Vintage Weston Instruments Gauge Question

Peter Holmander

Subscriber
I picked up this cool Weston Instruments temperature gauge at the flea market this weekend for $ 4.00. Its range is from 0 degrees F to 1000 degrees F. It has two small connectors on the top. When I got it there was a small piece of bell wire on one of the connectors. Can anyone tell me how you would wire this up to something to read the temp? Is there another unit that is needed like a probe or something like that? Or maybe just a battery and the unit itself senses the temp in the room or environment it's in. I'm not sure what this gauge was used for. A boiler maybe? I found a lot of info on Weston ammeters, ohmmeters, and voltmeters, but I can't seem to find anything on Fahrenheit gauges. I'm hoping a member here can answer my question.
 

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georgineer

Member
Interpreting the information on the meter dial, and the other details you have given, it needs an external thermocouple (T.C.) of Iron-Constantan (I.C.), in other words one made with one iron wire and one of constantan (which is a nickel-copper alloy). This is known as a Type J thermocouple. To get the most accurate readings, the thermocouple resistance should be 10.15 ohms.

It's a portable meter, so would have been used wherever high temperatures needed to be measured. I have only worked with permanently installed thermocouples, so with any luck somebody with wider experience will follow along and give you useful information about how, and what, and where you can get a suitable thermocouple probe. Meanwhile, there's loads of information on the internet, now that you know what to look for!

George
 

DustyBar

Subscriber
The thermocouple is likely Iron-Constantan but at 1000 deg I think they might have used some other combination of wire. I don't remember the different types of wire but type "J" is iron-constantan and temperature response is linear from 0 to about 600 degrees F. The wire looks like bell wire but its not the same thing. You also can't splice the wire to plain old copper wire. That will create additional theremocouples within the lead and mess with your readings. You need a cold junction compensator if you have long leads and need to splice it. The sensor is a simple as twisting the two different wires together but usually they are welded to make a little bead or both welded to the item being measured.
 

BobSaunders

New member
The one's I have or have used would have one lead made of silver wire and twisted together into a round iron disk to place on or against the hot surface. One brand had a choice of metal probes for measuring the temp of mold machine dies. No battery needed. One was for setting a clothes iron on to test.
 

Peter Holmander

Subscriber
Thanks to all who responded. Never even thought about using one to test a flat iron Bob. The one you speak of with the round disk and the silver wire, did it have just one silver wire lead or two? Would love to find a disk like that and then hook it up to my wood stove to monitor the temp. I think the gauge is pretty cool. Solid and well made too. I think I did ok for $4.00 The guy wanted $5.00 lol
 

Peter Holmander

Subscriber
Thanks guys. I think it's a keeper. I watched some youtube vids yesterday on thermocouples and how simple they are so now I know how it was connected up. I couldn't resist it when the guy at the flea market said 5 bucks. I save and collect anything vintage. I know, it's a sickness, but in my mind I'd trying to preserve history. Here's an example. The state of RI turned the former Quonset/Davisville Navy base into an industrial park when they closed the base. I worked for the Maintenance Dept. there and retired 6 years ago. We were responsible for maintaining the buildings that were left, grass cutting, plowing snow, etc. The majority of the water systems in the Quonset part of the base used transite pipe. It is water pipe made totally out of asbestos. Due to it's age we would often have large sections of it blow right out. When we excavated the pipe to repair it, we would often find old Coke bottles in the soil. The soil was very sandy and the bottles looked brand new when washed off with water. I brought many of them home. All around my barn on the wall sills are old Coke bottles in mint condition. Proof that I am sick lol
 
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