Pressure measurement because atmospheric pressure is always changing and the reference in this case is fixed at 1 bar. To produce an absolute pressure sensor, the manufacturer seals a high vacuum behind the sensing diaphragm. If the process-pressure connection of an absolute-pressure transmitter is open to the air, it will read the actual barometric pressure. The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N·m or kg·m·s). This special name for the unit was added in 1971; before that, pressure in SI was expressed in units such as N·m. When indicated, the zero reference is
ALCO PA display in the museum. Unit DH-17 (former D&H #17) was painted in the classic Southern Pacific Daylight colors, but as of February 2010 had been painted over in primer. Algoma Central 78 is the former Denver and Rio Grande PB-1 6002. It was converted to a steam generator car in October 1965. It gained Blomberg B trucks in 1980. It was sold to Ansco in late 1987 for service on the Ski Train. It was sold again in 2007 to the Algoma Central. ALCO PA ALCO PA refers to a family of A1A-A1A diesel locomotives built to haul passenger trains