Fluid handling – Processes – With control of flow by a condition or characteristic of a...
Patent
1986-06-27
1988-04-26
Walton, George L.
Fluid handling
Processes
With control of flow by a condition or characteristic of a...
73304R, 137392, 307118, 340620, 361178, 417 36, F17D 300
Patent
active
047397861
DESCRIPTION:
BRIEF SUMMARY
This invention relates to improved liquid level monitoring assemblies and to methods of manufacturing same.
The monitoring assembly of the present invention may be used for monitoring liquid levels in many types of liquid reservoirs such as water or liquid chemical reservoirs, sullage pits, sewage and effluent holding tanks. However, for illustrative purposes only, the invention will be described hereinafter with reference to the monitoring of levels in sewage holding tanks.
In a sewered area, sewage may be fed to a holding tank or pit provided with a submersible pump which is actuated automatically to maintain the sewage level in the pit between set upper and lower levels. These switching levels are at present monitored by separate mercury switches or sensing probes supported with their respective lower ends at the selected switching levels. Normally at least four probes are used. These comprise a common probe or earth probe held at all times in the liquid, a stop probe at the lower liquid level for stopping the pump when the liquid falls beyond that level, a start or duty probe at the upper liquid level for starting the pump when the liquid rises to that level and an alarm probe at a higher level to warn of liquid levels above the duty probe level. These probes may be stainless steel rods suspended from insulated electrical cables and held in spaced apart relationship by suitable spacers or they may be supported on brackets fixed to the pit wall.
There are many problems associated with such arrangements. For example, dissimilar metal joints may be formed at the junction between each probe and its support and this may lead to corrosion and breakage. Such junctions also provide a discontinuity at which foreign matter may accumulate and prevent effective operation of the probe. Foreign matter may also build up on mercury switches and inhibit their efficient operation.
A further major disadvantage associated with such level sensing assemblies is that is necessary to descend into the pit for maintenance purposes, such as cleaning, or for varying their switching level. These operations are frequently required as foreign matter including fat, builds up at the duty level. These maintenance operations may be dangerous and unpleasant.
The invention aims to alleviate the abovementioned disadvantages and to provide a liquid level monitoring assembly which will be reliable and efficient in use. Other objects and advantages of this invention will hereinafter become apparent.
With the foregoing and other objects in view, this invention in one aspect resides broadly in a liquid level monitoring assembly including an elongate body supporting a plurality of exposed sensors arranged at spaced intervals along the body and being insulated from one another and a plurality of leads extending from said body and each being connected to a respective sensor.
Preferably the leads from each sensor exit from the top end of the supporting body as cores of a multi-core cable and each core is colour coded or numbered or otherwise identified to indicate the sensor to which it is connected. Sealing means such as a gland may be provided to form a seal about the cable sheath at its connection to the supporting body. Alternatively the sheath may be glued to the body or sealed by a filler or it may be left unsealed if undesired.
In a preferred form the elongate body has a substantially continuous and preferably a substantially smooth outer surface so as to inhibit build-up of foreign matter thereon. The exposed portion of each sensor may be substantially co-extensive with the outer surface, or the exposed portion could be spaced outwardly or inwardly of the outer surface if desired. For example the exposed portion could be constituted by a screw or rivet head, the rivet passing into a tubular body to connect a suitable connector means associated with a respective lead. Thus in one form the monitoring assembly could be formed by connecting a plurality of metal rings to a suitable wiring harness such that the rings are held in spaced apart rela
REFERENCES:
patent: 2410278 (1946-10-01), Farris et al.
patent: 2412363 (1946-12-01), Silverman
patent: 4287756 (1981-09-01), Gallagher
patent: 4551068 (1985-11-01), Boudreaux
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