# How to compute the residence time for given flow rate in standard cubic meters?

I'm given a flow rate of a gas mixture of $3\ \mathrm{Nm^3/h}$ in standard cubic meters through a cylinder of length $50\ \mathrm{cm}$ and cross section $70\ \mathrm{cm^2}$, can I compute how long a particle will stay inside of the cylinder (which would equal the time the particle can react inside the cylinder)?

And what if the temperature changes during the reaction?

If the flow rate would be given in volume per time, I had an idea to compute this, but the use of standard cubic meters is baffling to me.

• $Nm^3/h$ is volume per time, you just need to transform it the the units you need. the correction for temperature can be done with the ideal gas law (Or Redlich-Kwong, if you want to be really exact). Also note that you will get a mean retention time, not all particles will spend the same time in the reactor. – mart Aug 14 '12 at 15:14
• Isn't the the unit with the N in from something else than just a length? – Nikolaj-K Aug 14 '12 at 17:29
• @chm: The English Wiki has only standard cubic feet... – cbeleites unhappy with SX Aug 16 '12 at 13:45