It is often desirable to be able to inject a liquid having certain characteristics into a flow of a second liquid having different characteristics. For example, in spraying water or fertilizer on a lawn it may be desirable to inject into the flow of water or fertilizer a second liquid, such as a herbicide or pesticide. Similarly, it may be desirable to inject a liquid detergent into a flow of water during a washing process.
Where the injection under pressure of one liquid into a flow of second liquid is desired, a separate pressurizing source for the injected liquid will usually be required.