290 



SEWAGE AND ITS PURIFICATION 



500 gals, per sq. yd., to be increased when necessary to 1,000 gals. 

 The total dry weather flow to be treated in this way will be 

 8 million gals. 



The nozzles used in the earlier experiments were in the form 

 of a jet playing against a disc or cone, " but these only threw a 

 ring of water, not an area." Afterwards the " Simplex Sprayer " 

 (Gjers and Harrison's patent) was employed: it has two impinging 

 jets Hke the fishtail gas burner, and throws a *' very even spray 

 over an oval area, and so suits our spacing of 5 to 10 ft."^ The 

 later used type is more complicated, and " throws an even 



Fig. 38. — " Acme " Fixed Sprays. 



circular area of spray": it has six holes in the base disc, 

 bored obliquely like a siren, so as to set the water whirling as 

 it passes out. 



(c) " Acme " Fixed Sprays (Ames-Crosta Sanitary Engineer- 

 ing Co., Ltd.). The jets are screwed into vertical Tee pieces 

 forming connectors in horizontal pipes run 4 or 5 inches below 

 the surface of the filter bed. The jets are spaced about 7 ft. 6 in. 

 apart on the pipes, and the pipe runs themselves are at 7 ft. 6 in. 

 centres. Head recommended i ft. 6 in. minimum and 3 ft. 

 maximum, giving a contracting spray from 4 ft. 6 in. radius to 

 the jet centre. Rate of discharge estimated at 2J gallons per 

 minute per jet or about 735 gallons per square yard per 24 hours. 

 The supply to the submerged pipes is regulated by an automatic 



1 Letter from Mr. Corbett, Borough Engineer, May 29, 1906. 



