Expert tips on containment, chemical compatibility and caring for your equipment
Containment of chemicals
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1. Containment of chemicals
Containing hazardous and corrosive materials during chemical reactions is paramount for the safety of the chemist and other users around them. It is also important in order to protect all of your laboratory equipment from getting damaged.
While we might not be too worried about a bit of corrosion on scaffolding for example fixed bars at the back of the fume hood, visible corrosion is an obvious sign of failed containment of corrosive materials. Corrosive fumes could reach pieces of equipment which are in the same fume hood and cause damage which might not be visible at first.
When performing reactions in your Mya 4 Reaction Station, you might be reassured to know that the vessels were designed to provide a really good seal. You should be able to apply a vacuum of about 10 mbar or lower, even while an overhead stirrer is running. This is thanks to the design of the vessels, which is based on the design of our jacketed reactors: a vessel with a flat flange, a lid with a flat flange, and an O-ring that gets compressed between the two.
[Please note that a continuous vacuum should only be applied via a side arm or a neck on the lid, rather than through the gas outlet of the Reflux or Manifold Head. This is to avoid solvents going up through the head. Vacuum can be applied through the head only when doing vacuum purge cycles: the vacuum is only applied for a couple of seconds in order to replace air with inerting gas.]
Despite the good seal inherently offered by the Mya 4 glassware, you will need to use a series of precautions in order to insure containment of your chemicals:
1.1 Neutralising off-gases
If your reaction uses or produces corrosive or toxic gases, these will need to be scrubbed. This can be done by using specifically designed gas scrubbers but can also be done using a locally-sourced Drechsel bottle containing a neutralising solution. Instead of allowing the gas to escape into the fume hood and potentially corroding laboratory items, the gas is directed to bubble inside a neutralising solution.
1.2 Inerting reactions
The Manifold and Reflux Head options make it easy to inert process vessels and round bottom flasks on the Mya 4 Reaction Station. An inerting gas such as Nitrogen or Argon can be connected to the back of the head and will be distributed to all four positions. In order to prevent a build-up of pressure in the glassware, it is important to either:
- Have the inert gas going into the reaction vessel but with a bubbler connected to, for example, the top of a condenser
- Have a bubbler upstream by using a Schlenk line to supply inert gas to the back of the head or by adding a bubbler between a direct supply and the head
- In the case of a reaction that generates toxic/corrosive gases, it is sometimes preferred to isolate the reaction vessel from the head by closing the tap on the PTFE cap and to have an outlet from the glassware assembly to a scrubber (as discussed above).
1.3 Performing additions of corrosive or toxic chemicals
Containment should also be considered when making additions. Chemists should use syringes or other contained additions tools when possible. Another option is to perform the addition in a separate fume hood which does not contain any laboratory equipment susceptible to corrosion.
One should also minimise, and eliminate if possible, open containers of corrosive or toxic materials in the vicinity of the equipment.
Working up of reaction mixtures at the end of an experiment should also be carefully performed to minimise the risks of spillage of corrosive and/or toxic materials. It is very easy to remove a Mya 4 overhead stirrer motor, close the valve on the cap and remove the glassware assembly in a contained way. This would allow the work-up to be carried out in a separate fume hood or glove box, away from the equipment, reducing the risk of corrosion to the equipment.
When working under reflux, it is important to do so in a controlled way.
Here a few guidelines to follow to ensure efficient refluxing and containment of solvent vapours when using the reflux head or the manifold head on the Mya 4 Reaction Station:
- Use of water/coolant in the reflux/manifold head is essential to maintain satisfactory refluxing to minimise chemical vapours passing up in to the head, potentially damaging it. Ensure the coolant temperature is appropriate, considering the boiling point of the chemicals being used. Use a of recirculating chiller can further reduce solvent losses.
- The maximum recommended volume of each vessel is 50% of its nominal volume. E.g. when using a 400 ml Process Vessel, the recommended maximum fill volume for refluxing is 200 ml. Overfilling the vessels could lead to too much vapour being produced.
- Do not overheat. Heating at a temperature too high above the boiling point could generate too much vapour for the reflux head or condensers to be able to condense. Aim for a gentle reflux, rather than vigorous boiling. For average boiling solvents, the block temperature should be set about 10 degrees above the boiling point.
When using a manifold head with water condensers, please note that, although the condensers are small, they have been designed and tested to work with the range of Mya 4 vessels when following the above guidelines.
The external surfaces of the Mya 4 and accessories are resistant to the majority of solvents, and are splash-resistant to alkalis and dilute acids at room temperature. However, it is recommended that you clean up any spillages or areas that have become contaminated immediately.
1.7 Chemical compatibility
When trying to contain chemicals, it is very important to consider chemical compatibility between the materials used in a reaction and the materials involved in the reaction vessel and other components. The next section is dedicated to chemical compatibility considerations.
2. Chemical compatibility
2.1 Wetted components
When considering chemical compatibility, you should consider the materials of construction of the parts which are considered to be ‘wetted components’. These are the parts which will be in contact with your reaction mixture. It is also recommended to consider components which are not in contact with your reaction mixture but are likely to be in contact with chemical vapours.
Wetted components are items such as: vessel and lid, O-ring between vessel and lid, condenser, stirrer bar or stirrer shaft, anything used for additions.
O-rings and seals can often be overseen when considering chemical compatibility. Please refer to the specific section of O-rings and seals below.
2.2 Material of construction available in Component Catalogue
As a Mya 4 user you will have access to the Mya 4 Component Catalogue which lists all the accessories available for the Mya 4 Reaction Station. The catalogue contains useful information on the various Mya 4 components, including materials of construction.
If you have misplaced your Component Catalogue or require an up-to-date version, please contact your local Radleys representative.
2.3 O-rings and seals: materials and care
As a general rule, O-rings and seals are consumables. They should be regularly checked for any change of shape, tearing, splitting etc. and replaced as required. It is not normal for these O-rings to need replacing very frequently, as the materials have been chosen for characteristics including chemical resistance, but their lifespan will depend on your application (which specific chemicals you use, and how you use the equipment). It is recommended you hold spares of O-rings and seals to avoid any downtime.
When there are alternative options for O-ring materials, please consult chemical compatibility tables online to check which material is most suitable for your chemistry. Please also think about chemical compatibility with the solvents you use for cleaning. For example, materials such as nitrile and Viton are not compatible with acetone and should be cleaned with an alternative solvent.
The O-ring used between vessels and multi-neck lids are a wetted component. These are nitrile O-rings as standard but are also available in FFKM (also known as Chemraz or Kalrez).
The O-rings in the PTFE caps and on the gas outlets on the reflux/manifold head are not strictly wetted components but could be in contact with chemical vapours. These are nitrile as standard but are also available in Viton.
Similarly, the seals in the stirrer guide of the Mya 4 overhead stirrers could be in contact with chemical vapours. Please note the material of these is Viton.
2.3.1 Stirrer guide care
The Mya stirrer guide is a precision-engineered component of your Mya 4 that allows proper connectivity, sealing, and alignment of the Mya Compact Stirrer, stirrer shaft, and Mya 4 glassware.
Always handle the Mya Stirrer Guide – PEEK Bearing Sub-Assembly with great care to avoid damage to the sealing surfaces and features. The sealing edge is very flexible and could easily be deformed if mishandled – damage to this part could affect the sealing performance as well as cause unwanted friction during use.
If the sealing edge (the section of the stirrer guide holding the O-ring) becomes deformed, gently reform it to a perfect circular shape (see instructions page 72-74). Spare O-rings (RR40834) come with a positioning tool to make the replacement easier.
2.4 Non-wetted components
As well as some components in direct contact with chemicals and components potentially in contact with chemical vapours, there are components which are not meant to be in contact with chemicals at all.
These components do not have as high a chemical resistance (since they are not designed to be in contact with chemicals) but could still get damaged when spills occur or when containment of vapours has failed. To avoid this from occurring, please refer to the first part of this guide: ‘Containment of chemicals’.
3. Equipment needs
The Mya 4 Reaction Station requires the following utilities:
- a mains power socket,
- a flow of coolant,
- an inert gas supply x2 (or divided at the source), or an inert gas supply and a dry gas supply,
- a drain connection (or a container at floor level) to evacuate any water collected inside the Reaction Station due to condensation.
3.1 Gas purge
A flow of inert or dry gas (nitrogen, argon, dry compressed air) is essential to protect the internal components of Mya 4 from ambient hazardous or corrosive gases and vapours, as well as condensation of atmospheric moisture.
|Minimum flow rate||3 L/min|
|Maximum flow rate||15 L/min|
To ensure correct operation of Mya 4, it is important to control and monitor the purge gas flow within the stated operating limits at all times by using the gas flowmeter supplied.
Operating Mya 4 without an inert/dry gas purge can damage the instrument and will void the warranty.
3.2 Coolant supply
Mya 4 requires a liquid coolant supply to be connected and running at all times when the unit is in operation. The coolant flows through Mya 4’s internal heat exchangers, which are located in each reaction zone, to dissipate heat from the cooling Peltier cells.
|Coolant supply||Mains water or ethylene glycol mix (max 30% vol.)|
|Max coolant temperature||35 °C|
|Min coolant temperature||5 °C|
|Max flow rate||5 L/min|
|Min flow rate||2 L/min|
|Max coolant pressure||2 bar|
|Min coolant pressure||0.3 bar|
|Coolant in/out connectors||Quick release, barbed 9.5 mm for 8–10 mm ID tubing|
If using a thermoregulator:
Both specs below required:
|Min cooling power at 15 °C||1.5 kW|
|Min cooling power at 0 °C||1.0 kW|
Always use the maximum flow available from the thermoregulator, up to a maximum of 5 L/min.
3.3 Internal drain
When operating at low temperatures or in high-humidity conditions, some internal condensation may form within the unit. This condensation is normal and will be confined and channeled to the Internal Drain Out outlet.
The tubing leading from the Internal Drain Out to the drain (or suitable container) must be level with or lower than the Internal Drain Out connector to ensure liquid properly drains from inside the unit, preventing serious damage.
If you have any doubts or questions, please contact us.