Patent ID: 7784332

Claim:
A device for measuring a concentration of fine particles contained in a fluid, comprising: a control volume body having a predetermined effective volume; an inlet path formed at an end of the control volume body to feed the fluid into the control volume body therethrough; an outlet path formed at another end of the control volume body to discharge the fluid from the control volume body therethrough; measuring instruments provided at the inlet path and the outlet path to emit electrical signals when the fine particles pass through the inlet path and the outlet path; and a computing machine for receiving the electrical signals transmitted from the measuring instruments and computing the number and the concentration of fine particles contained in the control volume body, wherein the computing being performed by the steps of: a) counting numbers of the fine particles passing through the inlet and the outlet of the control volume body; b) calculating a difference in the numbers of fine particles measured in the step a); and c) dividing the difference calculated in the step b) by the effective volume of the control volume body to give the concentration of the fine particles.