Measuring devices and apparatuses, particularly for measuring pressure, absolute pressure, differential pressure, temperature, density, pH value, quantity, particularly flow rate, humidity, force, acceleration, distance, angle, speed, density or level, filling level, namely, pressure gauges, combined pressure and vacuum gauges, barometers, altimeters, thermometers, thermo-hydrometers, hydrometers, pressure-measuring sensors, flow meters; measuring instruments in the nature of diaphragm seals for measuring pressure and water pressures; measuring devices for cooling devices, namely, pressure gauges for air conditioners, thermometers for refrigerators; leak detectors, namely, leak detectors for vacuum pumps, leak detectors for refrigeration, heating, ventilation, air conditioning and cooling equipment; measurement recorders for measuring devices, namely, electronic data loggers; transducers; electronic transducers; electric transducers with electronic output signal, namely, pressure transducers, differential pressure transducers, level measuring transducers; electronic apparatus, namely, remote electronic display screens; electronic apparatus, namely, remote electric luminescent display panels; electronic control and feedback control devices for oil and gas; flow monitors for fluids, gases, and particles; electrical relays, electrical contactors/contact makers, electrical switches; position regulators for electronic control devices; pressure controllers for fluids or gases; electrotechnical and fluidic devices and apparatuses, namely, electrical power supply units, electric amplifiers, electrical circuits, electrical switching elements and recording devices; calibrators and calibrating devices, namely, pressure scales; electric switches, particularly pressure switches, limit-value switches, level switches, contact-free operable magnetic switches, switches operable optically, inductively and capacitively, electric switches designed as float switches, as motion/running sensors, as indicators of metals present; electric switching devices for the level control of liquids on the basis of the electric conductivity of the liquid in question; test benches comprised of pressure testing and temperature testing equipment for calibrating of valves, sensors and cylinders and for use in testing the performance of valves and pipes; electronic apparatus for testing aeronautic engines and aircraft piston engine cylinder assemblies; electric and electronic control devices for speed measurement, speed control, standstill monitoring, rotation prevention monitoring, filling level indication, limit-value monitoring, phase angle control, machine control, and for machine monitoring; electric and electronic control devices for use in measuring and controlling pressure, temperature, position, chemical composition; electric time relays