The vent tube is a component of a vented (psig) submersible pressure transducer's cable that vents the chamber behind the diaphragm to atmospheric pressure. This is critical to the operation and accuracy of the sensor. The sensor's reference point is atmospheric pressure, meaning it automatically adjusts to changes in atmospheric (barometric) pressure - or that it tells you how much pressure is applied to the sensor in addition to atmospheric.
It's important to keep the vent tube both dry and unobstructed. We offer two options for keeping the tube dry: a desiccant cartridge and a hydrophobic, breathable vent cap. Make sure you have one of these installed on your vent tube to keep the sensor's electronics safe.
Blocking or obstructing the vent tube is also detrimental. If the sensor is not properly vented, then accuracy will suffer as the atmosphere's pressure will begin to change the way the sensor's diaphragm behaves. Sealing off the vent will fix the sensor's reference point to one pressure, leaving it vulnerable to changes in elevation and weather. As submersible pressure sensors are typically low pressure instruments, these small changes in the atmosphere can have a noticeable affect on your level reading.