Patent Description:
In petrochemical plants, oil-drilling rigs, process industry plants and other corresponding plants, it is necessary to safeguard against sudden and high pressure loads caused by explosions, sudden fires, or the like. Ventilation systems are safeguarded against such pressure loads by installing in them pressure valves or blast dampers that close automatically when a pressure load of the above-mentioned type is directed to them. Pressure valves of this type may also be installed at a desired location in a ventilation shaft or directly inside or outside a pressure load-resistant wall in connection with a ventilation shaft. Prior art pressure valves comprise plate-like closing blades arranged on turning axles. Normally, there are two or more axles in a pressure valve and they extend parallel at a distance from each other across a flow channel formed by the pressure valve, through which air or some other flowing medium flows through the pressure valve. One or more closing blades may be installed next to each other on one axle. In a normal operating mode, the closing blades are in an open position that allows air or some other flowing medium to flow through the closing blades and the pressure valve. Thus, in the open position, the closing blades are set in the flow direction of the air flowing through the pressure valve or at an angle relative to the flow direction. Normally a protective screen is also provided at an upstream end of the flow channel to prevent solid objects or the like from entering the flow channel.

Publication <CIT> presents a pressure valve that is provided with a protective screen. A problem with the protective screen of this known pressure valve is that is the protective screen has a complicated construction, and consequently that the protective screen is difficult to manufacture and that the protective screen has large extension in the direction of the flow through the flow channel.

The object of the invention is to provide a blast damper that solves the above-mentioned problems.

The blast damper of the invention is characterized by the definitions of independent claim <NUM>.

Preferred embodiments of the blast damper are defined in the dependent claims.

In the following the invention will described in more detail by referring to the figures of which.

Next the blast damper <NUM> and some variants and embodiments of the blast damper <NUM> will be presented in greater detail.

The blast damper <NUM> comprises a frame <NUM> defining a flow channel <NUM> for air flow through the blast damper <NUM>.

The flow channel <NUM> defines an upstream end <NUM> and a downstream end <NUM>.

The blast damper <NUM> comprises closing blades <NUM> pivotally arranged in the flow channel <NUM>. The closing blades <NUM> are preferably, but not necessarily, arranged in parallel in the flow channel <NUM>.

Each closing blade <NUM> can be pivoted about a pivot axis (not marked with a reference numeral) between a closed position and an open position. The pivot axes of the closing blades <NUM> are preferably, but not necessarily, parallel.

Each closing blade <NUM> is pivotally supported at the frame <NUM> by means of shaft means <NUM>.

The blast damper <NUM> comprises an actuating mechanism <NUM> configured to simultaneously pivot each closing blade <NUM> between the closed position so as to prevent air flow through the blast damper <NUM> and the open position so as to allow air flow through the blast damper <NUM>.

The actuating mechanism <NUM> comprises preferably, but not necessarily, a prestressing arrangement for prestressing the closing blades <NUM> into the open position and for triggering the closing blades <NUM> to turn into the closed position in response to a pressure increase in the flow channel <NUM>.

The prestressing arrangement can for example function so that the closing blades <NUM> are configured to pivot into the closed position in response to a pressure increase in the flow channel <NUM> sensed by at least one of the closing blades <NUM>. The closing blades <NUM> are in such case preferably, but not necessarily, configured to pivot into the closed position in response to a pressure increase exceeding a threshold value in the flow channel <NUM> sensed by at least one of the closing blades <NUM>.

The prestressing arrangement can for example function so that the closing blades <NUM> are configured to pivot into the closed position in response to a pressure increase in the flow channel <NUM> sensed by a separate pressure sensing device (not illustrated in the figures) that is functionally connected to at least one of the actuating mechanism and at least one of the closing blades. In such case, the closing blades <NUM> are preferably, but not necessarily, configured to pivot into the closed position in response to a pressure increase exceeding a threshold value in the flow channel <NUM> sensed by such separate pressure sensing device.

The blast damper <NUM> comprises a protective screen <NUM> at the upstream end <NUM> of the flow channel <NUM>. A purpose of the protective screen <NUM> is to prevent solid objects or the like from entering the flow channel <NUM>.

The protective screen <NUM> is formed of sheet material and being planar and being provided with flow openings <NUM>.

The sheet material has a monolithic structure.

The protective screen <NUM> has a monolithic structure. An example of a protective screen <NUM> of monolithic structure is a protective screen <NUM> formed of a metal plate by machining it into the final form and dimensions and design.

Because protective screen <NUM> is formed of sheet material and being planar and being provided with flow openings <NUM>, the protective screen <NUM> of the blast damper <NUM> is therefore of a simple construction, because it can for example be made of a metal sheet by machining the metal sheet to have the desired design and dimensions. Laser cutting can be used in the manufacturing especially if the sheet material is a metal plate. As the protective screen <NUM> is formed of a sheet material and being planar, the extension in the direction of the flow through the flow channel <NUM> of the blast damper <NUM> will also be small, because the extension in the direction of the flow through the flow channel <NUM> of the blast damper <NUM> is basically the thickness of the sheet material. This makes it possible to use and install the blast damper <NUM> also in thinner walls compared to what is possible with known blast dampers.

The frame <NUM> of the blast damper <NUM> comprises preferably, but not necessarily, a first planar flange <NUM> at the upstream end <NUM> of the flow channel <NUM>.

If the frame <NUM> of the blast damper <NUM> comprises a first planar flange <NUM> at the upstream end <NUM> of the flow channel <NUM>, the frame <NUM> comprises preferably, but not necessarily, a second planar flange <NUM> at the downstream end <NUM> of the flow channel <NUM> so that the first planar flange <NUM> and the and second planar flange <NUM> are essentially parallel, and the frame <NUM> comprises preferably, but not necessarily, a web section <NUM> between the first planar flange <NUM> and the second planar flange <NUM>.

The frame <NUM> of the blast damper <NUM> is preferably, but not necessarily, formed of metal sheet material.

If the frame <NUM> of the blast damper <NUM> comprises a first planar flange <NUM> at the upstream end <NUM> of the flow channel <NUM>, the protective screen <NUM> is preferably, but not necessarily, parallel with the first planar flange <NUM>.

If the frame <NUM> of the blast damper <NUM> comprises a first planar flange <NUM> at the upstream end <NUM> of the flow channel <NUM>, the protective screen <NUM> is preferably, but not necessarily, mounted to abut the first planar flange <NUM> of the frame <NUM>.

If the frame <NUM> of the blast damper <NUM> comprises a first planar flange <NUM> at the upstream end <NUM> of the flow channel <NUM>, the protective screen <NUM> has preferably, but not necessarily, a frame part <NUM> that configured to abut the first planar flange <NUM> of the frame <NUM> and that is provided with through holes <NUM> for fastening means to fasten the protective screen <NUM> to the first planar flange <NUM> of the frame <NUM>, so that the flow openings <NUM> are provided in a central part (not marked with a reference numeral) that is surrounded by the frame part <NUM>.

If the frame <NUM> of the blast damper <NUM> comprises a first planar flange <NUM> at the upstream end <NUM> of the flow channel <NUM>, the protective screen <NUM> has preferably, but not necessarily, essentially the same thickness as the first planar flange <NUM> of the frame <NUM>.

The flow openings <NUM> of the protective screen <NUM> are preferably, but not necessarily, formed by a grid (not marked with a reference numeral) with longitudinal grid members <NUM> and transversal grid members <NUM> formed by material of the planar monolithic part. At least some of the flow openings <NUM> can alternatively be round holes or have another form. The form and the dimensions of the flow openings can be selected for example in accordance with the required strength of the protective screen <NUM> or to have a certain look.

The actuating mechanism <NUM> comprises preferably, but not necessarily, turning levers <NUM> so that one turning lever <NUM> is fixed to the shaft means <NUM> of each closing blade <NUM> and a common operating lever <NUM> in turnably fixed to each turning lever <NUM> such that the closing blades <NUM> are configured to simultaneously pivot between the closed position so as to prevent air flow through the blast damper <NUM>, and the open position so as to allow air flow through the blast damper <NUM>.

A protective cover <NUM> can be provided to protect the actuating mechanism <NUM>.

The frame <NUM> comprises preferably, but not necessarily, a first profile section <NUM>, a second profile section <NUM> that is parallel with the first profile section <NUM>, a third profile section <NUM>, and a fourth profile section <NUM> that is parallel with the third profile section <NUM> so that the first profile section <NUM> and the second profile section <NUM> extend in parallel with the pivot axes of the closing blades <NUM>, and so that the first profile section <NUM>, the second profile section <NUM>, the third profile section <NUM>, and the fourth profile section <NUM> together limits the flow channel <NUM>.

Each closing blade <NUM> have preferably, but not necessarily, a leading edge <NUM> provided with a leading end section <NUM> that extends perpendicularly to a middle section <NUM> of the closing and a trailing edge <NUM> provided with a trailing end section <NUM> that extends perpendicularly to the middle section <NUM> of the closing blades <NUM> so that the closing blades <NUM> have an U-shaped cross-section form. Each closing blade <NUM> is preferably, but not necessarily, made of sheet metal. If the frame <NUM> comprises, a first profile section <NUM>, a second profile section <NUM> that is parallel with the first profile section <NUM>, a third profile section <NUM>, and a fourth profile section <NUM> that is parallel with the third profile section <NUM> so that the first profile section <NUM> and the second profile section <NUM> extend in parallel with the pivot axes of the closing blades <NUM>, and so that the first profile section <NUM>, the second profile section <NUM>, the third profile section <NUM>, and the fourth profile section <NUM> together limits the flow channel <NUM> and if each closing blade <NUM> have a leading edge <NUM> provided with a leading end section <NUM> that extends perpendicularly to a middle section <NUM> of the closing and a trailing edge <NUM> provided with a trailing end section <NUM> that extends perpendicularly to the middle section <NUM> of the closing blades <NUM> so that the closing blades <NUM> have an U-shaped cross-section form, the closing blades <NUM> are preferably, but not necessarily, dimensioned so that when each closing blade <NUM> is in the closed position, the leading end section of the closing blade <NUM> settles against the middle section of the adjacent closing blade <NUM> and so that the leading end section of the closing blade <NUM> closest to the first profile section <NUM> of the frame <NUM> settle against the first profile section <NUM> of the frame <NUM>, and so that the trailing end section of the closing blade <NUM> closest to the second profile section <NUM> of the frame <NUM> settle against the second profile section <NUM> of the frame <NUM>.

In the blast damper <NUM> illustrated in the figures, the first profile section <NUM> of the frame <NUM> has a step formation <NUM> and the leading end section of the closing blade <NUM> closest to the first profile section <NUM> of the frame <NUM> settle against the step formation of the first profile section <NUM> of the frame <NUM>. Provision of such leading end section and of such trailing end section makes the closing blades <NUM> stiffer and makes the closing blades <NUM> to more securely close the flow channel <NUM> in the closed position.

Claim 1:
A blast damper (<NUM>) comprising
a frame (<NUM>) defining a flow channel (<NUM>) for air flow through the blast damper (<NUM>), wherein the flow channel (<NUM>) defines an upstream end (<NUM>) and a downstream end (<NUM>),
closing blades (<NUM>) pivotally arranged in the flow channel (<NUM>), wherein each closing blade (<NUM>) can be pivoted about a pivot axis between a closed position and an open position and wherein each closing blade (<NUM>) is pivotally supported at the frame (<NUM>) by means of shaft means (<NUM>),
an actuating mechanism (<NUM>) configured to simultaneously pivot each closing blade (<NUM>) between the closed position so as to prevent air flow through the blast damper (<NUM>) and the open position so as to allow air flow through the blast damper (<NUM>), and
a protective screen (<NUM>) at the upstream end (<NUM>) of the flow channel (<NUM>),
characterized
by the protective screen (<NUM>) being formed of sheet material and being planar and being provided with flow openings (<NUM>),
by the sheet material being a metal plate.
by the sheet material having a monolithic structure. and
by the protective screen (<NUM>) having a monolithic structure.