With this arrangement, respective ones of the purge conduits 99A-99J (only 99E being shown in FIG. 2 connecting manifold outlet 98E to check valve 82E) are connected to apply air or nitrogen gas or other purging substance to the respective ones of the T-joints 80A-80J (80E being shown in FIG. 2) to purge conduits 68A-68E (68E being shown in FIG. 2) and 88A-88E (88E being shown in FIG. 2) and their