Reccomend me a NON-CONTACT temp sensor

Here's the tricky part... I need this to be Ex rated as it is intended to be installed to measure the temperature of an acetylene cylinder while it is being filled.

I need this to be a non-contact device with a range of -10 to about +50 C. We can get as close as 30mm to the cylinder or as far away as you like.

Could someone reccomend a brand of hardware that we could use ???

_Woody_ said:

Here's the tricky part... I need this to be Ex rated as it is intended to be installed to measure the temperature of an acetylene cylinder while it is being filled.

I need this to be a non-contact device with a range of -10 to about +50 C. We can get as close as 30mm to the cylinder or as far away as you like.

Could someone reccomend a brand of hardware that we could use ???

Click to expand...

I'd say an IR sensor will do just fine but here's the tricky part....for Ex the intensity of the light (IR part) may be a problem.
I'd contact a local rep and get all the info/specs/ratings prior to utilizing it.

bkottaras said:

I'd say an IR sensor will do just fine but here's the tricky part....for Ex the intensity of the light (IR part) may be a problem.
I'd contact a local rep and get all the info/specs/ratings prior to utilizing it.

Click to expand...

EXACTLY - now you see my problem, I must have spent the better part of half a day googleing this and making phone calls trying to find some thing suitable for this enviroment. The best I have come up with so far is the Fluke 68IS which is a hand held device but has no output I can connect up with the PLC so I am back to square one...

bkottaras said:

I'd say an IR sensor will do just fine but here's the tricky part....for Ex the intensity of the light (IR part) may be a problem.

Click to expand...

??????
Any object emits IR light with an intensity depending on the temperature.
Measuring this emitted IR light passively doesnt affect the hazard.

The problem is the sensor itself.
I thought that it would be easy to find such a sensor, but as you have found out, the market doesnt exactly overflow with these things.
The problem is probably that for Ex-i, the electronics inside the sensor is too complex, and for Ex-d the sensor has to look out of the housing.

Good luck finding one.

http://www.mikroninfrared.com/

We use there but we look through bullet proof glass.


M67FM


Patented Infraducer® 2-wire Linear 4-20mA Output Infrared Temperature Transmitters

This rugged, compact, self contained unit produces a 4-20mA linear or DC voltage output proportional to the temperature and is compatible with any existing instrumentation for recording or process control. The use of infrared temperature measurement technology allows non-contact readings of temperature to be made real time. Process applications include cement, chemical, food, glass, metals, paper, petrochemical, plastics, textiles, etc., with temperature ranges from -40°C to 3000°C (-40°F to 5400°F).

FM Approved Model The model M67FM Infraducer has been approved by Factory Mutual (FM) for usage in hazardous environments. When used in conjunction with the optional barriers, the entire system will be rated intrinsically safe. Approvals are for Class I, II, and III, Division 1, Group A, B, C, D, E, F, and G. At the time of order please specify that the FM approved version is required.

For applications requiring an intrinsically safe rating see page 7 of the M67S/M67 datasheet.

As it is Ex i, it does not have to be mounted in an Ex d enclosure.
And as he has to measure max 50 degr. he dont have to mount it in a special cooling jacket for example.

I just noticed this:

We can get as close as 30mm to the cylinder or as far away as you like.

Click to expand...

That Ex i rated sensor looks expensive.
How about placing a regular sensor so far away that it is not in the hazardous area ?

_Woody_ said:

Here's the tricky part... I need this to be Ex rated as it is intended to be installed to measure the temperature of an acetylene cylinder while it is being filled.

I need this to be a non-contact device with a range of -10 to about +50 C. We can get as close as 30mm to the cylinder or as far away as you like.

Could someone reccomend a brand of hardware that we could use ???

Click to expand...

Acetylene cylinders have been in use and filled for almost 100 years (?). I realize cylinders heat when being filled so has the gas industry been measuring temp on acet cyldrs all along or is this a new thing? Am curious why you want to do this. Are you measuring temp (and or temp rate) to control pressurization rate?

Also why non contact - you have to manually hook up the charging connector anyway so what is wrong with a surfact Thermocouple (allowing for lag time)

Dan Bentler

Are the cylinders empty when you begin filling them. If so them temperature will be a function of pressure - the two will be well correlated.

Isn't he just looking for an IR Thermocouple? Info from Omega.
It's a thermopile under a magnifying glass. Self powered. Typical output is type K, just like a standard T/C.

leitmotif said:

Acetylene cylinders have been in use and filled for almost 100 years (?). I realize cylinders heat when being filled so has the gas industry been measuring temp on acet cyldrs all along or is this a new thing? Am curious why you want to do this. Are you measuring temp (and or temp rate) to control pressurization rate?

Also why non contact - you have to manually hook up the charging connector anyway so what is wrong with a surfact Thermocouple (allowing for lag time)

Click to expand...

We intend to use weight and temp to control pressurization automatically (I'm not doing the Math just the code).

Why non-contact - because thats what the client asked for and if they are prepaired to pay for it - Why not?
I believe it is simply to remove the stupid factor - it is not possible for the filling process to start without the connector attacted to a cylinder but... if the operator forgets to connect the temp measurement device....

As a "simple device" a thermocouple is considered instrinsically safe when used with an IS barrier.

Exergen makes a line of non-contact IR sensors that mimic T/C mV output.

However, I'm not sure if an Exergen non-contact IR device can be used as an I/S device. Exergen units have a much higher impedance than an ordinary T/C (which has created problems with some temp transmitters I've used), so I'm not sure how it would be applied in an I/S circuit, but Exergen might know.

Be aware that Exergen's temperature vs output curves are much more non-linear than ordinary T/C's, so part of the selection is finding one linear enough to be used over the range needed.

If I recall properly, acetylene is Class 1, Div 1, group A, all by itself in group A due to its volatile chemistry. Make sure that whatever you use meets the group classification.

Dan

JesperMP said:

I just noticed this:
That Ex i rated sensor looks expensive.
How about placing a regular sensor so far away that it is not in the hazardous area ?

Click to expand...

Jesper,

we have done a similar set up and ended up with regular Sick Photo sensors and Fiber Optic adapters.(not for temperature though, just detection).
The units were mounted outside the Ex area, so far so good.
The actual fibers were in the Ex area. Since they were emitting some kind of light (which is still light/energy) according to ATEX the amount of light needs to be within certain levels in order to avoid rise in temperature/ignition. The product density will affect your numbers here and this is where it does get tricky, PPM is another factor (parts per million).
We did go through hell to get specifics as even Sick did not have the specifics on this.
His issue isn't the sensor as I see it (cheap, expensive, outside the area) but the actual light beam whatever that may be.

Are you working to the Equivilent of the European ATEX 137 classification?
(I just done my CompEx course)
What is your zone classification that you want to detect in?
Acetlylene is a starting point, how often will there the gas level be between the LEL and UEL? Less than 10hrs per year? etc.....

If you are ringing suppliers you will need to have a full classification of the area as reference.

Acetylene will need a T2 rating (max temp 300C), personally I would spec for T3(200C) as the auto ignition temp for Acetylene is 305C!

If you are pretty close to the bottle I am sure your going to be Zone 0 or Zone 1. If its classed as Zone 0 then you can only use "Is" (intrinsically safe). Also "Is" is sub divided into 2 sub catagories Ia and Ib; Ib is NOT allowed in zone 0!

Have a read of this page below. We have used these guys before, very helpfull over the phone too (although in USA you will need a late night or early morning to catch them!)

http://www.extronics.com/extronics/documents/Ex_Info/Explosive_Atmosphere.htm

NOTE: This is all EUROPEAN INFO! The following page combines US and European info.

http://www.extronics.com/extronics/documents/Ex_Info/protection_concepts.htm

Hope this helps a bit in speccing the unit

bkottaras said:

The actual fibers were in the Ex area. Since they were emitting some kind of light (which is still light/energy) according to ATEX the amount of light needs to be within certain levels in order to avoid rise in temperature/ignition.

Click to expand...

It does not make sense to me. The fiber does not add energy. It transports the light that is already there. It is passive.
If on the other hand it was a laser photo-cell for example, then the fiber would add additional light.
But then again, I am not a certified Ex wizard.