Coulter counter, operation

Coulter Counter operational conditions Gain index 4 Aperture 100 microns... 

Coulter Counter operational conditions Micrcxner ograph operational conditions ... 

As, the specific crystal surface area (m2/g of solids) can be obtained by the method recommended in the Coulter Counter Model D Operating Manual ... 

For pigments, counting is the most suitable method for several reasons. The counting operation is carried out in the binder medium of interest, whereas with sedimentation analysis or the Coulter counter the medium cannot be freely chosen. Furthermore, counting can be carried out under the dispersion conditions used for examination (in contrast to methods in which a specified binder medium must be used that can lead to a different state of dispersion). Problems associated with concentration are much less frequent than in other methods, which sometimes require extremely dilute suspensions (especially optical analysis and the Coulter coun-... 

Examination of the Coulter Counter data revealed that the larger oil drops were removed much more effectively than the smaller drops. Also, a net production of diops smaller than about 2 pm oc curred regardless of the system operating conditions. This net drop production was caused by the shear field generated by the air-inducing rotor. The production of small drops limited the removal efficiency of the process since these small drops are not removed. Although these experiments quantified overall system performance, they yielded limited information concerning the mechanism of the oil removal process. 

Fig. 8 Schematic representation of the operation of the Coulter counter. (From Ref. l)...

Electronic Zooplankton Counter. The electronic zooplankton counter (prototype) mounted on Batfish operates on a principle similar to the Coulter counter where an insulating particle, such as a zooplankter, displaces seawater in a tubular cell and causes a change of electrical con-... 

The latest Coulter Counter instruments incorporate a microprocessor and the operator can specify the form of the output data to be obtained. The instrument converts count-data to practically any format desired, with the exception of log-probability plots. 

Particle suspensions must be fairly dilute to avoid problems of coincident passage of several particles through the aperture. The volume sampled is set by electronic probes in the mercury column, which start and stop switches as the mercury passes. The instrument used for this work had settings for sample volumes of 50 /xL, 500 /xL, and 2,000 /xL, and was operated with four apertures, 30 /xm, 70 /xm, 140 /xm, and 280 /xm. The Coulter Counter was calibrated with polystyrene latex (PSL) spheres. A computer program was used to convert channel counts and calibration information to particle diameters, surface areas, and volumes after editing spurious data from the paper tapes. Particles were assumed to be solid spheres, since output from the Coulter Counter for sludge is that for spheres of volume equivalent to the randomly shaped particles in the suspension. 

On the other hand, considering the operating principle of the Coulter Counter, which is based on electrical conductivity differences between the suspending medium and the suspended particles, it could be expected that, if the particle conductivity changes on swelling owing to electrolyte absorption, the response of the Coulter Counter could be impaired. 

In the following description it is assumed that the reader has at his disposal a Model B Coulter Counter which has been set up as an operational instrument by a company representative. Precise details on the operation of this instrument are given in A Practical Manual on the Use of the Coulter Counter in Marine Science by R. W. Sheldon and T. R. Parsons (Published in 1966 by Coulter Electronics Sales Company — Canada) and the subject is discussed further by Sheldon and Parsons (/. Fish. Res. Bd. Canada, 24 909, 1967). The following account is to some extent an abbreviated set of instructions obtained from the publication cited above. Only the essential operation of the instrument, the preparation of samples, and two basic types of particle distributions are dealt with here. For greater working details as well as for descriptions of accessmy apparatus, the reader is referred to the manual cited above. 

The apparatus specified in the following procedures is a Coulter Counter Model B. A detailed description of the electronics of this instrument is given in a manual provided by the manufacturer. The description given here is only intended to serve as an introduction to the use of the apparatus and to identify certain controls which have to be operated. 

The Coulter principle is also standard for dry toners [8,9] and an accepted method for aluminum oxide powder [10], chromatography media [11], polymeric powders [12], plutonium [13], filter evaluation [14], catalytic material [15] and comparing particle size distribution using alternative types of particle counters [16]. In ASTM method C-21 it states that the experience of several laboratories indicates that the method is capable of a repeatability of 1% and a reproducibility of 3% at the 95% confidence level. Operating procedures for this technique are also covered in BS3405 [17]. The method is also the subject of an international standard [18]. 

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