Sensing apparatus and method

• US 8,892,399 B2
• Filed: 07/09/2012
• Issued: 11/18/2014
• Est. Priority Date: 05/14/2003
• Status: Active Grant

• Current Assignee: Garrett Thermal Systems Ltd. (Honeywell International Inc.)
• Original Assignee: Xtralis Technologies Ltd (Honeywell International Inc.)
• Inventors: Ajay, Kemal, Caprihan, Arjun Vinoo, Rezny, Michael
• Primary Examiner(s): Feliciano, Eliseo Ramos
• Assistant Examiner(s): SUAREZ, FELIX E
• Application Number:
  US13/544,214
• Publication Number:
  US 20130013227A1
• Time in Patent Office: 862 Days
• Field of Search: 702/14, 702/36, 702/59, 702/182, 702/183, 702/186, 702/189, 73/40, 381/159, 340/630
• US Class Current: 702/176
• CPC Class Codes: G01F 1/66 by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
• CPC Class Codes: G01F 1/667 Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
• CPC Class Codes: G01F 1/74 Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid
• CPC Class Codes: G01N 1/2205 with filters
• CPC Class Codes: G01N 1/2273 Atmospheric sampling
• CPC Class Codes: G01N 1/26 with provision for intake from several spaces
• CPC Class Codes: G01N 2015/0046 in gas, e.g. smoke
• CPC Class Codes: G01N 2015/1486 Counting the particles
• CPC Class Codes: G01N 2291/0217 Smoke, combustion gases
• CPC Class Codes: G01N 2291/02408 Solids in gases, e.g. particle suspensions
• CPC Class Codes: G01N 2291/02836 Flow rate, liquid level
• CPC Class Codes: G01N 29/024 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G08B 17/10 Actuation by presence of smoke or gases , e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
• CPC Class Codes: G08B 17/113 Constructional details

Abstract

A method of detecting one or more blocked sampling holes in a pipe of an aspirated smoke detector system. The method includes ascertaining the base flow of fluid through a particle detector using a flow sensor; monitoring subsequent flow through the particle detector; comparing the subsequent flow with the base flow; and indicating a fault if the difference between the base flow and the subsequent flow exceeds a predetermined threshold.

Claims

1. A method of detecting one or more blocked sampling holes in a pipe of an aspirated smoke detector system, said aspirated smoke detector system comprising a sampling network including one or more pipes having sampling holes, an aspirator for drawing air through the sampling network to a detector;

and a flow sensor, said method comprising;

ascertaining the base flow of fluid through a particle detector using the flow sensor;

monitoring subsequent flow through the particle detector using the flow sensor; and

comparing in a processor, the subsequent flow with the base flow, and determining that one or more sampling holes of the sampling network are blocked and indicating a fault, if the difference between the base flow and the subsequent flow exceeds a predetermined threshold.

2. The method of claim 1 wherein the flow sensor is an ultrasonic flow sensor.

3. The method of claim 1, wherein the difference between base flow and subsequent flow is compared over a length of time.

4. The method of claim 1 wherein the flow is determined according to the following general flow calculation:

f=s×

A

where f=volumetric flow;

A=cross sectional area of an air flow path through the detector system;

s=speed of air through the detector system such that s is given by;

5. A non-transitory computer readable medium encoded with a computer program containing instructions stored thereon for causing a computer processor to control a particle detector to perform a method comprising the steps of:

ascertaining the base flow of fluid through a particle detector using a flow sensor;

monitoring subsequent flow through the particle detector using the flow sensor; and

comparing in a processor, the subsequent flow with the base flow, and determining that one or more sampling holes of the sampling network are blocked and indicating a fault, if the difference between the base flow and the subsequent flow exceeds a predetermined threshold.

6. The non-transitory computer readable medium as claimed in claim 5, wherein in the method, the difference between base flow and subsequent flow is compared over a length of time.

7. The non-transitory computer readable medium as claimed in claim 5, wherein in the method, the flow is determined according to the following general flow calculation:

f=s×

A

where f=volumetric flow;

A=cross sectional area of an air flow path through the detector system;

s=speed of air through the detector system such that s is given by;

8. A non-transitory computer readable medium encoded with a computer program containing instructions stored thereon for causing a computer processor to control a particle detector to perform a method comprising the steps of:

ascertaining the base flow of fluid through a particle detector using an ultrasonic flow sensor;

monitoring subsequent flow through the particle detector using the ultrasonic flow sensor; and

comparing in a processor, the subsequent flow with the base flow, and determining that one or more sampling holes of the sampling network are blocked and indicating a fault, if the difference between the base flow and the subsequent flow exceeds a predetermined threshold.

9. An aspirated smoke detector comprising:

a particle detector,

a sampling network including one or more pipes with one or more sampling holes through which samples enter the one or more pipes; and

an aspirator for drawing an air sample through the sampling network to the particle detector;

wherein the aspirated smoke detector includes an ultrasonic flow sensor arranged to detect the flow rate of air entering the particle detector, and

wherein the aspirated smoke detector further comprises a processor configured to;

ascertain the base flow of fluid through the particle detector using the flow sensor;

monitor subsequent flow through the particle detector using the flow sensor; and

compare the subsequent flow with the base flow, and determine that one or more sampling holes of the sampling network are blocked and indicate a fault, if the difference between the base flow and the subsequent flow exceeds a predetermined threshold.