Claims
- 1. In a computer controlled system for filling a cylinder with a gas, the system including (a) a source of gas, (b) a plurality of valves for controlling flow of the gas to the cylinder, (c) a transducer for measuring pressure of the gas flowing to the cylinder, and (d) a weight scale for determining weight of the cylinder when filling the cylinder with the gas,
a method of filling the cylinder with a target weight of the gas comprising the steps of:
(a) successively measuring the weight of the cylinder at periodic time intervals to obtain successive actual weights of the cylinder; (b) opening a first valve and filling the cylinder with the gas at a high flow rate; (c) closing the first valve after reaching a predetermined weight difference between the target weight and an actual weight; (d) after step (c), opening a second valve and filling the cylinder with the gas at a low flow rate; (e) after step (d), controlling by an adjustable valve, flow of the gas to the cylinder; (f) differencing each successive actual weight measured in step (a) from the target weight of the gas to obtain a plurality of first difference values; (g) differencing adjacently measured actual weights obtained in step (a) to obtain a plurality of second difference values; and (h) controlling, by the adjustable valve, flow of the gas to the cylinder based on each first difference value and a corresponding second difference value.
- 2. The method of claim 1 in which step (h) includes
multiplying each first difference value by a constant value to obtain a respective scaled first difference value, comparing a scaled first difference value with a corresponding second difference value, and adjusting flow of the gas to the cylinder based on the comparison.
- 3. The method of claim 2 in which
step (g) includes logging into a buffer the plurality of second difference values; and step (h) includes either of the following sub-step (i) or sub-step (ii):
(i) maintaining flow of the gas to the cylinder, if the plurality of second difference values stored in the buffer are greater than the corresponding first scaled difference values; or (ii) adjusting flow of the gas to the cylinder, if the plurality of second difference values stored in the buffer are less than the corresponding first scaled difference values.
- 4. The method of claim 3 in which
sub-step (ii) includes sending a reduced current value to the adjustable valve to reduce the rate of flow of gas to the cylinder.
- 5. The method of claim 4 in which the reduced current value is based on a user mix tolerance value, and
the reduced current value sent to the adjustable valve is a first current value if the user mix tolerance value is less than or equal to 1 percent, and is a second current value if the user mix tolerance is greater than 1 percent, the first current value being smaller than the second current value.
- 6. The method of claim 5 in which the first current value is 0.00001 milliamperes, and the second current value is 0.0001 milliamperes.
- 7. The method of claim 1 including the steps of:
(i) establishing a tolerance range value between the target weight of the gas cylinder and a measured actual weight of the gas cylinder; and (j) rejecting the gas cylinder if the actual weight of the gas cylinder is outside the established tolerance range value; wherein the tolerance range value is based on a ratio of a user mix tolerance value and a mix tolerance divisor, the mix tolerance divisor being a first value when a pressure of the gas supplied to the cylinder is greater than 1000 psig and a second value when the pressure of the gas supplied to the cylinder is less than 1000 psig, the first value being larger than the second value.
- 8. In a computer controlled system for filling cylinders with at least one gas, including multiple valves for controlling flow of respective gasses to the cylinders, a method of controlling filling of the cylinders comprising the steps of:
(a) storing valve command data in a first array; (b) communicating the stored valve command data to the valves; (c) monitoring status of each of the multiple valves; (d) waiting a predetermined time after communicating the stored valve command data to the valves in step (b); (e) storing the status of the valves in a second array, after waiting the predetermined time in step (d); (f) comparing the valve command data stored in the first array with the valve status stored in the second array; and (g) continuing filling of the cylinders with the gas based on the comparison in step (f).
- 9. The method of claim 8 in which
step (f) includes determining if the valve status stored in the second array corresponds to the valve command data stored in the first array; and step (g) includes stopping the filling of the cylinders, if the comparison determines that the valve status is different from the valve command data.
- 10. The method of claim 8 further including the step of:
(h) displaying the valve status on a screen.
- 11. The method of claim 8 further including the steps of:
(h) displaying the multiple valves on a screen; and (i) programming virtual instruments to control the multiple valves and displaying the virtual instruments on the screen; and in which step (b) includes communicating the stored valve command data to the multiple valves using the virtual instruments.
- 12. The method of claim 11 in which
programming the virtual instruments includes configuring the virtual instruments on the screen using G programming language.
- 13. In a computer controlled system for filling a cylinder with a gas, the system including (a) a source of gas, (b) at least one valve for controlling flow of the gas to the cylinder, (c) a transducer for measuring pressure of the gas flowing to the cylinder, and (d) a weight scale for determining weight of the cylinder when filling the cylinder with the gas,
a method of filling the cylinder to a target weight of gas comprising the steps of:
(a) successively measuring the weight of the cylinder to obtain successive actual weights of the cylinder; (b) opening a first valve and filling the cylinder with the gas at a high flow rate; (c) closing the first valve after reaching a predetermined weight difference between the target weight and an actual weight; (d) after step (c), opening a second valve and filling the cylinder with the gas at a low flow rate; and (e) after step (d), controlling by a third valve, a flow of gas to the cylinder; wherein controlling by the third valve includes reducing the flow of gas to the cylinder, if a difference value between successive actual weights of the cylinder is smaller than a predetermined value.
- 14. The method of claim 13 in which
step (c) includes closing the first valve after reaching a weight difference of 30 grams or less between the target weight and the actual weight.
- 15. The method of claim 14 including the step of:
(f) measuring pressure of the gas flowing to the cylinder; and step (c) includes closing the first valve after measuring 1000 psi of pressure.
- 16. The method of claim 13 in which reducing the flow of gas to the cylinder includes
adjusting an amount of gas flowing through the third valve by a first value, if a user mix tolerance value is less than or equal to one percent, and adjusting the amount of gas flowing through the third valve by a second value, if the user mix tolerance value is greater than one percent.
- 17. The method of claim 16 in which control current is sent to the third valve to control the amount of gas flowing to the cylinder; and
the first value for adjusting the amount of gas flowing through the third valve is 0.00001 milliamperes, and the second value is 0.001 milliamperes.
- 18. The method of claim 16 in which reducing the flow of gas to the cylinder includes periodically adjusting the third valve until a difference between the target weight and the actual weight is less than or equal to 0.1 grams.
- 19. The method of claim 13 wherein the first valve is closed after reaching a 30 gram weight difference between the target weight and the actual weight, and the second valve is opened to fill the cylinder at the low flow rate.
- 20. The method of claim 13 wherein step (a) includes successively measuring the actual weight of the cylinder at a periodic rate of 10 sample measurements per second.
Parent Case Info
[0001] This application claims priority of U.S. Provisional Patent Application Serial No. 60/324,876 filed Sep. 26, 2001.
Provisional Applications (1)
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Number |
Date |
Country |
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60324876 |
Sep 2001 |
US |