Sensing apparatus and method
View Patent ↗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.
1. An aspirated smoke detector system comprising:
a particle detector,
a sampling pipe network, said pipe network including one or more elongate pipes, each pipe having a plurality of sampling holes spaced along the pipe and through which air samples are drawn from spaced locations along the pipe;
an inlet for connecting the particle detector to a pipe of the sampling pipe network;
an aspirator for drawing an air sample through the sampling pipe network to the particle detector; and
an ultrasonic flow sensor arranged to detect the flow rate of air entering the particle detector.
2. The smoke detector system of claim 1 , wherein the flow sensor is in fluid communication with the sampling pipe network and is operationally arranged to measure the partial flow of fluid through a sampling pipe network.
3. The smoke detector system of claim 1 , wherein the particle detector detects particles in a portion of the air flow flowing through the sampling pipe network.
4. The smoke detector system of claim 1 , wherein the flow sensor is located in a housing for the particle detector.
5. The smoke detector system of claim 1 , having a branch in the inlet allowing air to bypass the particle detector.
6. The smoke detector system of claim 1 further comprising a flow disruptor located upstream of the flow sensor.
7. The detector system of claim 6 , wherein the flow sensor is in fluid communication with the sampling pipe network and is operationally arranged to measure the partial flow of fluid through a sampling pipe network.
8. The smoke detector system of claim 6 , wherein the particle detector detects particles in a portion of the air flow flowing through the sampling pipe network.
9. The smoke detector system of claim 6 , wherein the flow sensor is located in a housing for the particle detector.
10. The smoke detector system of claim 6 , having a branch in the inlet allowing air to bypass the particle detector.
11. The smoke detector system of claim 6 wherein the flow disruptor is configured to remove laminar flow from steady air flow through the sampling pipe network.
12. The smoke detector system of claim 6 wherein the particle detector includes the flow disruptor.
13. The smoke detector system of claim 7 wherein the flow disruptor is between the flow sensor and the inlet.
14. The smoke detector system of claim 13 wherein the flow sensor is at or near a fluid inlet of the particle detector.