AU611312B2

AU611312B2 - Solvent wash unit

Info

Publication number: AU611312B2
Application number: AU38864/89A
Authority: AU
Inventors: Peter Allan Warren
Original assignee: Commonwealth Industrial Gases Ltd
Current assignee: Commonwealth Industrial Gases Ltd
Priority date: 1988-07-22
Filing date: 1989-07-21
Publication date: 1991-06-06
Anticipated expiration: 2009-07-21
Also published as: AU3886489A

Description

g 611312 COMMONWEALTH OF AUSTRALIA FORM PATENTS ACT 1952 COMPLETE SPECIFICATION FOR OFFICE USE: Class Int.Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: Name of Applicant: THE COMMONWEALTH INDUSTRIAL GASES LIMITED Address of Applicant: 500 Pacific Highway, St. Leonards, 2065 Actual Inventor: Peter Allan WARREN Address for Service: SHELSTON WATERS, 55 Clarence Street, Sydney Complete Specification for the Invention entitled: "SOLVENT WASH UNIT" The following statement is a full description of this invention.

including the best method of performing it known to me/us:- (Complete of PI9424 dated 22 July, 1988) S008903Q CO8321/07/89 -ra* ocn- This invention concerns a solvent cleaning apparatus and a method of solvent cleaning. In particular, but not exclusively, the invention relates to an apparatus and method for cleaning with toxic solvents, or solvents which produce noxious or toxic fumes.

It is known to clean small metallic items with degreasing solvents. These solvents tend to have a very low boiling point and once excess liquid has been drained off, the remaining solvent evaporates quickly. Speciel o00 apparatus has been devised to assist in such cleaning, 0 .0 0 0 00 and this typically comprises a drum and a spray-gun or 0 0 0 0 brush applicator. Solvent, sprayed from the gun or o 0 0. brush, flushes contaminants from the surface of the item 0 0 being cleaned into the drum. The solvent is then filtered before being pumped back to the gun or brush.

0oo The drum is typically open and may be associated with an oo0 o o 0adjacent draining surface. The operator usually stands over the drum holding the item to be cleaned and the 0o spray gun. This apparatus is not suited for use with S 20 toxic solvents because vapour from the cleaning process .is released into the atmosphere in the vicinity of the 0 operator. Protective clothing and breathing devices can be worn _y the operator to avoid the dangers however these are cumbersome and depend upon the operator's diligence.

It is an object of this invention to provide a solvent cleaning apparatus and a method of solvent cleaning which will overcome or at least ameliorate the 2 above disadvantages.

According to a first aspect of the present invention there is provided a solvent cleaning apparatus comprising a basket to receive items to be cleaned, a first drum to contain the basket, and a quantity of solvent in said first drum with the basket at least partly immersed in the solvent, a removable lid for said first drum to selectively seal the interior of the drum from the atmosphere, vapour extractor means selectively operable

I

1 0 to withdraw vapour from above the surface of the solvent, means to agitate the solvent in the first drum, a second 0 0 00 drum to contain the basket after removal from the solvent oo o 0 ,0 C o 0 of the first drum, said second drum including a gas inlet port and a gas outlet port, blower means to blow gas into said gas inlet port, and exhaust means to vent the 0ooo o 00...00 gaseous contents of the second drum to the atmosphere.

0 0 Preferably, the inlet for the vapour extractor means 00oo o00 o 0extend peripherally around each drum above the level of the solvent. In preference, said inlet is substantially o 0 in the form of an annular ring.

0 04 In a preferred arrangement a compressed gas motor is used to impart a vertical reciprocating motion to the basket in order to agitate the solvent when the basket is placed in the first drum. Advantageously a lid is supportably associated with the basket and it is with this that the compressed gas motor is connected; in this case a separate lid is associated with the first drum when the basket is elsewhere.

OAdvantageously timer means are associated with the 3 means to agitate the solvent and the blower means so that the length of each process may be automatically controlled.

Preferably also, switching means are associated with the lids to actuate the extractor means when they are removed.

According to a second aspect of the present invention there is provided a method of solvent cleaning comprising the steps of: placing items to be cleaned into a basket; opening a substantially sealed solvent bath and t ae tee immersing the basket, at least partly, in a solvent; t C resealing the solvent bath from the atmosphere, then agitating the solvent in the bath; opening the solvent bath, removing the basket from L the bath; confining the basket in a drying chamber, blowing gas through the drying chamber, and venting the gas to the atmosphere; wherein throughout the process vapour is selectively withdrawn, by suction, from the surface of the solvent.

Preferably the process step of agitating the solvent is achieved by imparting a reciprocating motion to the basiket.

Advantageously the vapour is selectively withdrawn by operating extractor means when the solvent bath is open.

The invention will now be described by way of 4 _j example only with reference to the accompanying drawing which is a schematic illustration of a preferred embodiment of a solvent cleaning apparatus according to the first aspect of the present invention.

The apparatus comprises a stainless steel benchtop 1 which houses a first washbath 2, a second washbath 3 and a drying chamber 4. First washbath 2 and second washbath 3 are equipped with drain valves 5, and have removable lids 6 (only one of which is shown) to seal the interior of the baths from the atmosphere. Separate micro-switches 7 are also associated with the lid engaging portion of each washbath.

Both washbaths share a vapour extraction vent 8 which opens in the region where the lids adjoin the baths. Vapour extraction vent 8 communicates with a suction plant 9 which is in communication with a remote exhaust vent Drying chamber 4 is fitted with an air inlet port 11 associated with a warm-air blower 12 connected to an electricity supply via timer 13. Drying chamber 4 is also fitted with an air outlet port 14 in communication i with a remote exhaust pipe A basket 16 in which items to be cleaned are placed is connected to the rod of a pneumatic cylinder 17 mounted on a lid 18. A solenoid valve 19 is also mounted on the lid and is connected to the pneumatic cylinder.

Solenoid valve 19 is connected to an electricity supply via timer 20, and to a source of compressed carbon dioxide 21 via a pneumatic supply line and regulator 22.

In use washbaths 2 and 3 are partly filled with cleaning scolvent and respective lids 6 are fitted to cover them. The slvent in washbaths 2 and 3 will ty-)ically remain in the baths for a large number of washes before being changed. Items to be cleaned are placed in basket 16 which may subsequently be placed in first washbath 2. In order to place basket 16 in bath 2 it is necessary to remove the respective lid 6. When this happens micro-switch 7 associated with basket 2 changes state and suction plant 9 is activated to draw off any vapour rising from the surface of the solvent in bath 2. In this way the operator is prevented from inhaling solvent fumes.

When basket 16 is placed in bath 2 its associated lid 18 seals the top of the bath and micro-switch 7 associated with bath 2 again changes state in order to deactivate suction plant 9. The solenoid valve 19 mounted on lid 18 is then connected to CO 2 supply cylinder 21 and to an electricity power supply via timer Timer 20 provides power impulses to solenoid valve 19 at approximately one second intervals in order to activate pneumatic cylinder 17 and impart a reciprocating up and down motion to basket 16 within bath 2, thus agitating the solvent therein. This agitation of the solvent continues for say five minutes, under the control of timer 20, before stopping. Subsequently, basket 16 is k removed from bath 2, respective lid 6 is put back onto 6 T- 0 0o o o 0 0 o°o o o 0 0 bath 2 and basket 16 is placed in bath 3.

Each time the lids 6 or 18 are removed from one of the baths the respective microswitch 7 changes state to activate suction plant 9. The vapours drawn off from the wash baths are vented to the atmosphere via a chimney in a remote location.

A second wash similar to the first and also of approximately five minutes duration takes place in washbath 3. Then the basket 16 is removed from bath 3, '10 respective lid 6 is replaced on the top of bath 3 and basket 16 is placed in drying chamber 4, again lid 18 0o 00 oo seals the top of chamber 4 when basket 16 is in situ.

00 O° Blower 12 is then switched on for a pre-determined 0 period of time determined by timer 13, and warm filtered air is introduced into drying chamber 4 via inlet port 11. The warm air passes over the surface of the items in basket 16 causing evaporation of any remaining solvent which is then vented to the atmosphere through a remote "i chimney 15 via outlet port 14. Drying may continue for say one and a half minutes. After drying has been completed the items may be removed from basket 16.

When not in use basket 16 conveniently resides in drying chamber 4.

In other embodiments of the invention the wash baths 2 and 3 may have individual extraction hoods, either coupled to a shared vent and suction plant, or having independant vents and suction fans.

Similarly, the microswitches 7 may be eliminated and 00 0 o0 0 0 0

G

no 0 as 7

I

the vapour extraction system operated on a continuous basis during use.

It should be appreciated that although the invention has been described with reference to a specific example many variations and alternatives are possible within the scope of the invention.

f t s.

8

Claims

1. A solvent cleaning apparatus comprising a basket to receive items to be cleaned, a first drum to contain the basket, and a quantity of solvent in said first drum with the basket at least partly immersed in the solvent, a removable lid for said first drum to selectively seal the interior of the drum from the atmosphere, vapour extractor means selectively operable to withdraw vapour from above the surface of the solvent, means to agitate the solvent in the first drum, a second drum to contain the brsket after removal from the solvent of the first drum, said second drum including a gas inlet port and a gas outlet port, blower means to blow gas into said gas inlet port, and exhaust means to vent the gaseous contents of the second drum to the atmosphere.

2. A solvent cleaning apparatus as claimed in claim 1 further including a further intermeditary drum also containing a quantity of solvent which is cleaner than in the first drum and having vapour extractor means similar to the first drum, into which the basket is placed after removal from the first drum and prior to transferring to Sthe second drum. u

3. A solvent cleaning apparatus as claimed in claim 1 or claim 2 having an inlet for said vapour extractor means peripherally extending around said first drum above the level of said solvent.

4. A solvent cleaning apparatus as claimed in claim 3 in which said inlet for vapour extractor means is ip14 substantially in the form of an annular ring. 9 9 A solvent cleaning apparatus as claimed in any one of the preceding claims having the basket supportably mounted with said removeable lid.

6. A solvent cleaning apparatus as claimed in claim having an agitating means mounted with the lid in association with the basket.

7. A solvent cleaning apparatus as claimed in claim 6 wherein said agitating means provides a vertical ,reciprocating motion of the basket. o I S 8 A solvent cleaning apparatus as claimed in claim 7 o 0 o° o wherein said agitating means is provided by a compressed o00" o gas motor mounted with the lid. 0 0 o

9. A solvent cleaning apparatus as claimed in any one of the preceding claims having a timer means associated with the means to agitate the basket. o000 10. A solvent cleaning apparatus as claimed in any one of the preceding claims having a timer means associated .0 0 0 o with the blower means.

11. A solvent cleaning apparatus as claimed in any one o of the preceding claims having switching means associated i. with the lid to activate said extractor means when the lid is removed.

12. A method of solvent cleaning comprising the steps of: a) placing items to be cleaned into a basket; b) ening a substantially sealed solvent bath and immersing the basket, at least partly, in a solvent; c) resealing the solvent bath from the atmosphere, then agitating the solvent in the bath; p- 10 00 Tlpj/ d) opening the solvent bath, removing the basket from the bath; e) confining the basket in a drying chamber, f) blowing gas through the drying chamber, and g) venting the gas to the ztmosphere; wherein throughout the process vapour is selectively withdrawn, by suction, from the surface of the solvent.

13. A method of solvent cleaning as claimed in claim 12 including repeating steps in a second bath prior to drying in the drying chamber.

14. A method of solvent cleaning as claimed in claim 12 or 13 including the step of agitating the solvent by imparting a vertical reciprocating motion to the basket. A method of solvent cleaning as claimed in claim 12, 13 or 14 wherein said vapour is selectively withdrawn by operating extractor means when the solvent bath is open.

16. A solvent cleaning apparatus substantially as herein t described with reference to the accompanying drawing.

17. A method of solvent cleaning substantially as herein described with reference to the accompanying drawing. DATED this THE COMMONWEALTH INDUSTRIAL GASES LIMITED Attorney: LEON K. ALLEN Fellow Institute of Patent Attorneys of Australia of SHELSTON WATERS E11- U~t~r U.L A IqE~