Post by thread:[OT] temperature compensated enclosure

Not sure if that describes what I am after... I have a project I am looking at where they have a heater and controller inside a 18"x14" enclosure and want to keep the temp around 70-100 C. Are there any off the shelf enclosures that have some sort if insulating properties so can maintain this? It will be sealed, and never opened during operation.

alan smith wrote: > Not sure if that describes what I am after... > > I have a project I am looking at where they have a heater and controller inside a 18"x14" enclosure and want to keep the temp around 70-100 C. Are there any off the shelf enclosures that have some sort if insulating properties so can maintain this? It will be sealed, and never opened during operation. > > > Depends. If this is a one-off for use in your lab only, consider an ice chest. The 100C end will need verification that it won't deform...

How about an oven? Cheerful regards, Bob On Wed, 3 Sep 2008 13:34:30 -0700 (PDT), "alan smith" <spam_OUTmicro_eng2TakeThisOuTyahoo.com> said: > Not sure if that describes what I am after... > > I have a project I am looking at where they have a heater and controller > inside a 18"x14" enclosure and want to keep the temp around 70-100 C. > Are there any off the shelf enclosures that have some sort if insulating > properties so can maintain this? It will be sealed, and never opened > during operation. -- http://www.fastmail.fm - And now for something completely different…

A dishwasher would probably work, too. Cheers, Bob On Wed, 3 Sep 2008 13:34:30 -0700 (PDT), "alan smith" <.....micro_eng2KILLspam@spam@yahoo.com> said: > Not sure if that describes what I am after... > > I have a project I am looking at where they have a heater and controller > inside a 18"x14" enclosure and want to keep the temp around 70-100 C. > Are there any off the shelf enclosures that have some sort if insulating > properties so can maintain this? It will be sealed, and never opened > during operation. -- http://www.fastmail.fm - Access your email from home and the web

2008/9/3 alan smith <micro_eng2KILLspamyahoo.com>: > Not sure if that describes what I am after... > > I have a project I am looking at where they have a heater and controller inside a 18"x14" enclosure and want to keep the temp around 70-100 C. Are there any off the shelf enclosures that have some sort if insulating properties so can maintain this? It will be sealed, and never opened during operation. What about a glass aquarium (or two) mounted one inside the other and fill the space between them with either nothing (suck the air out then seal it) or some fibreglass insulation. That's probably about as off the shelf as you are going to get for such a large enclosure. -- Jon Baker

Sucking enough of the air out to make it really insulate well will collapse the glass. You need a pretty serious vaccum to make that work. Best bet is to use styrofoam or equivalent. How critical the insulation is will depend on how stable you need to keep the temperature. -Pete On Sep 3, 2008, at 3:17 PM, Jon Baker wrote: {Quote hidden}> 2008/9/3 alan smith <.....micro_eng2KILLspam.....yahoo.com>: >> Not sure if that describes what I am after... >> >> I have a project I am looking at where they have a heater and >> controller inside a 18"x14" enclosure and want to keep the temp >> around 70-100 C. Are there any off the shelf enclosures that have >> some sort if insulating properties so can maintain this? It will >> be sealed, and never opened during operation. > > What about a glass aquarium (or two) mounted one inside the other and > fill the space between them with either nothing (suck the air out then > seal it) or some fibreglass insulation. > > That's probably about as off the shelf as you are going to get for > such a large enclosure. > > -- > Jon Baker > --

Don't know exactly, but styrofoam melts at a low temperature, maybe less than 300F, would suggest fiberglass or other higher melting point. A stuck thermostat would make a real mess. Peter Loron wrote: {Quote hidden}> Sucking enough of the air out to make it really insulate well will > collapse the glass. You need a pretty serious vaccum to make that work. > > Best bet is to use styrofoam or equivalent. > > How critical the insulation is will depend on how stable you need to > keep the temperature. > > -Pete > > On Sep 3, 2008, at 3:17 PM, Jon Baker wrote: > > >> 2008/9/3 alan smith <EraseMEmicro_eng2spam_OUTTakeThisOuTyahoo.com>: >> >>> Not sure if that describes what I am after... >>> >>> I have a project I am looking at where they have a heater and >>> controller inside a 18"x14" enclosure and want to keep the temp >>> around 70-100 C. Are there any off the shelf enclosures that have >>> some sort if insulating properties so can maintain this? It will >>> be sealed, and never opened during operation. >>> >> What about a glass aquarium (or two) mounted one inside the other and >> fill the space between them with either nothing (suck the air out then >> seal it) or some fibreglass insulation. >> >> That's probably about as off the shelf as you are going to get for >> such a large enclosure. >> >> -- >> Jon Baker >> --

If the insulation is good, and you're not pumping chilled fluid through the enclosure, you can get away with a very small heater. Obviously safety would be a prime concern. I'd build in a thermal fuse to the heater power line. -Pete On Sep 3, 2008, at 3:57 PM, Carl Denk wrote: {Quote hidden}> Don't know exactly, but styrofoam melts at a low temperature, maybe > less > than 300F, would suggest fiberglass or other higher melting point. A > stuck thermostat would make a real mess. > > Peter Loron wrote: >> Sucking enough of the air out to make it really insulate well will >> collapse the glass. You need a pretty serious vaccum to make that >> work. >> >> Best bet is to use styrofoam or equivalent. >> >> How critical the insulation is will depend on how stable you need to >> keep the temperature. >> >> -Pete >> >> On Sep 3, 2008, at 3:17 PM, Jon Baker wrote: >> >> >>> 2008/9/3 alan smith <micro_eng2spam_OUTyahoo.com>: >>> >>>> Not sure if that describes what I am after... >>>> >>>> I have a project I am looking at where they have a heater and >>>> controller inside a 18"x14" enclosure and want to keep the temp >>>> around 70-100 C. Are there any off the shelf enclosures that have >>>> some sort if insulating properties so can maintain this? It will >>>> be sealed, and never opened during operation. >>>> >>> What about a glass aquarium (or two) mounted one inside the other >>> and >>> fill the space between them with either nothing (suck the air out >>> then >>> seal it) or some fibreglass insulation. >>> >>> That's probably about as off the shelf as you are going to get for >>> such a large enclosure. >>> >>> -- >>> Jon Baker >>> --

With the added bonus that, if you're not careful, you can grow mushrooms :) -marc On Wed, Sep 3, 2008 at 8:54 PM, Apptech <@spam@apptechKILLspamparadise.net.nz> wrote: > > Sucking enough of the air out to make it really insulate well will > > collapse the glass. You need a pretty serious vaccum to make that work. > > Filling the gap with expanded Perlite will add strength, of sorts, and > still > leave good insulation properties. > > > Russell > > -

Rats! I was going to make the space mushroom quote! Yeah, you could use perlite as a filler, but I'm not sure it will provide the strength in compression you'd need to avoid having the glass crack. Best to get a proper dewar and stick the project in there if you want to go that route. I think you'd do almost as well with some kind of box with thick styrofoam sheets attached with expanding insulating foam. Of course if you do that, your fire resistance rating goes out the window... The real limiter here, of course, is what kind of precision is required for the temp control. If they need +/- 5C, then it should be pretty easy. If they need +/- 0.05C, then things get a little more involved. :-) -Pete On Sep 3, 2008, at 8:57 PM, Jinx wrote: >>> With the added bonus that, if you're not careful, you can grow >>> mushrooms >>> :) >> >> Not once you pull vaccuum on the Perlite. > > What about space mushrooms ? > > Another option for the enclosure might be a small fridge > > --

Thanks for the suggestions. This is a project where initially it will be defined as R&D.,,budget so many dollars to see how well it will work, then proceed to a very small and limited production...maybe 10 to 20 units. The temperature isn't critical, in other words it doesn't need to be tightly controlled, just within the range of 70-100. I've done projects in the past where I've had to use AC units to keep the inside of the enclosure cool for the electronics so I know that you have issues with thermal conductivity for steel boxes, typically use fiberglass for those applications. I don't want to have to fabricate a box (although I could but out of steel) so gluing foam pieces to the side and sealing the connections may be the best and easiest method. The other way of course is to make an inner wall with plastic sheets, and spray in foam insulation. Essentially the reason for the temperature is that gases will be flowing thru the box and being matrixed with valves, so they like to be kept warm for one reason or another. Nothing explosive or flammable, so no need to worry about those issues.

2008/9/4 alan smith <RemoveMEmicro_eng2TakeThisOuTyahoo.com>: > Thanks for the suggestions. This is a project where initially it will be defined as R&D.,,budget so many dollars to see how well it will work, then proceed to a very small and limited production...maybe 10 to 20 units. The temperature isn't critical, in other words it doesn't need to be tightly controlled, just within the range of 70-100. > Essentially the reason for the temperature is that gases will be flowing thru the box and being matrixed with valves, so they like to be kept warm for one reason or another. Nothing explosive or flammable, so no need to worry about those issues. Is it top secret or can you say what it's for.. I'm all curious now :-) -- Jon Baker

Go to Wal - Mart and buy an Igloo or Coleman small ice chest? We did that for some medical products that need cool circulating water. I actually duc taped up some of the holes we put in them and use them now for camping. You can even buy them with a cigar lighter plug now that actively heat or cool in the car? Just a thought............ Mike Jon Baker wrote: {Quote hidden}> 2008/9/4 alan smith <spamBeGonemicro_eng2spamBeGoneyahoo.com>: > >> Thanks for the suggestions. This is a project where initially it will be defined as R&D.,,budget so many dollars to see how well it will work, then proceed to a very small and limited production...maybe 10 to 20 units. The temperature isn't critical, in other words it doesn't need to be tightly controlled, just within the range of 70-100. >> > > >> Essentially the reason for the temperature is that gases will be flowing thru the box and being matrixed with valves, so they like to be kept warm for one reason or another. Nothing explosive or flammable, so no need to worry about those issues. >> > > Is it top secret or can you say what it's for.. I'm all curious now :-) > >

> Essentially the reason for the temperature is that gases will be > flowing thru the box and being matrixed with valves, so they like > to be kept warm for one reason or another. Nothing explosive or > flammable, so no need to worry about those issues. > Maintaining a temperature in a box through which you are continuously flowing "coolant" is going to be a significantly different problem than maintaining a temperature in a mostly inert lump of electronics. I suspect that most of the "insulated box" solutions people are suggesting are going to be pretty useless... BillW

Its not a coolant...its a matrix switch so to speak for a online analysis system, pretty much cant say much more as its a "special" project for "special" people. Its just in the bid phase now, so making sure I cover my R&D costs with them. All I know, is the IR sensory system works better when the material is warmer than colder. --- On Thu, 9/4/08, William "Chops" Westfield <TakeThisOuTwestfwEraseMEspam_OUTmac.com> wrote: {Quote hidden}> From: William "Chops" Westfield <RemoveMEwestfwTakeThisOuTmac.com> > Subject: Re: [OT] temperature compensated enclosure > To: "Microcontroller discussion list - Public." <piclistEraseME.....mit.edu> > Date: Thursday, September 4, 2008, 2:03 PM > > Essentially the reason for the temperature is that > gases will be > > flowing thru the box and being matrixed with valves, > so they like > > to be kept warm for one reason or another. Nothing > explosive or > > flammable, so no need to worry about those issues. > > > > Maintaining a temperature in a box through which you are > continuously > flowing "coolant" is going to be a significantly > different problem > than maintaining a temperature in a mostly inert lump of > electronics. I suspect that most of the "insulated > box" solutions > people are suggesting are going to be pretty useless... > > BillW > > --