Fire extinguishing agent concentration measuring system and method of measuring a fire extinguishing agent within an environment

A fire extinguishing agent concentration measuring system having a first window, a second window positioned relative to the first window thereby defining a sensing volume between the first window and the second window, and a structure positioned relative to the first window and the second window configured to cause fluid flowing into the sensing volume from an environment within which the fire extinguishing agent concentration measuring system is placed to swirl within the sensing volume.

BACKGROUND

Fire extinguishing systems employ agents that are deployed to an environment to extinguish fire in the environment. Some conventional systems employ Halon, a liquefied, compressed gas that stops the spread of fire by chemically disrupting combustion. Halon is contributing to ozone depletion, so alternatives to Halon are being sought. Some alternatives include dry solid particulates that are dispersed within the environment. The distribution and concentration of the particulates within the environment is important to the effectiveness of the system. As such, systems and methods to test and/or monitor such concentrations are of interest.

BRIEF DESCRIPTION

Disclosed herein is a fire extinguishing agent concentration measuring system. The system includes a first window, a second window positioned relative to the first window thereby defining a sensing volume between the first window and the second window, and a structure positioned relative to the first window and the second window configured to cause fluid flowing into the sensing volume from an environment within which the fire extinguishing agent concentration measuring system is placed to swirl within the sensing volume.

Also disclosed herein is a method of measuring a fire extinguishing agent within an environment. The method includes, allowing fluid from the environment to pass through a structure and into a sensing volume defined between a first window and a second window, swirling the fluid within the sensing volume, detecting light passing through the sensing volume, and determining a concentration of the fire extinguishing agent present in the fluid.

DETAILED DESCRIPTION

FIGS. 1 and 2depict an embodiment of a fire extinguishing agent concentration measuring system disclosed herein identified by reference character10. The system10includes, a structure14defining a sensing volume18through which a fluid20(the fluid20containing a fire extinguishing agent22) passes. Light is provided from a light source26through an optical fiber30. The light is transmitted from an end34of the optical fiber30through a first window or lens38, then through the sensing volume18, through a second window42and impinges on a mirror46. Light reflected from the mirror46travels in reverse back to a sensor50located near the light source26. The sensor50is calibrated to detect light received and correlate it to a concentration of the agent22present in the fluid20based on scatter of the light caused by the presence of the agent22. While the embodiments illustrated in the figures herein include items such as, the structure14, the mirror46, and the optical fiber30, alternate embodiments are contemplated that don't require these specific items.

The agent22may consist of solid particulates51that are emitted from a container52configured to hold the agent22until dispersion of the agent22is needed such as in the event of a fire, for example. The container52may be positioned within an environment53which may be housed within a turbine engine54or other system wherein quick extinguishment of a fire is desired.

Openings55in the structure14fluidically connect the sensing volume18to the environment53containing the fluid20with the agent22. As such, the fluid20is free to pass between the environment53and the sensing volume18through the openings55. Similarly, at least orifice60, with a plurality being illustrated herein, in the structure14also fluidically connects the sensing volume18to the environment53, thereby allowing an additional way for the fluid20containing the agent22to pass between the environment53and the sensing volume18. The orifices60differ from the openings55in at least two ways. Firstly, instead of being located near a center64between the windows38and42, the orifices60are located nearer to one of the windows38,42. And secondly, the orifices60are oriented such that the fluid20flowing through them from the environment53and into the sensing volume18is not directed toward an axis68of the system10but instead is directed to an offset dimension70, shown inFIG. 2, from the axis68. The axis68is defined by a path light travels between the end34of the optical fiber30and the mirror46. That is, the orifices60direct fluid20some distance (i.e., the offset dimension70) away from the path that light travels (i.e., the axis68).

These characteristics of the orifices60tend to move the fluid20flowing through them into the sensing volume18in such a way that settling of the particulates51on surfaces72and76of windows38and42, respectively, is discouraged. The proximity of the orifices60to one of the surfaces72,76urges the fluid20flowing through the orifices60to move with a larger velocity near to the surfaces72,76than if the orifices60were further from the surfaces72,76. The offset dimension70set by the aim of the orifices60relative to the axis68creates a swirling action of the fluid20as it flows into the sensing volume18through the orifices60. This swirling action also acts to maintain a larger velocity of the fluid20flowing within the sensing volume18than would occur if the offset dimension70did not exist, since flows could directly impinge on each other in opposing directions thereby decreasing velocity of the flows.