It is often necessary to provide a fluid additive to a primary fluid in a main fluid line. Additionally, the ratio of the fluid additive to the primary fluid must be maintained at a desired level. The flow rate of the fluid additive must be adjusted as the flow rate of the primary fluid changes to maintain the desired ratio of the mixed fluids.
A system currently used to control the flow rate of the fluid additive employs a conduit providing fluid communication between a reservoir for the fluid additive and the main fluid line. A pump is provided to introduce the fluid additive from the reservoir through the conduit and into the main fluid line. A solenoid actuated valve is disposed to alternately allow or prevent the flow of the fluid additive through the conduit into the main fluid line. The system provides an uneven supply of the fluid additive to the main fluid line. When averaged over a time interval, the desired flow rate of the fluid additive into the main fluid may be obtained. However, at any given point in time, the flow rate of the fluid additive into the main line is either greater than or less than the required flow rate.
It would be desirable to have a valve system providing a substantially continuous and proportional flow of a fluid additive into a main fluid line wherein the valve system detects a flow rate of a primary fluid in the main fluid line and adjusts the flow rate of the fluid additive to maintain a desired ratio of the fluid additive to the primary fluid in the main fluid line.