Title of Invention

A STOP-CHECK VALVE

Abstract

A stop-check valve comprising a body and bonnet containing the flow medium; a disc-plug travelling linearly for opening and closing the fluid passage in the valve in the extrem e positions of the disc-plug; a stem, when lifted, allowing the disc-plug to move freely linearly ~ said disc-plug having at least one through-hole connecting the high pressure zone above the disc-plug to the downstream side, so that the pressure in the high pressure zone is reduced and balanced with the downstream side pressure. whereby when there is a flow pressure on the upstream side of the flow passage the disc-plug moves freely to allow the fluid to pass.

Full Text

This invention relates to a stop-check valve Stop-check valves are flow control valves, which function both as a stop valve and a non-return valve (check-valve). The stop-check valve opens automatically due to line pressure and the closure can be either due to flow reversal or by force using an operator. Stop-check valves are similar in construction to that of globe valves, except that the closure member (disc) is not fixed to the stem; instead is only guided on the stem. When the stem is raised, the disc is free to slide on the stem and lift up. The disc is lifted up due to flow and pressure from the downstream side. The lifting movement of the disc is influenced by the pressure difference between the bottom and top sides of the disc. If the built up pressure in the high pressure zone, above the disc is lesser, the lifting of the disc will be easier. Hence the pressure above the disc is to be rediced or balanced with the downstream pressure. One version of a known stop-check valve has an equalizing pipe 5 external to the valve body connecting the region above the disc with the downstream side of the valve for reducing the pressure at the top side of the disc. In this case, an additional pipe is required in the assembly apart from openings made on the valve body. This invention proposes a stop-check valve having a simple and effective construction for reducing the pressure on the top side of the disc. According to this invention, the stop-check valve comprises a body and bonnet containing the flow medium; a disc-plug travelling linearly for opening and closing the fluid passage in the valve in the extreme positions of the disc-plug; a stem, when lifted, allowing the disc-plug to move freely linearly, characterised in that said disc-plug has at least one through-hole connecting the high pressure zone above the disc-plug to the downstream side, so that the pressure in the high pressure zone is reduced and balanced with the downstream side pressure whereby when there is a flow pressure on the upstream side of the flow passage, the disc-plug moves freely to allow the fluid to pass. This invention will now be described with reference to the single Figure 1 in the accompanying drawings which illustrate, by way of example, and not by way of limitation, one of possible embodiments of the stop-check valve proposed herein. The body (1) and the bonnet (2) are the pressure containing parts, which contain the flow medium and which can be used under pressure and temperature. The flow controlling element is the plug type disc (3), which travels linearly up and down to open/close positions of the valve. When the disc is in the "up" position, the valve is said to be in the open condition and when the disc is in the bottom position the valve is said to be in the closed position. When the stem (4) is lifted up by means of an operator (hand wheel/gear unit/electrical actuator), the dm will be floating and free to move linearly. When there is a flow / pressure in the upstream side of the valve, the disc will move up and allow flow to pass. The pressure in the high pressure zone is reduced and balanced with the downstream side pressure by means of the integral holes 5 provided in the disc which connects the high pressure zone 7 above the disc to the downstream side, thereby ensuring easy lifting of the disc. The terms and expressions herein are of description and not of limitation, having regard to the scope and ambit of this invention. We Claim: l.A stop-check valve comprising a body and bonnet containing the flow medium; a disc-plug travelling linearly for opening and closing the fluid passage in the valve in the extreme positions of the disc-plug; a stem, when lifted, allowing the disc-plug to move freely linearly, characterised in that said disc-plug has at least one through-hole connecting the high pressure zone above the disc-plug to the downstream side, so that the pressure in the high pressure zone is reduced and balanced with the downstream side pressure, whereby when there is a flow pressure on the upstream side of the flow passage, the disc-plug moves freely to allow the fluid to pass. 2.A stop-check valve substantially as herein described and illustrated. Dated this the 6th day of November 2004

Documents:

1168-che-2004-abstract.pdf

1168-che-2004-claims.pdf

1168-che-2004-correspondnece-others.pdf

1168-che-2004-correspondnece-po.pdf

1168-che-2004-description(complete).pdf

1168-che-2004-drawings.pdf

1168-che-2004-form 1.pdf

1168-che-2004-form 19.pdf

1168-che-2004-form 26.pdf