Issue Date: October 27, 2004
Revision Date: June 27, 2011

Western Fiberglass, Inc.

Co-Flow Hydraulic Interstitial Monitoring System

Continuous Interstitial Monitoring Method (Liquid Filled)

Certification Certified as a continuous, liquid-filled interstitial space leak detection system for use only with Western Fiberglass, Inc., double walled/coaxial flexible pipelines.
Maximum length is 200 feet.
No restrictions on pipeline diameter.
Operating Principle Similar to the methodology that has been applied to liquid-filled interstitial double walled tanks.
Propylene glycol is used to fill the interstice.
Two reservoirs are used to contain the liquid, one at each end of the system. The reservoir at one end is closed to the atmosphere, includes a valve that is used to fill the system, and is designed to operate at a lower elevation than the other reservoir. The reservoir at the other end is open at the top and contains a dual-point level sensor.
The dual-point level sensor system monitors the liquid level in the interstitial reservoir and provides an alarm if the liquid level is either too high (ingress of liquid) or too low (egress of liquid).
The method must be used with a dual-point sensor system that will properly fit into the reservoir, is compatible with the interstitial liquid, and is on the NWGLDE list.
Sensors can be used to shut down the turbine system and/or alert the operator that a potential problem exists.
Alarm Conditions
Leak Rate (gph) Time to Alarm* (hours) for 5-Inch Sensor Spacing as a Function of Leak Rate for Various Reservoir Diameters (in) Time to Alarm* (hours) for 3-Inch Sensor Spacing as a Function of Leak Rate for Various Reservoir Diameters (in)
3.75 3 2.87 2 1.5 3.75 3 2.87 2 1.5
0.05 4.8 3.0 2.8 1.4 0.76 2.9 1.8 1.7 0.8 0.5
0.10 2.4 1.5 1.4 0.68 0.38 1.4 0.91 0.84 0.41 0.23
0.20 1.2 0.76 0.70 0.34 0.19 0.71 0.46 0.42 0.20 0.11

*Time to alarm is based on evaluations conducted with 100% glycol solution and a leak (liquid egress) 190 feet from the highest reservoir. Leaks closer to the highest elevation reservoir, and the use of a diluted glycol solution, will shorten alarm times. Both theoretical calculations and laboratory measurements confirm that dilution of the propylene glycol used in the interstice of the WFG system will produce a significant reduction in the alarm time. This system has not been evaluated for locations with temperatures outside the range of 32 to 100 degrees Fahrenheit.

*Time to alarm for a catastrophic primary pipe failure with a pressure of 40 psi is 20 seconds at a distance of 10 feet from the reservoir and 84 minutes at a distance of 190 feet. This is based on a 5-inch spacing of the float sensors.
Applicability Western Fiberglass, Inc. underground double-walled/coaxial flexible pipelines containing gasoline, gasohol, diesel, heating oil #2, kerosene, aviation fuel, or motor oil. Other liquids may be stored after consultation with the manufacturer.
Calibration Equipment requires no calibration other than to insure the upper reservoir is half full.
The electronics must be calibrated and maintained in accordance with the sensor/monitoring equipment instructions.
Comments

Pipeline fittings with interstitial communication tubing must only be located in sumps or pump pits – direct burial is not permitted.
The liquid level in the reservoir must be at least 20 inches above the water table.
The interstice must be filled from the low point in the pipeline to minimize trapped air.
The evaluation was conducted in a Western Fiberglass, Inc., double walled/coaxial flexible pipeline with an interstitial capacity of 1.64 gallons, an inside diameter of 1.5 inches, and a length of 200 feet.
Installers must be certified by both the piping and sensor manufacturer.
Third-party evaluator certifies that this method performs equally well on the present version (manufactured beginning March, 2006) as the previous version of Western Fiberglass, Inc., double walled/coaxial flexible pipeline.

This method does not meet California's requirements for continuous monitoring of pressurized piping connected to UST systems installed on or after July 1, 2004.
  • Western Fiberglass, Inc.
    1555 Copperhill Parkway
    Santa Rosa, CA 95403
    Tel: (707) 523-2050
    Email: sales@westernfg.com
    URL: www.westernfg.com
  • Evaluator: Ken Wilcox Associates
    Tel: (816) 443-2494
    Date of Evaluation: 08/09/04

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