What is the maximum temperature of Heat-On?

Our general guidance for Heat-On is that blocks (including inserts) and covers can be used at up to 200°C without damage to the block or cover, and that up to 260°C could be achieved but there is a risk of some slight damage – polymer-coated Heat-On blocks may have some coating degradation, anodised blocks may become discoloured, and PTFE covers may experience some distortion. For the polymer-coated blocks, 200˚C is fine but above this the coating may be damaged by prolonged high temperatures.  Very high temperatures are more likely to lead to more damage (peeling etc.). Anodised blocks do not have this risk of coating damage.  At very high temperatures, the block may become discoloured, but this is an appearance issue only. We can’t give data on exactly when (times and temperatures) damage starts / is significant; in addition to temperature, the risk/extent of any damage will be affected by factors such as how old the blocks etc. are, how much they’ve been used previously, and what chemical exposure they’ve had. In terms of the maximum temperature a Heat-On block is physically able to reach, this will depend on the heat source, heat transfer and heat loss etc. – various factors including the particular magnetic stirring hotplate used, the load to be heated, and the ambient temperature etc.  Some customers report adding insulation to the flask, and reaching temperatures as high as 280˚C, although we cannot make any guarantees. If you would like to work at high temperatures, we would advise selecting the anodised version of Heat-On, as then there is only the risk of discolouration, rather than coating coming off.

How do I choose between polymer-coated and anodised Heat-On?

The Heat-On blocks, holders and inserts can be purchased either fluoropolymer coated or anodised. The polymer coating has been designed to give additional chemical resistance to the block. This is our most popular finish. Care should be taken not to damage the coating through abrasion/scratching, high temperatures, or chemical exposure.

Heat-On 5L Polymer coated

The anodised version is slightly lower cost. When working at high temperatures, we would advise selecting the anodised version of Heat-On, as then there is only the risk of discolouration, rather than damage to the coating.

Heat On 5L Anodised finish

Is Heat-On chemically resistant?

Anodised Heat-On blocks are resistant to the majority of solvents and splash resistant to dilute acids and alkalis at room temperature. The fluoropolymer coated Heat-On blocks offer superior resistant to the majority of solvents, acids and alkalis. However, it is important to clean off any chemical spills as soon as possible.  Be careful that there is not chemical spillage between the flask and the Heat-On. Extended exposure to acids or alkalis will attack the surface of the Heat-On blocks. The stronger the concentration and the longer the exposure time the higher the likelihood of damage and the greater the degree of any damage.  Heat will also speed up and intensify any attack.

Will Heat-On crack my flask?

Heat-On has an advanced, proprietary design (shape) that means it does not have the same risk of shearing flasks as other companies’ blocks. Heat-On’s proprietary design also means that flasks sit lower down in the block than other companies’ blocks, maximising the heated surface area, and meaning that if there ever was a break in the glass, the block can contain the contents, unlike competitor blocks. If used correctly (see below), flasks should not break in Heat-On.  The few reports we have received of flask breakages have been due to one or more of the factors below. Factors to consider:
  • Use suitable size/shape flasks
  • Ensure flasks are in good condition – not scratched, no hairline cracks or chips, and annealed during manufacture (purchased from a reputable supplier)
  • Ensure the glassware and Heat-On are clean – no chemicals/residue/grit between the two
  • Don’t pressurise flasks – don’t seal heated flasks closed (unless specifically designed for pressure)
  • Don’t use very large/heavy equipment set-ups above the Heat-On
  • Preferably load your glassware into the block when the block is at ambient (room temperature).  If this is not possible, at least ensure that flasks are removed at or above the temperature they were originally inserted – e.g. don’t heat up the Heat-On, then insert your flask, then allow the Heat-On to cool back down to below the temperature when the flask was added

Can I use all my glass flasks with Heat-On?

As part of Heat-On product development, Radleys have evaluated flasks from a variety of glass manufacturers to ensure that Heat-On blocks will accept the widest possible range of sizes and styles.  However, because the tolerances on mass produced glassware can vary greatly, it is not possible to guarantee that all brands will fit.  Indeed, experience shows us that glassware from a single manufacturer may vary considerably in size and shape from batch to batch and also from item to item.  We therefore advise that customers pre-select appropriate sized glassware to use with Heat-On.
Heat-On has a slightly narrower diameter at the top of the block well, to help stop oversized flasks from fitting through.  Of flasks that can be inserted into the Heat-On block, suitable flasks should sit at the bottom of the well, and be a loose fit in the well – able to spin freely in the Heat-On well, without catching or sticking on the sides of the well.  If the flask is catching or sticking, it may be misshapen, and may result in jamming or even cracking of the flask when the Heat-On block is cooling.  If the flask does not spin freely then it is unsuitable for use in the Heat-On and an alternative flask should be used.We can provide maximum flask outer diameter dimensions for specific Heat-On blocks; please contact us.

I have a square/rectangular hotplate – can I use Heat-On?

Yes, you can. To secure Heat-On to square or rectangular hotplates, use RR61087 Heat-On Adapter Plate for Square Hotplates. It has four sliding (adjustable) jaws that enable you to fit it onto your hotplate.  There is a circular protrusion on top that fits the recess in the bottom of Heat-On.  This means the Heat-On block is secure and there is good heat transfer between the hotplate and the Heat-On. RR61087 is suitable for hotplates from 140 x 140 mm to 200 x 200 mm.

My hotplate is 145 mm in diameter. Will Heat-On fit?

Yes, Heat-On is suitable for use with hotplates with a 145 mm diameter, such as Heidolph hotplates.   Heat-On blocks have a 145 mm diameter recess in the base to locate onto the hotplate.

When should I use a Heat-On Multi-Well Holder?

Heat On Multi Well Holder

The Multi-Well Holder is designed secure Heat-On inserts to the hotplate.  Inserts are smaller than stand-alone blocks, and are available for small flasks and tubes/vials.

Heat On Multi Well Holder

We recommend that the Multi-Well Holder is used when working with Heat-On inserts, because it is safer since the insert is secured to the hotplate (less chance of being knocked off), and there could be improved heat transfer from the hotplate compared to using the inserts alone.  Furthermore, it has probe holes, while older inserts did not have them. However, you may choose to use inserts on hotplates without the Multi-Well Holder.

Does Heat-On have handles?

We offer optional, removable safety lifting handles (part number RR61080), which have a simple and secure mechanism that allows the user to quickly attach the handles and remove the Heat-On block (or Multi-Well Holder) from the heat source, even whilst it remains hot.

Heat on handles

Please check your laboratory safety health and safety policy.  Many laboratories do not permit the handling of hot liquids or objects and therefore the use of the optional handles may not be permitted.

Do Heat-On blocks nest (have one base block, and achieve smaller sizes by adding inserts and building up)?

No, Heat-On blocks are stand-alone rather than requiring nesting.  This means you can carry out more reactions at once (use your different volume Heat-On blocks at the same time), and the heating is more efficient than if using nested inserts.

Can you provide performance data for Heat-On?

Yes – you can download ‘TDS02S Heat-On Application Bulletin’ from our Technical Information Downloads webpage

How can I protect my fluoropolymer-coated Heat-On from damage?

The fluoropolymer coating is our most popular format of Heat-On.  It offers additional chemical resistance compared to the anodised aluminium finish. However, care should still be taken to prolong the life of your polymer-coated Heat-On. The coating may be damaged by the factors listed below.  For some applications, the anodised Heat-On may therefore be more suitable.
The fluoropolymer coating has excellent chemical resistance, but it can be damaged through exposure to some chemicals, particularly high concentrations of corrosive chemicals, or over extended periods of time, or if heated. It is important to clean off any chemical spills as soon as possible.  Consider also any chemicals that could be on your glassware – glassware should be kept clean if using with Heat-On.
Physical abrasion
Rubbing, scratching, scraping, wearing etc. could all damage the coating. Possible causes of this are use of glassware with a rough surface (scratched or uneven etc.), chemical residue / grit between the glassware and the Heat-On, use of a magnetic stirring bar directly in the Heat-On, or placing other equipment inside the Heat-On (e.g. during storage).
High temperatures
Our general advice is that Heat-On can be used up to 200°C without damage to the block, with temperatures up to 260°C possible but with a risk of minor surface degradation. For the polymer-coated blocks, above 200°C the coating may be damaged by prolonged high temperatures. Very high temperatures are more likely to lead to more damage.  If the coating has already been weakened by chemical exposure and/or physical abrasion, it is likely to be more sensitive to temperature. (For further details, you can refer to the FAQ entry, ‘What is the maximum temperature of Heat-On?’)

How many Heat-On inserts can I fit together in a Multi-Well Holder?

You can fit one of the largest insert, for 150 ml round bottom flasks, into the Multi-Well Holder.

Heat-On multi well holder 150ml insert

For all other inserts (smaller flask volumes and tubes), you can fit two inserts alongside each other in the Multi-Well Holder.

Heat-On multi well two inserts

What are the dimensions of the Heat-On Heated Vacuum Desiccator?

The overall dimensions of the Heat-On Heated Vacuum Desiccator are as follows (in mm): Dimensions

What material is the Heat-On Heated Vacuum Desiccator O-ring? Can I buy a replacement?

The Heat-On Heated Vacuum Desiccator red O-ring is silicone.

Heat-On Vacuum Desiccator base showing O-Ring

It is available as a spare part:
  • RR68006: Silicone O-Ring
We could potentially supply this O-ring in an alternative material as custom if required; please contact Technical Support to discuss further.

Are the metal connectors on the Heat-On Heated Vacuum Desiccator available spare parts?

Heated Vacuum Desiccator

Yes, the metal fittings (quick connects) shown to the right in the images can be purchased as spare parts:
  • RR68008: Quick Release Threaded Chrome Fitting
  • RR68010: Quick Release Probe to Barb Chrome Fitting

Vacuume desiccator chrome fittings
(The black O-rings are not available separately.)