Systems and methods for automatically regulating the flow of fumes suctioned through a welding fume gun are provided. In certain embodiments, an automatic flow control assembly includes a vacuum system configured to suction a vacuum fume flow through an internal passage of a welding fume gun. The automatic flow control assembly also includes a sensor configured to measure a parameter related to the vacuum fume flow. The automatic flow control assembly further includes a flow regulation device configured to regulate an ambient air flow introduced into the vacuum fume flow. In addition, the automatic flow control assembly includes control circuitry configured to control the flow regulation device based at least in part on the measured parameter related to the vacuum fume flow.

There is provided a method of automatically controlling the mass flow rate of a gas through an orifice through which, in use, choked flow is arranged to occur. The method uses an electronic valve located downstream of a gas source, a piezoelectric oscillator in contact with the gas upstream of the orifice and downstream of the electronic valve and a temperature sensor. The method comprises: a) driving the piezoelectric crystal oscillator at a resonant frequency b) measuring the resonant frequency of the piezoelectric oscillator c) measuring the temperature of the gas; and d) controlling the electronic valve in response to the resonant frequency of the piezoelectric oscillator and the temperature of the gas in order to regulate the mass flow rate of gas through said orifice.

For the purpose of balancing (S3) a group of consumers in a fluid transport system in which each consumer is configured with a motorized regulating valve for the purpose of regulating the flow through the consumer, characteristic data for the consumer is saved (S2) which determines a valve position of the corresponding regulating valve for the target throughput through each consumer. A momentary total throughput through the group of consumers is determined (S32) by means of a common throughput sensor, and based on the momentary total throughput and a sum of the desired target throughputs through the consumers, a balancing factor is determined (S34). By setting (S31) the valve positions of the corresponding regulating valves based on the characteristic data and the balancing factor, a dynamic balancing of the consumers is carried out.

A pressure type flow control system with flow monitoring includes an inlet, a control valve including a pressure flow control unit connected downstream of the inlet, a thermal flow sensor connected downstream of the control valve, an orifice installed on a fluid passage communicatively connected downstream of the thermal flow sensor, a temperature sensor provided near the fluid passage between the control valve and orifice, a pressure sensor provided for the fluid passage between the control valve and orifice, an outlet communicatively connected to the orifice, and a control unit including a pressure type flow rate arithmetic and control unit receiving a pressure signal from the pressure sensor and a temperature signal from the temperature sensor, and a flow sensor control unit to which a flow rate signal from the thermal flow sensor is input.

A refrigeration apparatus includes a primary circuit with a first expansion valve, a bypass circuit extending between branching and joining portions on the refrigerant primary circuit, a heat exchanger, a second expansion valve disposed upstream of the heat exchanger in the bypass circuit, first and second refrigerant flow rate calculating components, and a determining component. The primary circuit also includes a compressor, radiator, and evaporator. The heat exchanger includes first and second refrigerant flow paths disposed on the primary and bypass circuits, respectively, to cause heat between refrigerant flowing in the paths. The first and second refrigerant flow rate calculating components calculate first and second flow rates of refrigerant flowing through the bypass circuit based on refrigeration cycle theory and fluid theory, respectively. The determining component determines whether there is refrigerant leakage or refrigerant charge deficiency based on comparison of the first and second refrigerant flow rates.

A fluid supply system includes a pressure tank configured to contain a pressurized gas and a fluid, a delivery point configured to be connected to a point of use, a recirculation piping connecting the pressure tank to the delivery point, and a return pump connected to the recirculation piping. The recirculation piping defines a circulation path for the fluid from the pressure tank through the delivery point and back to the pressure tank. The return pump is downstream of the delivery point and upstream of the pressure tank in the circulation path.

A flow control valve for use in oil well bore holes. The flow control valve includes a plurality of flow paths connected in parallel. The flow control valve operates by successively opening different flow paths, starting with a flow path that requires a reduced force to operate its inlet valve. The flow rate through the flow control valve is controlled by opening and closing different ones of the plurality of flow paths individually or in combination. A flow path that allows fluid to flow at substantially the full flow rate of the valve is provided as one of the parallel paths. A simple mechanical design using poppet valves and at least one cam is described.

A refrigeration apparatus includes a primary circuit with a first expansion valve, a bypass circuit extending between branching and joining portions on the refrigerant primary circuit, a heat exchanger, a second expansion valve disposed upstream of the heat exchanger in the bypass circuit, first and second refrigerant flow rate calculating components, and a determining component. The primary circuit also includes a compressor, radiator, and evaporator. The heat exchanger includes first and second refrigerant flow paths disposed on the primary and bypass circuits, respectively, to cause heat between refrigerant flowing in the paths. The first and second refrigerant flow rate calculating components calculate first and second flow rates of refrigerant flowing through the bypass circuit based on refrigeration cycle theory and fluid theory, respectively. The determining component determines whether there is refrigerant leakage or refrigerant charge deficiency based on comparison of the first and second refrigerant flow rates.

Mass flow controllers and methods for improving the control of a flow of a variety of fluid types are described. The method includes selecting a process gas type for the process gas that will be controlled and obtaining molecular mass information for the selected processed gas type. General characterization data is obtained that includes, for each of a plurality of flow and pressure value pairs, a corresponding control signal value and operating characterization data is generated by modifying the flow values in the general characterization data based upon the molecular mass for the selected process gas type. The operating characterization data is then used to operate a valve of the mass flow controller in open loop control mode.

A pressure type flow control system with flow monitoring includes an inlet side passage, a control valve comprising a pressure-type flow control unit connected downstream of the inlet side passage, a thermal-type flow sensor connected downstream of the control valve, an orifice installed on a fluid passage connected downstream of the thermal-type flow sensor, a temperature sensor provided near the fluid passage between the control valve and orifice, a pressure sensor provided for the fluid passage between the control valve and orifice, an outlet side passage connected to the orifice, and a control unit comprising a pressure-type flow rate arithmetic and control unit to which a pressure signal from the pressure sensor and a temperature signal from the temperature sensor are input, and which computes a flow rate value of fluid flowing through the orifice, and outputs a control signal to a valve drive unit of the control valve.