Typically a channel will read “OPEN” when either the positive or negative wire of the thermocouple has been damaged or has cracked. The most common place to find this is at the tip of the thermocouple whereby the twisted pair junction needs to be re-made. Ideally the junction should also be welded using a thermocouple welder as this prevents the wires from becoming separated and hence prolongs the overall lifetime of the thermocouple loom. Welded thermocouples are less likely to result in repeat temperature mapping studies due to open circuits. QualUs have a range of thermocouple welders to suit all requirements, contact QualUs today for further details.