To answer the question in the title, we use it as a measurement of pressure. REALLY, it is a measurement of distance. First, any scale CAN be used to measure vacuum (negative pressure) and positive pressure. The trick is knowing which is best suited for which and the size of the scale. Larger units of […]

Educators love lockout relays, and we also love pretending you will still see them out in the field all the time. Sometimes, I have to look myself in the mirror in the morning and sadly repeat, “Lockout relays are dead.” I have to say it several times before the reality sinks in. Before I get […]

In HVAC, we work with thermocouples for temperature measurement all the time, but we may not understand the difference between a thermocouple and other types of temperature measurement sensors. A thermocouple is just two different types of metal connected at a “junction” that generates a small voltage with a temperature change. Older furnaces would often […]