Title of Invention

A LOW EMISSION VALVE

Abstract A low emission gate valve comprising a valve body having a flow passage provided with an inlet and outlet for the inflow and outflow of fluids therethrough; a wedge located in the said passage; a stem, the lower portion of which is fixed to the wedge, for raising and lowering the wedge, to control the flow of fluids through the passage; a rotatable shaft, the lower portion of which is hollow to receive the upper portion of the stem; a drive bush, disposed over a bonnet bush, said drive bush also receiving, and threadedly engaging with, the upper portion of the stem, with the lower portion of the shaft fixed to the drive bush; a low emission packing located at a region substantially higher than the region of the bonnet bush, said packing surrounding the shaft in contact therewith; means provided for the upper portion of the shaft for rotating it, whereby, on rotating the shaft, in one direction or the other, with the shaft in rotating contact with the packing, the guide bush is constrained to rotate along with the shaft, in the corresponding direction, to cause the stem to be raised or lowered, in threaded engagement with the guide bush, to raise or lower the wedge in the passage.
Full Text

This invention relates to a low emission gate valve, that is to say, a gate valve, the fugitive emission from which has a value equal to or less than a value predetermined by acceptable standards; and such value is retained over an acceptable period of time.
Low emission gate valves are known to the art. One such valve is the bellows type gate valve which completely isolates the fluid medium handled by the valve from the environment. Although this valve can be called as a low emission valve, it costs much more than the standard gate valve. Furthermore, any failure of the bellows used in this valve will lead to leakage through its secondary graphite packing system.
Another known low emission gate valve is the standard type of valve using a low emission packing. Although this valve provides an economical solution, the leakage levels over a period of time will increase in as much as the valve is stroked a number of times by a moving component ,under pressure and will require frequent adjustment of the packing or replacement, of the packing.
This invention proposes a gate valve which has the advantage of low emission as well as reasonably low cost.

The low emission feature of the gate valve proposed herein is achieved by causing the moving component of the valve, which rubs against the packing to execute a rotating movement and not a pure 1inear movement, The former movement produces a lesser abrading action on the packing than the latter, whereby a lesser amount of packing material is taken off the packing by the rotating movement. The life of the packing is thus increased to retain the low emission characteristics of the valve for a greater length of time*
The low emission feature of the valve proposed herein is also achieved by the fact that the packing is located, not near the bonnet bush of the valve as in known valves, but at a higher level whereby the temperatures of the fluids handled by the valve have a 1esser detrimental effect on the packing• The various other features of the low emission valves proposed herein will be apparent from the following further description thereof•
The low emission gate valve, according to this invention, comprises a valve body having a flow passage provided with an inlet and outlet for the inflow and outflow of fluid there through; a wedge located in the said passage 5 a stem, the lower portion of which is fixed to the wedge, for raising and

lowering the wedge» to control the flow of fluids dirough the passage; arotatable shaft, the lower portion of which is hollow to receive the upper portion of the stem; a drive bush, disposed over a bonnet bush, said drive bush receiving, and threadedly engaging with, the upper portion of the stem, with the lower portion of the shaft fixed to the drive bush; a packing located at a region substantially higher than the region of the bonnet bush, said packing surrounding the shaft in contact therewith; means provided for the upper portion of the shaft for rotatmg it, whereby, on rotating the shaft, in one direction or the other, the drive bush is constrained to rotate along with the shaft, in the corresponding direction, to cause the stem to be raised or lowered, without rotating, in threaded engagement with the drive bush, to raise or lower the wedge in the passage. This invention will now be described with reference to the acompanying drawings which illustrate by way of example, an not by way of limitation.
In Fig.l an embodiment of the valve proposed herein And In Figs.2 and 3 two variations of the said embodiment.
The body (I) and bonnet (10) are die pressure containing parts which contain the operating medium which can be under pressure and temperature. The flow controlling

element is wedge The rising stem « The lower end of the shaft The shaft (9) is held in the bonnet (10) between two thrust washers -
The place where shaft (9> comes out of the pressure retaining component namely the bonnet
This area namely the stuffing box can accommodate double packing system as well as lantern ring (12) arrangement . This provides enhanced sealing.
The packing (11) is kept in compressed state by means of a gland follower (15) , eye bolt (13) and gland (14). The loading is done uniformly by means of the two eyebolts(13) The axial compression of the packing(ll)creates a radial pressure which provides a sealing of the line media. Any loss of the axial load will lead to the leakage of the line media to the atmosphere and has to be compensated by tightening the gland eye bolts (13). In this embodiment to maintain the gland load a live loading arrangement(16)in the form of Bellivele springs are provided
The stem (4)is raised up or down without rotating by means of a screw threads in the drive bush ( 7). The drive bush (7) is in turn rotated by means of shaft(9)which in turn is rotated by a hand wheel (21) or through power operation ( not shown ) The rotation of the drive bush (7) in clockwise direction will make the stem (4) to move downwards and close the wedge (2). The anticlockwise rotation of the drive bush(7) will move the stem(4) in upward direction and open the valve.

In otherwords only the stem (4) moves up and down to open and close the wedge (2) whereas the shaft(9) has only the rotary movement.
This movement of the shaft(9) does not affect the packing material transfer there by leading to improved performance. Also the packing (11) which provides the sealing to the environment is kept at higher level so that the temperatm*e of the line media will have less influence on the packing, PTFE based packing can be used which has been found to provide superior sealing performance. . Optionally fins will be provided on the valve bonnet to keep the packing cool . The fins(22) as shown in the Fig 3 will dissipates the heat and help to keep the stuffing box area where the packing is placed at an acceptable {Operating level. Optional provision is made for injecting a sealant through sealant injector (17) to strengthen the packing in the event of packing failure. It is to be noted that the above valve proposed herein will work with standard packing although better results will be obtained if a low emission packing is used. The latter packing is therefore preferred.
The terms and expressions in this specification are of description and not of limitation, in^asmuch as other embodiments of the low emission gate valve proposed herein are possible without departing from the scope and ambit of this invention.




We Claim:
l.A low emission gate valve comprising a valve body having a flow passage provided with an inlet and outlet for the inflow and outflow of fluids therethrough; a wedge located in the said passage; a stem, the lower portion of which is fixed to the wedge, for raising and lowering the wedge, to control the flow of fluids through the passage; arotatable shaft, the lower portion of which is hollow to receive the upper portion of the stem; a drive bush, disposed over a bonnet bush, said drive bush receiving, and threadedly engaging with, the upper portion of the stem, with the lower portion of the shaft fixed to the drive bush; a packing located at a region substantially higher than the region of the bonnet bush, said packing surrounding the shaft m contact therewith; means provided for the upper portion of the shaft for rotatmg it, whereby, on rotating the shaft, in one dire(^on or the other, the drive bush is constrained to ratals along with the shaft, in the corresponding direction, to cause the stem to be raised or lowered, without rotating, in threaded engagement with the drive bush, to raise or lower the wedge in the passage.

2.A valve as cUumed in Claim 1 wherein the packing is a standard packing.
3.A valve as claimed in Claim 1 wherein the packing is a low emission packing.
4.A valve as claimed in any one of the preceding Claims wherein the shaft is keyed to the drive bush and thereby fixed to the drive bush.
S.A valve as claimed in any one of the preceding Claims wherein the means provided at the upper portion of the shaft for rotating it comprise a handle.
6.A valve as claimed in any one of die preceding Claims 1 to 4 wherein the means provided at the upper portion of the shaft for rotating it comprise amotorised drive.
7.A valve as claimed in any one of tiie preceding Claims wherein the valve body is provided externally with fins for heat dissipation.
S.A valve as claimed in any one of the preceding Claims wherein the valve body is provided with a position indicator.

9.A valve as claimed in any one of the preceding Claims wherein the valve body is provided with means for injecting a sealant into tiie packing.
10.A low emission gate valve substantially as herein described and illustrated with reference to the accompanying drawings.


Documents:

457-che-2003 form 2.pdf

457-che-2003-abstract.pdf

457-che-2003-claims duplicate.pdf

457-che-2003-claims original.pdf

457-che-2003-correspondnece-others.pdf

457-che-2003-correspondnece-po.pdf

457-che-2003-description(complete) duplicate.pdf

457-che-2003-description(complete) original.pdf

457-che-2003-drawings.pdf

457-che-2003-form 1.pdf

457-che-2003-form 19.pdf

457-che-2003-form 26.pdf


Patent Number 195339
Indian Patent Application Number 457/CHE/2003
PG Journal Number 08/2007
Publication Date 23-Feb-2007
Grant Date 24-Aug-2006
Date of Filing 06-Jun-2003
Name of Patentee ADUCO INDIA LIMITED
Applicant Address MOUNT POONAMALLEE ROAD MANAPAKKAM CHENNAI
Inventors:
# Inventor's Name Inventor's Address
1 SRINIVAS CHANDRAMOULY ADUCO INDIA LIMITED MOUNT POONAMALLEE ROAD MANAPAKKAM CHENNAI
PCT International Classification Number F16K3/12
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA