US3842796A

US3842796A - Apparatus for treating materials

Info

Publication number: US3842796A
Application number: US00327460A
Authority: US
Inventors: E Hilditch; C Nightingale
Original assignee: Cuprinol Ltd
Current assignee: Cuprinol Ltd
Priority date: 1972-02-07
Filing date: 1973-01-29
Publication date: 1974-10-22
Anticipated expiration: 1991-10-22
Also published as: DK145486C; AT355793B; ATA93073A; CA982359A; AU5171073A; DE2305905A1; BE795069A; DE2305905C2; DK145486B; GB1416428A

Abstract

Means for determining the amount of impregnant consumed includes a vacuum immersion chamber, a reservoir for treating fluid and an amplifying vessel communicating the reservoir to the treatment chamber. Means transfer a measured amount of treating fluid from the reservoir to the treatment chamber and after treatment return the remainder of the fluid to the vessel. Means associated with the vessel indicates the amount of fluid consumed during the treating operation.

Description

United States Patent 1 Hilditch et al.

[ 1 APPARATUS FOR TREATING MATERIALS [75] Inventors: Edward Austin Hilditch, Frome;

Charles Arnold Nightingale, Bognor Regis, both of England [73] Assignee: Cuprinol Limited, Somerset,

England 22 Filed: Jan. 29, 1973 21 Appl. No.: 327,460

[30] Foreign Application Priority Data Feb. 7, 1972 Great Britain 5676/72 [52] US. Cl 8/50, 21/63, 118/429, 134/113 [51] Int. B05c 11/10 [58] Field of Search 118/50, 429,9, 10; 117/113, 116; 73/113; 134/113; 21/63, 65

[56] References Cited UNITED STATES PATENTS 1,315,763 9/1919 Dickey 118/50 1,986,319 l/l935 Bongrand et al H ll8/50 UX Oct. 22, 1974 2,837,764 6/1958 HuIIum cltll. i. 113/50 3.233.57 2/1966 Arvidsson 118/50 FOREIGN PATENTS OR APPLICATIONS 5,043 3/1899 Great Britain ll8/50 Primary Examiner-Morris Kaplan Attorney, Agent, or Firm-Wenderoth, Lind & Ponack [5 7] ABSTRACT Means for determining the amount of impregnant consumed includes a vacuum immersion chamber, a reservoir for treating fluid and an amplifying vessel communicating the reservoir to the treatment chamber. Means transfer a measured amount of treating fluid from the reservoir to the treatment chamber andafter treatment return the remainder of the fluid to the vessel. Means associated with the vessel indicates the amount of fluid consumed during the treating operation.

5 Claims, 8 Drawing Figures 1 APPARATUS FOR TREATING MATERIALS This invention relates to a machine in which diverse materials may be treated with liquids for a variety of purposes.

ln particular, this invention relates to a single machine in which all or any of the following processes for wood preservation may be carried out:

1. Immersion Treatment whereby the timber tobe treated is totally immersed in the preservative fluid for any period from a few seconds to several days. This is a commonly used method of applying wood preservative for many purposes.

2. Immersion Treatment with Vacuum Recovery whereby the timber is first treated by immersion; as described in 1. above, and after removal from the preservative fluid is subjected to a vacuum to remove excess preservative fluid from the timber. This process has been used to reduce the amount of preservative fluid retained in highly absorbent timbers.

3. Vacuum Treatment whereby the wood to be treated is subjected to a vacuum to remove air from within the wood prior to immersion in the preservation fluid. Atmospheric pressure is restored only after the timber is immersed in the fluid whereupon preservative fluid is drawn into the timber. Alternatively, release of vacuum while the timber is immersed in the fluid may only be partial, final release occurring after the timber has been removed from the fluid. This process can be used to obtain deep penetrations and high preservative loadings, particularly in permeable timbers.

4. Double Vacuum Treatment whereby the wood to be treated is first subjected to a vacuum to remove air from within the wood, subsequent immersion of the wood in the preservative fluid, the vacuum being maintained until immersion is complete. On complete or partial release of the vacuum, preservative fluid is drawn into the wood. The wood is next removed from the preservative fluid and a second vacuum is drawn to remove part of the absorbed preservative fluid. Such a method of treatment is used for joinery, cladding and other timbers and is claimed to give increased penetra. tion for a given preservative absorption when compared to a simple immersion treatment.

The present invention provides apparatus for treating materials, which apparatus comprises a treatment chamber having a lower part for containing a treating fluid, and an upper part, means for supporting the material to be treated, means for moving the supporting means between the upper and lower parts of the treatment chamber, a port providing access to the upper part of the chamber and means for altering the pressure within the treatment chamber relative to ambient pressure.

While in its preferred embodiment, apparatus according to this invention will, for economic reasons, normally be constructed so as to be usable only under atmospheric pressure, vacuum or a low positive pressure, provided that suitably strong construction is employed and suitable pumps provided, this apparatus may equally well be used for application of fluids by processes involving pressure, for instance, those wood preservation processes normally referred to as the Bethell, Lowry or Reuping processes, or any of the many variations thereof.

While for the treatment of any particular timbers or other materials with a particular preservative for a par- 2 ticular purpose, a specific schedule of times, vacuum or pressure appropriate to the process being carried out will be employed, and while for economy or convenience specific examples of the apparatus in accordance with this invention may be constructed which will only operate for a given cycle, or a limited range of cycles, the invention is not intended to be so restricted, and by adoption of a suitably strong construction and provision of suitable pumps and controls, as described below, all or any of the processes referred to can be carried out in apparatus according to this invention.

Such apparatus is not restricted as to the type of fluid which it may be used to apply; for instance, it can equally well be used to apply wood preservatives of the organic solvent type, such as solutions of copper naphthenate, zinc naphthenate, pentachlorophenol, tributyl tin oxide, lindane or dieldrin, or other commonly used chemicals in an organic solvent such as white spirit, petrole um distillate or coal tar naphtha, or creosote or other coal tar oils, or water-borne materials such as copper-chrome-arsenic salts such as are described in British Standard 4072 1966 or any of the many other compositions that have been used in wood preservation. Other materials which can be applied to wood are solutions of fire retardants, water repellents, resins, or

resin monomers which may subsequently be polymerized, and dyes, stains or other colourants.

Timber which may be impregnated in this apparatus may be in any form and may include converted timbers such as are normally used in buildings or in civil engineering or in any wood fabrication industry. They may either be rough sawn or prepared, may be fabricated component parts, e.g., window frames or door parts or may be assembled items, e.g., window frames. They may be round timbers such as'fence or transmission posts, small wooden articles or components, or woodbased sheet material, e.g., plywood, blockboard etc. Laminated structures, fibreboards such as chipboard, hardboard or insulation board may also be treated in this apparatus. I

This apparatus may also be used to impregnate textiles, rope, yarn, cordage or any other material with fluids or solutions designed to confer a variety of beneficial properties prominent amongst which are resistance to fungal or insect attack (including moths), fire retardancy, water repellency, stiffness, softness, crease resistance or colour. 7

Whereas other machines are known which will carry out individually all the processes described, the advantage of the present invention lies in the flexibility with which different processes maybe carried out within the same apparatus, and, with certain types of processes where several stages are involved, in that the transfer from one stage to the next can be accomplished much morerapidly than in conventional equipment with a consequent reduction in total cycle time, enabling treating chamber. When it becomes necessary to immerse the timber in the preservative fluid, this fluid must be transferred from the holding tank to the treating chamber. The rate of transfer is limited, both by mechanical transfer considerations such as pump capacity, pipe diameter etc., and by the necessity to maintain a vacuum within the treating cylinder while transference is in progress. Commonly this operation takes minutes or more. In a machine according to the present invention, the timber is loaded onto a support, e.g., into a cage, held in the upper portion of a single chamber, the treating, e.g., preservative, fluid being held in the lower portion of this same chamber. The initial vacuum is pulled on the whole chamber and immersion of the timber is effected simply by lowering the cage into the fluid. This operation typically takes half a minute or less and is much quicker than can be effected in even the most efficient of the conventional plants.

There is a similar time reduction at the conclusion of the immersion period when the timber and fluid must be separated. In a conventional plant the fluid is pumped away from the treating chamber and again, commonly requires 10 minutes or thereabouts, whereas in an apparatus as herein described, the cage containing the timber is simply raised, again typically taking half a minute or less. Thus, on a double vacuum treatment cycle there is a saving of approximately 20 minutes as compared to a conventional plant, which in the schedules adopted for treatment of many timbers represents a reduction of over 30 percent in the time taken to effect a treatment.

An additional advantage of the present apparatus over those commonly used for treatments involving vacuum or pressure is that there is only a small difference in the times for which timbers at the top and bottom of the load are immersed. In both this apparatus and that of a conventional design, the lowest timbers become immersed in the fluid first and are removed from the fluid last. With the times to effect total immersion in the two plants already referred to, if a treatment schedule calls for immersion of all timbers for 5 minutes (which must be measured according to the immersion of the top timbers) then in a conventional plant the bottom timbers in the charge can have been immersed in the fluid for a period exceeding 25 minutes; whereas in an apparatus according to this invention, they would typically have been immersed for only 6 minutes.

This advantage is of greatest benefit when carrying out double vacuum treatments or when a plant primarily designed for a vacuum treatment is used for simple immersion treatments (see Examples 2 and 4). A similar saving in time is, however, also effected when equipment is used for pressure or vacuum pressure treatments, although with total treating schedules normally of 4 to 6 hours the proportionate saving in time is correspondingly less.

When used for immersion treatments the timber is loaded into the cage as before, which is immediately lowered without any need for any fluid transfer. Thus the total cycle time including loading, unloading etc., for a treatment in which the timber is kept fully immersed for three minutes is about 5 minutes, a performance fully comparable with the most efficient of the machines designed specifically for, and used only for immersion treatments. When a conventional double vacuum plant is used for such an immersion treatment,

because of the time involved in fluid transfer, the total cycle time can exceed 25 minutes, and because of the variation in the immersion times for timbers at the top and bottom of the charge already referred to, there is considerable variation in the level of treatment obtained throughout the load.

The invention will be further described with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view, with some hidden parts shown dotted, of apparatus according to the invention,

FIG. 2 is a diagrammatic representation of the arrangement of valves,

FIGS. 3 and 4 are sectional side elevations with the cage in the up and the down position respectively, and

FIGS. 5 and 6 are sectional end elevations corresponding to FIGS. 3 and 4, respectively,

FIGS. 7 and 8 are sectional end elevations corresponding to FIGS. 5 and 6 of an alternative form of the apparatus of the invention.

The machine consists of a tank or chamber 1 which may be cylindrical or rectangular or shaped to suit any special requirement. This chamber is constructed to have adequate strength for its intended processes. Thus, for example, for use in carrying out double vacuum treatments together with either immersion or immersion with vacuum recovery, the chamber will be constructed so as to operate safely at a vacuum up to about 710 mm (28 inches) mercury gauge. For use with pressure processes such asthat of Lowry, it will be constructed to operate at a like vacuum but also at a positive pressure of up to 14.1 Kg/cm (200 lbflin Exceptionally, as for the treatment of resistant woods such as Eucalyptus, it may be constructed to operate at pressures greater than 70.3 Kg/cm (1,000 lbf/in The volume, length and other dimensions of the chamber are varied to suit the needs of a particular user. Typically for use in the treatment of timber the plant would be between 4.57 and 12.2 meters (15 and 40 feet) long with the main cylinder between 2.14 and 3.66 meters (7 and 12 feet) in diameter. For treatment of textiles and like materials, a much shorter plant down to 1.83 meters (6 feet) in length may be utilized. The invention is not, however, intended to be restricted to any particular dimensions whatsoever.

Inside the chamber is a support in the form of a cage 2 supported on jacks 6 as defined below by means of which the cage can be raised or lowered between guide bars 17. While constructed to have the necessary strength to carry a load of timber or other material to be treated, this cage has a sufficiently open base, sides and top to allow free passage of fluid. This cage is usually but not necessarily of a square or rectangular crosssection and is of such a size that it can be held fully raised out of the fluid which is held in the lower portion of the tank, and also fully immersed in this fluid (as illustrated diagrammatically in FIGS. 3, 4, 5 and 6). For a satisfactory treatment the cage and the load contained in it must be fully immersed in the fluid. This full immersion may result from the depth of liquid in the bottom of the treating chamber being greater than the depth of the cage or alternatively, the depth of liquid may be less than the depth of the cage but full immersion still achieved because of the displacement of the fluid by the cage and load.

A port or door 5 is fitted in the top of one of the end walls of the main treating chamber, and aligns with the end of the cage 2 when it is in the raised position. Usually, but not necessarily, the cage is fitted with rails so that the material to be treated can be loaded on trolleys and simply loaded through the door 5 into the cage 2. When required, a second door may be fitted in the other end of the cylinder to allow loading and unloading from either end. The lower edge of the door (as in FIG. 3) may be well above the static liquid level (LI) and also above the level to which the liquid is displaced by the cage and full load. With this construction the door need not be closed when the apparatus is used for simple immersion or any other process not involving vacuum or pressure. Alternatively, the lower edge of the door may be almost as low as the static liquid level (Ll) in which case the door must always be closed before the cage is lowered.

Raising and lowering of the cage is effected by jacks 6 operated usually from above. The number of jacks may vary from two up to any required number. Commonly two jacks would be used for apparatus of less than 5.5 meters l 8 feet) length; three or four for apparatus between about this length and 12.2 meters (40 feet) with correspondingly more for longer plants. The invention is not intended to be limited as to the number of jacks illustrated.

These jacks may take the form of any of the known methods of raising or lowering items; particularly they may be screw jacks electrically or mechanically operated, or may be hydraulic or pneumatic rams. Jacks may operate directly onto the cage or may be connected to it through chains or cables running on pulleys. A counterweight may be used to reduce the load on the jacks and while it is envisaged that jacks will normally operate from above, it is to be understood that the use of lifting devices working from below is not excluded.

In its preferred embodiment, for use with processes involving vacuum, the apparatus is provided with a vacuum pump (not shown) capable of achieving the highest vacuum required for the process connected into the top of the treating chamber by pipe 7.'Similarly, when used for a process requiring pressure, the apparatus is provided with an air pressure pump of suitable capac-- Optionally the machine may be fitted with a measuring device to enable measurements to be made of the amount of fluid absorbed by the material being treated.

This may be effected by connecting suitable load cells Y to the cage 2 to enable direct measurements of the weight of the material before and after treatment. Alternatively, the amount of fluid taken up can be determined by measuring the volume of fluid in the base of the treating chamber, and although this can be done by measuring the changes in the level by means of a simple sight glass or series of level sensors, it is preferred-to fit a separate amplifying vessel 8. The details and operation of this measuring device are described more fully below.

The main chamber is connected to a holding tank 13, through the amplifying vessel 8 where fitted, from which the fluid in the chamber may be replenished.

The apparatus is provided with a series of vacuum or if required, pressure release valves. These may be adjustable but it is preferred to employ preset release valves set to vent when a predetermined vacuum or pressure is attained. A simple on/off valve is fitted be tween the chamber and each vacuum release valve so that they can be sealed off from operation. Alternatively, vacuum or pressure release may be effected by providing a series of pressure sensitive switches which will cause an open/closed valve venting to atmosphere to open or close as necessary to maintain the vacuum/- pressure to which the switch has been set. The manner of operation of these valves is made clear in the succeeding example. These valves or switches may be fitted into the main treating chamber anywhere above the fluid level, or may be fitted into a pipe or chamber which is connected directly to it, or may be situated on a control panel at some distance from the treating chamber and connected to it by a pipe or tube. (The vacuum release valves and associated on/off valves are not shown on FIG. 1 but are represented diagrammatically in FIG. 2 and FIG. 3 as a joint unit SVl, SV2, SV3 and SV4). The number of such valves referred to are appropriate to conduction of double vacuum or similar treatments of timber, but it will be apparent that for alternative processes a greater or smaller number of such valves may be fitted.

Air valves (MVl an MV2) can be fitted into pipe line 7 to control the application of vacuum or pressure to the treating chamber 1 and the amplifying vessel 8. Fluid transfer valves (MV3 and MV4) are fitted to control the transfer of fluid between the amplifying vessel and the treating chamber and from the holding tank to the amplifying vessel.

In its preferred embodiment, these and all other valves are electrically operated valves. Their operation is then controlled automatically by a series of electronic relays, time clocks, position and pressure switches (as described in Examples 3 and 4). In another preferred embodiment these valves may be pneumatically operated and the whole process of the operation may be controlled through appropriate pneumatic switches etc. It will also be obvious that the processes described could be carried out with equal efficiency even if less conveniently when the apparatus is fitted only with'manual control valves.

Apparatus according to this invention may additionally be fitted with steam, electrical, or other heating elements to enable operation to be carried out at an elevated temperature.

The machine is preferably installed with its lower part sunk into the ground, so that load trolleys may be conveniently run in at ground level. This is shown in FIG. 1 where the plane 0000 represents ground level. Such installation is, however, in no way essential to the operation of this invention.

THE AMPLIFYING VESSEL The amount of fluid absorbed into the treated material can be obtained by measuring the difference in volume in the fluid in the lower portion of the treating chamber before and after treatment, but because the amount of fluid absorbed into a single charge is only a very small proportion of the total fluid and consequently only caused a small change in level, measurements of the change in volume made by measuring the change in level are insufficiently accurate for most purposes.

The amplifying vessel enables changes in the volume of fluid utilized to be measured more accurately. This vessel 8 is a tall cylinder of relatively small diameter, so that small changes in volume correspond to quite a large change in level. Level measuring devices are then attached to this cylinder. Any of the well-known methods may be used; examples are a simple sight glass, float-type gauges or a series of level sensors. These may be connected to a recorder and level actuated switches may be inserted at different levels.

It will be understood that the amplifying vessel need not be cylindrical in shape, but may be of any desired cross section, square, rectangular, pentangular, etc., so long as the ratio of height to cross section is such that small changes in volume give a large change in level. If, for any purpose, it is desired to make very accurate measurements when the total absorption is small, but relatively inaccurate measurements suffice when it is larger, or if it is desired to maintain the same relative percentage accuracy over the whole range, then the amplifying vessel need not have parallel sides but may assume a conical or similar shape.

The amplifying vessel may be completely separate from the main treating chamber, but it may equally well be fixed onto it or may even be fabricated as an integral part of the whole apparatus. It may be positioned at any convenient place around the treating chamber.

In the Figures the amplifying vessel 8 is connected at its lower end by pipe 9 to the end or side of the treating chamber. Pipe 9 joins the treating chamber at level L1 which corresponds to the level of fluid in the chamber both before and after treatment (as illustrated below). The joint between pipe 9 and the treating chamber must allow free flow of liquid to achieve level L1 sufficiently quickly. One fabrication that has been found suitable is for pipe 9 to enter below L1 and to extend or bend so as to terminate as L1 in a horizontally machined end, this end being smooth and preferably knife-edged. Alternatively, the pipe may join an open box with one or more knife edges, these edges being horizontal at L1.

The amplifying vessel is also joined to a holding or storage tank 13 through pipe 12, the flow of fluid being controlled by valve MV4.

The amplifying vessel is constructed so as to withstand vacuum and is fitted with a vent SV4. With SV4 open, pressure inside the amplifying vessel is restored to atmospheric.

For automatic operation the amplifying vessel is provided with three level switches: A fitted towards the top representing the upper level of fluid; C fitted at the bottom representing the lower level of fluid; and which B may be adjustable between A and C or may alternatively take the form of several level switches positioned at different heights, one of these being selected for use in each particular treatment in accordance with the principles outlined in the examples.

Alternatively, the amplifying vessel may be provided with a float switch actuating electrical circuits, levels A, B and C being fixed, adjusted and indicated or recorded by appropriate controls or instruments fitted into these electrical circuits.

The size of the amplifying vessel must be such that the total volume measured by the difference between levels A and C is greater than the maximum volume of fluid which will be taken up by a charge of the material to be treated.

The preferred positioning of the amplifying vessel in relation to the treating chamber is such that level C is higher than L1 so that either fluid may be transferred from the amplifying vessel to the treating chamber by means of gravity or if C is below L1 that the difference in levels is sufficiently small for fluid to be drawn from the amplifying cylinder into the main treating chamber by vacuum applied to the treating chamber as described in the examples below. A pump 10 is usually provided in the line connecting the amplifying cylinder to the treating chamber to transfer fluid back from the treating chamber to the amplifying cylinder. This pump may also be used in reverse for the initial transfer or fluid from the amplifying cylinder to the treating chamber. Pump 10 can, however, be omitted and both transfers effected by applying differential vacuums. The holding tank 13 may be a separate tank (as shown in FIG. 2)but a convenient and beneficial arrangement particularly with a cylindrical treating chamber is to partition off the two sides of the chamber on either sides of the cage and to use these sides as the holding tank. This is represented in section in FIGS. 7 and 8, XX and YY' being bulkheads and 15 and 16 then being holding tanks. The benefits of this arrangement are that both the amount of fluid which must be held for treating and the amount of air that must be evacuated is reduced.

A pump (14) is normally incorporated in pipe 12 connecting the holding tank to the amplifying vessel but if with a separate storage tank levels are such as to allow flow under gravity from the storage tank to the amplifying cylinder, pump 14 may be omitted.

The operation of the amplifying vessel is similar for all treatment processes, and is illustrated in Example 1.

EXAMPLE I OPERATION OF AMPLIFYING VESSEL At the commencement of operations, the treating chamber is filled with fluid to level L1. Commonly this will be the state in which the chamber was left after the previous treatment. If not however, fluid is allowed to flow from the holding tank through the amplifying vessel into the treating chamber by holding both valves MV3 and MV4 open, any excess fluid in the vessel above L1 being withdrawn into the amplifying vessel, as described in the later stages of this example.

The fluid level being at Ll, valve MV3 is closed; valve MV4 is open and fluid is transferred from the storage tank 13 until the fluid reaches the high level A in the amplifying vessel. A level switch positioned at level A (not shown) causes MV4 to close and opens MV3 allowing the fluid from the amplifying vessel 8 to flow into the treating chamber 1. (It is assumed in this example that positioning of the amplifying vessel 8 and the holding tank 13 is such as to allow flow under gravity from 13 to 8, from 8 to 1. If this is not so, transfer is effected by operating pumps 10 and 14 at the appropriate stage). During this transfer vent SV4 is open. When the fluid level falls to C a level switch causes MV3 and SV4 to close.

It will be appreciated that in addition to transferring fluid as described, the transfer may be effected by applying a vacuum to the vessel into which the fluid is to be drawn. It will also be understood that reference to level switches includes any suitable levelling device especially those previously referred to. It will also be understood that while the initial operation of adjusting the fluid in the treating chamber to L1 and in the amplifying cylinder to the high level A may be consecutive automatic operations followed automatically by the main treating cycle, they may also be separately controlled as to be two separate operations prior to commence- 7 opening valve MV2 with SV4 closed. All fluid in the treating chamber above L1 is now caused to flow into the amplifying vessel (this operation may be carried out by use of pump 10, if fitted). When transfer of fluid is complete the fluid level in the amplifying vessel 8 will have risen above C to B. B is below A and the volume corresponding to the difference between levels A and B is the volume of fluid absorbed by the material during treatment.

As already related, level B may either simply be measured for record purposes or alternatively, level B can be preselected so that the difference between A and B corresponds to the amount of fluid with which it is desired to impregnate the material being treated; that fluid may be transferred from the treating chamber 1 to the amplifying vessel 8 continuously during the final recovery cycle and the whole treatment terminated when the fluid rises to level B. With this type of operation it is normally preferred to draw an equal vacuum on the treating tank and the amplifying cylinder and to effect transfer of fluid by use of pump 10, but it can equally well be achieved by applying differential vacuums to the two vessels.

Operation of the apparatus constructed in accordance with this invention is further illustrated in Examples 2, 3, and 4. The use of the equipment is not, however, intended to be restricted to these examples, particularly since satisfactory treatment of timbers of species other than those here quoted, or with other preservatives, of for various purposes, or of materials other than timber, may necessitate use of different magnitudes of vacuum, pressure, time, etc. Different processes may also require a different sequence of operations, and even for the processes which form the subject of Examples 2, 3 and 4, although typical values are quoted particularly for time, it is preferred to provide the apparatus with adjustable time clocks so that opera-' tions can be varied according to need and experience.

EXAMPLE 2 Treatment of Baltic Redwood (Pinus Sylvestris) with an Organic Solvent Type Wood Preservative Containing Pentachlorophenol by a Double Vacuum Process An automatic plant is used; it is equipped with three time switches, T1, T2, T3., T1 controls the duration of the first vacuum stage, T2 the period for which the timber remains immersed in the fluid and T3 the duration of the final vacuum stage.

Three vacuum release valves are provided SVl, SV2 and SV3 on the treatment chamber and one, SV4 on the amplifying vessel. SVl is set so that when open it vents at the vacuum required during the first vacuum stage. SV2 when open vents at the vacuum required during the final vacuum stage. SV3 and SV4 when open both vent directly to atmospheric pressure.

This example illustrates the use of an apparatus in which the vacuum vents are set at predetermined levels on manufacture, and where the operator causes more or less fluid to be absorbed by the material being treated by varying the duration of the different time cycles. Such variations could, however, equally be obtained by providing adjustable vents and varying the magnitude of the different vacuum.

For carrying out treatments such as here described, SVl is set to vent when a vacuum of 381 mm (15 inches) mercury gauge has been reached, and SV2 at 635 mm (25 inches) mercury gauge.

Operations are commenced by switching the machine on. This ensures that cage 2 is positioned as shown in FIGS. 3, 5 and 7 and that all valves are closed.

. Door 5 is open; timber previously loaded on trolleys is run into cage 2; door 5 is closed.

Time clock T1 is set, typically at 10 minutes, time clock T2 at 5 minutes and time clock T3 at 20 minutes.

It is assumed-that the liquid level in the treating chamber is correctlyat L1. If not, an operating cycle, as described in Example 1, is carried out to ensure this.

A starter button is pressed, whereupon the plant proceeds through the following operations:

l. MV4 opens, MV2 opens, vacuum pump starts.

2. Fluid is drawn from the holding tank 13 into the amplifying vessel 8 until the fluid level reaches A.

3. Level sensor at A causes MV2, MV4 to close; MVl, MV3, SV4 to open.

4. Fluid is drawn from the amplifying vessel 8 into the treating chamber 1 until the level in the amplifying vessel falls to C. i I

5. Lever sensor in the amplifying vessel at C causes MV3, SV4 to close; SVl to become operative.

6. Pump continues to draw vacuum ontreating chamber untilvacuum reaches 381 mm (15 inches) mercury gauge when SVl will vent to allow air into the treating chamber to balance the action of the vacuum pump to maintain constant vacuum at 381 mm (15 inches) mercury gauge. A pressure switch within the treating chamber (not shown) actuates time clock T1.

7. At the expiry of the preset time (10 minutes), time clock Tl actuates the cage lowering mechanism 6 and cage 2 is lowered into the treating fluid, taking up the position shown in FIGS. 4, 6 and 8 (fluid level rises above Ll due to displacement). Vacuum pump stops.

8. A lower positional switch (not shown) is activated when cage 2 reaches the low position shown in FIG. 4, which causes SV3 to open allowing pressure to fall to atmospheric, SVl to close and actuates the time clock T2 (it is assumed that restoration to atmospheric pressure is rapid; if, for any process, it is slow, then T2 is actuated by an additional pressure switch-which only operates when atmospheric pressure or any other low required vacuum is reached);

9. Cage remains in position of FIG. 4, i.e., timber remains immersed in preservative fluid at atmospheric pressure until expiry of the time period minutes) set on T2. During this period fluid is drawn into the timber by the vacuum which was created inside the timber.

10. On the expiry of this time period, time clock T2 actuates the lifting mechanism 6 and cage 2 is raised to its upper position as shown in FIGS. 3, 5 and 7. SV3 closes, vacuum pump starts; MV2, MV3 open (MVl remains open); SV2 becomes operative.

l 1. When vacuum reaches 635 mm (25 inches) mercury gauge, SV2 vents to atmosphere, maintaining a vacuum of 635 mm (25 inches) mercury gauge. A second pressure switch (not shown) actuates T3.

12. The vacuum within treating chamber 1 remains constant. Excess fluid is drawn out of the wood. The vacuum pump acts both on the treating chamber 1 and the amplifying vessel 8. The amplifying vessel is not at this stage vented so that the higher vacuum within the amplifying vessel draws any fluid which rises above level L1 in the treating chamber into the amplifying vessel.

13. either (a): Fluid level in amplifying vessel 8 reaches level B indicating that sufficient fluid has been withdrawn from the charge to bring its retention down to the required level. A sensor switch (not shown) set at level B initiates operation 14. or (b): The time set (20 minutes) on time clock T3 expires. Time clock T3 initiates operation 14. It is generally experienced that beyond this time period removal of further fluid from the wood is progressively so much slower as to be not worth while. This dual operation guards both against under-treatment due to withdrawal of too much fluid and avoids undue prolonging of the treatment time in attempting to recover minor additional quantities of fluid. If for any reason it is imperative to reduce the absorption as far as possible, then time clock T3 is set to a long period.

14. Vacuum pump stops, MV3 close, SV4 opens, allowing pressure within treating chamber and amplifying cylinder to return to atmospheric; MVl, MV2 close.

l5. When pressure has fallen to atmospheric, green light indicates safe to open door. SV3 and SV4 close, automatic cycle ends.

16. Door 5 is opened and the timber discharged. The total treatment time is between 40 and 45 minutes and is thus approximately 20 minutes shorter than would be expected in a conventional double vacuum machine carrying out the same treatment.

EXAMPLE 3 Treatment of Baltic Redwood (Pinus Sylvestris) with an Organic Solvent Type Wood Preservative Containing Pentachlorophenol by a Double Vacuum Process The treatment here described is similar to that of Example 2 except that the automatic plant is equipped with pressure switches PS1 and PS2 set for vacuums of 330 and 635 mm (l3 and 25 inches) mercury gauge, respectively, both operating a single vent valve V1 which vents the treating chamber to atmosphere. Pump is provided and is used to transfer fluid from the treating chamber to the amplifying cylinder and the initial filling of the amplifying cylinder is carried out as a separate operation to the main treatment cycle. Valves MVl, MV2 are omitted.

Operations are commenced by switching the machine on. This ensures that cage 2 is positioned as shown in FIGS. 3 and 5 and that all valves are closed.

Door 5 is opened. Timber previously loaded on trolleys is run into cage 2. Door 5 is closed.

Time clocks are set, for example T1 at 20 minutes, T2 at 15 minutes and T3 at 10 minutes.

It is again assumed that liquid level in the treating chamber is correctly at Ll.

Topping up switch is pressed whereupon the following operations occur:

l. The valves MV4, SV4 open. Pump 14 starts.

2. Liquid is pumped from holding tank to amplifying cylinder until level A is reached.

3. Float gauge fitted to the amplifying cylinder causes pump 14 to stop, valves MV4, SV4 to close.

Topping up operation is complete.

Although the topping up operation is here described as occurring after the load has been charged into the treating chamber, with operation as here described it may equally well be carried out before or simultaneously with loading.

The treatment cycle starter button is now pressed whereupon the plant proceeds through the following operations:

1. MV3 opens, vacuum pump starts, SV4 opens.

2. Fluid is drawn from the amplifying cylinder 8 into the treating chamber 1 until the fluid level in the amplifying cylinder falls to C.

3. Float gauge in the amplifying cylinder causes MV3, SV4 to close; PS1 becomes operative.

4. Pump continues to draw vacuum or treating chamber until vacuum reaches 330 mm (13 inches) mercury gauge when PS1 causes V1 to open and allow air into the treating chamber. Should air entering be sufficient to allow the vacuum to fall below 330 mm (13 inches) mercury gauge, PS1 will cause V1 to close and thus a balance is maintained between the vacuum pump and venting.

It will be understood that if PS1 is sensitive to small changes in pressure and if the size of V1 is such that the rate at which air is admitted is suitably balanced against the capacity of the vacuum pump, then the vacuum within the treating chamber will be maintained uniformly close to the predetermined vacuum, but that if PS1 is only sensitive to relatively large changes in pressure and if V1 is capable of admitting air much faster than it can be exhausted by the vacuum pump, then an oscillating vacuum will result. Use of oscillating pressures has been found beneficial in the treatment of certain resistant timbers and it may also have a beneficial effect in this process.

When a vacuum of 330 mm (13 inches) mercury gauge is first reached, PS1 starts time clock T1. Subsequent operation of PS1 do not affect T1.

5. At the expiry of the preset time (20 minutes) time clock T1 actuates the cage lowering mechanism 6 and cage 2 is lowered into the treating fluid taking the position shown in FIGS. 4 and 6 (fluid level rises above Ll due to displacement); vacuum pump stops.

6. A lower positional switch (not shown) is activated when cage 2 reaches the low position as shown in FIG. 4 which causes V1 to open, allowing the pressure to fall to atmospheric, PS1 to cease to be operational and actuates time clock T2.

7. Cage remains in position at FIG. 4, i.e., timber remains immersed in preservative fluid at atmospheric pressure until expiry of the time period (15 minutes) set on T2. During this period fluid is drawn into the timber by the vacuum which was created inside the timber.

8. On the expiry ofthis time period, time clock T2 actuates the lifting mechanism 6 and cage 2 is raised to its upper position as shown in FIGS. 3 and 5; V1 closes, vacuum pump starts, MV3 opens and PS2 becomes operative; pump starts up, time clock T3 starts.

9. When the vacuum reaches 635 mm (25 inches) mercury gauge, PS2 causes V1 to open and a vacuum of 635 mm (25 inches) mercury gauge is maintained as described for stage 4.

l0. Excess fluid is drawn out of the wood. The vac uum pump acts both on the treating chamber 1 and the amplifying vessel 8. Any fluid which rises above level L1 in the treating chamber is transferred to the amplifying cylinder by pump 10.

' ll. either (a): Fluid level in amplifying vessel 8 reaches level B'indicating that sufficient fluid has been withdrawn from the charge to bring its retention down to the required level. The float gauge initiates operation 12. or (b): The time set (10 minutes) on clock 3 expires. Time clock T3 initiates operation 12.

l2. Vacuum pump stops, MV3 closes, pump 10 stops, V1 and 8V4 open. Pressure throughout returns to atmospheric.

13. When pressure has fallen to atmospheric, green light indicates safe to open door; V1, 5V4 close; automatic cycle ends.

' 14. Door 5 is opened and the timber discharged.

EXAMPLE 4 Treatment of Baltic Redwood (Pinus Sylvestris) with an Organic Solvent Type Wood Preservative Containing Copper Naphthenate by Total Immersion for Three Minutes The same machine as in Example 1 is used.

Timber to be treated is placed on trolleys which are loaded through door 5 into cage 2, as previously described.

For simple immersion treatment at atmospheric pressure, it is unnecessary to close door 5. This is therefore left open.

Time clock T2 is set to the time for which the timber is to be immersed 3 minutes. Clocks T11 and T3 need not be set.

Operations are commenced by activating a separate immersion starter switch. This selects only those operations which are necessary for an immersion treatment and the plant proceeds through the following sequence:

1. The lowering mechanism 6operates and cage 2 drops to the position shown in FIG. 4.

2. When cage 2 reaches this position, the lower positional switch (not shown) activates T2.

3. Timber remains immersed until expiry of the time period (3 minutes) set on T2; T2 then activates the raising/lowering mechanism 6 and cage 2 is raised to the position shown on FIG. 2.

4. On reaching this position the automatic cycle ceases, and the timber can be discharged immediately, although it may be preferred to leave it draining in the tank for a few minutes.

It is not customary to measure absorptions for immersion treatments, so the amplifying vessel has not been used in this example. If, however, so desired, measurements may be made using the vessel as described in any of Examples 1, 2 or 3.

When used for a series of immersion treatments without measurement of retention, it is unnecessary to maintain the liquid level exactly at L1, and it is only necessary to replenish the fluid within the treating chamber when the level falls too low to cover cage 2 in its lower position. This operation is then carried out by opening valves MV3, MV4 and allowing the fluid to flow through the amplifying vessel.

The total cycle time for immersion such as here described is 4 to 5 minutes, an efficiency fully equal to that of the best machines designed and operated solely for immersion treatment.

Although Examples 2, 3 and 4 have described the sequence of operations in an automatic machine, it will be understood that the same cycle of events could be carried out under manual control or indeed that certain parts of the whole process may be automated while other parts remain manual.

What is claimed is: d i

d 1. Apparatus for the treatment of wood, textiles, rope and cordage, which apparatus comprises: a treatment chamber having a lower part for containing a treating liquidyand an upper part; a support for material to be treated; means connected to said support for moving said support from the upper to the lower part of the treatment chamber, so as to immerse material on the support in a treating flmfi entrained in'the lowe rpar t of the treatment chamber and for returning the support to the upper part of the treatment chamber; a port in said treatment chamber for access to the upper part of the treatment chamber for loading material onto and unloading material from, the support when the support is in the upper part of the treatment chamber; means coupled tosaid treatment chamber for altering the pressure within the treatment chamber relative to ambient pressure; a holding tank for holding a reserve supply of treatment-liquid; and an amplifying vessel coupled between the holding tank and the treatment chamber, said amplifying vessel being of small horizontal cross-section relative to the treatment chamber, and having a capacity at least equal to the largest volume of treatment liquid to be consumed in a single'operation of said apparatus; means operatively coupled for transferring a measured amount, within said largest vol-.

ume, of treatment liquid from said holding tank through said amplifying vessel and into said treatment chamber; means operatively coupled for transferring, after completion of the treating operation, the remainder of said measured amount from said treatment chamber to said amplifying vessel; and means operatively associated with said amplifying vessel for indicating the amount of liquid consumed by said treating operation.

2. Apparatus as claimed in claim 1, wherein the supporting means is a cage. I 1

3. Apparatus as claimed in claim 1, wherein the treatment chamber is elongated, the port is at one end of the chamber, and the apparatus includes rail means for moving material onto and off from the supporting means. 1

4. Apparatus as claimed in claim 1, wherein a pipe connecting the amplifying vessel to the treatment vessel positioned with its axis horizontal, the interior of 5 the vessel being divided by vertical bulkheads extending the length of the vessel into a sector-shaped compartment on each side of the treatment chamber, which compartments comprise said holding tanks.

* II! l

Claims

1. Apparatus for the treatment of wood, textiles, rope and cordage, which apparatus comprises: a treatment chamber having a lower part for containing a treating liquid, and an upper part; a support for material to be treated; means connected to said support for moving said support from the upper to the lower part of the treatment chamber, so as to immerse material on the support in a treating fluid entrained in the lower port of the treatment chamber and for returning the support to the upper part of the treatment chamber; a port in said treatment chamber for access to the upper part of the treatment chamber for loading material onto and unloading material from, the support when the support is in the upper part of the treatment chamber; means coupled to said treatment chamber for altering the pressure within the treatment chamber relative to ambient pressure; a holding tank for holding a reserve supply of treatment liquid; and an amplifying vessel coupled between the holding tank and the treatment chamber, said amplifying vessel being of small horizontal cross-section relative to the treatment chamber, and having a capacity at least equal to the largest volume of treatment liquid to be consumed in a single operation of said apparatus; means operatively coupled for transferring a measured amount, within said largest volume, of treatment liquid from said holding tank through said amplifying vessel and into said treatment chamber; means operatively coupled for transferring, after completion of the treating operation, the remainder of said measured amount from said treatment chamber to said amplifying vessel; and means operatively associated with said amplifying vessel for indicating the amount of liquid consumed by said treating operation.

2. Apparatus as claimed in claim 1, wherein the supporting means is a cage.

3. Apparatus as claimed in claim 1, wherein the treatment chamber is elongated, the port is at one end of the chamber, and the apparatus includes rail means for moving material onto and off from the supporting means.

4. Apparatus as claimed in claim 1, wherein a pipe connecting the amplifying vessel to the treatment chamber terminates in a horizontal opening at the predetermined liquid level in the treatment chamber.

5. Apparatus as claimed in claim 1, wherein said treatment chamber comprises a generally cylindrical vessel positioned with its axis horizontal, the interior of the vessel being divided by vertical bulkheads extending the length of the vessel into a sector-shaped compartment on each side of the treatment chamber, which compartments comprise said holding tanks.