Need CCTV camera for high temperature area? 1

[krajesj]

Hello,
I'm not sure that this is the best forum to discuss this topic, but I'll give it a try.
I have need of a high temperature CCTV camera for monitoring the area around a nuclear reactor cooling loop. The ambient temperature I'm told is about 150-160 degrees F.
Right now we have a 1/3" color CCTV camera with PT and an 8-24mm zoom lens mounted in a fabricated metal housing box controlled from a remote controller outside the loop area. We were burning up cameras, then I found that almost every off the shelf camera is only rated for ~120 degrees max. Our lenses also experience "browning." What causes this? Is it related to high temperature, radiation exposure, or both?
I've seen very sophisticated high grade auxiliary cooled units as for refractories, etc. I've also seen Peltier cooled cameras (best solution so far), but Peltiers draw LOTS of current I'm told. Maybe a housing within a housing filled with coolant?
Is there a lower priced solution to the refractory camera style? Is there an off the shelf camera good for higher temps? I'd like to compare some ideas with everyone about this. Any experience?
Thanks,
krajesj

 

[IRstuff]

Is there an elevated ambient radiation level?

Is the "browning" permanent? Can you tell if it's a a surface phenomenon or a bulk change?

TTFN

 

[krajesj]

>Is there an elevated ambient radiation level?

Yes, four of the cameras will be about 12 feet from each of the main reactor cooling pumps while they are in operation.

>Is the "browning" permanent? Can you tell if it's a surface phenomenon or a bulk change?

Yes, the lens browning is permanent. If you open up the iris and hold up the lens to the light the lens color looks like the "ambervision" sunglass lens color. The depth of the color seems to vary with time and distance from the source of the radiation.

Thanks for asking,
Steve

 

[IRstuff]

The browning is most likely from the radiation. UV will, over time, cause glass to turn brown, blue, etc. The anti-reflection coatings, having high metal content are probably also susceptible to radiation damage.

The Peltier cooling applies only to the CCD itself, so the remaining electronics would still need to be high temp rated.

As for the temperature ambient, you might look at commercial surveillance cameras intended for outdoor use, since they will typically get into the temperature ranges you've indicated. While this is probably overkill, the Cohu camera listed below is spec'd for 74°C max temp:

http://www.cohu-cameras.com/products/3920.htm

TTFN

 

[melone]

Can you build an enclosure to themally control the enviornment surrounding the camera? This will allow you to drop in any camera you chose.

 

[nbucska]

I think in your application it would be cheaper to use forced air cooling.

I don't think you can get effective shielding against neutrons. You may get lens which is more resistant.



<nbucska@pcperipherals.com>

 

[dydx]

1/ A Peltier cooled camera is unlikely to work in above application as Peltier can only create a temperature difference between 2 surfaces. You must still dissipate the heat generated at the higher temp surface to the background ambient [with an appropriate cooling fan].

2/ Cheapest solution: worth a try.
Is there any proviso about the 120degF max. temp. limit?
Is this for a &quot;still&quot; air application or for a &quot;forced&quot; air application?
If it is a &quot;still&quot; air specification [and assuming the camera has no internal fan] then fit an external fan to blow air at the camera. Direct air stream through any vents in camera to allow air flow to work. There must be an entrance and an exit for airflow. This will increase the air circulation and also the cooling to the camera.

Prior to hot zone implementation, experiment this arrangement first in a laboratory box natural convection oven with air at 160degF and a blower rated for this temp. Alternatively use a forced convection box oven with set-point at 160degF.

There is a very funny and easy reading book on this subject.
Title: &quot;Hot air rises and heat sinks: Everything you know about cooling Electronics is WRONG&quot;
Author: Tony Kordyban
ISBN: 0791800741

3/ Compressed air
Can you get a compressed air or N[sub]2[/sub] source to the camera? What temp. would the air or N[sub]2[/sub] be at when it reaches the camera? Gas expansion might reduce the temp of flowing gas.

Hope this helps.

 

[krajesj]

Thanks for your replies:

1/ Peltier can only create a temperature difference between 2 surfaces.

> I thought to attach the &quot;hot&quot; side of the Peltier to the inside of the housing, and a large heat sink to the other side of the housing. I had hoped that the heat of the junction would be dissipated throught this housing/cooling &quot;sandwich&quot;.

2/ 120degF max. temp. limit?
Is this for a &quot;still&quot; air application or for a &quot;forced&quot; air application? Fit an external fan to blow air at the camera.

> I didn't think that this would work, as the air that the fan would be drawing into the housing with the fan would be ~150 deg. F. I didn't think that would be creating much of a delta T with supply air that hot.

forced convection box oven with set-point at 160degF.

> Good idea! I though of doing that once I got a prototype assembled.

Can you get a compressed air or N2 source to the camera?

> I though of this too. I have a readily available instrument air source nearby, but the Instrumentation guys would be mighty upset if I tapped off of it with a constant drain!

Thanks for your ideas. Keep them coming.
Steve

 

[melone]

Who says it has to be a constant drain? Put a temp sensor in your box and blast cool air when it gets to warm....