Abstract: To be able to determine an ice or snow formation reliably, a cold conductor connected to an electrical power source is provided, with which the heat abstraction intensely occurring due to ice or snow is measured and used as a signal for ice or snow formation. The intensified heat abstraction on the cold conductor is determined by a current meter for determining an increased power consumption or by a thermistor which is in heat-conductive connection with the cold conductor and switches the power supply of the cold conductor on and off as a function of the temperature.

Abstract: The invention relates to a fluid flow monitor and control system which prevents excessive fluid loss and property damage. The invention warns of impending distribution pipe freeze conditions, or ruptures from other causes, shuts off the fluid supply, and vents and drains the piping network under freeze and rupture conditions. Furthermore, the invention shuts off fluid flow if the volume of flow or the velocity exceeds desired norms. An example of its application is as a water main shut-off for residential houses and commercial buildings, it also can be used for industrial processing applications.

Abstract: A system which prevents the formation of ice on the external surfaces of aircraft structures by heating impinging atmospheric supercooled water droplets to above the freezing point by the transmission of microwave electromagnetic energy to the droplets which if unheated would freeze upon impact and adhere to the aircraft structures. The frequency of the microwave electromagnetic energy is such that it is strongly absorbed by the liquid water droplets but weakly absorbed by ambient air, frozen water or the aircraft structures, thus resulting in very efficient heating of the supercooled water droplets.

Abstract: Sensor and reference wires are directly exposed to the airflow past a vehicle. The wires are electrically conductive, and each has a resistance varying with its temperature. A continuous fixed voltage is passed through the reference wire. A short pulse of greater constant voltage is passed through the sensor wire, the voltage of sufficient magnitude to cause the rapid heating of the sensor wire during the pulse. The resultant rate of heat of the sensor wire, and its final temperature at the end of the pulse, is determined by whether ice or water is on the sensor wire. Circuitry is provided to generate an ice present signal when the difference in current flow during the pulse through the sensor wire and through the reference wire is of such magnitude and sign as to indicate that ice was in contact with the sensor wire. Due to water's heat of fusion, the effect of ice on the sensor wire is readily distinguished from the effect of water.

Abstract: A method and apparatus is provided for detection of the onset of a physical change in state of a flowing fluid medium or component of a flowing fluid medium, e.g. freezing, boiling, sublimation, crystallization. A surface in contact with the fluid medium is maintained at a temperature that is an approximately fixed amount below or above the general stream temperature of the fluid, by means of a thermo-electric heat pump, the temperature difference being sensed by thermo-couple means to obtain a control signal for regulating the output of an amplifier that drives the heat pump. Upon occurrence of the physical change in state to be detected, the amplifier output will fall or rise rapidly as the system tries to regulate the power input to the pump to keep the temperature difference constant and this swing is detected by a signal generator monitoring the output of the amplifier.

Abstract: A thermal detection and alarm system for indicating the irradiation of a surface by a heat source such as a laser beam has been invented. The detector element may form an integral portion of the vehicle's outer surface or may be parasitically mounted thereto. The proposed system is light weight, energy efficient, durable and highly sensitive. The invention is especially suited for use with Boron-Tungsten composite surfaces as found on aircraft and spacecraft.

Abstract: An early warning signal is produced when there is a danger of ice forming on a road surface by means of a device comprising a temperature sensor for determining the ambient temperature, a sensor unit for determining the temperature and moisture of the road surface, a heatable sensor unit having a heating element and a moisture-detecting gap, and comparators for comparing the voltages supplied by the temperature sensors and the moisture sensors with reference voltages, comprises in addition thereto a sensor unit having a further moisture-detection gap, one or more elements for alternately cooling or heating this further moisture-detection gap, and a temperature sensor for determining the temperature of this further moisture-detection gap, as well as signal generators generating signals in response to the output signals of the comparators for indicating whether the road surface is dry, wet, or icy.

Abstract: In a refrigeration mechanism including a refrigerant, a means for pressurizing the refrigerant, a means for liquifying the refrigerant, a means for vaporizing the refrigerant, and a means for circulating air to be refrigerated, the improvement comprising a means for sensing frost accumulation which includes a capacitance sensitive element disposed within the means for vaporizing the refrigerant.