Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Content or effect of a constituent of a liquid mixture
Patent
1993-04-27
1994-09-27
Williams, Hezron E.
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Content or effect of a constituent of a liquid mixture
73 6142, G01N 1506
Patent
active
053498496
DESCRIPTION:
BRIEF SUMMARY
This Invention relates to hydraulic and other liquid flow systems, and tn particular to a mechanism by which the degree of contamination of the fluid tn such a system can periodically be measured. Examples of such mechanisms, which have already been put into use, are described in Patent Specifications GB-B-2112530 and GB-B-2141240. Each of those two specifications describes a mechanism which periodically tests the contamination of the system fluid by isolating a sample volume of that fluid, using a dedicated power source to pass that isolated volume through a small orifice of a particular kind, measuring the degree of contamination by reference to how quickly the orifice becomes blocked, and then re-setting the mechanism In readiness for the next test. The mechanisms described In both specifications are aimed primarily at testing for the presence of particles of metal and other very hard materials that are the typical contaminants of many hydraulic fluid power systems. Consequently both specifications state that the orifices should be of the kind. sometimes referred to as viscous-loss, tn which the accumulation of small particles of metal or other such materials tends to vary predictably with the volume of hydraulic fluid that has passed through the orifice, assuming a constant degree of contamination of that fluid. The typical viscous-loss orifices described with reference to the drawings of those specifications are all defined between spool-like members and the cylindrical housings in which they move, and are tn the form of small annular clearances between spool and housing and coaxial with both of them.
Such clearances, whilst suitable for hydraulic fluids contaminated by metal or like hard particles with a typical maximum dimension of the order of say 11/2-5 microns, are much less so for fine particulate slurries of the kind commonly processed in the china clay industry for example, in which the typical contaminant particles are softer, plate-like in shape, and with a much greater maximum dimension of the order say of 35-50 microns. Such particles tend not to accumulate at the mouth of an annular, viscous-loss orifice as just described, but to intrude into the orifice and jam it. This not only affects the result of the test by restricting the orifice much more quickly than would be the case if the particles came to rest at the orifice mouth, but also tends to interfere with the subsequent axial movement of the spool, at the end of the test, to clear the orifice and re-set it for the next test.
One aim of the present invention is to provide an alternative mechanism more suitable to measure the contamination of fluids by such larger and softer particles. The invention also facilitates using the main pumping source of the system, rather than dedicated sources as described in the two quoted prior speciflcations, as the power source for conducting the tests also.
The invention is described by the claims, the contents of which are to be read as included within the disclosure of this specification, and the invention includes liquid flow systems as described by way of example with reference to the accompanying drawings in which:
FIG. 1 is a cross section through a valve;
FIGS. 2 and 3 are schematic circuit diagrams showing alternative arrangements of such a valve within a hydraulic flow system;
FIGS. 4 and 5 are similar to FIGS. 2 and 3, but show alternative arrangements of power source for both the system and a mechanism for determining contamination;
FIG. 6 is a cross section through an alternative power source for such a system and mechanism, and
FIG. 7 is a schematic layout showing the controls and auxiliary power sources for a system including the pump of FIG. 6.
In FIG. 1 a valve member 1, comprising a stem 2 and a head 3, can slide within a housing 4 in the direction of their common axis 5. Bellows 6 and 7 prevent access of contaminants to the surfaces of member 1 and housing 4 that are in sliding contact with each other. At the end remote from head 3, a flange 8 is fixed to stem 2 by a screw 9. A ring
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patent: 4495799 (1985-01-01), Fisher et al.
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British Technology Group Limited
Brock Michael
Williams Hezron E.
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