Usable Flow Rate 



While the above procedure laterally oversprayed and lost considerable volume to each 

 side of the fuel bed, it produced a uniform pattern over the 18 -inch fuel bed width. The actual 

 amount of material falling into the fuel bed per second was determined by spraying directly into 

 18 -inch -wide pans for a given time period, then weighing the pans and computing the rate. 

 Table 3 shows the resultant usable flow rates. 



Table 3 . - - Retardant calibration and application data 

 (based on rate of 1 gallon per 100 square feet) 



Retardant 



:Calibration: 

 : Measured : 

 : density 1 : 



Flow 



Viscos- 



Time 4 





Application amount 





rate 



ity 3 



Chemical : Water 



Total 





Lb. /gal. 



G.p.m. 



C.p.s. 



Sec . 



Grams 



Percent Grams 

 Drying Pans 



Percent 



Grams 



Gelgard 



8.36 



1.82 





2.4 



1 



1 114 



99 



114 



Algin-gel 



8.33 



1.92 



1,360 



2.5 



1 



1 113 



99 



113 



Bentonite 



8.76 



2.00 



5,090 



1.9 



10 



8 109 



92 



119 



Phos -Check 202 



8.83 



1.85 



2,610 



1.9 



14 



11 106 



89 



120 



Fire-Trol 



9.49 



2.00 



2,637 



2.5 



32 



25 97 

 Burning Trays 



75 



129 











Sec. 



Lbs. 



Percent Lbs . 



Percent 



Lbs. 



Short-term 







3,505 



7.8 



0.09 



8 0.96 



92 



1.05 



Long-term 







2,780 



10.0 



.29 



25 .85 



75 



1.14 



Residual bubbles may have caused minor errors, even though at least 18 hours elapsed between mixing and 

 measuring. 



2 Nozzle tip diameter: 9/64 inch; tank pressure: Phos -Check 202 - 15 p.s.i.; all others - 12 p.s.i. 

 3 See table 7, p. 28. 



4 Nozzle height above fuel bed: Phos-Check 202 - 110 cm.; all others - 100 cm. 

 5 By volume: 0.01 gal. /sq.ft. for all retardants. 



Retardant Application 

 Selection of Amounts 



Retardant dropped from an air tanker does not form a uniform lateral layer on the ground. 

 The amount may vary from less than 0.5 gallon per hundred square feet (0.5 gal. /1 00 sq.ft.) to 

 more than 5.0 gal./lOO sq.ft. Seldom does a continuous strip of air-dropped retardant contain 

 more than 3.0 gal./lOO sq.ft. From this range of field-attainable amounts we used the quanti- 

 ties of 1, 2, and 3 gal./lOO sq.ft. for the series of drying and burning tests. Preliminary 

 burning tests verified that these amounts would produce a satisfactory range of results. 



Penetration 



Application of all the retardant onto the upper surface of the 3-inch-deep fuel bed created 

 a situation similar to what occurs in field application- -an unequal vertical distribution of the 



7 



