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Fluid heater


Pwyll
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This may seem a little OT, but the reason behind it is that I am experiencing difficulties when triallin my LR. So, please Mods, can I run with this?

Some background, not forthe squeemish amongst you. My kidneys are shot. I am on what they call peritoneal dialisys. This means that a sugar/salt solution is held in the layers of my peritoneum and absorbs all the nasties out of my system. When I am trialling I have to leave the fluid out as there is a risk of internal damage due to all the bumping and jolting.

At the moment, I leave the housein the morning "dry" and then reload with fluid when I get home. The trouble is that my giblets are used to a little padding now. they do not take kindly to being sloshed around foreight hours without their little buffer.

My plan is to drain out when I arrive at the event and then refill at the end, before I come home.

The problem I face is that putting cold fluid in is painful and can be dangerous (core temp drops right down). I have a heater pad for the bags of fluid, but that is 240v. I really need something on a timer so that it can be set to start to warm up before i get back to where my road vehicle is parked. This counts out an inverter as I don't think my battery will take being sucked on by one of those for half an hour.

So, is there a 12v solution? Or am I being a little over ambitious with this? I need to heat a two litre bag of fluid to body temp(37C). I have asked around on some of the renal failure forums(yes, there are some) and nobody seems to make a 12v heater. One guy even suggested that I just leave the bag in the window to warm. But, then again, he was from California not Herefordshire!

If anyone can help, this would make my Sundays sooooo much more comfortable. If not, guess I'll just have to put up with it.

Ta,

Paul

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Could you not make something up that your fluid's can be held in with a compartment at the bottom to take a 12v coffee warmer thing?? Like the one's you can get from camping / caravan shops?

They plug into the cigarette lighter and you just put them into a cup. leace for a while & then hot drink. Don't think they actually bring to the boil? just heat to drinking temp??

You could warm it as you play??

Just a thought! Might be of some help??

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So, is there a 12v solution? Or am I being a little over ambitious with this? I need to heat a two litre bag of fluid to body temp(37C). I have asked around on some of the renal failure forums(yes, there are some) and nobody seems to make a 12v heater. One guy even suggested that I just leave the bag in the window to warm. But, then again, he was from California not Herefordshire!

If anyone can help, this would make my Sundays sooooo much more comfortable. If not, guess I'll just have to put up with it.

Ta,

Paul

Heating 2kg of watery stuff up by 37 degrees (e.g. requires 2 x 4200 x 37 Joules of energy, or 311 kJ (in an insulated container). Over 30 minutes this is 172 J/s, or 172 Watts. At 12V, thats 15A, or 7.5 amp hours. This is all do-able, you just need a thermostat to turn it off...

How about a pet bed heater which you can just leave on (15W is only just over an amp)?

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Or even a diesel heater?? They are 12v & have a thermostat. I beleive you can set a timer on them aswell. If you put the air pipe into an insulated container in the car, you could play & it will heat the container from the timer??

Don't think they use alot of juice (battery or fuel)??

Holyzues had one but he's just sold it on. I am sure if you send him a pm he can confirm / answer some questions on this matter??

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If you warm the fluids before you go you just need to maintain the temperature at 37 degrees correct?

If that is the case would an insulated box or thermos do the trick?

Have a look at aquarium supplies for 12v heaters. An insulated box with a 12v heater pad in should do the trick - pretty sure they use these for transporting tropical fish an such like.

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Nice to see errol's brought some maths to the conversation smile.gif, but the bags will (I guess) not be colder than ambient, so they will only need warming up by say 20 - 25 degrees.

Of course, putting the heat in is no good if it just leaks out again.

What about heating the fluid up on a 240 heater at home, then transporting and storing them in an insulated container, like a small cool box (just dragged off google)

sale_%206136.jpg

You could easily mod the box to take your 12v heat source, if the insulation wasn't up to the job.

Edit: took too long to post, few similar posts above!

Edited by LandyManLuke
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That's the sort of thing :)

Also, maybe contact http://projectmobility4x4.org/

They have been working at this sort of thing, if they haven't got a solution yet it would be good for them to look into for their future vehicles perhaps. I know they considered keeping insulin cool for people, but maybe they have also considered this as well. Worth a message.

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Nice to see errol's brought some maths to the conversation smile.gif

Glad to be of service :D It's too late in the working day for me to work out heat losses, but 15W in a well insulated box will probably be good enough to maintain 37 degrees provided that ambient isn't too low, but will struggle from "cold".

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If you use the thermos box then you could add a small heat source to it, say a light bulb inside, and a thermostat. The bulb doesn't need to be big as a 100w mains bulb can cook a chicken in a straw oven!

Trial and error will probably get you a bulb size that doesn't run down your battery. The thermos box will keep the heat in and the thermostat will control the temperature.

Adding more insulation to the box will make it even more effective and reduce the heatable volume to only what you need for your fluids.

Make sure your thermostat is rated to work with 12v dc at the current required or use it to run a relay.

Just noticed the pet bed heater reference. That would be a good one to use.

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Hi just to add my two penith I have a 12v DC fridge from halfords (brought years ago) if I turn the power cord around it turns into a hot locker to keep the food warm, we use it on the boat i.e. cook the food first and then plug it in and it keeps our lunch warm not boiling but still warm enough to eat, you would have to check the spec for the level. It is an insulated box so you could heat them before take them in this and then plug it in to add any further heat you needed.

They are not that power hungry but seem to do the trick, it would certinaly run all day on a lesiure battery but may even be a little to warm.

This type of thing:

http://cgi.ebay.co.u...=item3efe156fdb

Although this is on it's side.

Or even this one fairly small.

http://cgi.ebay.co.uk/fridge-cooler-warmer_W0QQitemZ170462578149QQcmdZViewItemQQptZLH_DefaultDomain_3?hash=item27b05c85e5

Cheers, Jason.

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since you already have the 'complicated' bit - the heater and the timer, I would be tempted to think about a simple split charge system and a second battery. £40 for the split charge, £25 for the inverter plus £50 for a budget leisure battery - all sorted for £115, with the added benefit that you have both a 12 and 240 volt supply in your vehicle that won't kill the main battery that you can use for other things.

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I suggest a cheap Peltier-effect fridge set to "heat". Not particularly efficient but you could just run it off a scrap car battery in the boot of your road car, which you charge up when you're at home.

In fact, I've got just such a fridge which you're welcome to have on long term loan to see if it's going to work before you splash out yourself? Drop me a PM.

A cleverer plan would be to use the stored heat in the coolant of one car or the other, to flash heat the salty solution. The salts are likely to have a much higher specific heat capacity than water so the calcs above are probably an underestimate.

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Firstly, thank you to all that have responded. There has been a much better response to my question than I ever hoped for.

I do like the idea of a leisure battery, split charge and inverter. Unfortunately, my bank balance is not at the moment. Maybe a future project for when I am in gainful employment once more.

I have decided to give the warm it up before you go and then keep it warm option. I have just purchased a small fridge/warmer for the princely sum of £16 on FleaBay. When it arrives there will be a few dry runs to see how it gets on. If they are not successful you will see my latest purchase in the for sale section.

So, watch this space, I will let you know how it goes.

Next job is to fit power steering to the trialler so I don't look like a big girly.

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  • 3 weeks later...

Job Done! Worked a treat, got a few funny looks when I was heavy duty handwashing in the middle of a field. But nothing I can't cope with.

Thanks again for the input that lead to the solution below.

post-14521-127134225323_thumb.jpg + post-14521-127134217876_thumb.jpg + post-14521-127134232489_thumb.jpg

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