Method for correlating a monitoring device to the end of service life of a filter cartridge

Patent metadata

Field	Value
Publication number	US-9291484-B2
Application number	US-201113876402-A
Country	US
Kind code	B2
Filing date	Aug 31, 2011
Priority date	Oct 1, 2010
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

Methods of correlating a monitoring device to the service life of a filter cartridge include providing a monitoring device, and calibrating the monitoring device to correspond to the service life of a filter cartridge. The monitoring device comprises a demand substance within a receptacle, a sensing element with a detection point, a reader for the sensing element, and a fluid delivery device. Calibration includes determining the ratio of the residence time of the monitoring device to the residence time of the filter cartridge, and utilizing the ratio to correlate the response of the sensor within the monitoring device to the service life of the filter cartridge. The response of the sensor is correlated to the service life of the filter cartridge by control of the fluid delivery parameters of the fluid delivery device. The fluid delivery parameters include the flow rate, the demand substance mass, the receptacle cross sectional area, the receptacle volume, the receptacle length, and the demand substance packing density.

First claim

What is claimed is:

1. A method of correlating a monitoring device to the service life of a filter cartridge comprising:
providing a monitoring device; and
calibrating the monitoring device to correspond to the service life of a filter cartridge,
wherein the monitoring device comprises:
a demand substance capable of absorbing an organic vapor within a receptacle;
a sensing element with a detection point;
a reader for the sensing element; and
a fluid delivery device, the fluid delivery device comprising fluid delivery parameters, wherein the fluid delivery parameters and the detection point of the sensing element are correlated to the service life of a filter cartridge, and

wherein calibrating the monitoring device to correspond to the service life of a filter cartridge comprises:
determining a residence time for the filter cartridge;
determining a residence time for the monitoring device;
determining the ratio of the residence time of the monitoring device to the residence time of the filter cartridge; and
utilizing the ratio to correlate the response of the sensor within the monitoring device to the service life of the filter cartridge.

2. The method of claim 1 , wherein the response of the sensor within the monitoring device is correlated to the service life of the filter cartridge by control of the fluid delivery parameters of the fluid delivery device, wherein the fluid delivery parameters comprise: the flow rate, the demand substance mass, the receptacle cross sectional area, the receptacle volume, the receptacle length, and the demand substance packing density of the monitoring device.

3. The method of claim 2 , wherein the demand substance and the demand substance packing density for the monitoring device and the filter cartridge are the same.

4. The method of claim 3 , wherein the demand substance for the monitoring device and the filter cartridge comprises activated carbon, treated activated carbon, alumina, silica gel, hopcalite, molecular sieves, metal-organic frameworks, or a combination thereof.

5. The method of claim 2 , wherein the flow rate for the monitoring device is different from the flow rate for the filter cartridge.

6. The method of claim 1 , wherein the fluid delivery device controls the flow rate to make the ratio of the face velocity of the monitoring device to the face velocity of the filter cartridge equal 1:1.

7. The method of claim 1 , wherein the fluid delivery device controls the flow rate to make the ratio of the residence time of the monitoring device to the residence time of the filter cartridge is less than 1:1.

8. The method of claim 1 , wherein the detection point of the sensing element comprises an optical change.

9. The method of claim 8 , wherein the optical change comprises a change in color.

10. The method of claim 1 , wherein the reader for the sensing element comprises the human eye or an optical detector.

11. The method of claim 1 , wherein the demand substance is a layered film.

12. The method of claim 1 , wherein the receptacle contains the demand substance and at least one sensing element.

13. The method of claim 1 , wherein the receptacle comprises a tube, a cartridge or a disk.

14. The method of claim 1 , wherein the monitoring device further comprises additional sensing elements.

15. The method of claim 1 , wherein the fluid delivery device comprises a pump or fan.

16. The method of claim 3 , wherein the service life of the filter cartridge is described by the equation:
t SL =t b ( W cartridge Q monitor /W monitor Q cartridge )
wherein
t SL is the service life time of the filter cartridge;
t b is the service life time of the monitor;
W cartridge is the weight of demand substance in the cartridge;
Q monitor is the flow rate in the monitor;
W monitor is the weight of demand substance in the monitor;
Q cartridge is the flow rate in the cartridge.

17. The method of claim 16 , wherein t b is the same as the detection point of the sensing element.

18. The method of claim 16 , wherein W cartridge Q monitor =W monitor Q cartridge .

19. The method of claim 17 , wherein the detection point is less than t b .

20. The method of claim 1 , wherein the sensing element is a layered film.

Assignees

• Rakow Neal A
• Gryska Stefan H
• 3M Innovative Properties Co

Inventors

• Rakow Neal A
• Gryska Stefan H

Classifications

• B01D2253/106

  Silica or silicates · CPC title

• B01D2259/4541

  for portable use, e.g. gas masks · CPC title

• B01D2257/708

  Volatile organic compounds V.O.C.'s · CPC title

• G01F25/00

  Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume · CPC title

• G01D18/00 Primary

  Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00 · CPC title