Downstream Chemical Injector
A downstream chemical injector is a device that is used to introduce a chemical solution into a pressurized water stream, typically for cleaning or disinfecting purposes. It is called a "downstream" injector because it is placed downstream of the pump, after the water has been pressurized.
Downstream chemical injectors are commonly used in pressure washing systems to add cleaning agents or disinfectants to the water stream. They allow the user to easily control the amount of chemical that is mixed with the water and apply it consistently to the surface being cleaned.
Typically, commercial pressure washers do not have a chemical injection line built into the pump. This is more done for residential machines where the owner may want soap for their car or degreaser for their driveway. A downstream chemical injector is a part that attaches between the pressure washer unloader and the hose, typically with quick connections. The injector will have a barb fitting designed to receive a ¼-⅜” hose which is fed into the chemical that the operator desires to be injected.
Downstream injectors have three important technical specifications to be aware of. The PSI rating or Pressure Per Square Inch. This will tell you how much pressure the device is rated for. Do not use a Downstream Injector that has a lower PSI rating than your pressure washer.
Next is its GPM (Gallons Per Minute) rating. Typically this will be communicated as a range; like 3-5 GPM or 5-8 GPM. Make sure that the pressure washer GPM falls within the range of the downstream injector rating.
Lastly is its injection ratio or draw rate. Sometimes this specification is not advertised. Most downstream injectors will pull 1 part chemical per 10 parts water or have a 1:10 ratio. Some downstream injectors have an adjustable injection barb that allows you to vary the amount of chemical injected. Most commercial systems have a fixed downstream injection ratio between 1:6 and 1:10. If you look at the chart below, you will see that Ratios on the left and the the final SH mixture percentages when using a 10% Sodium Hypochlorite concentration and a 12.5% concentration.
Sodium Hypochlorite Concentration % |
||
Ratios |
10.00% |
12.50% |
| 1:4 or 25% | 3.00% | 2.50% |
| 1:5 or 20% | 2.50% | 2.00% |
| 1:6 or 16.6% | 2.00% | 1.60% |
| 1:8 or 12.5% | 1.50% | 1.25% |
| 1:10 or 10% | 1.25% | 1.00% |
Need to Purchase A Downstream Injector?
General Pump Injector - 3 to 5 GPM - 4500 Max PSI - 20% Draw Rate
General Pump Injector - 5 to 8 GPM - 4500 Max PSI - 20% Draw Rate
