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
Free Pascal Free Pascal Free Pascal Compiler (FPC) is a compiler for the closely related programming language dialects, Pascal and Object Pascal. It is free software released under the GNU General Public License, with exception clauses that allow for static linking against its runtime libraries and packages for any purpose in combination with any other software license. It supports its own Object Pascal dialect as well as the dialects of several other Pascal family compilers to a certain extent, including those of Turbo Pascal, Delphi, and some historical Macintosh compilers. The dialect is selected on a per-unit (module) basis, and more than