Fluid handling – With indicator – register – recorder – alarm or inspection means – Fluid pressure responsive indicator – recorder or alarm
Reexamination Certificate
1999-02-08
2001-04-03
Chambers, A. Michael (Department: 3753)
Fluid handling
With indicator, register, recorder, alarm or inspection means
Fluid pressure responsive indicator, recorder or alarm
C137S552000, C116S070000, C128S202220
Reexamination Certificate
active
06209579
ABSTRACT:
TECHNICAL FIELD
The invention is directed to a low supply pressure alarm to notify the operator of gas supply depletion and preferably integrally housed together with a gas regulator, and flow controller.
BACKGROUND OF THE ART
Breathable gas is administered to patients during medical treatment and often in emergency situations. Breathable gas is provided from compressed sources through mobile cylinders. Such devices are typically used in trauma situations by hospital and ambulance crews, firefighters, military medics, and the like during life threatening emergencies.
The pressure of breathable gas in cylinders is much higher than the pressure at which the breathable gas is administered to patients. In order to regulate the gas pressure during medical treatment, a gas pressure regulator is placed on gas cylinders. If the supply of breathable gas is depleted, the patient may suffer and devices driven by the gas pressure may cease to operate.
It is crucial for the operator of such devices to monitor the supply of gas. In the case of gas cylinders, the regulator generally includes a cylinder contents gauge which visually indicates the pressure remaining within the cylinder.
The operator of such devices is generally preoccupied with administering medication or providing other medical treatment during such emergency situations. However, the operator must maintain monitoring of the gas supply pressure to ensure that the patient receives a sufficient breathable gas supply. In the case of emergency medical treatment, small sized cylinders are generally carried in bags or cases to the emergency site. The regulator and gas pressure gauge mounted thereon are often not readily visible. Unfortunately, the monitoring of gas supply is a matter that can be easily overlooked in the crisis of an emergency medical situation.
Therefore, it is desirable to provide a low pressure alarm which relieves the operator of the burden of checking the input supply pressure to the regulator and ensure the presence of gas supply.
It is also desirable to provide an audible alarm indication of gas supply depletion to relieve the operator of the necessity of visually checking the cylinder contents gauge during an emergency situation.
DISCLOSURE OF THE INVENTION
The invention provides an in-line low supply pressure alarm device preferably housed together with a gas pressure regulator and a gas flow controller, thereby eliminating the need for the operator to monitor gas availability.
The alarm device is designed to be inserted in-line and includes a hollow housing with a gas inlet, a gas outlet, and an elongate internal chamber. There is only one moving part to reduce wear and maintenance, as well as to improve reliability. The piston is spring loaded to the alarm-on position and switches to trigger a gas flow through the alarm when the input gas pressure falls below a selected minimum pressure. The residual pressure in the supply system is sufficient to drive the alarm for a reasonable period of time thereby warning the operator before the gas supply completely expires.
In a commercial embodiment, the alarm device is housed together with a regulator and flow controller in a compact combined housing. The provision of a low cost input pressure alarm as part of a regulator/controller improves operation and reliability of the system and permits the introduction of a price premium as an upgraded high level regulator.
The pressure sensing piston is disposed within the chamber for axial sliding between the alarm-on and an alarm-off position depending on the pressure of gas acting on the piston head. The piston head is sealed in sliding engagement with an actuating compartment of the chamber. The actuating compartment of the chamber is filled with pressurised gas in flow communication with the gas inlet in operation.
The piston includes an axially extending valve stem with a lateral alarm port in flow communication with the gas inlet. The valve stem is in sliding engagement with axially spaced apart seals defining an alarm plenum within the chamber. The alarm port of the valve stem is in flow communication with the alarm plenum when the piston is in the alarm-on position. A biasing spring engages the piston to bias the piston against the pressure of gas in the actuating compartment to the alarm-on position.
The low pressure alarm is activated by a gas activated alarm device in communication with the alarm plenum when low pressure is detected. Preferably the alarm port is aligned with a sealed compartment within the chamber when the piston is in the alarm-off position to eliminate any leakage of high pressure gas that could possibly trigger a false alarm.
Further details of the invention and its advantages will be apparent from the detailed description and drawing included below.
REFERENCES:
patent: 3224409 (1965-12-01), Femger
patent: 3611981 (1971-10-01), Warncke
patent: 3719160 (1973-03-01), Christianson
patent: 3785333 (1974-01-01), Warncke et al.
patent: 3811400 (1974-05-01), Smilg
patent: 4064899 (1977-12-01), Lehmann
patent: 4275723 (1981-06-01), Warncke et al.
patent: 4350115 (1982-09-01), Pasternack
patent: 5040477 (1991-08-01), Schiffmacher
patent: 5135023 (1992-08-01), Ross
patent: 36 02 724 A1 (1987-08-01), None
patent: 195 16 485 A1 (1996-11-01), None
patent: WO 99/13945 (1999-03-01), None
Bowden Kevin D. J.
Zauner Helmut F
Chambers A. Michael
Kusner Mark
McShane Thomas L.
O-Two Systems International Inc.
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