Wall Washing - Funnel Method
Prepare a blank sample (an unused portion of the wash liquid before it was used for wall washing). The wall wash and blank sample must be labelled immediately following collection. Submit to the laboratory for required analysis. Wall wash reports should specify where each wash sample was taken in the tank. 7.5.2 Filter Paper / Blotter Method Put on plastic gloves prior to starting the testing. Rinse wide mouth sample bottle with a small amount of wash liquid. Hold a piece of laboratory filter paper against the surface of the wall a few inches above the floor. Use the laboratory wash bottle to spray about 50 ml of wash liquid onto the test site, about 3 ft. (1 m) above the floor, in a stream about 4 in. (0.1 m) wide. Allow the wash liquid to run down the wall and be absorbed by the filter paper being held near the floor. Do not rub or wipe the filter paper on the tank wall. Note: clean plastic gloves, forceps, or tweezers should be used to handle filter papers. As the test papers are saturated, carefully fold and place them in the wide mouth bottle. Caution: do not permit perspiration to drop into the sample bottle or onto the filter papers.
If required, wash the tank bottom by placing a filter paper on a spot wetted with the wash liquid. Then lift the filter paper carefully, fold it, and place into the wide mouth bottle. Do not take tank bottom samples where there has been foot traffic. Rinse the inside of the plastic cap with a small amount of wash liquid and cap the bottle containing the wall wash filter papers. Prepare a blank sample as follows: Rinse a wide mouth bottle with a small amount of the wash liquid. Take an unused filter paper from the box and place it into the rinsed wide-mouth bottle. Add wash liquid from the wash liquid spray bottle. Rinse the plastic cap with wash liquid and securely cap the bottle containing the blank sample and filter paper. Samples must be labelled immediately following collection
The process shall be repeated at the applicable number of sites. Approximately 250 mL of reagent shall be collected. If approximately 250 mL is not collected from the number of sites continue wall washing at additional sites until approximately 250 mL is collected. Rinse the inside of the bottle cap with a small amount of wash liquid and place securely onto the bottle.
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