Heidolph Heat-On - Manual (Page 11)

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Page 10
Set-Up
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Heat-On Instructions
Description of Problem
1. The flask does not spin freely and therefore is deformed and is catching or sticking on the inside of the well. The flask may well crack
when the Heat-On block cools.
2. There is grit or an object between the flask and the well.
3. The flask was sealed with a closure or cap and there was a build up of pressure in the flask during heating.
4. The flask was scratched, or cracked and failed due to weakness.
5. The flask was not properly annealed during manufactured and has cracked due to stress.
Remedy
1. There is simple rule when using glassware with the Heat-on: “If it does not spin, then throw it in the bin”. If the flask does not spin
freely then it is unsuitable for use in the Heat-On and an alternative flask should be used.
2. Always thoroughly clean the Heat-On block before and after use.
3. Never heat sealed glass vessels, unless they are specifically pressure rated.
4. Never use glassware that shows signs of scratching, cracking or has chips, as this causes inherent weaknesses in the glass strength.
5. Always buy glassware from reputable sources.
Warning
Factors that could lead to a flask failure...
Flask selection process
Heat-On is designed so that over sized flasks cannot fit through the slightly narrower opening at the top of the block well. This means that
all suitable flasks should sit at the bottom of the block well, be a loose fit and as such spin freely in the Heat-On well.
When a flask is inserted into the well it is important to ensure that the flask touches the bottom of the well and does not ‘catch or stick’
on the sides of the block well. If the flask is ‘catching or sticking’ it may be deformed and may result in jamming and even cracking of the
flask when the Heat-On block is cooling.
There is a simple rule when using glassware with the Heat-on: “If it does not spin, then throw it in the bin”. If the flask does not spin
freely then it is unsuitable for use in the Heat-On and an alternative flask should be used.
Heidolph-Heat-On Instructions 23-03-09:2nd draft amends 16-03-09 23/3/09 15:37 Page 11