26 METERING AND PROPORTIONING PUMPS; PNEUMATIC CONTROLLERS; INDICATORS AND RECORDERS; VACUUM CONTROL SYSTEMS; RESIDUAL CHLORING ANALYZRS, INDICATORS, RECORDERS AND CONTROLLERS; GAS FLOW MEASURING, INDICATING, RECORDING AND CONTROLLING INSTRUMENTS; RESIDUAL CHLORINE COMPARATOR AND TEST KIT, BAROMETERS AND VACUUM GAUGES, AND DIFFERENTIAL PRESSURE INDICATORS