S. I. Agafonov and E. V. Ferapontov have introduced a construction
that allows naturally associating to a system of partial differential equations of conservation laws a congruence of lines in an appropriate
projective space. In particular hyperbolic systems of Temple class
correspond to congruences of lines that place in planar pencils of lines. The language of Algebraic Geometry turns out to be very natural in the study of these systems. In this article, after recalling the
definition and the basic facts on congruences of lines, Agafonov-Ferapontov's construction is illustrated and some results of classification for Temple systems are presented. In particular, we obtain the classification of linear congruences in P^5, which correspond to some classes of T-systems in 4 variables.
