Computer controlled apparatus and method of filling cylinders with gas

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).

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.