Tank gauges

U.S. EPA, Automatic Tank Gauging Systems for Release Detection Reference Manual for Underground Storage Tank Inspectors, EPA 510-B-00-009, U.S. EPA, Washington, 2000. 

Water discharge is typically handled by the existing treatment and discharge facilities, or treated by carbon filtration prior to discharge where the quantity of recovered water has been minimal. LNAPL is periodically pumped out of the tank and transported to a recycling facility. Periodic tank gauging and product transfers avoid the accumulation of LNAPL to the point where it could be inadvertently discharged with the water. 

Automatic tank gauging equipment may be used if it can detect a leak of two-tenths (0.2) of a gallon per hour or larger with a probability of detection of 95% and probability of false alarm of 5% or less. Monitoring must be carried out once per week or... 

Pratt, T.H., Electrostatic considerations for automatic tank gauges, J. Loss Prev. Process. Ind., 5, No. 2, 1992. 

A hydrostatic tank gauge applied to a pressurized, spherical tank. (Courtesy of The Foxboro Co.)... 

Automatic tank-gauging systems are found in almost all tank farms for inventory monitoring. The wire-guided float tape gauge systems are most... 

A second is hydrostatic tank gauging, where level is inferred from pressure. Again, density, particularly if two phases exist (aqueous and foam), may render this approach questionable. 

Compare regulator gauge and tank gauge to confirm they read the same. 

Compare the tank gauge with the regulator gauge to be sure they have the same reading (Figure A.9). 

Open the cylinder valve slowly until the tank gauge on the regulator registers the cylinder pressure. At this point, the cylinder pressure should be checked to see if it is at the expected value. If there is a large variance, check for leaks, cylinder valve malfunction, or pressure gauge malfunction. 

Operators of Buncefield-type sites should protect against loss of containment of petrol and other highly flammable liquids by fitting a high integrity, automatic operating overfill prevention system (or a number of such systems, as appropriate) that is physically and electrically separate and independent from the tank gauging system. 

A high integrity overfiii prevention system shouid, as a minimum, provide a ievei of SiL 1 as defined in BS EN 61511 -1. To reduce risk as iow as reasonabiy practicabie the overfiii prevention system shouid preferabiy be automatic and shouid be physicaiiy and eiectricaiiy separate from the tank gauging system. Automatic overfiii prevenfion may inciude, but not be restricted to, measures such as automatic shutdown of the suppiy iine or automatic diversion of the flow to another tank. 

Dutyhoiders wiii need to prepare a robust demonstration that aiternative measures are capabie of achieving an equivaient ALARP oufcome fo an overfiii prevention system that is automatic and physicaiiy and eiectricaiiy separate from fhe tank gauging system. 

Some tank monitoring systems include alarms and systems which monitor for stuck tank gauges and unscheduled movement . 

Logic solvers Whether there is sufficient independence between the overfill protection system and the tank gauging system. 

Dutyholders should proactively monitor control systems, such as the tank gauge system, so that designated level alarms etc do not routinely sound. (This does not exclude the use of properly managed variable alarms or warnings set below the established alarm levels). 

Bulk tank overfilling Number of times the tank is filled above the safe operating limits Number of times ullage checks not done correctly before product transfer begins. Number of times inspection and maintenance of tank gauging system not oarried out to required frequency. 

Tank gauging. Release can occvu during gauging operations when the thief hatch is opened and vapors of high concentrations of HgS are released into the breathing zone. 

If air monitoring is not performed prior to tank gauging operations especially, and there is a significant concentration of H2S present in the crude oil, then employees must assmne the atmosphere smrounding the hatch opening is immediately dangerous to life and health. 

Normally, tank levels were controlled from a control room using an automatic tank gauging (ATG) systan. A level gauge measured the liquid level. The operator in the control room used the ATG systan to monitor levels, temperatures and tank valve positions, and to initiate the remote operation of valves. 

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