Abstract: The flow rate of a fluid, e.g. hot water, is determined by measuring the temperature of the fluid and the cooling time between two temperature thresholds of a previously heated probe. On the basis of these values, by way of a first interpolation based on a table comprising the cooling times of the probe as a function of different temperatures and flow rates, the cooling times at the temperature measured are calculated for all the flow rates recorded on the table, then, by way of a second interpolation between the values thus calculated which are higher and lower than the value measured, the flow rate corresponding to this value is calculated.

Abstract: This apparatus incorporates an enclosure (1) designed to contain water in which are immersed two electrodes (9,10) connected to an alternating current source (S). A tube (13) terminating in a nozzle (14) connect the top of this enclosure (1) to a venturi (15) which is connected upstream to the atmosphere and downstream to an inhalation mask (17), so as to form an air/water vapor mixture at a controlled temperature.

Abstract: The ratio of fuel to oxidant in a gas mixture to main burners in a furnace, wherein the fuel is of variable composition, is controlled to a predetermined level by burning a portion of the fuel in a control burner, adjusting the oxidant to obtain a ratio of fuel to oxidant near the stoichiometric ratio in the control burner and supplying the main burners with independent preset multiples of the fuel and oxidant flow in the control burner such that the predetermined ratio of fuel to oxidant is achieved.The stoichiometric ratio is determined by automatic searching for the peak value of a burning or burned fuel property which has a maximum value as a function of the fuel/oxidant ratio at or near the stoichiometric ratio. For example, the temperature of the burned fuel is a property which may be used to find the stoichiometric ratio.