CREAMERY MECHANICS 



303 



C 



When using right and left nipples, that is, nipples with 

 a right thread at one end and left thread at the other, 

 screw each end separately into the pipe which it is to fit 

 and count the number of threads covered. If, for exam- 

 ple, four right threads are covered and six left threads, 



then cover two left threads be- 

 < fore joining with the other 



' end. In this way the two ends 



turn tight at the same time, 

 which is necessary to prevent 

 leaking. 



VALVES. 



The subject of valves is an 

 important one and deserves 

 much attention. Usually the 

 ordinary creamery contains 

 from twenty-five to fifty, 

 valves. It is, therefore, not sur- 

 prising to find steam and 

 water leaks in a creamery building. To replace a valve 

 as soon as it begins leaking is too expensive. The proper 

 thing to do is to repair it. In the following paragraphs 

 a brief discussion will be given of the kinds of valves 

 and the methods of repairing them. 



Globe Valve. This valve, shown in Fig. 91, takes 

 its name from its globular form. It is preferably so 

 placed as to allow the pressure of the steam to come 

 under the valve. 



Check Valve. This is placed between the boiler and 

 the feed pipe to prevent the return of water and steam. 



Fig. 91. Globe valve. 



