Issue Date: October 19, 2007
Revision Date: June 27, 2011

Western Fiberglass, Inc.

Liquid-Filled Reservoir for Double-Wall Sumps
with Liquid Sensor Models WF-3 and WF-750


Certified as a continuous, liquid-filled interstitial space leak detection system for use only with Western Fiberglass, Inc., double-walled sumps or under dispenser containment sumps.

Operating Principle:
Hydrostatic monitoring using single-level float switch. Methodology is similar to that which has been applied to liquid-filled interstitial double-walled tanks.
Propylene glycol is used to fill the interstice of Western Fiberglass’ double-walled sumps or under dispenser containment sumps.
An interstitial liquid reservoir is connected to a port at the highest point of the double-walled space.
Single-level liquid sensor model WF-3 or WF-750 monitor the liquid in the interstitial reservoir and provide an alarm if the liquid drops too low (egress of liquid).

Alarm Conditions:





0.05 gph Leak, Plastic
Reservoir with WF-3 Sensor



0.05 gph Leak, Stainless Steel
Reservoir with WF-750 Sensor


Liquid Volume
Liquid Volume


Liquid Volume
Liquid Volume
*Volume of Liquid
Lost at Alarm (ml)



Time to Alarm (min)


< 1

< 1

< 1

< 1


Time to Reset (min)


< 1

< 1

< 1

< 1

* Volume of liquid lost to alarm depends on the amount of liquid in the reservoir. This amount is determined by the operator when filling the reservoir. This amount needs to be sufficient to prevent false alarms from occurring due to the normal fluctuations in the reservoir which result from temperature and pressure variations in the sump. Minimum alarm volumes were obtained by filling the reservoir to the lowest possible level to reset the alarm. While this condition provides the shortest response time, it is also subject to the highest false alarm rate.

Western Fiberglass, Inc. underground double-walled sumps and under dispenser sumps designed to contain water, gasoline, gasohol, diesel, heating oil #2, kerosene, aviation fuel, or motor oil. Other liquids may be stored after consultation with the manufacturer.

Reservoir requires no calibration other than to insure the upper reservoir is half full.
Sensors must be calibrated and maintained in accordance with manufacturer’s instructions.

Fluid reservoir volumes and connection tightness between reservoir and sump should be inspected annually.
Liquid level in the stainless steel reservoir should be visible in the sight glass.
Liquid level in the plastic reservoir should be approximately one inch above the float switch.

Western Fiberglass, Inc.

Evaluator:  Ken Wilcox Associates

1555 Copperhill Parkway

Tel:  (816) 443-2494

Santa Rosa, CA  95403

Date of Evaluation:  12/20/2006

Tel:  (707) 523-2050




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Equipment should be installed and operated in accordance with all applicable laws and regulations.
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