Vapor monitoring can be performed manually on a periodic basis or continuously using permanently installed equipment. Interstitial monitoring methods range from a simple dip stick to a continuous automated vapor or liquid sensor permanently installed in the system. Automatic Tank Gauging Systems Monitors permanently installed in the tank are linked electronically to a nearby control device to provide information on product level and temperature. During a test period of several hours when nothing is put into or taken from the tank, these monitors are used to automatically calculate the changes in product volume that can indicate a leaking tank. This is strictly a combination method using periodic tank tightness testing and monthly inventory control.
Tightness tests require temporarily installing equipment in the tank.
A volumetric test involves filling the tank to a specified level and precisely measuring the change in level and temperature over several hours. Non-volumetric test methods include ultrasound techniques and tracer gas detectors. These are sophisticated tests and must be performed by trained, experienced professionals. In addition to tightness testing, you must use monthly inventory control. Inventory control is basically like balancing a checking account.