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DRUG-FREE CALIBRATION SYSTEM FOR A VAPORIZER FLOWMETER

IP.com Disclosure Number: IPCOM000126272D
Publication Date: 2005-Jul-12
Document File: 4 page(s) / 176K

Publishing Venue

The IP.com Prior Art Database

Abstract

In an embodiment, a drug-free calibration system for a vaporizer flowmeter includes a laminar restriction made up of a number of plates and spacers. The geometry of the resulting flow passages is configured to ensure laminar flow of any media combination that may flow through the flowmeter. If certain gas properties are known for example, a viscosity of the media, the flowrate of the gas can be predicted with great accuracy by measuring pressure drop over a laminar flow restriction. Once the restriction is calibrated by a known media, for example oxygen, then the flowrate of any other media or mixtures of media can be predicted based on the knowledge of the viscosity of the media flowing through the flowmeter.

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DRUG-FREE CALIBRATION SYSTEM FOR A VAPORIZER FLOWMETER

FIELD OF THE INVENTION

[0001]               This invention relates generally, to vaporizer flowmeters, and more particularly to, systems for drug-free calibration for a flowmeter, used especially in an electronic vaporizer.

BACKGROUND OF THE INVENTION

[0002]               Generally, vaporizers are configured drug specific, having features that enable the vaporizers to be used implementing one drug only.  For example, drug specific filling devices allow only the vaporizer to be filled with the drug it is intended to deliver. Also, certain internal features may be optimized for the thermal characteristics of the drug or its intended concentration settings, e.g. the thermal compensation system.

[0003]               Vaporizers are conventionally calibrated and checked using the drug that the device is designed to deliver.  As such, in the manufacturing environment, special procedures are needed in handling the drug before it is used in the vaporizer, whilst delivering drug and after the calibration process is complete.  Also different characteristics of the drug require slight variations of certain parts leading to a larger number of variants than is ideal in a lean manufacturing system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004]                 FIG. 1 shows a perspective view of a flowmeter construction according to one embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION

[0005]                Various embodiments of this invention provide a system for drug-free calibration of a flowmeter used especially in an electronic vaporizer.

[0006]                In some embodiment, the invention utilizes laminar flow principles for a flowmeter design.  If certain gas properties are known for example, a viscosity of the media, the flowrate of the gas can be predicted with great accuracy by measuring pressure drop over a laminar flow restriction.  Once the restriction is calibrated by a known media, for example oxygen, then the flowrate of any other media or mixtures of media can be predicted based on the knowledge of the viscosity of the media flowing through the flowmeter.

[0007]               In a vaporizer application, there can be an infinite number of media combinations due to the variations of carrier gases (oxygen, nitrous oxide, air etc) and the drug that is being delivered.  Examples of drugs include Halothane, Enflurane, Isoflurane, Sevoflurane and Desflurane.  Additionally over temperature ranges, concentration of the drugs can vary by as mu...