all-or- nothing sensors

«All-or-nothing» (TOR (“tout ou rien”) in French) sensors are used in safety applications generating an immediate reaction on the equipment or alerting the operator. These sensors are also used on process pipelines.

All-or-nothing sensors used for safety purposes are mainly:

• pressure switches;
• thermostats;
• limit switches (position detection) based on a mechanical or induction principle;
• equipment presence detectors, based on optical principles;
• rotation regulators based on the induction principle;
• mechanical or electronic stress regulators (intensity threshold detector);
• level detectors: float, rotary vane, vibration, ultrasonic, radio frequency, optical or conduction;
• electro-chemical cell, catalytic cell or semi-conductor gas concentration detectors.

All-or-nothing sensors used for process control are mainly:

• fluid circulation detectors based on the thermal or oscillating vane principle;
• foam presence detectors based on the thermal or conduction principle;
• sludge concentration detectors using optical or ultrasonic techniques.

Some flowmeters are pulse generators, allowing the throughput volume to be recorded.