GB2136539A

GB2136539A - Valve for use in blast cleaning apparatus

Info

Publication number: GB2136539A
Application number: GB08405701A
Authority: GB
Inventors: David Trevor Billows
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-03-15
Filing date: 1984-03-05
Publication date: 1984-09-19
Also published as: GB8405701D0

Abstract

Valve means for use in blast cleaning apparatus comprise a valve having a valve member (32) slidably mounted for opening or closing communication from an air supply to a conduit (26) communicating with a usual T-junction part (22) of the apparatus, with the usual closure member (12) for the filling aperture of the pressure vessel (10) of the apparatus, and with the interior of the pressure vessel itself (Fig. 1), the valve member being under the control of a flexible control diaphragm (44) acted upon by a pressure of air constituting a control signal. A second valve, comprising a diaphragm 56, is subjected to the same control signal and closes communication between the pressure vessel and exhaust first prior to opening of the valve 32. <IMAGE>

Description

SPECIFICATION Valve for use in blast cleaning apparatus The invention relates to a valve for use in blast cleaning apparatus.

Blast cleaning apparatus in which the valve will be used may be of the kind for cleaning a wide variety of surfaces, for example the surfaces of small articles such as engineering components to the external surfaces of buildings or otherstructures. In such apparatus an abrasive material is entrained in a blast of air and directed against the article to be cleaned.

The abrasive material is contained in a pressure vessel. Avalve beneath the pressure vessel is arranged to meter the flow ofabrasive material into a T-junction partthrough whichthe blast of air is caused to flow. An aperture in an upper part ofthe pressure vessel, through which the vessel can be charged with abrasive material, is closed duringtheoperation ofthe apparatus buy a closure member operated by air under pressure.Valve means in the upper part of the vessel are provided to allow the escape of pressure from the pressure vessel when it is required to open the aperture forthe charging of the vessel with abrasive material.

Apparatus of the kind described has been used quite extensively and generallyworks quite well. However, the valves which are required to be opened and closed during the operation of the apparatus are relatively expensive items of equipment and the object of the invention isto provide a single valve which will replace the at least two valves previously employed and which will thus reduce the cost of the apparatus.

According to the invention, there is provided a valve for use in apparatus ofthe kind described, the valve including a main body in which a valve member is slidably mounted for opening or closing communication from an air supply to a conduit communicating with the Junction partofthe apparatus, with the closure memberforthefilling aperture ofthe pressure vessel of the apparatus, and with the interior of the pressure vessel itself, the valve member being under the control of a flexible control diaphragm acted upon by a pressure of air, constituting a control signal, in a control chamber of the valve, a further diaphragm being acted upon by said control signal to close off a fluid inlet connection by way ofwhich pressure can be allowed to escape when required from the pressure vessel of the apparatus. Preferably, the control chamber ofthe valve will be formed by an annular ring member, the flexible control diaphragm being located on one side of said ring member and the said further diaphragm being located on the other side. A resilient insert will preferably overlie the further diaphragm for closing offthefluid inlet connection. The valve member will preferably be a poppettype of valve member and will preferably be urged by spring pressure towards a closed condition.

Inorderthattheinvention may be fully understood and readily carried into effect, the same will now be described, byway of example only, with reference to the accompanying drawings, of which: Figure lisa perspective partly cut-away view of blast cleaning apparatus embodying the invention, Figure 2 is a semi-diagrammatic sectional view through a valve for use in the kind of blast cleaning apparatus illustrated in Figure 1, and Figure 3 is a view similarto Figure 2 and illustrating a possible modification which will be referred to.

Referring nowto Figure lithe blast cleaning apparatusthereillustrated includes a pressure vessel 10 for containing a quantity of an abrasive material. An aperture 12 in an upper part of the vessel is closed during the operation ofthe apparatus by a closure member 14 shown only diagrammatically in the drawing and maintained in an upwardly displaced position by air under pressure in an air line 16. A conduit 18 is shown to be connected into the pressure vessel for the entry of air under pressure to maintain the pressure above the quantity of abrasive material at a pre-determined pressure during the operation of the apparatus.A connection 19 in an upper part of the pressure vessel communicates, as shown, with an upper end of a valve 28 and is arranged to allow the escape of pressure from the pressure vessel, when required, underthecontrol of said valve.

Avalve 20 beneath the pressure vessel is arranged to meter the flow of abrasive material from the pressure vessel into a T-junction part 22 through which a blast of air is caused to flowfrom the valve 28 when the apparatus is in use. A conduit24which extends from the T-junction part 22 carries the blast of airtogetherwith abrasive material entrained therein to a nozzle (not shown). A conduit 26 which carries air totheT-junction part communicates with the air line 16 and with the conduit 18, air under pressure being supplied to both, from asource notshown, byway of the valve 28.

Referring now in particular to Figure 2, the valve 28 is of relatively simple construction with very few moving parts. The valve includes a main body 30 in which a valve member 32 is slidably mounted. At its lower end the valve member carries a poppet valve element 34which in a raised position closes an entry port to a valve chamber 36. An outlet port 38, which opens from the valve chamber 36, communicates with the conduit 26 (see Figure 1). A lower valve cover 40 which is bolted to the lower end of the main body is provided with an inlet port 42 through which air under pressure is supplied from the source not shown.

At the upper end of the main body a peripheral portion of a control diaphragm 44 is clamped against an annular seating surface by an annular ring member 46. The upper end of the valve member 32 is connected to a central portion ofthe diaphragm by means of a pair of washers 48 and a nut 50. A coil compression spring 52 acts to urge the valve member upwardly. A stem portion of the valve member has a spaced pairofO-rings 54which act to prevent the leakage of air under pressure from the valve chamber 36 to the space immediately beneath the control diaphragm.

Afurther diaphragm 56 overlies the annular ring member 46 and is clamped thereon by an upper valve cover 58. The upper valve cover is provided with a fluid inlet connector60 (to which the outlet connection 19 in Figure 1 is connected whereby the upper part of the pressure vessel communicates with the upper end of the valve) and an exhaust elbow 62 is connected into the side of the uppervalve cover whereby the space within the latter and overlying the diaphragm 56 can communicate to atmosphere. However, a resilient insert 64 overlies the diaphragm 56 so that the presence of a control pressure in the space overlying the control diaphragm 44 urges the diaphragm 56 upwardlywherebythe resilient insert closes offthe fluid inletconnector60.

As shown in Figure 1,a pilot control system, generally indicated 66, which is provided separate from the valve 28, is connected to the inlet side of the valve 28 by means of an air line 68 and connected to the control chamber 45 overlying the control diaphragm 44 by means of an air line 70. Acontrol signal in the form of a pressure ofaircan be transmitted to the control chamberfrom the pilot control system so that, sequentially, the outlet connection 19 is closed and the valve member is displaced downwardly to allow air under pressure to flowfrom the valve chamber36through the outlet port 38.When a flow of air has been established in this way through the conduits 26 and 24, the valve 20 beneath the pressure vessel can be opened to meter the flow of abrasive material into the T-junction part 22.

Thus itwill be seen that the control system forthe blast cleaning apparatus is very simple and thatthe valve includes a bare minimum of moving parts. It can be provided at lower cost than valves previously required for blast cleaning apparatus control systems previously employed.

Various modifications may be made. For example, in Figure 3 there is illustrated a modification in which the control diaphragm 44 is in the form of a completely plain disc. Instead of being clamped between a pair of washers 48 it is acted on by a single such washer on its underside, the washer being connected by means a central screw to the upper end of the valve member 32 and being urged into engagement with the diaphragm 44 by means of the spring 52. It will however be understood that the valve works in exactly the same way as before.

Claims

1. Avalveforusein apparatusofthe kind described, the valve including a main body in which a valve member is slidably mounted for opening or closing communication from an airsupplyto a conduit communicating with the Tjunction part of the apparatus, with the closure memberforthe filling aperture of the pressure vessel of the apparatus, and with the interior of the pressure vessel itself, the valve member being underthecontrol of a flexible control diaphragm acted upon by a pressure of air, constituting a control signal, in a control chamber of the valve, a further diaphragm being acted upon by said control signal to close off a fluid inlet connection byway of which pressure can be allowed to escape when required from the pressure vessel of the apparatus.

2. Avalve according to claim 1, in which the control chamber ofthe valve is formed by an annular ring member, the flexible control diaphragm being located on one side of said ring member and the said further diaphragm being located on the other side.

3. Avalveaccording to either one of the preceding claims, in which a resilient insertoverlies the further diaphragm for closing off the fluid inlet connection.

4. Avalve according to any one ofthe preceding claims, in which the valve member is a poppettype of valve member and is urged by spring pressure towards a closed condition.

5. Avalveforusein blastcleaningapparatus,the valve being constructed, arranged and adapted to operate substantially as hereinbefore described, with reference to and as illustrated by Figures 1 and 2 or Figure 3 of the accompanying drawings.