Which configuration will allow the largest flow to a vacuum pump?

Which configuration will allow the largest flow to a vacuum pump?

• A. One 1 inch hose
• B. One 1/2 inch hose
• C. Two 1/2 inch hoses
• D. Three 2 inch hoses

Answer: (C)

In vacuum work, how much gas can reach the pump is governed by the piping’s conductance—the easier it is for gas to move through the path, the higher the flow. Conductance adds when you have parallel paths, so splitting the flow into multiple hoses can increase the total flow compared to using a single path, especially if the single path has bottlenecks or restrictions elsewhere in the system. Two smaller hoses in parallel give you two conductance paths that sum, which often results in greater total flow into the pump than a single larger hose that might be limited by the same upstream restrictions, or than multiple very long, complex routes with more fittings. The practical effect is that the two 1/2 inch hoses provide a larger combined flow capability under typical setup conditions than the other configurations shown, making them the best setup for achieving the largest flow to the vacuum pump in this context.

In vacuum work, how much gas can reach the pump is governed by the piping’s conductance—the easier it is for gas to move through the path, the higher the flow. Conductance adds when you have parallel paths, so splitting the flow into multiple hoses can increase the total flow compared to using a single path, especially if the single path has bottlenecks or restrictions elsewhere in the system.

Two smaller hoses in parallel give you two conductance paths that sum, which often results in greater total flow into the pump than a single larger hose that might be limited by the same upstream restrictions, or than multiple very long, complex routes with more fittings. The practical effect is that the two 1/2 inch hoses provide a larger combined flow capability under typical setup conditions than the other configurations shown, making them the best setup for achieving the largest flow to the vacuum pump in this context.