Early in my career I did tensile testing on adhesive coupons. I was running an experiment to simulate heating and cooling cycles on a bond. I had a nice big thermal chamber from the 1960’s, lined with heating elements (and undoubtedly asbestos), a big old dewar of liquid nitrogen, some thermocouples, and a PID controller the size of a German Shepherd.
Problem is, cold air sinks. My samples are sitting on the bottom of this huge chamber and their temperature is fluctuating wildly every time a bit of LN2 is added. The ancient PID controller cannot cope with my shitty test setup, it’s trying to turn on the damned heaters to control the temperature when I’m trying to go cold and this is a multi-hour test and I just want to go home.
But… I have a cardboard box. Nice, insulative cardboard, just the right height to get my samples off the floor of the chamber and into a zone where the temperature is more stable. I am brilliant! Cardboard box deployed, I can finally begin my thermal cycling.
I learned a few things that day:
thermal cycles include both hot and cold phases
the floor of the thermal chamber has much less temperature stability while cooling AND while heating
specifically the floor contains a heating element and gets ridiculously hot
cardboard combusts at a temperature much lower than you might expect
opening the door of a smoking thermal chamber to investigate allows in a rush of oxygen
rapid introduction of oxygen to a smoldering cardboard box leads to very large exciting pretty flames
fire extinguishers leave a fine dust of particles all over everything that you will be cleaning up for MONTHS
Early in my career I did tensile testing on adhesive coupons. I was running an experiment to simulate heating and cooling cycles on a bond. I had a nice big thermal chamber from the 1960’s, lined with heating elements (and undoubtedly asbestos), a big old dewar of liquid nitrogen, some thermocouples, and a PID controller the size of a German Shepherd.
Problem is, cold air sinks. My samples are sitting on the bottom of this huge chamber and their temperature is fluctuating wildly every time a bit of LN2 is added. The ancient PID controller cannot cope with my shitty test setup, it’s trying to turn on the damned heaters to control the temperature when I’m trying to go cold and this is a multi-hour test and I just want to go home.
But… I have a cardboard box. Nice, insulative cardboard, just the right height to get my samples off the floor of the chamber and into a zone where the temperature is more stable. I am brilliant! Cardboard box deployed, I can finally begin my thermal cycling.
I learned a few things that day:
Brilliant writing, funny story told well, 10/10, would set my experiment on fire for.