Exhaust demand control system and methods
AssigneeMeasured Air Performance, LLC
InventorEric Desrochers
Life of this patent
Estimating the term…
Abstract
Methods and apparatus for an exhaust demand control system for measuring one or more contaminants at one or more exhaust locations within one or a plurality of exhaust ducts or plenums served by an exhaust fan system. Example systems and methods can include sensing the one or more contaminants within the one or more exhaust duct locations using a multipoint air sampling system having one or more sensors and comparing contaminant concentration measurements from the one or more of said exhaust duct or plenum locations against an action level to create a fan setback signal.
Claims20
An exhaust demand control system for measuring one or more contaminants at one or more exhaust locations within one or more exhaust ducts or plenums served by an exhaust fan system having one or more exhaust fans, comprising systems configured to:
- sense the one or more contaminants within the one or more exhaust locations using a multipoint air sampling system having one or more sensors and flow control elements, which include a high flow element to provide a purge flow and a low flow element to provide a sensing flow;
- compare contaminant concentration measurements from the one or more exhaust locations against an action level to create a fan setback signal which controls a setback state of the exhaust fan system;
- prevent exhaust fan system instability by controlling operation of the one or more exhaust fans according to a sequence delay provided by control logic of a control system where the sequence delay is enabled when the contaminant concentration measurements from the one or more exhaust locations exceeds the action level, wherein the sequence delay in part determines a minimum time that the fan setback signal is disabled;
- and
- ensure sensor accuracy and reliability by implementing a sensor protective mode for a period of time designated by the sequence delay, wherein the sensor protective mode is enabled when the contaminant concentration measurements from the one or more exhaust locations exceeds the action level, wherein the sensor protective mode includes the combined steps of:
- discontinuing an air sampling process performed by the multipoint air sampling system, isolating the one or more sensors from the contaminant source, and enabling a tubing flushing function which uses a negative pressure of the one or more exhaust locations to flow ambient air through each tube which connects between the multipoint air sampling system and the one or more exhaust locations via a flow path to ambient that is enabled within the multipoint air sampling system when the sensor protective mode is enabled.
A method of performing exhaust demand control using a system for measuring one or more contaminants at one or more exhaust locations within one or more exhaust ducts or plenums served by an exhaust fan system having one or more exhaust fans, comprising:
- sensing the one or more contaminants within the one or more exhaust locations using a multipoint air sampling system having one or more sensors and two flow control elements which include a high flow element to provide a purge flow and a low flow element to provide a sensing flow;
- comparing contaminant concentration measurements from the one or more exhaust locations against an action level to create a fan setback signal which controls the setback state of the exhaust fan system;
- preventing exhaust fan system instability by controlling the operation of the one or more exhaust fans according to a sequence delay provided by control logic of the control system where the sequence delay is enabled when the contaminant concentration measurements from the one or more exhaust locations exceeds the action level, wherein the sequence delay in part determines a minimum time that the fan setback signal is disabled;
- and
- ensuring sensor accuracy and reliability by implementing a sensor protective mode for a period of time designated by the sequence delay, which sensor protective mode is enabled when the contaminant concentration measurements from the one or more exhaust locations exceeds the action level;
- sensor protective mode at least consisting of the combined steps of:
- discontinuing the air sampling process performed by the multipoint air sampling system, isolating the one or more sensors from the contaminant source, and enabling a tubing flushing function which uses the negative pressure of the one or more exhaust locations to flow ambient air through each tube which connects between the multipoint air sampling system and the one or more exhaust locations via a flow path to ambient that is enabled within the multipoint air sampling system when sensor protective mode is enabled.
Dependencies are inferred from the claim text.