A vacuum is created in a tank, such as a fermenter or bright tank, primarily due to specific pressure conditions arising from improper ventilation or equipment malfunction.
Understanding Vacuum Creation
Creating a vacuum within a tank involves the internal pressure dropping significantly below the external atmospheric pressure. This pressure difference is what we perceive as a vacuum.
Based on the provided information:
- Cause 1: Poor Ventilation
If a tank is not adequately vented to allow air or gas to enter as the internal pressure decreases (for instance, during cooling or liquid removal), a vacuum can form. - Cause 2: Malfunctioning Relief Valve
Similarly, if the tank's relief valve (specifically, a vacuum relief valve or a combination pressure/vacuum relief valve) fails to open when the internal pressure drops too low, external atmospheric pressure will push inwards, creating a vacuum.
The reference states: "Vacuum pressure occurs if your tank is poorly vented or the relief valve is malfunctioning." It further explains that this scenario leads to the pressure within the tank dropping, which causes "a pressure differential between your tank's internal pressure and the atmospheric pressure."
The Mechanism
When the internal pressure inside the tank falls below the surrounding atmospheric pressure, the stronger external pressure exerts force on the tank walls. Without proper venting or a functioning vacuum relief mechanism to equalize the pressure, this differential can cause the tank to collapse inward, a phenomenon known as implosion.
Think of it like sucking liquid through a straw – the action reduces the pressure inside the straw, and the higher atmospheric pressure on the liquid pushes it up. In a tank, the "sucking" effect might be caused by condensation (cooling vapor shrinks), draining liquid without replacing the volume, or rapid temperature drops.
Preventing Vacuum
To prevent the formation of a damaging vacuum, tanks are typically equipped with:
- Ventilation Systems: Allowing controlled airflow in and out.
- Pressure/Vacuum Relief Valves: These safety devices are designed to open and equalize the pressure if it drops too low or rises too high.
Ensuring these systems are properly installed, maintained, and functioning correctly is crucial for tank integrity and safety.
