ANALYTICAL
28 A
CHEMISTRY
Efficient, Non-Sparking, Perfectly Controlled W e l c h M O T O R STIRRER Especially Adapted for use with Explosive Materials Sparkless Induction Motor Eliminates the Explosion Hazard f r o m Brush Contacts
Delicately Controlled Variable Range of Speed (200 t o 1,500 R.P.M.) Speed Controlled by a W a t t Governor, Eliminates
No.
5230.
Rheostats, Gears, or Friction-Drive Discs T h r u s t Ball Bearings Insure Long Life, C o n t i n uous Running
5230. NON-SPARKING MOTOR STIRRER. This motor stirrer is efficient and perfectly controlled. The motor is of the induction type and, having no brushes, eliminates one of the greatest dangers of explosion found in all other stirrers when used over such solvents as ether, alcohol, benzine, acetone, etc. The motor runs on the regular 60-cycle, 110-volt A.C. circuit, has practically the same power input at high or low speeds and will not burn out if stalled. A binding post is provided on the support rod of the motor and is thereby electrically connected through the motor shaft to the stirrer so t h a t the latter can serve as the rotating anode in electrolytic analysis. This is not a friction drive outfit, the stirring rod being direct-connected to the motor shaft by means of a chuck which takes any size shank from 0 to 6.5 mm. and can be very tightly adjusted with the fingers. The speed of the motor is delicately controlled, over a range from 200 to 1500 R.P.M. by means of a governor contained in the housing and activated by means of a very positive screw adjustment. The speed range is, therefore, from a minimum as low as ever desired up to the maximum speed of the motor. While the
W.
M.
WELCH
speed is manually controlled through the setting of the adjusting screw, the particular construction of the governor makes this speed control for a given setting automatic in t h a t a decrease of speed (which might be due to an increase in viscosity of the liquid as the stirring progressed) brings the governor weights further in, thus reducing the friction between the control surfaces and automatically speeding up the motor. The reverse would be true in case the resistance to the stirring were suddenly or gradually lowered. In all other stirrers employing either the friction disc or the worm gear drive, there is no constancy of speed when variations of the line voltage or variations of the load occur. The motor shaft is provided with thrust ball bearings, both top and bottom. The motor and governor have no wearing parts and the outfit will last for years. By arranging the angle of the motor shaft the stirring can be accomplished in any position desired. E a c h , $37.00 5230A. N O N - S P A R K I N G MOTOR STIRRER. Similar to No. 5230 but for 220-volt, 60 cycle A.C. circuit. A "stepdown" transformer from 220 to 110 volts is provided in the lines. E a c h , $47.50
SCIENTIFIC
COMPANY
. Established 1680 - . . _ . _ - - 1 5 1 5 SEDGWICK STREET, Dept. A, CHICAGO 10, ILLINOIS, U. S. A. Manufacturers of Scientific Instruments and Laboratory Apparatus
