S.H.C Heating Elements

A teacher has asked me to search out some shorter Immersion heating rods, as the ones we have to go in our Block Calorimeter Aluminium blocks poke out about 1/2 their length from the core.
He believes they are loosing quite allot of heat to the air, but I'm having trouble finding ones that area only 70mm long.
From what I can find, they all seem to be quite long (150mm), but generally specify that only the last 70mm of the tip actually contain a heating element. Is this standard for these, making shorter ones rather pointless? Would insulating the upper 1/2 be a better course of action?

Any pointers on this would be great.

link:- https://www.philipharris.co.uk/prod...sfer/immersion-heater-12v-50w-bundle/b8r07759
 

Nick Mitchener

COMMITTEE
I saw some shorter ones recently from one of the cheaper suppliers, they had red leads. I agree, the heating element is in the lower part of the rod and given the results people get I don't think it is an issue. It is also something useful to discuss with students when you look at limitations of the equipment and the experiment. I would have thought the type of power supply used and the resultant accuracy of the voltage reading might be a bigger issue.
 
I saw some shorter ones recently from one of the cheaper suppliers, they had red leads. I agree, the heating element is in the lower part of the rod and given the results people get I don't think it is an issue. It is also something useful to discuss with students when you look at limitations of the equipment and the experiment. I would have thought the type of power supply used and the resultant accuracy of the voltage reading might be a bigger issue.
That's my view on it, the lost heat is a good discussion of experimental error.
do you happen to know which supplier had the shorter ones, just so I can pass it to him to have a look?
many thanks.
 

Nick Mitchener

COMMITTEE
SLS and Better equipped both do immersion heaters of 100mm length.
I tried SLS and didn't get any results, but I've found the 100mm ones on better equipped.
Many thanks.
 
I tried SLS and didn't get any results, but I've found the 100mm ones on better equipped.
Many thanks.
I had the same problem until I realised they were called immersion heaters. There seemed to be nothing related to SHC from a search. I had to find them in the catalogue (non digital version) before I tracked them on the website.
 
I had the same problem until I realised they were called immersion heaters. There seemed to be nothing related to SHC from a search. I had to find them in the catalogue (non digital version) before I tracked them on the website.
The name caught me. I would have gone for "heat rods", "heating elements". "immersion heaters" sounds like what you would put in a fish tank.
 
I've heated, horizontally in air, one of the heaters we have and it appears it heats along the whole 150mm length uniformly.
- I placed a line of Petroleum Jelly in a row, like a short wall, the full length of the heater, it all melted uniformly, and after around 60s it all slid off together leaving a small blob near the tip that fell a short time after.
Maybe we have some older ones with long internal elements.
 
Our cylindrical heaters the top third don't heat up and stick up out of the top of cylinders , it's SHC I wonder if a member of teaching staff needs to have a rethink ,,,,!,,,,,! It's kids measuring things I would think the heat loss wouldn't effect the results we never had a problem in thirty years !!!!!!
 
Our cylindrical heaters the top third don't heat up and stick up out of the top of cylinders , it's SHC I wonder if a member of teaching staff needs to have a rethink ,,,,!,,,,,! It's kids measuring things I would think the heat loss wouldn't effect the results we never had a problem in thirty years !!!!!!
The kids all got about half of the SHC value should have been. It made a good discussion on experimental error for the calss.
 
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