  The present paper is meant as an update of the presentation given in a
previous Resistive Plate Chamber (RPC) workshop, aimed at finding an
eco-friendly gas mixture for streamer operation of RPCs. Indeed the streamer
working regime is still suitable for building large RPC systems dedicated to
low rate applications, such as cosmic ray and neutrino physics. In addition to
other studies about gas mixtures for streamer mode operation, in this paper the
replacement of R134a with CF4, a gas widely used in other gaseous detectors,
has been investigated. The effect of the gas gap thickness on the discharge
quenching has also been studied; this is an important check because thin gas
gaps of 1 mm, one half of the typical used value, have been introduced for high
rate applications. Finally preliminar results about the streamer formation
timing are also reported.
