8 Channel Thermocouple Based Temperature data logger

[AtApi]

Hi
First of all sorry for my English, not my native language.
Im searching for a 8 Channel Thermocouple Based Temperature Data Logger kit.
Im gonna use it to log the temperature that coming out from my dragster mufflers

Here`s some specs:

The Data Logger should be battery power so i can put it on-board.
Im gonna use a Thermocople probe type K, that i already have, off course in this case i have 8 of them.
Should have a temperature acquisition range between 0F and 2000F for every channel.
Accuracy is very important.. it should be i think at least 8 bits
Sampling rate per second . this cars use nitro-methane where there s detonations and temperature shock (extremely rapid changes in temperature), i guess has to be at least 3 samples/sec.
It would be nice to have a LCD display but not necessary.
Storing the readings - obviously EEPROM is an easy option but if we can implement a SD-card would be great!
Off course if you choose EEPROM a USB or SERIAL connection to the PC is required.
Look at this Data Logger

http://ifamilysoftware.com/8307.html

is has pretty much same specs i need but single channel.
And has to be strong enough so G forces will not tear this unit apart.
My Type-K thermocouple assemblies (Nickel-Chromium/Nickel-Aluminum) are terminated with a two pin male miniature-connector.

Ok i think i give you the idea, There`s someone that can help me?
Thank`s for your attention and if you have some question please write me back.

Best regards

AtApi

 

[itsmoked]

You need far higher resolution than 8 bits! That means 256 different values are allowed. Are you telling us you don't mind resolution of (2000-0)/256 = 7.8 degrees?

Have you searched on the Web? There are lots of them.
Look at how you unload the data from them and how you see it as this will greatly influence the usability.

Most of them won't care a bit about your G forces.
Here is just one place to check.

http://www.omega.com/toc_asp/subsectionSC.asp?subsection=S08&book=Temperature

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[IRstuff]

Not sure where you came up with your 3 samples per second. At 6000 rpm, that's 10 revs per second; that means that a detonation has come and gone in a few tens of milliseconds. You need to be sampling at least 100 Hz, which is a relatively non-trivial datalogger.

Assuming something like 10 runs at 2 minutes each before dumping the data, you need to be able to store something like a million samples. The only Omega system that fits that bill is:

http://www.omega.com/ppt/pptsc.asp?ref=OMB-LOGBOOK

It's a bit of an overkill, but you could turn this thing on at the beginning of the day and it'll be able to easily store 24 hrs of samples. The only downside is that the channel sampling is sequential, albeit, it's only a total of 80 microseconds to run all 8 channels.

TTFN

FAQ731-376

 

[IRstuff]

oops, 100 revs per second, hence > 100 samples per second is required

TTFN

FAQ731-376

 

[itsmoked]

I don't see why he'd need samples that frequently since the temperatures will all be heavily integrated by each header's thermal mass.

I suspect he's after tuning sysmmetry not realtime control.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[danw2]

The design and mounting of the thermocouple will influence the readings, too. Bare metal junctions made from a roll of wire might not last too long, but will pick up changes much more rapidly than the metal sheathed type.

General aviation aircraft use monitors (not loggers) for comparing cylinder temperature variations:

http://www.insightavionics.com/gemseries.htm

 

[btrueblood]

The speed of this is not quite what you want, but all else is there:

http://www.measurementcomputing.com/cbicatalog/USB-5201.asp?dept_id=414&pf_id=1718

The price is a bit better than the Omega jobbie.

 

[Pud]

I would suggest that the response rate of a "fast" bare t/c junction would much longer than 1/3s - assuming you have the usual thickness wires. "Fast" response time t/c's are classed as 1s.

Cheers


Harry

 

[analogkid2digitalman]

Omega has 0.025mm unsheathed fine wire T/C's with response times (63.2%) of 0.05 seconds in still air

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"It's the questions that drive us"
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[VEBill]

If the instantaneous exhaust gas temperature is going up and down over each cycle (likely), and there is no form of low-pass filtering (such as using a sensor with too quick a response time), and the sampling rate is free running (almost certainly) and too low (as described), then you may run into aliasing.