246 



A. DAIGGER & COMPANY, CHICAGO, U. S. A. 



3703 

 Mounted with Motor 



PUMPS CENCO-NELSON HIGH VACUUM 



These pumps represent the most recent development in High Vacuum Pumps for 

 laboratory and commercial purposes. They are compact, operate with very small ex- 

 penditure of power, require no attention when in operation and should last indefinitely. 

 They measure about seven inches high by five inches in diameter at the base and weigh 

 approximately ten pounds. The pulley is grooved for %-inch round belt. 



Under favorable conditions, a vacuum of 0.1 mm. may be obtained with the Two- 

 stage Pump. On continuous service, some heating takes place, which lowers the vacuum 

 somewhat. With the Three-stage Pump, water cooled, a vacuum of .05 mm. may be 

 obtained by using proper precautions. 



The displacement of these pumps in free air, according to tests in our laboratory, 

 is approximately 285 cu. in. per minute, or 10 cu. ft. per hour, at a speed of 900 r. p. m. 



They will evacuate a flask of one liter capacity to a vacuum of 1 mm. in two minutes. 



No A B 



Number of stages 2 



Vacuum, mm 0-1 0.05 



A PUMPS Nelson, unmounted $25.00 $35.00 



B PUMPS Nelson, on hardwood base, without motor 30.00 40.00 



C PUMPS Nelson, on hardwood base, with 110-volt A. C. Motor 60.00 70.00 



D PUMPS Nelson, on hardwood base, with 110-volt D. C. Motor 60.00 70.00 



Pumps See also Blowers. 



PYROMETERS 



3705 



3705 HIGH RESISTANCE PYROMETER, Brown. This type of Pyrometer 

 is entirely unaffected by changes in the length of wire connecting the 

 thermo-couple to the instrument, and is a superior type of instrument 

 where the greatest accuracy is required. It should always be used 

 with platinum thermo-couples, and is desirable for use with base-metal 

 thermo-couples also ;.'; ' " 60>0 



3705(a) PLATINUM RHODIUM THERMO-COUPLES in porcelain tubes, with 

 heads and binding posts. 

 18 inches 

 27 inches 

 36 inches.. 



