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We present low resolution spectroscopic observations for a sample of 53planetary nebulae (PNe) located in the southern sky between Vela and Normaconstellations and pertaining to the Galactic disk with expected Galactocentricdistance range of 5 to 10 kpc.  We derive nebular chemical composition and plasma parameters with theclassical empirical method. For most of the observed objects, this has beendone for the first time. The distributions of the chemical abundances of theobserved disk sample are generally indistinguishable from Galactic bulge andinner-disk PNe populations. The exceptions are possible differences in the He/Hdistribution, as compared to bulge PNe and Ne/Ar, compared to inner-disk PNesample. The derived O/H ratios for the observed disk PNe fit to the concept offlattening 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 observedsample. We found 6 new emission-line central stars comprising examples of allknown types: WEL, VL and [WR]. We confirm that these types represent threeevolutionary unconnected forms of enhanced mass-loss in the central stars ofPNe. We note on the problem of high ionisation PNe with nebular CIV emissionthat can mimic the presence of WEL central stars in 1D spectra.

Spectroscopy of southern Galactic disk planetary nebulae. Notes on chemical composition and emission-line stars