readable

THE TRANSDUCER SYSTEM

There has to be a method of turning the water pressure to form an output that relates to the differential pressures that can be used by the meter.
In the Victorian (mechanical age) this would have to be a mechanical movement that could be used.

How then can you turn the water pressure, into a mechanical movement. The obvious thing to consider is that it is two measurements that are being taken. Perhaps two pistons working against each other (i.e pressures turned into mechanical force, Fd = Fin - Fout, where P = F/A ... A = area, in this case related to the diameter of the cylinder ... the actual measurement would be distance). When you look at when the meter was designed this was not such an obvious way and the water had foreign bodies and the cylinder piston been quite a large load (with stiction) .

It however serves as a way to show how a transducer systems works, in that you transfer from one type of pressure to a mechanical force. If we now remove health and safety, and consider other ways you come to the scientific measurement of pressures, what other methods are there? Look back at the piston and open up the spectrum, the water will push one way and push less the other. Perhaps a ball in a pipe, but any flow between the pipes and the pressure information is lost.

What other pressure meters where there? Barometer? Why not use of a U bend of mercury (density highest for liquids, and so makes a compact meter, like barometers), and sack the yet appointed health and safety executive. Eureka! I hope you see that this is merely one approach, from dual acting cylinder, to ball (solid) to the other end of the spectrum a fluid in a pipe.

Please note on later systems there was an isolation chamber, to transfer fluids (water to paraffin, good as kept the muck from the mercury), funny enough these generally worked on a piston system, which if where jointed together would remove the requirement for the U tube all together. But evolution of design, is with hindsight, foresight is looking at the spectrum of the solution.