  We present low resolution spectroscopic observations for a sample of 53
planetary nebulae (PNe) located in the southern sky between Vela and Norma
constellations and pertaining to the Galactic disk with expected Galactocentric
distance range of 5 to 10 kpc.
  We derive nebular chemical composition and plasma parameters with the
classical empirical method. For most of the observed objects, this has been
done for the first time. The distributions of the chemical abundances of the
observed disk sample are generally indistinguishable from Galactic bulge and
inner-disk PNe populations. The exceptions are possible differences in the He/H
distribution, as compared to bulge PNe and Ne/Ar, compared to inner-disk PNe
sample. The derived O/H ratios for the observed disk PNe fit to the concept of
flattening of the chemical gradient in the inner parts of the Milky Way.
  We use the spectra to search for emission-line central stars in the observed
sample. We found 6 new emission-line central stars comprising examples of all
known types: WEL, VL and [WR]. We confirm that these types represent three
evolutionary unconnected forms of enhanced mass-loss in the central stars of
PNe. We note on the problem of high ionisation PNe with nebular CIV emission
that can mimic the presence of WEL central stars in 1D spectra.
