A hydraulic bellow type scale comprises a scale body, a plurality of hydraulic bellows, a variable capacitor, an integrated circuit and a display unit. By means of the pressure in the hydraulic bellow, the weight of an object on a pan of the scale body is transmitted in terms of force for the variable capacitor to translate into a capacitance signal. The capacitance signal is further calculated by the integrated circuit. The weight and price thus calculated are displayed by the display unit.

An apparatus for measuring the volume rate of flow of flowing fluids by means of a flow meter, called rotameter, in which a linear light source and a plurality of light sensing means are engaged along diametrically opposing generatrices of the transparent measuring tube of the rotameter, and the float in the measuring tube intercepts the light path so that the state of illumination of the light sensing means corresponds to the position of the float in the rotameter tube, and the outputs of the light sensing means are combined in a logical circuit to produce a signal combination representing said float position.

A digital position transmitter is disclosed which uses a fixed array of physicoelectric proximity switches to locate a physical exciter and transmit the position of the exciter as a hexadecimal coded number or as a string of pulses. The position transmitter uses solid state components, has no moving parts and requires less power than any one proximity operated alone. The transmitter attains moderate resolution while displaying excellent accuracy and precision. The transmitter is completely non-intrusive; there is no contact between the physical exciter and the switch array, making the transmitter particularly suited for determining the position of objects that must be completely isolated because of pressure, temperature, of chemical hazards. Further circuits are described for converting the inherently digital output signal to industrial standard 4-20 mA or voltage signals. Applications are described for determining the "fullness" of a constant pressure cylinder used in sampling liquids and gaseous materials from pipelines, the status of hydraulic valve positioners the liquid level contained in storage vessels, and differential pressure. Practical variations of the physicoelectric proximity switch array are described for applying the position transmitter to movements as small as one inch and as large as hundreds of feet.

An Early Flood Warning System provides advanced warning of probable flash floods and/or stage floods to potential flood victims by collecting and analyzing rainfall and stream level data, and by providing means for disseminating alarms and instructions to individuals in threatened areas. Said Early Flood Warning System contains: a plurality of automated electronic digital liquid level gauges, some of which are specially adapted as rain gauges, and some of which are specially adapted as stream level gauges; a plurality of gauge actuated transmitters; a receiver; a decoder and validity logic unit; a data analysis unit; a central disaster alert station; and a plurality of disaster alert modules. Said digital liquid level gauges are energy and environmental intensive devices which electronically measure, using digital techniques, liquid levels such as rainfall and stream level, and transmit data by coded radio frequency (R.F.) signals to a central data analysis facility. Said digital liquid level gauges are remotely located and independent of each other.

A humidifier for gases, for example for medical administration, may be adapted for insertion into a well of a heater for warming liquid in the humidifier. A seamless metal can defines a cylindrical wall and a closed bottom end, containing wick means for absorbing water and presenting it in dispersed form to gases flowing through the can. Transparent probe means extend into the can and serve as a liquid level control for preferably automatically controlling the liquid level in the can to be maintained in the lower one third of the can.