area cleaned in a given time. Example: at 690 kilopascals a 9.5-millimeter 

 (3/8 inch) nozzle will clean 2.25 times the rate of a 6.4 millimeter (1/4 

 inch) nozzle. 



(h) Sand and Abrasive Consumption Rates . Sand is the most 

 widely used abrasive and for this reason, will be used as the basis for 

 consumption rates presented. Other abrasives, infrequently used, include 

 aluminum oxide, walnut shells, steel shot and steel grit. Rates for other 

 materials are related in general to sand consumption rates. Specific 

 consumption rates for each material will depend on the specific density of 

 the abrasive and its velocity. 



Upon impingement on a surface, the energy released by an abrasive 

 particle will be directly related to its cleaning rate. That is, the more 

 energy released, the faster the cleaning rate. The energy of a particle 

 in motion is determined by its mass and its velocity according to the 

 equation E = 1/2 MV 2 , where E is the energy of a moving abrasive particle 

 (energy is released when particle strikes the surface) , M the mass of 

 abrasive particle, and V the velocity. Thus, the cleaning rate increases 

 as the mass and velocity increase. 



Sand consumption rates and airflow consumption are presented in Table 

 48. The increased sand and air consumption results in a greater area 

 being cleaned per hour. The actual production per hour is affected by the 

 condition of the surface to be prepared for coating and the cleanliness or 

 surface preparation to be achieved, as shown in Table 49. 



Table 48. Sand and airflow consumption. 



Nozzle 

 Diameter 

 (nun) 





Nc 



zzle Pressure (kPa) 









344.7 



413.7 



482.6 



551.6 



620.5 



689.5 





3.2 



.32 

 298 



.37 

 342.5 



.43 

 391.4 



.48 

 449.2 



.52 

 498.2 



.57 

 547.1 



Air ( 

 Sand 



m 3 /min) 

 (N/hr) 



4.8 



.74 

 667.2 



.85 

 760.6 



.93 

 871.8 



1.08 

 960.8 



1.16 

 1058.6 



1.27 

 1174.3 



Air 

 Sand 





6.3 



1.33 

 1192 



1.53 

 1387.8 



1.73 

 1574.6 



1.92 

 1814.8 



2.09 

 1992.8 



2.29 

 2197.3 



Air 

 Sand 





7.9 



2.18 

 2081.7 



2.52 

 2375.2 



2.86 

 2686.6 



3.2 

 2989 



3.57 

 3291.5 



3.88 

 3611.8 



Air 

 Sand 





9.5 



3.06 

 2971.3 



3.57 

 3398.3 



4.05 

 3843.1 



4.56 

 4270.1 



4.9 

 4679.3 



5.55 

 5124.1 



Air 

 Sand 





11.1 



4.16 

 3985.4 



4.81 

 4590.3 



5.49 

 5230.8 



6.14 

 5835.8 



6.79 

 6440.7 



7.19 

 7045.6 



Air 

 Sand 





12.7 



5.52 

 5159.7 



6.34 

 5942.5 



7.13 

 6725.4 



7.92 

 7472.6 



8.74 

 8255.5 



9.57 

 9002.8 



Air 

 Sand 





339 



