Abstract: A bottle closure testing apparatus includes a plurality of testing modules mounted side by side on a base plate. Each testing module includes a base block having a pressure input, a pressure signal output, and a holder for a test vessel. The test vessel is a plastic bottle blow-molding preform having a bottle finish and a pressure entry port. A preform is mounted to each of the modules with the pressure entry port in fluid communication with one of the pressure inputs. A closure is screwed onto each of the preforms and the preforms are pressurized to a preselected test pressure via the module. The pressure within the preforms can be monitored by pressure gauges at the signal outputs, or by transducers at the signal outputs which communicate a pressure signal to remote monitoring equipment.