How can the purity of my Nitrogen Generator be affected?

How can the purity on the Nitrogen Generator changes when it is sized to deliver constant Nitrogen flow at required purity?

Pneumatech Gas Generator Family

Pneumatech Nitrogen Generators purity levels depend on the control flow through the carbon molecular sieve (CMS) of the unit. Low flow results in higher purity and high flow results in lower purity.

The flow is influenced exclusively by the pressure difference between the air vessel and the nitrogen vessel. The higher the pressure difference, the higher the flow. The generator is sized to deliver 100% nitrogen to the nitrogen vessel during normal operation. When the application consumes less than 100% of the generator's capacity (example: 30%), the generator is able to maintain the pressure in the nitrogen vessel at a constant level. This also means the pressure diffference between the air and nitrogen vessels remains constant. This results in a stable flow through the generator's adsorbant and a stable purity.
When the needle valve is opened further, more flow from the nitrogen vessel can be consumed. If this flow consumption is higher than the maximum flow the generator can deliver (example: 150%), the pressure in the nitrogen vessel will decrease.
With this, the pressure difference between the air and nitrogen vessel will increase, resulting in a high flow through the adsorbant because the air vessel pushes high pressure air to the nitrogen vessel which is at a low pressure. Due to this high flow through the adsorbant, the purity will decrease.