Top tips for working under vacuum in jacketed lab reactors

Author: Technical Support
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Date: Jan 10, 2018

A number of factors can affect the vacuum level you achieve in your jacketed lab reactor.

Firstly, we highly recommend that you use glass cone stoppers (first image below) instead of Rodaviss sealing caps (second image below) on any unused lid sockets.

 Glass cone stopper              Reactor-Ready Pilot lid - Rodaviss sealing caps

A common problem when using Rodaviss sealing caps is that the internal seal can be sucked out by the vacuum.  Glass cone stoppers do not experience this issue, and are more chemically resistant too.

Troubleshooting checklist for working under vacuum

Further to using glass cone stoppers, there are a number of additional steps which can help if you would like to improve the performance of the reactor under vacuum.

  • Check that all your O-rings are in good condition and replace any that aren’t. (It is good practice to check and replace your O-rings regularly for all applications, not just those under vacuum.)
  • Ensure that all the other components of your system (such as the stirrer shaft and guide) are positioned correctly and are in good condition.
  • Make sure all joints are clean, tight, and assembled correctly.
  • Check that any valves are closed properly.
  • Ensure the vessel/lid clamp is tightened appropriately.
  • If the vacuum pump or tubing is new, allow the experiment to run for a few hours to achieve the best vacuum levels.
  • Make sure there is no moisture in your system, which can increase the pressure and reduce the vacuum.
  • Some chemists choose to use vacuum (or silicone) grease in glass joints for improved vacuum level, although this is usually not necessary.
  • Ensure you have a suitable vacuum pump (considering the ultimate vacuum etc.) for your application.
  • If you are using a basic jacketed lab reactor, you may need to switch to a more advanced design for better sealing, such as Reactor-Ready.

Other factors that could affect the vacuum level

  • The reaction taking place within the vessel.
  • The stirring speed and the viscosity of material being stirred.
  • The temperature within the vessel.

Using Radleys’ Reactor-Ready series

The type of reactor you use will influence the vacuum levels you can achieve. Our Reactor-Ready series of jacketed reactors have been specially designed to give improved performance compared to traditional systems, and one of these improvements is in vacuum tightness.

You can typically achieve a vacuum of around 10-20 mbar, but 3-5 mbar can be obtained under specific test conditions. You can download a guide to testing the gas tightness of Reactor-Ready using vacuum or pressure.

In addition to improved vacuum level, the improved sealing in Reactor-Ready means the equipment lasts longer because it is less likely to be corroded, less of the valuable product is lost, and the reactor is safer to use.

If you would like any additional information or advice, please email techsupport@radleys.co.uk and we’ll be happy to help.

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