Modular electronic ph meter - uses pluggable cassettes in box-shaped housing with hermetic lid which contains control elements

摘要

The pH meter has a housing with pluggable, contacted cassettes and with external control elements. The housing is box-shaped and has a lid forming a hermetric closure. The cassettes are mounted on plug strips. From the plug sockets electric leads are brought out to the control elemens, whose moving parts are brought out through a sealed aperture each. All the circuits from the cassette plug sockets preferably have safety devices, screw terminals on the cassettes providing connections to other circuits without such safety devices. The lid may have a screwing device, preventing unauthorised access to the cassettes, and releasable only by a special tool. The lid may have an optical system. whose input lies in front of a cassette indicator and whose output is externally visible, using e.g. a pneumatic rod. The latter and the control element may be supported by a control panel, hermetically set in a recess in the lid.