Leeds Northrup Model

Apparatus. All electrical resistances were measured with an electrolytic conductivity bridge (Leeds and Northrup model 4666) which was constructed according to specifications set forth by Jones (28) and described by Dike (29). The audio-frequency source was a General Radio Co. type 1311-A audio oscillator used with the frequency regulated at 1000 Hz and the output at about 5 V. The detector circuit consisted of a high-gain low-noise tuned amplifier and null detector (General Radio Co. type 1232-A) and an oscilloscope (Heathkit model O-ll) ... 

Experimental. A Parr model 1221 oxygen bomb calorimeter was modified for isothermal operation and to ensure solution of nitrogen oxides (2). The space between the water jacket and the case was filled with vermiculite (exploded mica) to improve insulation. A flexible 1000-watt heater (Cenco No. 16565-3) was bent in the form of a circle to fit just within the jacket about 1 cm. above the bottom. Heater ends were soldered through the orifices left by removing the hot and cold water valves. A copper-constantan thermocouple and a precision platinum resistance thermometer (Minco model S37-2) were calibrated by comparison with a National Bureau of Standards-calibrated Leeds and Northrup model 8164 platinum resistance thermometer. The thermometer was used to sense the temperature within the calorimeter bucket the thermocouple sensed the jacket temperature. A mercury-in-glass thermoregulator (Philadelphia Scientific Glass model CE-712) was used to control the jacket temperature. 

Gas Chromatograph. Two Wilkens Aerograph Hy-FI chromatographs equipped with electron capture detectors were used interchangeably with a Leeds and Northrup model H recorder. The recorder had a 0-1-mv. span and a W per minute chart speed. 

The IR spectra were recorded using Pye-Unicam spectrophotometer, model 3-300. The specific conductivity of catalyst systems was studied using Leed Northrup conductivity bridge and cell. 

A Jarrell-Ash Model 82-532 MV spectrophotometer equipped with a Perkin Elmer nebulization system and a Leeds-Northrup Type W calibrated AZAR Recorder was used for the molybdenum analysis. The 3133 primary molybdenum absorption wavelength coupled with an acetylene-nitrous oxide flame were the basic parameters of the instrument. The recorder was set for a 5-fold signal expansion along with the amplifier at 3/4 damped position. 

Another important application of an electromagnetic flowmeter is in the external sodium line from the model tank to the dump storage systems. A Leeds Northrup direct current amplifier, Model 9835-B, is used to amplify the flowmeter signal to drive a Brown 0 to 4-mv. recorder to any desired amplitude for a given flow rate. This technique is very convenient to maintain a flow rate of 1 to 2 gallons per minute for the cold trap operation which follows the sodium charging. 

Apparatus. A Wilkens Aerograph HyFi Model A-610-B with electron capture detector was used. Two standard accessories, a detector heater and voltage control. Model A-630, were also employed. The output of the chromatograph was recorded on a Leeds Northrup Speedo-... 

Jacket temperature was controlled by connecting the thermoregulator and the heater to an American Instrument Co. relay model No. 4-5300. Power to the heater was supplied by a 60-cycle variable transformer normally operated at about 10 volts. Jacket temperature was recorded by feeding the thermocouple output through a Leeds and Northrup d.c. amplifier (No. 9835-B) to a Speedomax H Azar strip chart recorder. 

Emf measurements were made with a Leeds and Northrup K-5 potentiometer equipped with a Leeds and Northrup DC null detector (Model 9829). The temperature of the bath was regulated to within 0.02 K. Details of the experimental procedure, including preparation of the electrodes (19), cell design, preparation of solutions, purification of the hydrogen gas, and other experimental aspects, have been reported elsewhere (13,14). 

Instruments and Methods of Measurements. A Leeds and Northrup Type K-3 universal potentiometer, in conjunction with a General Electric Model 29 galvanometer, was used to measure electromotive force. The potentiometer was calibrated by means of a Weston Standard Cell which had been calibrated against a National Bureau of Standards (NBS) certified standard cell. Galvanic cells which were maintained at constant temperatures of 25°, 35°, and 45°C d= 0.01° by being immersed in a water bath at the desired temperature. The temperatures of the baths were set using a Fisher Scientific calibrated standard thermometer, with calibration traceable to the NBS. An adaptation of the cell sketched by Ives and Janz (II) was used. The modification of the cell was that described by Mclntrye and Amis (10). 

Activity Software imports data from Micromeretic s Sedigraph 5100, Leeds and Northrup s Microtrac and Cilas Model 920. In operation data such as particle size distribution, surface area, filler costs or other properties are entered into the software. Target values are next assigned to the data components with the values scaled to reflect each component s... 

Leeds and Northrup Microtrac Series 9200 Ultrafme Particle Analyzer Model 9230 operates in the 0.003 pm to 6 pm size range (Figure 10.19) and gives reproducible results in the concentration range 2 to 2000 ppm... 

Analytical Apparatus. In the cold-trap method, mercury is detected by the gas-phase absorption of elemental mercury at 2537 A using a Coleman Instruments mercury analyzer (MAS-50) equipped with a Leeds and Northrup Speedomax recorder (model XL60I). The mercury ana-... 

Recorder, with millivolt range(s) compatible with the AA spectrometer and with a similar 0.5-sec response time. A Jarrell-Ash model 82-500 AA spectrometer and a Leeds and Northrup Speedomax W 10 mV recorder were used in the development of this method. 

With the controlled atmosphere heated sample holder, it was a simple matter to connect a thermistor-type thermal conductivity cell to the system and, by means of an external multichannel recorder, record the DRS and the evolved gas detection lEGD) curves simultaneously (17). This modification of the apparatus is shown in Figure 9.4. The cell was connected to a Carle Model 1000 Micro-Detector system by means of metal and rubber tubing. The thermal conductivity cell was enclosed by an aluminum block which was heated to 100 C bv means of a cartridge heater. The block was connected to a preheat chamber, also operated at 100 C, which was used to preheat the helium gas stream before it entered the detector. The output from the detector bridge was led into one channel of a four-channel 0-5 mV Leeds and Northrup multipoint strip-chart potentiometric recorder. The temperature programmer from a Deltatherm III DTA instrument was used to control the temperature rise of the DRS cell. Output from the Beckman Model DK-2A... 

Pyrolysis gas chromatograms (PGC) were obtained on a model AIOOC Wilkens Aerograph gas chromatograph equipped with a Leeds and Northrup Speedomax G Recorder. The copper chromatography column was packed with acid washed chromosorb W and 20% SE-20. Pyrolysis was accomplished by placing a small, dry sample of polymer on a Rh-W, code 13-002, Gow-Mac coil and pyrolyzing for a predetermined time. 

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