Pneumatic detection using a liquefied compressed gas

Patent metadata

Field	Value
Publication number	US-9728057-B2
Application number	US-201414287969-A
Country	US
Kind code	B2
Filing date	May 27, 2014
Priority date	May 27, 2014
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

A pneumatic detection system and a method of forming the pneumatic detection system are described. The system includes a sealed tube, a refrigerant disposed within the sealed tube, and a switch configured to be activated based on a specified pressure being reached within the sealed tube.

First claim

What is claimed is:

1. A pneumatic detection system, comprising:
a sealed tube;
a refrigerant disposed within the sealed tube;
a first switch configured to be activated until a fault condition is reached, the first switch being operated by a first diaphragm until the fault condition is reached indicating a drop in pressure from a default pressure; and
a second switch configured to be activated based on a specified pressure being reached within the sealed tube, the second switch being operated by a second diaphragm when the specified pressure is reached.

2. The system according to claim 1 , further comprising the second diaphragm coupled to the sealed tube configured to expand based on the specified pressure being reached within the sealed tube and to active the second switch.

3. The system according to claim 1 , wherein the refrigerant has a concentration to reach the specified pressure when a first temperature is reached over a first length of the sealed tube.

4. The system according to claim 3 , wherein the refrigerant has the concentration to reach the specified pressure when a second temperature, lower than the first temperature, is reached over a second length, longer than the first length, of the sealed tube.

5. The system according to claim 1 , wherein the refrigerant exhibits an exponential increase in pressure based on temperature increase.

6. The system according to claim 1 , wherein the refrigerant is a liquefied compressed gas.

7. The system according to claim 1 , wherein the refrigerant is trifluoromethane or bromotrifluoromethane.

8. The system according to claim 1 , further comprising an inert gas in the sealed tube.

9. A method of forming a pneumatic detection system, the method comprising:
selecting a refrigerant;
obtaining specifications including a first threshold temperature and first length of a sealed tube at which an alarm switch must be activated;
determining a concentration of the refrigerant to dispose in a sealed tube based on the specifications;
arranging a fault switch to be activated by a first diaphragm until pressure of the refrigerant falls below a default pressure; and
arranging the alarm switch to be activated by a second diaphragm based on the specifications.

10. The method according to claim 9 , wherein the selecting the refrigerant is based on an environment in which the pneumatic detection system is to be used.

11. The method according to claim 9 , wherein the selecting the refrigerant includes selecting the refrigerant that exhibits an exponential increase in the pressure based on temperature increase.

12. The method according to claim 9 , wherein the selecting the refrigerant includes selecting a liquefied compressed gas.

13. The method according to claim 9 , wherein the determining the concentration of the refrigerant is based on reaching a specified pressure over a full length of the sealed tube when the first length of the sealed tube reaches the first temperature, the specified pressure being a required pressure to activate the alarm switch.

14. The method according to claim 13 , wherein the determining the concentration of the refrigerant is based on reaching the specified pressure when a second temperature, lower than the first temperature, is reached over a second length, longer than the first length, of the sealed tube.

15. The method according to claim 9 , further comprising disposing inert gas as a filler in the sealed tube.

Assignees

• Kidde Tech Inc

Inventors

• Frasure David
• Hagge Harlan
• Wallace Steven
• Seebaluck Dharmendr Len

Classifications

• Y10T29/49828

  Progressively advancing of work assembly station or assembled portion of work · CPC title

• G01L7/00

  Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements ({G01L11/004 takes precedence;} transmitting or indicating the displacement of mechanical pressure-sensitive elements by electric {, e.g., photoelectric} or magnetic means G01L9/00; measuring differences of two or more pressure values G01L13/00; measuring two or more pressure values simultaneously G01L15/00) · CPC title

• H01H35/34 Primary

  actuated by diaphragm · CPC title

• G08B17/04 Primary

  Hydraulic or pneumatic actuation of the alarm, e.g. by change of fluid pressure · CPC title

• H01H47/00

  Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current · CPC title