Arizona Agricultural Experiment Station 



307 



lodged in the impeller passages, throwing the pump out of balance and 

 causing vibration and noise. Reduced capacity of a pump has many 

 baneful results including lower plant efficiency, increased percentage of 

 seepage loss in ditches, longer periods of pumping and increased cost, 

 rrhe gland and the joints in the suction pipe should be watched. 



TEST OF PUMPING PLANT 



A new pumping plant was tested on the ranch of the Agricultural 

 Products Corporation in Pima County. The plant consists of a 15-inch, 

 52-foot type C. H. C. Layne & Bowler vertical turbine pump and a 35- 

 horsepower Commercial oil engine. The pump has six stages, one more 

 than usual for the same conditions, thus permitting of a slow speed 

 w hen irrigating and a speeding up when pumping for the high service 

 or in case the water table should fall during drought years. The pump 

 was purchased with high fuel economy guarantee and the guarantees 

 were not reached in the first tests. An expert from the engine factory 

 visited the plant and made a number of changes after which the guaran- 

 tees were made good, and the plant is now very efficient. Some of the 

 changes were lengthening of the connecting rod one-half inch to in- 

 crease the compression pressure, change in shape of end of fuel nozzle 

 to give better atomization, lengthening inlet valve spring to reseat valve 

 more quickly, advancing the ignition to about 35°, and restricting the 

 cooling water circulation. The first named was the one most effective 

 and shows that purchasers should insist on the optimum degree of com- 

 pression even though locality where the engine is to be located is at a 

 high altitude. The plant tests are given in Table XXVI. 



TABLE XXVI. TESTS OF PUMPING PLANT AT CONTINENTAL, ARIZONA 



In order to ascertain whether it was the pump or the engine that did 

 tiot meet the specifications, a prony brake was put on the engine, and 

 brake tests were made for capacity and fuel economy. With No. 1 en- 

 gine distillate, the engine would carry a load of only 32 horsepower, but 

 with tops of 42° B. it carried 35 horsepower. The brake tests were made 

 on November 24 before the connecting rod was lengthened. 



