I've noticed a trend of techs and nurses alike on the unit using the Salem sump to clamp off the primary lumen of the NG tube. I remember hearing in nursing school that this was not to be done. I have scoured the internet and textbooks for an answer. Everything says that the Salem sump cannot be clamped externally, which makes sense because this defeats the purpose of that lumen, but they don't mention anything about using the Salem sump to clamp off the primary lumen. Thanks for your help!