What is a Manometer and an Aneroid?
‘Aneroid’means without air.so an aneroid barometer is one where you have a small metal can ,usually with corrugated sides,which has had the air pumped out of it and then sealed.As atmospheric pressure changes out side the can the can shrinks or expands according to the outside pressure.Any kind of device ,mechanical optical or electric can be used to interpret the change of can length in terms of atmospheric pressure. Bourdon gauges are generally used for to measure pressures much higher than aneroids.The principal is that an arc or spiral of (usually)metal tube is sealed at one end while the other end is connected to the pressurised fluid.As the pressure rises the the Bourdon tube straightens,If it.s a spiral it rotates.This change in shape is measured and used,usually on a dial gauge to measure pressure.An example is a tyre pressure gauge. Manometers are simple U-tubes,bend at lowest point,partly filled with liquid (like coloured water).one end of the tube is open to atmosphere ,the
