Patent Description:
The distribution and concentration of particles in an environment may be determined for a number of reasons. In the exemplary case of a fire suppression system that deploys an agent to extinguish a fire, the concentration of fire suppression agent in the environment may be determined and used to verify that the fire suppression agent has reached a sufficient concentration or to control the release of additional agent. In other scenarios, the concentration of a particular (hazardous) material in the air may trigger an alert. <CIT> discloses a flame arrester and methods of preventing or mitigating flame propagation. <CIT> relates to systems and methods which analyze light to determine the size and characteristics of particles.

In a first aspect there is provided a sensor according to claim <NUM>.

In an embodiment, the plurality of shield openings is arranged in one or more layers relative to the volume.

According to the invention, the flow restrictor includes a first restrictor and a second restrictor arranged to define an orifice between the volume and the channel.

Additionally or alternatively, in this or other embodiments, the channel is copper.

According to the invention, the sensor is a particle concentration measurement sensor.

According to the invention, the particles of interest are particles of fire suppression agent and the particle concentration measurement sensor measures a concentration of the fire suppression agent in the gas.

Additionally or alternatively, in this or other embodiments, the flow shield is aluminum.

Additionally or alternatively, in this or other embodiments, the flow shield is steel.

In a second aspect there is provided a method according to claim <NUM>.

In an embodiment, the method also includes arranging the plurality of shield openings in one or more layers relative to the volume.

According to the invention, the method also includes forming the flow restrictor to include a first restrictor and a second restrictor arranged to define an orifice between the volume and the channel.

According to the invention, the sensor is a particle concentration measurement sensor.

According to the invention, the gas includes particles of fire suppression agent and the particle concentration measurement sensor measures a concentration of the fire suppression agent in the gas.

As previously noted, determining the concentration of a type of particle in an environment may have different applications. Embodiments of the systems and methods detailed herein relate to a flow control device for particle concentration measurement sensor. The particle concentration measurement sensor may be part of a fire suppression system, for example, and may measure the concentration of a fire suppression agent in the environment. The particle concentration measurement sensor includes an inlet to draw in particle-laden gas from the environment. Due to differences in sizes of the different components of the particle-laden gas, the inlet may not capture particles in the same concentrations in which they are present in the environment. As detailed, the flow control device at the inlet of the particle concentration measurement sensor ensures a consistent extraction of particle-laden gas in order to accurately determine the concentration of particles of interest (e.g., fire suppression agent).

<FIG> is a cross-sectional view of a particle concentration measurement sensor <NUM> with a flow control device <NUM> according to one or more embodiments. According to an exemplary embodiment, the particle concentration measurement sensor <NUM> is part of a fire suppression system <NUM> and is used to determine the concentration of a fire suppression agent in particle-laden gas <NUM> that is drawn into a housing <NUM> of the particle concentration measurement sensor <NUM> through the flow control device <NUM> at an inlet <NUM>. A vacuum source <NUM> may be coupled at an outlet <NUM> of the housing <NUM> to draw gas through from the inlet <NUM> to the outlet <NUM>. As the cross-sectional view of the particle concentration measurement sensor <NUM> indicates, a first window <NUM> and a second window <NUM> define an interaction region <NUM> within the housing <NUM>.

According to the exemplary embodiment of the particle concentration measurement sensor <NUM> shown in <FIG>, a light source <NUM> provides input light <NUM> via an optical fiber <NUM> to the housing <NUM>. In the interaction region <NUM>, the light <NUM> and the particle-laden gas <NUM> entering the housing <NUM> via the inlet <NUM> interact. This interaction is detected at a detector <NUM> outside the interaction region <NUM>. Specifically, the detector <NUM> measures an intensity of the post-interaction light that corresponds with the particle of interest (e.g., fire suppression agent) in the particle-laden gas <NUM>. A controller <NUM> may map that intensity to a concentration. According to alternate embodiments, the particle concentration measurement sensor <NUM> may include a mirror at the location at which the detector <NUM> is shown in <FIG>. The mirror reflects the result of the light interaction in the interaction region <NUM> back through the second window <NUM> and first window <NUM> toward the light source <NUM>. Thus, the detector <NUM> and controller <NUM> may be located at the same side as the light source <NUM> in the alternate embodiment.

The flow control device <NUM>, according to one or more embodiments, includes features that ensure that the concentration of the particle of interest (e.g., fire suppression agent) in the environment is accurately reflected within the housing <NUM> in the interaction region <NUM>. The flow control device <NUM> includes a flow shield <NUM> with shield openings <NUM> (i.e., perforations or entryways) that slow the flow of particle-laden gas <NUM> flowing therethrough into a volume <NUM>. A first layer 207a and a second layer 207b (generally referred to as <NUM>) of the shield openings <NUM> are shown around the volume <NUM> in <FIG>. That is, particle-laden gas <NUM> entering the volume <NUM> must pass through a shield opening <NUM> in one or both layers <NUM> according to the exemplary embodiment shown in <FIG>. The flow shield <NUM> also includes a flow restrictor <NUM> within the volume <NUM> that restricts the opening between the volume <NUM> and a channel <NUM> to the inlet <NUM> of the housing <NUM>. The channel <NUM> between the flow shield <NUM> and the inlet <NUM> ensures laminar flow of the particle-laden gas <NUM> that is captured by the flow control device <NUM> into the inlet <NUM>.

Based on the shield openings <NUM>, flow of the particle-laden gas <NUM> within the volume <NUM> that is defined by the flow shield <NUM> is slower and less turbulent than in the environment. The slowing of the flow in the volume <NUM>, based on the shield openings <NUM> of the flow shield <NUM>, keeps larger particles from escaping entry into the housing <NUM> through the flow restrictor <NUM>. The flow shield <NUM> may be aluminum or steel, for example. The flow restrictor <NUM> is further discussed with reference to <FIG>. The flow restrictor <NUM> provides a near-constant extraction rate of the particle-laden gas <NUM> from the environment. This near-constant extraction rate is achieved because the magnitude of the pressure drop across the flow restrictor <NUM> far exceeds any dynamic pressure variations observed within the volume <NUM>. Based on the presence of the flow restrictor <NUM>, a stronger vacuum may be needed from the vacuum source <NUM> to achieve an optimal extraction rate of particle-laden gas <NUM> from the environment. The flow of the particle-laden gas <NUM> into the housing <NUM> is driven by pressure gradients. In that regard, the pressure difference between the inlet <NUM> and outlet <NUM> of the housing is minimal, and the largest pressure difference is across the flow restrictor <NUM>. The length of the channel <NUM> is not intended to be limited by the exemplary depiction. The channel <NUM> may be copper, for example.

<FIG> and <FIG> show side views of two exemplary embodiments of the flow control device <NUM> according to one or more embodiments, and <FIG> and <FIG> respectively show cross-sections of the Exemplary flow control devices <NUM> shown in <FIG> and <FIG>. As <FIG> illustrate, the shield openings <NUM> may have different shapes. As <FIG> and <FIG> illustrate, the cross-sectional shape of the flow shield <NUM> is not limited by the exemplary embodiment of the flow control device <NUM> shown in <FIG>.

<FIG> is a side view of a flow control device <NUM>. The shield openings <NUM> of the exemplary flow control device <NUM> shown in <FIG> are oval in shape. <FIG> is a cross-sectional view of the exemplary flow control device <NUM> shown in <FIG>. As <FIG> illustrates, the exemplary flow control device <NUM> of <FIG> does not include an additional layer <NUM> of shield openings <NUM> on each side as in <FIG>. In alternate embodiments, the flow control device <NUM> may instead include additional (i.e., more than two) layers <NUM> of shield openings <NUM> as compared with the example shown in <FIG> in alternate embodiments. The expected turbulence in the environment may drive a selection of the number of layers <NUM> of shield openings <NUM> used in the flow control device <NUM>. The flow restrictor <NUM> is further detailed in <FIG>. As shown, the flow restrictor <NUM> is made up of a first restrictor 225a and a second restrictor 225b that are arranged to define an orifice <NUM> between them. More specifically, the relative spacing between the first and second restrictors 225a, 225b defines a size of the orifice <NUM> through which particles in the particle-laden gas <NUM> may enter the channel <NUM> and, subsequently, the inlet of the housing <NUM> of the particle concentration measurement sensor <NUM>. The closer the first and second restrictors 225a, 225b are arranged to each other, the smaller the orifice <NUM> and, thus, the more restricted the flow from the volume <NUM> into the channel <NUM>.

<FIG> is a side view of an exemplary flow control device <NUM> according to one or more embodiments. The shape of the shield openings <NUM> shown in <FIG> is rectangular. In alternate embodiments, the shield openings <NUM> may have a round, square, or other shape and are not limited by the oval and rectangular shapes illustrated in <FIG> and <FIG> is a cross-sectional view of the flow control device <NUM> shown in <FIG>. As <FIG> shows, the cross-sectional shape of the flow shield <NUM> is circular. In alternate embodiments, the cross-sectional shape of the flow shield <NUM> is not limited by the exemplary illustrations. The numbers of shield openings <NUM> are also not limited by any exemplary illustration. Like the number of layers <NUM> of shield openings <NUM>, the number and relative spacing of the shield openings <NUM> in each layer may be selected based on the expected turbulence in the environment and, thus, on how much the flow of the particle-laden gas <NUM> may need to be slowed.

Claim 1:
A sensor (<NUM>) for measuring a fire suppression agent in a gas, the sensor comprising:
a housing (<NUM>) with an inlet (<NUM>) and an outlet (<NUM>);
a first window (<NUM>) and a second window (<NUM>) defining an interaction region (<NUM>) within the housing (<NUM>);
a detector outside the interaction region (<NUM>) and a controller (<NUM>);
a light source (<NUM>) providing input light (<NUM>) via an optical fiber (<NUM>) into the housing (<NUM>),
a vacuum source (<NUM>) outside of the housing (<NUM>) coupled at the outlet (<NUM>); and
a flow control device (<NUM>) outside of the housing (<NUM>) coupled to the inlet (<NUM>), the flow control device (<NUM>) configured to ensure that a concentration of particles of interest is accurately reflected in the housing (<NUM>), the flow control device (<NUM>) comprising:
a flow shield (<NUM>) defining a volume (<NUM>), the flow shield (<NUM>) including a plurality of shield openings (<NUM>) formed therein;
a channel (<NUM>), between the flow shield (<NUM>) and the inlet (<NUM>), that directs the gas from the volume (<NUM>) to the inlet (<NUM>); and
a flow restrictor (<NUM>) within the volume (<NUM>) that restricts the opening between the volume (<NUM>) and the channel (<NUM>) and creates a pressure drop for the gas flowing from the volume (<NUM>) to the inlet (<NUM>),
wherein:
the channel (<NUM>) ensures laminar flow of a particle-laden gas (<NUM>) that is captured by the flow control device (<NUM>) into the inlet (<NUM>);
the flow restrictor (<NUM>) is made up of a first restrictor (225a) and a second restrictor (225b) that are arranged to define the orifice (<NUM>) of the opening between the volume (<NUM>) and the channel (<NUM>), the relative spacing between the first and second restrictors (225a, 225b) defines the size of the orifice (<NUM>) through which particles in the particle-laden gas (<NUM>) may enter the channel (<NUM>) and, subsequently, the inlet of the housing (<NUM>) of the sensor (<NUM>); and
the vacuum source draws gas through from the inlet (<NUM>) to the outlet (<NUM>), the light (<NUM>) and the particle-laden gas (<NUM>) entering the housing (<NUM>) via the inlet (<NUM>) interact in the interaction region (<NUM>), the detector (<NUM>) detects this interaction and measures an intensity of the post-interaction light that corresponds with the particle of interest, the controller (<NUM>) maps that intensity to a concentration.