Would You Build Your Own Test Setup

Sure, we do it all the time; especially to obtain temperature profiles and chamber volumes that can't be had with commercial equipment. When you design the heating system you can get profiles that are not obtainable with off-the-shelf chambers. If the chamber is going to run unattended, you need to design fail safes that are sometimes left out of in-house fabricated stuff, and are kind of a pain. You should also provide short circuit protection. These little things add complexity, but can be important.

I often use my household fan oven set to 40 *C to test precision components for temperature drift and compensation...

I do have an evironmental chamber, but its easier to use the fan oven, plus with the fan oven you get a slight vibration in the instrument so that allows any adjustable components to 'settle' into their final calibration positions!

Its good fun just as long as someone doesn't turn the temperature up to 200 *C

John.

I have the same problem with availability of calibration equipment. For level transmitters, I had a level calibration jig fabricated that uses a length of 3 inch pipe, some 1/2 inch tubes and a few 1/2 inch ball valves.

This contraption is installed right next to the tanks so there's no need to lug the heavy transmitters the 200 meters to the calibration lab.

We'd put the transmitter on the flange and power it up. Then we open the drain and close the water inlet. When all the water had drained out, we'd zero the transmitter.

Once zero has been done, we close the drain, open one of the upper valves, which one depends on the height of the tank where the transmitter came from. We'd open the water inlet and wait for the water to come out of the overflow. Once that happens, we close the water inlet and wait for the overflow to stop. This ensures that the water level in the pipe is steady and at the right height. Then we do the span.

The guys liked it so much they preferred doing the calibration on it than at the lab.

Good idea Vulcan........

When testing temperature coefficients of smallish components, I don't bother with an oven I made a plastic container filled with liquid paraffin and a flexible heater in the bottom. Then using a bench power supply adjust the power in the heater to get a consistant temperature and pop the component into the liquid while still connected to the calibration instrument...

A nice and fast way to see temperature changes and to get a 'feel' for the component.

John.