fix srd and langevin

I want to use fix srd command with fix langevin in an input file to simulate one polymer in a diluted fluid. What relation could exist between damp parameter and SRD viscosity that was printed in log file when i was running srd example (in.srd.mixture)?
Thanks for your help in advance;

There are various subtle issues with thermostatting
SRD particles, which is why fix srd has its own thermostatting
option (see fix srd tstat). I suggest you use that
instead of fix langevin. If you want to use fix langevin
on the large particles (polymer monomers in your case?)
that would be fine, although odd, since the SRD particles
will thermostat the polymer. By using fix langevin you're adding
a 2nd thermostat of implicit background particles, when
you already have explicit background particles (the SRD ones).