GB2136703A - Apparatus for supplying a mixture of gases - Google Patents

Apparatus for supplying a mixture of gases Download PDF

Info

Publication number
GB2136703A
GB2136703A GB08405412A GB8405412A GB2136703A GB 2136703 A GB2136703 A GB 2136703A GB 08405412 A GB08405412 A GB 08405412A GB 8405412 A GB8405412 A GB 8405412A GB 2136703 A GB2136703 A GB 2136703A
Authority
GB
United Kingdom
Prior art keywords
valve
gas
gases
mixture
gear
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08405412A
Other versions
GB2136703B (en
GB8405412D0 (en
Inventor
Horst Frankenberger
Lothar Kleinschmidt
Winfried Kimmig
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Draegerwerk AG and Co KGaA
Original Assignee
Draegerwerk AG and Co KGaA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Draegerwerk AG and Co KGaA filed Critical Draegerwerk AG and Co KGaA
Publication of GB8405412D0 publication Critical patent/GB8405412D0/en
Publication of GB2136703A publication Critical patent/GB2136703A/en
Application granted granted Critical
Publication of GB2136703B publication Critical patent/GB2136703B/en
Expired legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
    • A61M16/10—Preparation of respiratory gases or vapours
    • A61M16/104—Preparation of respiratory gases or vapours specially adapted for anaesthetics
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/10—Mixing gases with gases
    • B01F23/19—Mixing systems, i.e. flow charts or diagrams; Arrangements, e.g. comprising controlling means

Landscapes

  • Health & Medical Sciences (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Emergency Medicine (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • Engineering & Computer Science (AREA)
  • Anesthesiology (AREA)
  • Biomedical Technology (AREA)
  • Chemical & Material Sciences (AREA)
  • Hematology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Pulmonology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Accessories For Mixers (AREA)
  • Control Of Non-Electrical Variables (AREA)
  • Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)
  • Measuring Volume Flow (AREA)

Abstract

The apparatus comprises supply lines (4,6) brought together to form a mixed gas line (7). Adjustable valves (1, 9) are connected by way of a gear unit (13) in such a way that they are opened or closed in the same direction when actuated, the gear ratio of the spur gears (15, 17) determining the mixture ratio of the gases. When used to supply an anaesthetic to a patient, the gases may be N2O and O2. The O2 valve (9) may be by-passed by an O2 line (11) which comprises a valve (12), and by opening this valve, the O2 content in the respiratory gas can be increased, the minimum proportion of O2 in the mixture still, however, being determined by the gear ratio. Thus a minimum concentration of oxygen in the respiratory gas is always obtained and above the minimum concentration the mixture ratio can be independently adjusted. <IMAGE>

Description

SPECIFICATION Apparatus for supplying a mixture of gases The invention relates to an apparatus for supplying a mixture of gases.
A patient's respiratory circulatory system is supplied with oxygen and an anaesthetic gas by way of a gas dosing apparatus. Such an apparatus must guarantee that throughout the whole possible range of adjustment of the ratio of gases there is always at least a minimum supply of oxygen. In other words, a situation where the oxygen falls below a minimum concentration in the respiratory gas must be prevented from arising.
A known dosing apparatus is disclosed in German Auslegeschrift No. 22 25 683. This apparatus is used in an anaesthesia apparatus for the purpose of producing a continouslyflowing gas mixture in a mixing line, and comprises two pressure regulators each connected to a respective gas source. A control pressure is supplied to the regulators from an in-feed pressure regulator. The apparatus further comprises a proportioning device, which affects the gases which are to be mixed in opposite directions in respect of each other, and a flow meter disposed in each individual gas line between the pressure regulator and the mixing line.
As the pressure regulators are controlled by the control pressure in such a way that the same pressure constantly prevails in their outlet lines, the gases are fed to the proportioning device at the same pressure. A constant flow quantity is thereby obtained in the mixing line irrespective of the adjustment of the proportioning device. The total flow quantity is dependent on the control pressure which is adjusted at the in-feed pressure regulator.
In addition to the fact that it is not easy to regulate the total quantity of respiratory air by means of the pressure, it is difficult to prevent the oxygen quota from falling below a minimum percentage value.
A known anaesthesia device is disclosed in German Offenlegungsschrift No. 30 38 563. This device has a proportionally limiting control system, the device receiving separate supplies of oxygen and N2O and giving off a mixture of the two gases for anaesthetic purposes. The relative proportion of the individual gases in the mixture given off can be varied selectively, and a locking system can prevent itfrom being possible for certain mixture ranges to be unintentionally obtained by the user.
The system comprises flow meters for the individual flows of 02 and N2O and individual needle valves which can be adjusted for the purpose of controlling the flow of the individual gases in such a way that the relative proportion ofthe individual gases is obtained. A safety system connects the needle valves in such a way that the opening or closing movement of each individual valve is affected or restricted by movement of the other valve; for example, they may be connected in such a way that the oxygen needle valve can be opened without hindrence, yet, when the N2O valve is open and the oxygen valve is caused to close resistance is met. The connection between the two valves is a chain connection which forcedly connects pinions on rotatable valve shafts.As a result one pinion is mounted in a fixed manner on the valve shaft and the other is movably mounted on its valve shaft within predetermined limits of motion. When the one valve is actuated, the other will carry out the same action after a certain amount of delay.
The above device is expensive in terms of mechanics and requires corresponding handling and maintenance.
A further apparatus for controlling the gas ratio for anaesthesia apparatus is known from European Publication No. 0039932. This apparatus monitors the oxygen quota in the gas mixture by means of a differential pressure absorber. The oxygen and the N2O are fed to the anaesthesia apparatus via a collecting line of the gas mixture by way of individual lines having adjusting valves, throttles and flow meters. The adjusting valves can be adjusted by hand in orderto determine the gas flow.
The proportion of oxygen in the collecting line is monitored by comparing the oxygen pressure from the flow of the oxygen through the throttle in the 02 line with the N2O gas pressure from the flow of N2O gas through the throttle in the N2O line. The difference in pressure is determined in membrane groups which are acted upon by the gas pressures. A connecting piece between the membrane groups, which piece is moved with these, acts upon a flow controller in which a valve in the N2O line is opened or closed accordingly. With, for example, a limiting value of 25% 2 in the anaesthetic gas, the force exerted by the individual 2 pressure on the membrane outweighs the force exerted by the N2O gas on its membrane so that the connecting piece opens the valve in the N2O line and N2O gas can flow.With the ensuing increase in the pressure of the N20 gas upstream of the throttle the differential pressure absorber reequalizes.
The above-mentioned dosing apparatus for anaesthesia apparatus require a complicated form of construction and thus become correspondingly expensive to use and also to monitor and to maintain.
In accordance with the present invention there is provided an apparatus, for supply a mixture of gases, comprising: first and second gas supply lines for supplying first and second gases respectively; first and second adjustable valves disposed in the first and second supply lines respectively; a third gas line for supplying the mixture, in communication with the first and second gas supply lines downstream of the valves; and means for adjusting the valves comprising a gear system which includes a first gear for adjusting the first valve, a second gear for adjusting the second valve and an intermediate gear which engages the first and second gears so that the first and second gears turn in the same direction to adjust the first and second valves respectively, the relative degrees of adjustment of the valves being dependent on the gear ratio of the gear system.
Preferably one of the first and second gears is provided with a projection by means of which it can be turned, thereby causing the other of the first and second gears to turn. In this case, the first gas may be oxygen and the second gas may be nitrous oxide, the second gear wheel being provided with the projection.
The apparatus may further comprise a by-pass line in communication with the first gas supply line upstream and downstream of the first adjustable valve, the by-pass line including a control valve.
In one embodiment, the gear ratio is 1:1, the first and second adjustable valves having seat crosssections dimensioned in respect of one another according to a desired ratio of the first and second gases in the mixture. This embodiment is useful if the valves are different for the types of gases, and results in a simple gear system which is insensitive to insulating defects. A similar result could be obtained by the gradients of valve spindles of the first and second valves being dimensioned in the desired ratio, instead of the seat cross-sections.
It is possible for first and second flow meters to be arranged in the first and second supply lines respectively, downstream of the adjustable valve in each supply line. In this way it is possible to monitor the flow-rates of each of the first and second gases. As an alternative, a flow meter may be arranged in the by-pass line, downstream of the control valve, with a further flow meter being arranged in the third gas line for monitoring the flow-rate of the mixture of gases. In this case it is possible to take a reading of the total mixed gas flow, with the gases in the desired ratio and without the oxygen flowing in the by-pass line. The choice between the two arrangements depends on the prospective use of the apparatus.
Thus, in an embodiment of the present invention, the gear system has: an anaesthetic gas spur gear, which actuates the anaesthetic gas control valve and which has an adjusting knob; and an 2 spur gear, which is interlocked with the anaesthetic gas spur gear by way of an intermediate spur gear and which actuates the 2 control valve, the gear ratio of which gears is selected according to the chosen anaesthetic gas /02 ratio, and the 2 control valve is by-passed by an 2 line, which includes an 2 control valve.
Through choice of various sizes of spur gears, it can be arranged that, even with the smallest opening of the N2O/O2 valves, the necessary opening for guaranteeing a particular 2 quota in the respiratory gas is ensured, this quota being that necessary for respiration. The circumference of the valve openings ensures the necessary quantity of respiratory gas when there is a minimum quota of 2 which is to remain the same. The fine-control valve in the by-pass line can only allow the 2 content to increase: when it closes, the latter drops to, at the very least, the quota determined by the gear ratio.
For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 diagrammatically shows an apparatus in accordance with an embodiment of the present invention; Figure 2 shows a suitable gear unit; and Figures shows an apparatus in accordance with another embodiment of the present invention.
In Figure 1, an N2O control valve 1 is connected to an N2O supply 2. An N20 flow meter3 is disposed downstream of the N2O valve 1 in an N20 supply line 4, which is connected with an 2 supply line 6 at junction 5 to form a mixed gas supply line 7.
An 2 supply 8 is connected to the 2 supply line 6 in which is disposed an 2 control valve 9 with an 2 flow meter 10 downstream thereof. The 2 control valve 9 is by-passed by an 2 line 11 which includes an 02 fine-control valve 12.
The 2 control valve 9 and the N2O control valve 1 are forcedly coupled with each other by way of a gear unit 13. The gear unit 13 comprises an N2O spur gear14, an spur gear 16 and an O2spurgear 17 (Figure 2). The gear 14 is connected to the N2O control valve 1 and has an adjusting knob 15 for controlling the quantity of mixed gas, and the gear 17 is connected to the 2 control valve 9. The gear ratio of the two spur gears 14 and 17, which are connected by way of the intermediate spur gear 16, produces the mixture ratio N2O/O2. For example, a ratio of 25% by volume of 2 can be selected.
Different degrees of opening of the control valves are controlled by the adjusting knob 15 to produce the desired quantities of gas having a mixture ratio which is determined by the gear ratio.
Independent actuation of the 2 fine-control valve 12 can in addition allow a desired quantity of 2 to flow into the supply line 7 to increase the 2 concentration. If control valves 1 and 9 are closed, a 100% 2 concentration can be reached.
The individual gas flow quantities in the supply lines 4 and 6 are measured by the N2O flow meter 3 and the 2 flow meter 10 respectively which may be read.
In the embodiment according to Figure 3 the N2O control valve 1, which is arranged in the N20 supply line 18, is connected with the N20 supply 2. The 2 control valve 9 is arranged in the 2 supply line 19 and is connected with the 2 supply 8. The control valves 1,9 are forcedly coupled with each other by way of the gear unit 13. The N2O supply line 18 and the O2supply line 19 are brought together at junction 20 to form a supply line 21 for mixed gas having a mixture ratio which is determined by the gearing of the gear unit 13. A mixed gas flow meter 22 is arranged in the supply line 21.
The 2 control valve 9 is by-passed by an 2 line 11 which includes the 2 fine-control valve 12 and the 2 flow meter 10. At junction 23 the 2 line 11 is connected with the supply line 21 to form the mixed gas line 7.
In this embodiment the 02 flow meter 10 indicates the flow quantity of additional oxygen and the mixed gas flow meter 22 indicates the flow quantity of mixed gas of the standard composition, which, when the 2 fine-control valve 12 is closed, is also the total flow quantity of mixed gas.

Claims (8)

1. An apparatus, for supplying a mixture of gases, comprising: first and second gas supply lines for supplying first and second gases respectively; first and second adjustable valves disposed in the first and second supply lines respectively; a third gas line for supplying the mixture, in communication with the first and second gas supply lines downstream of the valve; and means for adjusting the valves comprising a gear system which includes a first gear for adjusting the first valve, a second gear for adjusting the second valve and an intermediate gear which engages the first and second gears so that the first and second gears turn in the same direction to adjust the first and second valves respectively, the relative degrees of adjustment of the valves being dependent on the gear ratio of the gear system.
2. An apparatus as claimed in claim 1, wherein one of the first and second gears is provided with a projection by means of which it can be turned, thereby causing the other of the first and second gears to turn.
3. An apparatus as claimed in claim 2, wherein the first gas is oxygen and the second gas is nitrous oxide, the second gearwheel being provided with the projection.
4. An apparatus as claimed in claim 3, wherein a by-pass line is in communication with the first gas supply line upstream and downstream of the first adjustable valve, the by-pass line including a control valve.
5. An apparatus as claimed in any preceding claim, wherein the gear ratio is 1:1, the first and second adjustable valves having seat cross-sections dimensioned in respect of one another according to a desired ratio of the first and second gases in the mixture.
6. An apparatus as claimed in any preceding claim, wherein first and second flow meters are arranged in the first and second supply lines respectively, downstream of the adjustable valve in each supply line.
7. An apparatus as claimed in claim 4, or in claims 4 and 5, wherein a flow meter is arranged in the by-pass line, downstream of the control valve, and a further flow meter is arranged in the third gas line for monitoring the flow-rate of the mixture of gases.
8. An apparatus for supplying a mixture of gases substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.
GB08405412A 1983-03-25 1984-03-01 Apparatus for supplying a mixture of gases Expired GB2136703B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19833310858 DE3310858A1 (en) 1983-03-25 1983-03-25 GAS DOSING DEVICE FOR ANESTHESIC EQUIPMENT

Publications (3)

Publication Number Publication Date
GB8405412D0 GB8405412D0 (en) 1984-04-04
GB2136703A true GB2136703A (en) 1984-09-26
GB2136703B GB2136703B (en) 1986-09-03

Family

ID=6194605

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08405412A Expired GB2136703B (en) 1983-03-25 1984-03-01 Apparatus for supplying a mixture of gases

Country Status (5)

Country Link
JP (1) JPS59174164A (en)
CH (1) CH662738A5 (en)
DE (1) DE3310858A1 (en)
FR (1) FR2543002B1 (en)
GB (1) GB2136703B (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4972831A (en) * 1988-03-30 1990-11-27 Dragerwerk Aktiengesellschaft Gas ratio controlling device for anesthetic appliances
EP0569247A2 (en) 1992-05-07 1993-11-10 Instrumentarium Corporation Apparatus and method for mixing gases
US5335652A (en) * 1991-04-06 1994-08-09 Dragerwerk Aktiengesellschaft Gas ratio control device for anesthetic apparatus
GB2309911A (en) * 1996-02-09 1997-08-13 Toshiharu Ando Flow adjusting valve for anaesthetic device
US5722449A (en) * 1994-05-06 1998-03-03 Instrumentarium Oy Arrangement in connection with a gas mixer
US6857443B2 (en) * 2003-02-24 2005-02-22 George A. Volgyesi Electronic gas blender and gas flow control mechanism therefor

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3707942A1 (en) * 1987-03-12 1988-09-22 Draegerwerk Ag GAS DOSING DEVICE, IN PARTICULAR FOR MEDICAL APPARATUS
JPH0481870U (en) * 1990-11-28 1992-07-16

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB296063A (en) * 1927-08-24 1929-08-29 Ig Farbenindustrie Ag Improved device for regulating the quantity and composition of a gas mixture
GB329370A (en) * 1929-02-16 1930-05-16 Cecil Featherstone Hammond Improvements in and connected with valves
GB1429435A (en) * 1973-02-07 1976-03-24 Jungner Instrument Ab Mixing devices for gases
DE3038563A1 (en) * 1979-10-19 1981-04-30 Airco, Inc., Murray Hill, N. J. Anesthesia device with proportional limitation control system

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR773898A (en) * 1933-08-24 1934-11-27 General anesthesia machine
DE1931354C3 (en) * 1969-06-20 1974-10-24 Draegerwerk Ag, 2400 Luebeck Method for mixing gases and gas mixing device for gases, in particular for breathing and medical devices
DE1932141C3 (en) * 1969-06-25 1974-11-28 Draegerwerk Ag, 2400 Luebeck Method for mixing compressed gases, in particular for breathing and medical devices
DE1941669C3 (en) * 1969-08-16 1979-04-19 Draegerwerk Ag, 2400 Luebeck Device for mixing gases
SE342145B (en) * 1970-06-16 1972-01-31 Lkb Medical Ab
US3739799A (en) * 1971-09-07 1973-06-19 Fraser Sweatman Continuous flow anesthesia apparatus
DE2945575A1 (en) * 1979-11-10 1981-05-27 Drägerwerk AG, 2400 Lübeck FRESH GAS DEVICE WITH MIXER FOR MEDICAL AND VENTILATORS
US4328823A (en) * 1980-05-14 1982-05-11 N.A.D. Inc. Oxygen flow ratio controller for anesthesia apparatus
JPS5995055A (en) * 1982-11-24 1984-05-31 シチズン時計株式会社 Nitrous oxide sucking tranquilizer

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB296063A (en) * 1927-08-24 1929-08-29 Ig Farbenindustrie Ag Improved device for regulating the quantity and composition of a gas mixture
GB329370A (en) * 1929-02-16 1930-05-16 Cecil Featherstone Hammond Improvements in and connected with valves
GB1429435A (en) * 1973-02-07 1976-03-24 Jungner Instrument Ab Mixing devices for gases
DE3038563A1 (en) * 1979-10-19 1981-04-30 Airco, Inc., Murray Hill, N. J. Anesthesia device with proportional limitation control system
GB2061745A (en) * 1979-10-19 1981-05-20 Airco Inc Anaesthesia machine having proportion limiting control system

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4972831A (en) * 1988-03-30 1990-11-27 Dragerwerk Aktiengesellschaft Gas ratio controlling device for anesthetic appliances
US5335652A (en) * 1991-04-06 1994-08-09 Dragerwerk Aktiengesellschaft Gas ratio control device for anesthetic apparatus
EP0569247A2 (en) 1992-05-07 1993-11-10 Instrumentarium Corporation Apparatus and method for mixing gases
EP0569247A3 (en) * 1992-05-07 1994-06-08 Instrumentarium Corp Apparatus and method for mixing gases
US5435332A (en) * 1992-05-07 1995-07-25 Instrumentarium Corp. Apparatus and method for mixing together gases flowing in different channels
US5722449A (en) * 1994-05-06 1998-03-03 Instrumentarium Oy Arrangement in connection with a gas mixer
GB2309911A (en) * 1996-02-09 1997-08-13 Toshiharu Ando Flow adjusting valve for anaesthetic device
US5755220A (en) * 1996-02-09 1998-05-26 Ando; Toshiharu Flow adjusting valve for anesthetic device
GB2309911B (en) * 1996-02-09 1999-07-07 Toshiharu Ando Flow adjusting valve for anesthetic device
US6857443B2 (en) * 2003-02-24 2005-02-22 George A. Volgyesi Electronic gas blender and gas flow control mechanism therefor

Also Published As

Publication number Publication date
GB2136703B (en) 1986-09-03
DE3310858C2 (en) 1990-09-06
FR2543002A1 (en) 1984-09-28
JPS59174164A (en) 1984-10-02
JPS6366B2 (en) 1988-01-05
DE3310858A1 (en) 1984-09-27
FR2543002B1 (en) 1987-07-24
GB8405412D0 (en) 1984-04-04
CH662738A5 (en) 1987-10-30

Similar Documents

Publication Publication Date Title
EP0691137B1 (en) Gas mixing devices for resuscitation/lung ventilation apparatus
DE69424386T2 (en) Nitric oxide feed system
DE3586895T2 (en) VENTILATION SYSTEM.
DE69314513T2 (en) Flow control of a pressurized gas
DE69110785T2 (en) Anesthetic vaporizer.
US4023587A (en) Method and apparatus for mixing two gases in a predetermined proportion
US4546794A (en) Gas mixing apparatus
US4266573A (en) Anesthesia machine having proportion limiting control system
US3809109A (en) Method and apparatus for mixing gases under pressure particularly for respirators and medical devices
DE2225683A1 (en) CONTINUOUS FLOW ANARCOTISING DEVICE
CH649714A5 (en) DEVICE FOR SUPPORTING BREATHABLE AND / OR ARTIFICIAL VENTILATION VARIABLE IN THE BREATH RHYTHM.
DE2552148A1 (en) TODDLER AND YOUTH VOLUME BREATHERS
DE3010014A1 (en) DEVICE FOR ADJUSTING THE COMBUSTION AIR FLOW FOR COMBUSTION GAS CONSUMERS
DE19648269A1 (en) Low pressure vaporisation method for medical narcotic fluid for patient respiration device
EP0685238B1 (en) Gas mixer
US4015617A (en) Analgesic apparatus
US4313436A (en) Fresh gas device with mixer for medical and respiration apparatus
GB2136703A (en) Apparatus for supplying a mixture of gases
US5335652A (en) Gas ratio control device for anesthetic apparatus
SE503291C2 (en) Gas preparation system for an anesthetic device
US5435332A (en) Apparatus and method for mixing together gases flowing in different channels
US3848617A (en) Means for maintaining a fixed flow through a breathing regulator in an inhalation system
US3762427A (en) Method and apparatus for mixing pressure gases particularly for respirators and medical apparatus
GB2216807A (en) Gas-ratio control device for an anaesthetising apparatus
GB1571023A (en) Gas mixing apparatus

Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee