AU617428B2 - A trickle bleed system for evaporative air coolers - Google Patents

Description

THE COMMISSIONER OF PATENTS This form must be accompanied by either a provisional specification (Form 9 and true copy) or by a complete specification (Form 10 and true copy).

j AUSTRALIA LL P/00/011 Form PATENTS ACT 1952 COMPLETE SPECIFICt TION

(ORIGINAL)

FOR OFFICE USE 617428 Short Title: Int. CI: SApplication Number: S•-Lodged: SComplete Specification-Lodged: Accepted: Lapsed: Published: Priority: e Related Art: poP1 z 27,

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Narm of Applicant: Address of Applicant: Actual Inventor: Address for Service: /0 a/I? TO BE COMPLETED BY APPLICANT GLEN FRANCIS HOST 97 DARLOT ST. MEEKATHARRA, W.A. 6642 GLEN FRANCIS HOST 1 1 HANCOCK QOO3U6U;eQtJ wv t'01% E-E-K-1H-A-RR:A- W-A 6,4-2- Complete Specification for the invention entitled: A TRICKLE BLEED SYSTEM FOR EVAPORATIVE AIR COOLERS The following statement is a full description of this invention, including the best method of performing it known to me:- SNote: The description is to be typed in double spacing, pica type face, in an area not exceeding 250 mm in depth and 160 mm in width, on tough white paper of good quality and it is to be inserted inside this form.

14599/78-L Printed by C. J. THOMPSON, Commonwealth Government Printer, Canberra PAGE 1 DESCRIPTION A TRICKLE BLEED SYSTEM FOR EVAPORATIVE AIR COOLERS Present evaporative air coolers, which are fitted with mains water feed and have water circulation pumps, usually have a trickle bleed system incorporated, which discharges to waste a continual small flow of reservoir water, when the pump is in operation. This action is critical in districts where the mains water feed is saline or hard, because the reservoir water would otherwise get to such concentrations of salt, that salt crystals start to form. Such salt buildup can foul the operation and effectiveness of the cooling pads, the pump filter basket, the pad's feeding slots, the ball float, and the .trickle bleed system itself.

So a trickle bleed off system, for optimum effectiveness, must expell reservoir water at a sufficient rate to subdue the salt concentration level, and also be totally reliable in its operation.

SAn excellent method is outlined in U.S. patent 2,856,166 S wherein dripping water from one of the cooling pads is directed to waste, but the modification of existing models of evaporative air coolers to that system is difficult. Another trickle bleed invention is documented in U.S. patent 3,456,927.

One method uses a sort of swivelling gate valve in a branch off from the circulation pump's discharge tube, thus enabling manual adjustment of this branch's flow rate of trickle bleed off water, to a waste outlet. A variation of that method' is a manually adjustable clamp used instead of a valve, which clamp squashes a tube which is connected to the branch off, thus forming an adjustable constriction to bleed water flow. A third variation of this type provides a fixed flow of bleed off water by the formation of a very fine bore constriction in the branch outlet of the actual plastic branch fitting or moulding. These last three types all virtually control the bleed off flow rate by means of constricting the bore in the passage of water flow in the bleed off path Since these methods all control the bleed off flow rate by a single point of constriction in the flow path this constriction by these methods, is generally too fine at the optimum bleed off rate to be safeguarded from

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PAGE 2 DESCRIPTION obstruction by minute solids suspended in the water circulation system. The swivel valve is also easily disturbed from its adjustment and the clamp method falters to varying conditions affecting the plastic tubing.

Yet another invention uses a branch off of circulation water for a bleed discharge. A tube connected to the branch off conducts some water to a small vessel which is mounted over the main reservoir, keeping that vessel full to overflowing.Another smaller tube connected almost to the bottom of that vessel conducts water to a waste outlet via gravity. The vessel has therefore a constant level and gravity pressure of water by which to regulate the trickle bleed off flow rate. Unfortunately, being such a low pressure expulsion makes its reliability subject to the lie of its waste outlet tubing as air traps in this tube are able to resist its bleed off flow.

S It can be appreciated by the above list of inventions, and the numerous attempts at designing-dumping or purge valves for evaporative air coolers recorded in the patent office, that the f5roblem of water salts is a big hindrance to the evaporative air cooler industry. It still is because of the unreliability e• of the majority of these present designs.

The invention outlined following is inherently accurate and reliable in controlling bleed 6ff water flow rate and S 25 should obviate any further requirement for dumping or purge facilities. It is also extremely simple as it is merely a thin tube of special dimensions, connected to the branch off of the circulating pump's discharge tube, by which special tube the bleed off water flow is both'controlled andconveyed to a waste outlet. The principle is exactly the same as is employed in refrigerant air cooling systems where a fine bore tube provides a controlled flow of recycled refrigerant. This invention is in the application of that same method to control the bleed off rate of evaporative air coolers, with also a claimed addition of a fine filter fitted at the branch off point to further ensure against blockages of branch water flow by suspended solids in the water.

A fine tube resists flow of water by virtue of its length as T I-i.

PAGE 3 DESCRIPTION well as by the small size of its bore. So for a set flow rate, the longer the special bleed off tube length is set to be the larger the bore size tubing can be chosen or manufactured to Obviously, the larger the bore is the less the tube becomes prone to blockages by solid particles in the water stream.It altogether provides a much larger control bore than is required by the point of constrictioni methods related to previously herein, and places little strain on the design requirements of this invention's additional claim of a fine filter fitted into the branch of the branch off fitting. This filter should be provided for the total overall reliability of this bleed off facility, which the industry earnestly needs. It is advised to make this filter out of a rigid fine meshing, and fitting it into the branch fitting of the circulating pump's discharge tube. The filter is to cover the branched outlet only and yet partially oe: protrude into the main stream of the pumped water flow, so that a measure of washing of the filter meshing occurs. The fine tubing should be chosen of a black plastic which is also kink resis- 0 tdnt by nature of its substance and design, and is suggested to be approximately one or two metres in length Its bore size and S actual length is chosen to suit the discharge rate required for bleed off. The free end of the thin tubing is trailed into a waste outlet while the intermediate length to the branch off is S 25 coiled up out of harm's way.