  There is a class of binary post-AGB stars with a remarkable near-infrared
excess that are surrounded by Keplerian or quasi-Keplerian disks and extended
outflows composed of gas escaping from the disk. The Keplerian dynamics had
been well identified in four cases, namely the Red Rectangle, AC Her, IW Car,
and IRAS 08544-4431. In these objects, the mass of the outflow represents ~ 10
% of the nebular mass, the disk being the dominant component of the nebula. We
present interferometric NOEMA maps of 12CO and 13CO J=2-1 in 89 Her and 12CO
J=2-1 in AC Her, IRAS 19125+0343, and R Sct. Several properties of the nebula
are obtained from the data and model fitting, including the structure, density,
and temperature distributions, as well as the dynamics. We also discuss the
uncertainties on the derived values. The presence of an expanding component in
AC Her is doubtful, but thanks to new maps and models, we estimate an upper
limit to the mass of this outflow of < 3 10^-5 Mo, that is, the mass of the
outflow is < 5 % of the total nebular mass. For 89 Her, we find a total nebular
mass of 1.4 10^-2 Mo, of which ~ 50 % comes from an hourglass-shaped extended
outflow. In the case of IRAS 19125+0343, the nebular mass is 1.1 10^-2 Mo,
where the outflow contributes ~ 70 % of the total mass. The nebular mass of R
Sct is 3.2 10^-2 Mo, of which ~ 75 % corresponds to a very extended outflow
that surrounds the disk. Our results for IRAS 19125+0343 and R Sct lead us to
introduce a new subclass of binary post-AGB stars, for which the outflow is the
dominant component of the nebula. Moreover, the outflow mass fraction found in
AC Her is smaller than those found in other disk-dominated binary post-AGB
stars. 89 Her would represent an intermediate case between both subclasses.
