A new representation of the viscosity of ammonia is presented. The rep
resentative equations are based on a set of experimental data selected
as a result of a critical assessment of the available information. Th
e validity of the representation extends from 196 K to the critical te
mperature for both liquid and vapor phases. In the supercritical regio
n the temperature range extends to 680 K for pressures at or below amb
ient and to 600 K for pressures up to 50 MPa. The accuracy of the repr
esentation varies from 0.5% for the viscosity of the dilute gas phase
at moderate temperatures to about 5% for the viscosity at high pressur
es and temperatures. Tables of the viscosity generated by the correlat
ing equation at selected temperatures and pressures and along the satu
ration line are presented to provide easy reference as well as for the
validation of computer codes. (C) 1995 American Institute of Physics
and American Chemical Society.