Fuel Oils for Pump Irrigation 407 



flash point indicates the ease or difficulty of starting a cold engine. A 

 moderately low flash point, say below 115° F., is desirable for electric- 

 ignition engines. 



Many different patterns of apparatus are in use to determine the 

 flash point, and the results obtained vary considerably. The Arizona 

 Agricultural Experiment Station uses the Elliott or New York State 

 tester, which is semiclosed.* 



Large purchasers of oil, such as farmers' oil associations, should 

 own and use a flash-point tester. There is an advantage in using the 

 same type of testing apparatus as that used at the Experiment Station, 

 inasmuch as comparisons can then be made with Experiment Station 

 records. 



BURNING POINT 



The burning point is the temperature at which the "flash" be- 

 comes permanent. This point is obtained with the flash-point tester. 

 After the flash point has been obtained, the temperature is raised 

 further until the flash continues as a steady flame. 



BOILING RANGE 



The distillation or boiling-range test is made by heating the oil in 

 a small still, and noting the temperature at which the first drop and 

 successive fractions of the oil are carried over into the cup in which 

 the distilled oil is caught. The U. S. Bureau of Minesf recommends 

 that the temperature be noted for the first drop, and each successive 

 ten percent up to ninety percent, and also for ninety-five percent and 

 the dry point. 



The American Petroleum Institute distinguishes between "dry 

 point" and "end point" in the following manner. The dry point is 

 usually stated to be the point at which the bottom of the distillation 

 flask becomes dry, and frequently this is indicated by a puff of smoke 

 leaving the bottom of the flask. The end point is determined by con- 

 tinuing the heating until the column of mercury (thermometer) reaches 

 a maximum and then starts to recede consistently. For light oils, the 

 end point, or maximum boiling temperature, can be obtained quite ac- 

 curately and consistently. For heavy oils, not much dependence can be 



•In a recent private communication from the U. S. Bureau of Mines, the Tag closed 

 tester is recommended for oils having specified limits less than 150° F., and the Pensky-Mar- 

 tens closed tester for fuel oils flashing above 150° F. These instruments will be obtained and 

 tried by the Experiment Station at once. 



■f Bureau of Mines Technical Paper 214, "Motor Gasoline; Properties, Laboratory Methoda 

 of Testing, and Practical Specifications." 



