I recently bought 15cm (6")-spaced 12mm (0.5") drip line, with a 16mm LDPE supply pipe.
As a test, I connected a 2-metre (6') run of supply pipe to a 1-metre (3') run of drip line (with a stop-end attached). I have a 2-bar pressure reducer connected between the tap and the supply pipe.
Unfortunately some water leaked from the end of the drip line and also from where the drip line connected to the LDPE supply pipe. Some of the drip line emitters were also not emitting water.
Is this happening because the overall length of pipe I used for the trial is rather short? Presumably the emitters don't have to be facing downwards in order to work effectively?