stall it. Test by running with the hose open and no nozzle.
Can I run SH through it?
Yes, that's what downstream injection is for. It keeps SH out of your pump. SH still corrodes injector internals over time, so flush clean water through after every use and plan to rebuild the ball, seat, and spring as they wear.
