초록 ▼

An ultra accurate gas injection system includes an input device for inputting setpoint data including a target flow rate for the flow of gas into the system. The gas flows through a mass flow controller at an actual flow rate. The mass flow controller issues a flow rate signal indicative of at least

An ultra accurate gas injection system includes an input device for inputting setpoint data including a target flow rate for the flow of gas into the system. The gas flows through a mass flow controller at an actual flow rate. The mass flow controller issues a flow rate signal indicative of at least the actual flow rate and receives a flow control signal. The mass flow controller is configured to control the actual flow rate dependent at least in part upon the flow control signal. A programmable controller is electrically connected to the input device and the mass flow controller. The programmable controller receives the setpoint data from the input device and issues the flow control signal, the flow control signal being dependent at least in part upon the target flow rate contained within the setpoint data. The programmable controller repeatedly reads the flow rate signal and compares the actual flow rate with the target flow rate. The programmable controller adjusts the flow rate signal dependent at least in part upon the comparison of the actual flow rate with the target flow rate, and is configured to adjust the flow control signal such that the actual flow rate is substantially equal to the target flow rate. The programmable controller issues an output signal dependent at least in part upon the flow rate signal. An output device is electrically connected to the programmable controller and receives the output signal. The output device indicates the actual flow rate.

대표청구항 ▼

1. A method of injecting a precise concentration of at least one gas into an external system of known volume, said method comprising the steps of:determining a desired concentration of each at least one gas to be contained within the external system; selecting a desired flow rate at which the at lea

1. A method of injecting a precise concentration of at least one gas into an external system of known volume, said method comprising the steps of:determining a desired concentration of each at least one gas to be contained within the external system; selecting a desired flow rate at which the at least one gas is injected into the external system; calculating a time period during which the at least one gas is injected into the external system, said time period determined at least in part by said desired concentration, said desired flow rate and the volume of the external system; inputting said desired flow rate and said time period to a programmable controller, said programmable controller receiving a flow rate signal and issuing a flow control signal dependent at least in part upon said flow rate signal; injecting at an actual flow rate the at least one gas into the external system; controlling said actual flow rate with a mass flow controller, said mass flow controller issuing said flow rate signal and receiving said flow control signal, said mass flow controller adjusting said actual flow rate dependent at least in part upon said flow control signal; adjusting said flow control signal such that said actual flow rate is substantially equal to said desired flow rate; and ceasing said injecting step upon the expiration of said time period.