US3886801A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Decompression meter
Assignee: National Research Development Corp UK
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Filing: 1973-10-30
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Granted: 1975-06-03
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Expires: 1993-10-30
Abstract
Abstract A decompression meter for a diver or a caisson worker to indicate when it is safe to continue decompression during a superatmospheric excursion, comprising means for providing an analogue of the absorption of an inert gas such as nitrogen in solution as tissue around a capillary with varying ambient total pressure and for integrating the rate of absorption and depression with respect to time to indicate when the total volume of gas absorbed will be in excess of a tolerable value beyond which the onset of decompression sickness is likely.
Inventors
- 👤 Brian Andrew Hills
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:16
CPC Classifications
B; B63; B63C; B63C11/00; B63C11/02; B63C11/32; G; G01; G01C; G01C13/00; G01C13/008
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
285 words
A decompression meter as hereinbefore defined, comprising: a. first means responsive to the ambient total pressure for generating a first liquid pressure signal; b. second means responsive to the ambient total pressure for generating a varying second liquid pressure signal which represents the solution pressure of oxygen and nitrogen in body tissue and has a value representative of the local partial pressure of a dissolved gas in capillary blood and a rate of change proportional to said ambient total pressure for simulating gradual absorption of a gas in solution in body tissue, said second means comprising analogue means for simulating gradual absorption of oxygen and nitrogen in solution in body tissue at various radially successive concentric annuli of body tissue around a capillary blood vessel; c. third means responsive to said first and second liquid pressure signals for sensing in the analogue of each of said annuli a condition of excess of the value of said second signal over the value of said first signal; and d. fourth means responsive to said excess condition to simulate liberation of a dissolved gas as gaseous phase in body tissue and for generating a third signal to indicate the presence of said gaseous phase, said fourth means being constructed to sense excess over said first signal of a predetermined fraction of the second signal which fraction corresponds to the partial pressure of nitrogen in solution in the body tissue as a fraction of the total solution pressure of oxygen and nitrogen in the tissue; e. said third means being adapted to sense local excess of said predetermined fraction of said second liquid pressure signal in the analogue of each of said radially successive annuli over said first signal.
Claim 2
Dependent Claim
285 words
A decompression meter as hereinbefore defined, comprising: a. first means responsive to the ambient total pressure for generating a first liquid pressure signal; b. second means responsive to the ambient total pressure for generating a varying second liquid pressure signal which represents the solution pressure of oxygen and nitrogen in body tissue and has a value representative of the local partial pressure of a dissolved gas in capillary blood and a rate of change proportional to said ambient total pressure for simulating gradual absorption of a gas in solution in body tissue, said second means comprising analogue means for simulating gradual absorption of oxygen and nitrogen in solution in body tissue at various radially successive concentric annuli of body tissue around a capillary blood vessel; c. third means responsive to said first and second liquid pressure signals for sensing in the analogue of each of said annuli a condition of excess of the value of said second signal over the value of said first signal; and d. fourth means responsive to said excess condition to simulate liberation of a dissolved gas as gaseous phase in body tissue and for generating a third signal to indicate the presence of said gaseous phase, said fourth means being constructed to sense excess over said first signal of a predetermined fraction of the second signal which fraction corresponds to the partial pressure of nitrogen in solution in the body tissue as a fraction of the total solution pressure of oxygen and nitrogen in the tissue; e. said third means being adapted to sense local excess of said predetermined fraction of said second liquid pressure signal in the analogue of each of said radially successive annuli over said first signal.
Claim 3
Dependent Claim
285 words
A decompression meter as hereinbefore defined, comprising: a. first means responsive to the ambient total pressure for generating a first liquid pressure signal; b. second means responsive to the ambient total pressure for generating a varying second liquid pressure signal which represents the solution pressure of oxygen and nitrogen in body tissue and has a value representative of the local partial pressure of a dissolved gas in capillary blood and a rate of change proportional to said ambient total pressure for simulating gradual absorption of a gas in solution in body tissue, said second means comprising analogue means for simulating gradual absorption of oxygen and nitrogen in solution in body tissue at various radially successive concentric annuli of body tissue around a capillary blood vessel; c. third means responsive to said first and second liquid pressure signals for sensing in the analogue of each of said annuli a condition of excess of the value of said second signal over the value of said first signal; and d. fourth means responsive to said excess condition to simulate liberation of a dissolved gas as gaseous phase in body tissue and for generating a third signal to indicate the presence of said gaseous phase, said fourth means being constructed to sense excess over said first signal of a predetermined fraction of the second signal which fraction corresponds to the partial pressure of nitrogen in solution in the body tissue as a fraction of the total solution pressure of oxygen and nitrogen in the tissue; e. said third means being adapted to sense local excess of said predetermined fraction of said second liquid pressure signal in the analogue of each of said radially successive annuli over said first signal.
Claim 4
Dependent Claim
285 words
A decompression meter as hereinbefore defined, comprising: a. first means responsive to the ambient total pressure for generating a first liquid pressure signal; b. second means responsive to the ambient total pressure for generating a varying second liquid pressure signal which represents the solution pressure of oxygen and nitrogen in body tissue and has a value representative of the local partial pressure of a dissolved gas in capillary blood and a rate of change proportional to said ambient total pressure for simulating gradual absorption of a gas in solution in body tissue, said second means comprising analogue means for simulating gradual absorption of oxygen and nitrogen in solution in body tissue at various radially successive concentric annuli of body tissue around a capillary blood vessel; c. third means responsive to said first and second liquid pressure signals for sensing in the analogue of each of said annuli a condition of excess of the value of said second signal over the value of said first signal; and d. fourth means responsive to said excess condition to simulate liberation of a dissolved gas as gaseous phase in body tissue and for generating a third signal to indicate the presence of said gaseous phase, said fourth means being constructed to sense excess over said first signal of a predetermined fraction of the second signal which fraction corresponds to the partial pressure of nitrogen in solution in the body tissue as a fraction of the total solution pressure of oxygen and nitrogen in the tissue; e. said third means being adapted to sense local excess of said predetermined fraction of said second liquid pressure signal in the analogue of each of said radially successive annuli over said first signal.
Claim 5
Dependent Claim
26 words
A decompression meter as set forth in claim 1, wherein said means for generating a third signal includes indicator means to warn against immediate further decompression.
Claim 6
Dependent Claim
60 words
A decompression meter as set forth in claim 1, wherein said third signal indicates the liberation of gaseous phase upon excess of said predetermined fraction of the second signal over said first signal, and said fourth means integrates said third signal with respect to time to provide a measure of the total volume of gaseous phase liberated in the tissue.
Claim 7
Dependent Claim
107 words
A decompression meter as set forth in claim 1 wherein said radially successive annuli have equal radial depths and said means for simulating gradual absorption of gas in a plurality of radially successive annuli of body tissue around a blood vessel comprise a plurality of individual simulating units connected in series so that said first liquid pressure signal is fed to a first unit of the series to cause in that simulating unit a build-up of pressure which is in turn supplied to the second simulating unit, and each successive simulating unit is fed with a signal responsive to the pressure built up in a preceding unit.
Claim 8
Dependent Claim
70 words
A decompression meter as set forth in claim 4, wherein each gas absorption simulating unit consists of a liquid-filled chamber, a calibrated orifice to said chamber, and resiliently deformable means for allowing increase of the liquid volume in said chamber with increasing resistance to pressure build-up in proportion to the existing pressure build-up, thereby simulating the gradual approach of the concentration of solution in the tissue to a saturation condition.
Claim 9
Dependent Claim
53 words
A decompression meter as set forth in claim 5, wherein said third means comprises a porous wall portion to said chamber; a liquid impermeable diaphragm covering said chamber wall portion externally, and means subjecting the exterior of said diaphragm to a liquid whose pressure is directly proportional to the said first liquid signal.
Claim 10
Dependent Claim
67 words
A decompression meter as set forth in claim 6, wherein the pressure of the liquid in contact with the outer side of each diaphragm is in excess of the said first liquid pressure signal and bears a fixed relationship with the first liquid pressure signal in proportion to the ratio of the total ambient pressure of air to the partial pressure of inert gas in that air.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-02 | 1978-12-02 | 1979-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-02 | 1982-12-02 | 1983-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-02 | 1986-12-02 | 1987-06-03 | $7700.00 | Window Closed / Lapsed |