Ultrasonic hand-held refrigerant leak detector

• US 4,879,546 A
• Filed: 04/26/1989
• Issued: 11/07/1989
• Est. Priority Date: 11/30/1987
• Status: Expired due to Term

• Current Assignee: GSLE Subco, LLC (SPX Corporation)
• Original Assignee: Kent-Moore Corp. (SPX Corporation)
• Inventors: Murray, Gary P., Bulla, Don A., Dunham, Byron J.
• Primary Examiner(s): Orsino, Joseph A.
• Assistant Examiner(s): JACKSON, JILL
• Application Number:
  US07/344,422
• Time in Patent Office: 195 Days
• Field of Search: 340/632-634, 340/627, 340/693, 324/455, 324/469, 324/58.5 A, 73/24, 73/40.7, 73/40.5 A, 250/336.1, 250/343, 250/373
• US Class Current: 340/632
• CPC Class Codes: G01N 2291/012 Phase angle
• CPC Class Codes: G01N 2291/0215 Mixtures of three or more gases, e.g. air
• CPC Class Codes: G01N 29/024 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 29/22 Details , e.g. general constructional or apparatus details
• CPC Class Codes: G01N 33/0049 Halogenated organic compounds

Abstract

Hand-held apparatus for detecting presence of halogen refrigerant agents in air in which a pair of ultrasonic transducers are spaced from each other within a measurement probe and test air is continuously drawn between the transducers by a fan. One transducer is energized at constant ultrasonic frequency, and the other transducer is coupled to a rectifier or a phase detector for providing a measurement signal as a function of radiation received at and reflected by such other transducer. A reference signal level is established by selectively sampling and electronically storing of the measurement signal, such that the reference level is automatically or manually updated to reflect changes in ambient conditions. An audio/visual alarm is activated when the measurement signal departs from the ambient reference level by more than a preselected threshold.

Claims

1. Apparatus for detecting presence of contaminants in air comprising:

sensor means including a spaced pair of radiant energy transducers, means for admitting a test air sample between said transducers, means for continuously applying a periodic signal to one of said transducers to launch radiant energy toward the other of said transducers, means including rectifier means coupled to said other of said transducers for providing an electrical measurement signal as a continuing d.c. output signal that is a function of velocity of radiant energy between said transducers, means for selectively sampling and electrically storing said measurement signal, means for deriving a reference signal from said sampled and stored measurement signal, means for continuously comparing said measurement signal to said reference signal, alarm means coupled to said continuous comparing means for indicating an alarm condition when a difference between said reference and measurement signals exceeds a preselected threshold indicating an increase in contaminants between said transducers, and means coupled to said continuously comparing means and to said alarm means and responsive to a change in said measurement signal indicating a decrease in contaminants following an indication of alarm condition at said alarm means for automatically resampling and storing said measurement signal as a new reference signal and thereby automatically terminating said indication of alarm condition at said alarm means.

2. The apparatus set forth in claim 1 wherein said means for providing said measurement signal comprises means responsive to phase angle between energies at said transducers;

and wherein said signal-comparing means comprises means responsive to a decrease in measurement signal phase angle as compared with reference phase angle to indicate a said alarm condition, and being substantially independent of increase in said measurement signal phase angle and thereby independent of increase in humidity content between said transducers.

3. The apparatus set forth in claim 1 wherein said alarm means comprises audible alarm means, and means for energizing said audible alarm means when said measurement signal varies from said reference signal by more than said preselected threshold.

4. The apparatus set forth in claim 1 wherein said alarm means comprises illumination means, and means for energizing said illumination means in response to said alarm condition in the test air sample.

5. The apparatus set forth in claim 1 wherein said measurement signal is provided as a function of amplitude of energy received at the other of said transducers.

6. The apparatus set forth in claim 1 wherein said measurement signal is provided as a function of phase angle of energy received at the other of said transducers.

7. The apparatus set forth in claim 1 wherein said sensor means comprises a housing having said transducers mounted therewithin, means forming an air inlet and an air outlet in said housing, and fan means for drawing a test air sample through said inlet between said transducers and to said outlet.

8. The apparatus set forth in claim 1 wherein said sampling-and-storing means includes means for automatically sampling and storing said measurement signal at periodic intervals.

9. The apparatus set forth in claim 8 wherein said sampling-and-storing means includes operator switch means, and means responsive to actuation of said operator switch means for sampling and storing said measurement signal.

10. The apparatus set forth in claim 9 wherein said switch means comprises apparatus electrical power switch means, said actuation-responsive means being responsive to application of electrical power to said apparatus for automatically sampling and storing said measurement signal.

11. The apparatus set forth in claim 9

wherein said sampling-and-storing means comprises a sample-and-hold circuit including a capacitor for selectively storing said measurement signal, and analog switch means having a signal input coupled to said rectifier means, a signal output coupled to said sample-and-hold circuit, control inputs individually coupled to said switch means, to said means for automatically sampling at periodic intervals and to said decrease-responsive means, and an inhibit input coupled to said comparing means.

12. Apparatus for detecting contaminants in air comprising:

a sensor probe including a housing, a pair of ultrasonic transducers mounted within said housing at fixed positions spaced from each other, means forming an air inlet and an air outlet in said housing, a hollow base, a hollow flexible conduit connecting said housing outlet to said base, and a fan within said base for continuously drawing test air through said inlet, housing, conduit and base between said transducers, and

an elongated electronics enclosure including means for applying ultrasonic energy to one of said transducers and means responsive to energy received at the other of said transducers for determining contaminant level in said test air, means for removably affixing said base to said enclosure to form a unitary assembly, and means on said enclosure for indicating contaminant level to an operator.

13. Apparatus for detecting contaminants in air comprising:

a sensor probe including a housing, a pair of ultrasonic transducers mounted within said housing at fixed positions spaced from each other, means forming an air inlet and an air outlet in said housing, a hollow base, a hollow flexible conduit connecting said housing outlet to said base, and a fan within said base for continuously drawing test air through said inlet, housing, conduit and base between said transducers, and

an elongated electronics enclosure including means for applying ultrasonic energy to one of said transducers and means responsive to energy received at the other of said transducers for determining contaminant level in the test air, means for removably affixing said base to said enclosure to form a unitary assembly, and means on said enclosure for indicating contaminant level to an operator,

said base being of generally L-shaped construction and being removably affixed to said enclosure along one leg of said L-shaped construction with the other leg projecting along a side edge of said enclosure, said conduit and housing projecting from said other leg, said enclosure having an integral head of generally L-shaped construction opposed of said base, said head having a socket for removably receiving said housing inlet means when said base is affixed to said enclosure.

14. The apparatus set forth in claim 13 further comprising a multiple-conductor coiled cord connecting said electronics enclosure to said sensor probe.

15. The apparatus set forth in claim 14 wherein said electronics enclosure includes means for receiving batteries to power said apparatus.

16. The apparatus set forth in claim 15 wherein said electronics enclosure is constructed for holding lengthwise in an operator'"'"'s hand.

17. coupled to said switch means, to said means for automatically sampling at periodical intervals and to said decrease-responsive means, and an inhibit input coupled to said comparing means.

18. Apparatus for detecting presence of contaminants in air comprising:

sensor means including a spaced pair of radiant energy transducers, means for admitting a test air sample between said transducer, means for providing an electrical measurement signal as function of velocity of radiant energy between said transducers, means for selectively sampling and electrically storing said measurement signal, means for deriving a reference signal from a sampled and stored measurement signal, means for comparing said measurement signal to said reference signal and indicating an alarm condition when a difference between said reference and measurement signals exceeds a preselected threshold, and means responsive to a change in said measurement signal indicating a decrease in contaminants following an indication of an alarm condition for automatically resampling and storing said measurement signal as a new reference signal,

said means for providing said measurement signal comprising means responsive to phase angle between energies at said transducers; and

said signal-comparing means comprising means responsive to a decrease in measurement signal phase angle as compared with reference phase angle to indicate a said alarm condition, and being substantially independent of increase in said measurement signal phase angle and thereby independent of increase in humidity content between said transducers.

19. Apparatus for detecting presence of halogen gas in air comprising:

sensor probe means including a housing having a central axis, a pair of ultrasonic transducers having identical nominal design frequencies mounted at fixed positions coaxially within said housing with radiating surfaces spaced from each other axially of said housing by a distance between 1.0 and 1.5 times ultrasonic wavelength at said nominal design frequency, means forming an air inlet and an air outlet at axially opposed ends of said housing coaxially with said housing, and means for continually drawing test air through said housing between said transducers, and

an electronics package coupled to said probe and including means for applying ultrasonic energy to one of said transducers, and means responsive to ultrasonic energy received at the other of said transducers for indicating presence of halogen gas in air between said transducers,

said energy-responsive means comprising means responsive to a decrease in ultrasonic energy at said other of said transducers for indicating presence of halogen gas, while being substantially independent of increase in energy at said other of said transducers and thereby being substantially independent of humidity between said transducers.

20. Apparatus for detecting presence of halogen gas in air comprising:

sensor probe means including a housing having a central axis, a pair of ultrasonic transducers having identical nominal design frequencies mounted at fixed positions coaxially within said housing with radiating surfaces spaced from each other axially of said housing by a distance between 1.0 and 1.5 times ultrasonic wavelength at said nominal design frequency, means forming an air inlet and an air outlet at axially opposed ends of said housing coaxially with said housing, and means for continually drawing test air through said housing between said transducers, and

an electronics package coupled to said probe and including means for applying ultrasonic energy to one of said transducers, and means responsive to ultrasonic energy received at the other of said transducers for indicating presence of halogen gas in air between said transducers,

said transducers being externally peripherally engaged by said housing, and said inlet and outlet means including a pair of diametrically opposed axially extending grooves in said housing adjacent and external to each said transducer periphery, a first of said pair of grooves being positioned ninety degrees around said housing with respect to the other said pair.

21. The apparatus set forth in claim 20 wherein said one of said transducers is positioned within said housing adjacent to said inlet, and wherein said inlet-forming means includes a conical tip that tapers narrowingly from said housing to said inlet and is spaced from said one transducer to permit passage of that air therebetween.

22. Apparatus for detecting presence of halogen gas in air comprising:

sensor probe means including a housing having a central axis, a pair of ultrasonic transducers having identical nominal design frequencies mounted at fixed positions coaxially within said housing with radiating surfaces spaced from each other axially of said housing by a distance between 1.0 and 1.5 times ultrasonic wavelength at said nominal design frequency, means forming an air inlet and an air outlet at axially opposed ends of said housing coaxially with said housing, and means for continually drawing test air through said housing between said transducers, and

an electronics package coupled to said probe and including means for applying ultrasonic energy to one of said transducers, and means responsive to ultrasonic energy received at the other of said transducers for indicating presence of halogen gas in air between said transducers,

the entire said apparatus comprising an elongated enclosure contoured for holding in an operator'"'"'s hand, said sensor probe means comprising a base removably affixed to said enclosure, a fan within said base and a hollow flexible conduit connecting said base to said housing, test air being drawn by said fan through said probe housing, said conduit and thence into and discharged from said base, the remainder of said apparatus being contained within said enclosure and being connected to said sensor probe means by a multiple-conductor coiled cord.