Issue
Date: November 22, 1995
Revision Date: May 3, 2006
Triangle
Environmental, Inc.
TEI
System 5000, Version 1.0, Version 1.0W
NON-VOLUMETRIC
TANK TIGHTNESS TEST METHOD (VACUUM)
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Certification
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Leak
rate of 0.1 gph with PD = 100% and PFA = 0%.
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Leak
Threshold
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A
tank system should not be declared tight when the acoustic
noise level of the tank under vacuum is greater than the
calibrated background acoustic noise level (prior to evacuation).
A tank system should not be declared tight if any water
ingress is detected.
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Applicability
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Gasoline,
diesel, aviation fuel, fuel oil #4, waste oil.
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Tank
Capacity
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Maximum
of 20,000 gallons.
Tank must be minimum 14% full.
Microphone should be located within 24 feet of all points
within the tank.
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Waiting
Time
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None
between delivery and testing.
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Test
Period
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Minimum
of 1 minute when groundwater is below bottom of tank.
When groundwater is above bottom of tank, either of the
following water sensors may be used:
TEI System 5000 water sensor Minimum of 10 minutes (time
begins after sensor is set up and calibrated).
Horner EZ-3 conductivity water sensor Minimum test time
must be calculated using Horner EZ-3 operations manual.
Calculation is based on tank size, groundwater elevation,
and product elevation, but not less than 1 hour.
There must be no dispensing or delivery during test.
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Test
Pressure
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Vacuum
as directed in operating instructions.
If vacuum cannot be maintained, see manufacturer's instructions.
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Temperature
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Acoustic
signal is independent of product temperature.
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Water
Sensors
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Either
Triangle or Horner water sensor must be used to detect
water ingress. TEI System 5000 water sensor Minimum detectable
water level is 0.0532 inch.
Minimum detectable change in water level is 0.00013 inch.
Minimum water level in tank must be adjusted to at least
0.0532 inch at the sensor before starting the test.
Horner EZ-3 conductivity water sensor minimum detectable
water level is 0.014 inch.
Minimum detectable change in water level is 0.0095 inch.
Minimum water level in tank must be adjusted to at least
0.014 inch at the sensor before starting the test.
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Groundwater
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Per
California regulations, depth to groundwater in tank excavation
backfill must be determined.
If groundwater is above bottom of tank, either the TEI
System 5000 water sensor or the Horner EZY 3 conductivity
water sensor must be used and the test time extended to
allow sufficient time to ensure water ingress detection
during test..
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Calibration
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Acoustic
sensor, and TEI System 5000 water sensor or Horner EZY
3 conductivity water sensor, must be calibrated before
each test in accordance with manufacturer's instructions.
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Comments
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Manifolded
tank systems must be isolated prior to test.
Evaluated using unleaded gasoline.
Microphone was 24 feet away from the leak source during
evaluation.
Headphones are used during test to listen for air ingress
signal. Noise signals are tape recorded rather that recording
the noise levels in decibels.
Vacuum test method may not be effective in some tank excavation
backfill (such as clay) because it may plug holes in tank.
If soil is saturated with product, air or water ingress
may not be detected by vacuum test.
A well point in tank excavation backfill may help identify
presence of this condition.
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