Component injection system

System for introducing a predetermined amount of a first fluid into a main stream of a second fluid in an intermittent fashion, so that a predetermined concentration of the first fluid in the second fluid is obtained, said predetermined amount being determined without a flowmeter, said system comprising:

• a. means for providing a circuitous path through which the first fluid can be circulated;
• b. pumping means for continuously circulating the first fluid through the circuitous path at a predetermined rate;
• c. means for diverting the flow of the first fluid from said circuitous path into the main stream of the second fluid, said diverting means having a first mode wherein the first fluid is circulated only through the circuitous path and a second mode wherein the first fluid flows only from the circuitous path into the main stream;
• d. means for measuring the flow rate of the main stream of the second fluid and producing signals related to the flow rate;
• and
• e. means, responsive to the signals produced by the measuring means, for maintaining a predetermined concentration of the first fluid in the second fluid, by controlling the diverting means so that it is moved from its first mode to its second mode, and back to its first mode after a predetermined length of time has elapsed, thereby permitting a predetermined amount of the first fluid to be introduced into the main stream of the second fluid after a predetermined amount of the second fluid has flowed through the measuring means.