US2469434A

US2469434A - Apparatus and method for filling gas storage cylinders

Info

Publication number: US2469434A
Application number: US474368A
Authority: US
Inventors: Odd A Hansen; George H Smith
Original assignee: Linde Air Products Co
Current assignee: Linde Air Products Co
Priority date: 1943-02-01
Filing date: 1943-02-01
Publication date: 1949-05-10
Anticipated expiration: 1966-05-10
Also published as: GB584920A

Description

May 10, 1949. O HANSEN ETAL 2,469,434

APPARATUS AND METHOD FOR FILLING GAS STORAGE CYLINDERS Filed Feb. 1, 1945 2 Sheets-Sheet l INVENTORS ODD A. HANSEN GEORGE H. SMITH M QRSM y 949. o. A. HANSEN ETAL 2,469,434

APPARATUS AND METHOD FOR FILLING GAS STORAGE CYLINDERS Filed Feb. 1, 1943 2 Sheets-Sheet 2 INVENTORS ODD A. HANSEN GEORGE H. SMITH Patented May 10, 1949 APPARATUS AND METHOD FOR FILLING GAS STORAGE CYLINDERS Odd A. Hansen and George H. Smith, Kenmore,

N. Y., assignors to The Linde Air Products Company, a corporation of Ohio' Application February 1, 1943, Serial No. 474,368

Claims. 1

This invention relates to apparatus and method for filling gas storage containers and more particularly to continuously operated systems for first evacuating and then charging gas storage cylinders in a predetermined cycle.

The main objects of the invention are to provide an improved speedy method of filling gas storage cylinders with valuable gas material such as oxygen, nitrogen, hydrogen, argon or the like;

. to provide inexpensive and highly efificient mobile equipment for evacuating and charging gas storage cylinders with valuable gas material transported in the liquid phase, for example, by said equipment; and to provide a novel method of and means for transporting liquid oxygen and evacuating and charging gas storage cylinders with such oxygen in the gas phase, which eliminates the delay and expense heretofore involved in the shipment of empty gas storage containers from a warehouse to an oxygen producing plant for. charging and subsequent shipment of the filled containers back to the warehouse.

According to the invention, there is provided a mobile unit comprising a transport truck having means, such as a tail-gate, adapted to provide a temporary station for gas storage containers which are to be evacuated and filled with valuable gas material, such as oxygen in the gas phase. Mounted on the truck is suitable equipment for first evacuating andthen charging the containers at the temporary station with such gas material in the gas phase from a source such as a container of such gas material in the liquid phase, which source is also mounted on the truck together with the necessary apparatus for converting such gas material from the liquid to the gas phase. Such equipment also includes a rack or manifold adapted to be suitably positioned with respect to the temporary station for connection to the gas storage containers. The tailgate and rack are adapted to be moved back into normal position with respect to the transport truck when not in use for evacuating and filling gas storage containers, to provide a mobile unit that is safe, neat and compact.

Such apparatus for first evacuating and then charging gas storage cylinders with the valuable or precious gas material preferably comprises a vacuum pump connected through a valve'to the manifold. Connected to the liquid container is a liquid pump and a vaporizing device which is connected to the manifold through another valve. An automatic pressure actuated shut-off valve is also disposed in the connection between the vaporizing device and the manifold. In order to prevent an excessive rise of pressure by the pump continuing to operate when the shut-off valve Y a pluralityof racks or manifolds through each of which at least one gas storage cylinder is adapted to be evacuated and charged with oxygen, for example, in the gas phase. These manifoldsare connected through suitable valves to a single vacuum pump and to a single liquid oxygen pump and vaporizing device, which valves are opened and closed by common control means in sequence so that gas storage cylinders connected to each manifold are first evacuated and then charged with oxygen in the gas phase in a cycle moving from a one manifold to another, whereby the charged cylinders connected to each rack may, in turn, be replaced with empty cylinders while gas storage cylinders connected to the other racks are being evacuated and charged with oxygen in the gas phase.

The novel method of filling gas storage cylinders in accordance with the invention is set forth in detail below. In general, the aim of such method is to maintain the apparatus in continuous and efficient operation and to keep a man busy in changing charged cylinders with empty ones during the period required to fill a given number of empty cylinders.

Referring to the drawings:

Fig. 1 is a view in side elevation of a mobile unit exemplifying the invention, in operation in filling gas storage cylinders;

Fig. 2 is a plan view of the mobile unit shown in Fig. 1;

Fig. 3 is a simplified schematic flow diagram of the gas storage cylinder filling system shown in Figs. 1 and 2;

- Fig. 4 is a fragmentary View similar to Fig. l of a modification;

Fig. 5 is a fragmentary view similar to Fig. 2 of the modification shown in Fig. 4;

Fig. 6 is a simplified schematic flow diagram of the three-rack two-cylinder systems shown in Figs. 4 and 5; and

Fig. 7 is a schematic flow diagram of a tworack four-cylinder system illustrating a preferred form of the invention.

In the past, warehouses have been supplied with oxygen "in the gas phase in full cylinders from a producing plant, the shipment generally being made by rail or truck freight. The empty cylinders at the warehousewere returned to the producing plant for refilling and such repairs as might be necessary. Such arrangement entails considerable freight exepnse because the cylinders are heavy compared to the contents and freight must be paid on the shipment both ways. he high cost of freight shipment incurred in the distribution of oxygen in gas storage cylinders points toward the advisability of supplying the warehouses with oxygen which is transported in the liquid phase and converted to the gas phase for filling gas storage cylinders by means of inexpensive equipment.

The factory practice is not adapted for handling only a few cylinders in a speedy and economical manner. Precautions are taken at the factory to fill the cylinders with a predetermined precise amount of gas not in excess of the amount allowed by the Interstate Commerce Commission regulations. For example, when the cylinders being charged are nearly filled it has been cus-- tomary to make an estimate of the overall charging time. The room temperature is taken and a chart is consulted to determine what the final pressure should be for the given filling time and temperature. Shortly before the final pressure has been obtained, the overall pumping time is re-estimated and the room temperature ascertained again and any errors in the first determination are corrected. While this procedure is satisfactory in the factory where a large number of cylinders are charged simultaneously, it becomes unsuitable where comparatively few cylinders are charged at a time, is too time consuming and requires too much labor for the few cylinders charged.

There are at present a few warehouses supplied with liquid oxygen from a producing plant, which is converted to the gas phase by means of the Cascade oxygen converter, such as that disclosed and claimed in Hansen application Serial No. 369,023, filed December 7, 1940, now Patent 2,363,960, dated November 28, 1944. At such warehouses the filling procedure is closely similar to that employed in the producing plants in that permanent manifolds or racks are installed in the warehouse and the cylinders are charged with oxygen in the gas phase in large batches of 36 or 48 cylinders. Such system is. more economical than freight shipment of cylinder oxygen at some warehouses but further economies appear possible, the principal disadvantages of the "Cascade oxygen converter warehouse system being as follows:

(a) Losses in conversionare considerable.

(b) A large investment is required at the warehouse.

(c) The labor cost of charging the cylinders is high, since several men are used with the usual charging rate.

In order that the delivery of oxygen in the liquid phase to warehouses and the conversion of the oxygen to the gas phase at the warehouses may be carried out economically at small as well as large warehouses, a different system of conversion must be employed, the large investment at the warehouses must be reduced or eliminated, and the charging procedure should be such that economies can be obtained in the latter. In order that such features can be obtained, according to this invention, a small number of cylinders are charged at one time to be handled by only one operator, in exact opposition to the trend in prior plant practice where the full length of every rack is used to charge a maximum number of 4 an?" cylinders in an eflort to obtain 1 w .operating cost. In order to obtain a continuity o uniformity of load on the vacuum pump and charging pump, it is not desirable to use less than two pumps since such set-up provides for one pump to be evacuating while the other is filling, and vice versa. Since the minimum time for evacuation is greater than the time for the minimum filling of a single cylinder, and since the time out of service for the machine is increased by an increase in the number of cylinders, a twostation or two-rack, four-cylinder machine might not be as emcient as regards utilization of the maximum facilities of the pumps. However, the over-all equipment is simpler than a large number of stations or racks which would permit more continuous flow of gas from or to the cylinders.

v The difference is clearly shown in the two separate systems which are described below.

A two-station or two-rack, four cylinder unit is shown in Figs. 1, 2 and 3 of the drawings. Such unit comprises a suitable vehicle I0, such as a transport truck, which is equipped with a container II for low boiling point liquefied gas, such as liquid oxygen, a liquid pump and vaporizing device I2 for the pumped liquid from container II, and a vacuum pump I3 for evacuating the cylinders before charging them. Suitable charging connections and controls are arranged at the rear of the truck I0 with a charging rack or manifold I4 which with it header or racks I6 and. H are adapted to swing out over a member such as a tail-gate I5 of the truck when the latter is moved into proper position to rovide a charging fioor at platform level, or to be connected at a lower level so as to fill gas storage cylinders on the ground and at both sides of the tail-gate.

Two four-cylinder racks I6 and I! are shown connected through the manifold It to filling and vacuum lines I8 and I9, the former being provided with an adjustable regulator or pressure actuated shut-01f valve 20 for relieving the operator of watching a pressure gauge to determine the proper time to conclude the filling operation. The filling line I8 is also provided with an accumulator 2I for preventing an excessive rise of pump pressure when the automatic valve 20 operates to shut off any further flow of oxygen in the gas phase to the gas storage cylinders and the charging pump continues to operate.

The operation of the portable cylinder filling equipment shown in Figs. 1, 2 and 3 is as follows:

1) Upon arrival of the unit I0 to a warehouse, the tail-gate 15 of the truck is lowered to its extended position, and the two filling racks I6 and I! being substantially rigid as illustrated are swung out over the tail-gate I5, and the charging and vacuum pumps I2 and I3 are started.

(2) Cylinders C1, C2, C3 and C4 are installed in one rack, the rack I6, for example, and an evacuation valve 22 is opened to connect suchrack with the vacuum pump I 3.

(3) Gas storage cylinders C5, C6, C7 and C8 are installed in the other rack I1.

(4) When the proper vacuum has been obtained in cylinders C1, C2, C3 and C4 such as by the vacuum pump operating for a given time, the evacuation valve 22 is closed, a filling valve 23 is opened to cause oxygen in the gas phase to flow into these cylinders, and an evacuation valve 24 is opened to start the evacuation of cylinders C5, C6, C7 and Cs.

(5) When the proper amount of oxygen in the gas phase has been pumped into the cylinders C1, C2, C3 and C4, the regulator or shut off valve 20 operates automatically in response to pressure on these cylinders to shut oil? the oxygen flow so that the pump discharge flows into the accumulator 2|. At about the same time the evacuation of the cylinders C5, C6, C1 and C8 is completed, since evacuation takes longer than filling, whereupon the evacuation valve 24 is closed and the filling valve 25 is opened.

The cylinder valves of cylinders C1, C2, C3 and C4 are closed and these cylinders are replaced with empty cylinders which are carried through the same cycle as that outlined above in connection with cylinders C1, C2, C3 and C4. Likewise, cylinders C5, C6, C7 and C8 are shut oil? when they are filled and are replaced by empty cylinders which are carried through the same cycle as that outlined above for cylinders C5, Ce, C7 and Ca. The same cycles are continuously carried out as outlined above until all empty cylinders at the warehouse have been filled.

Since some mechanical devices are advisable to expedite the'operation and reduce the amount of work for the operator the

valves

22, 23, 24 and 25 may be power operated, for example, they may be diaphragm operated valves controlled by a simple two-way valve or by a cycle controller. Also, any suitable means for expediting the closing or the cylinder valves and of makin and breaking the filling connection may be used. With these mechanical devices, the operator is enabled to carry out the pumping procedure at a very rapid rate.

A three-station or three-rack, two-cylinder system is shown in Figs. 4, 5 and 6 of the drawings. The assembly of this system is somewhat similar to that discussed above in connection with the two-rack unit, the principal difierence being that in place of the two racks for four cylinders each, this system utilizes three

racks

26, 21 and 28, each having connections for two cylinders. The operation of this mobile equipment is as follows:

(1) Assuming the truck to have arrived at a warehouse, the tail-gate i is lowered, the

racks

26, 21 and 28 are swung out, and the charging and vacuum pumps l2 and I3 are started.

(2) Cylinders C1 and C2 are connected tothe rack 26 and the evacuation valve 22 to the vacuum pump I3 is opened.

(3) Cylinders C3 and C4 are connected to the rack 21 and the evacuation valve 24 to the vacuum line [9 is opened. At about this time the evacuation of cylinders C1 and C2 is completed, so that the evacuation valve 22 is closed and the charging valve 23 is opened to the filling line [8. The reason two cylinders containing different pressures may be simultaneously exhausted as stated so that one may be completed ahead of the other, i. e., without equalizing pressures within the cylinder, is due to thevacuum pump being of the size hereinafter mentioned. This enables the vacuum in the vacuum racks to be close to absolute zero. The standard orifice in the usual valve on the top of each cylinder is the limiting factor requiring more time to. exhaust the cylinders than to charge them since much higher pressure differences exist on each of these orifices for filling than for evacuating the cylinders.

(4) Cylinders C5 and C6 are connected to the rack 28 and an evacuation valve 29 to the vacuum line I9 is opened. At about this time evacuation of cyinders C3 and C4 is completed, and the evacuation valve 24 is closed and charging valve 25 is opened. Also, at about this time, the filling of cylinders C1 and C2 is completed and the chargclosed and a charging valve 30 is opened. Also,

at about this time, the filling of cylinders C3 and C4 is completed and the charging valve 25 is closed, and the cylinders Ca and C4 are replaced with empty ones.

(6) This sequence of operations is carried on until all of the empty cylinders at the warehouse have been filled.

The foregoing outline gives the essential features of the operation and, as in the previous case, the necessary mechanical devices are used to allow the system to be operated by only one man. As in the previous case, mechanical operating means for rack-cylinder connection and disconnection, and power-operated means for closing the cylinder valves, may be used. The regulator 20 controls a motor M driving a cycle controller (Fig. 6) which operates the

evacuation valves

22, 24 and 29 and the filling

valves

23, 25 and 30 in the proper sequence, so that as each pair of cylinders is filled it may be replaced with empty cylinders by the operator, it being only necessary for the operator manually and initially to open the vacuum valve to start evacuation of empty cylinders after they have been connected to the manifold.

Comparison of the two systems disclosed above indicates that the two-rack four-cylinder system has the advantage of a lesser number of filling and evacuation valves and the three-rack twocylinder system has the advantage of a lesser number of cylinder connections. Since the additional cy.'inder connections are not as complicated as the filling and evacuation valves, in regard to complexity, the two-station system is at an advantage. However, the three-rack system has a marked advantage as regards uniformity of fiow in the operation of the charging pump because the charging pump operates against more nearly constant pressure throughout the cycle and so requires a somewhat smaller accumulator. The three-rack system is also lighter, has a larger capacity, and requires less operating space than the two-rack system.

Referring to Fig. '7, there is shown a diagram of another and a preferred two-rack four-cylinder system. The assembly consists of a manifold framework F about 8 feet wide by about 6 feet long with stations for four cylinders C along the two short sides S, S. Along the same sides are provided manifold racks l6 and l! which are illustrated as being rigid and which lead to the evacuation and filling

control valves

22, 24 and 23, 25. These valves are located on the closed end of the assembly, the opposite end being open so that cylinders can be rolled in and out. The

evacuation control valves

22 and 24 are mechanically connected to each other to prevent accidentally opening a valve when it should not be opened and each is connected to the vacuum line l9 which is in turn connected to a suitable vacuum source (such as a Kinney type 7 x '7 vacuum pump), the vacuum line [9 being provided with a bursting disc D responsive to slight positive pressure in the line and a trap T to prevent any flow of lubricant from the vacuum source to the cylinder racks l6 and I! in the event valve 3 l and a blow-off valve B. The blow-ofi valves B are to permit release of manifold pressure'before the cylinders are disconnected. Connected to the oxygen charging line I8 is a safety valve 32, a gas pressure indicator 33, and such as a pneumercator, the pressure control valve or regulator 20, and a receiver or accumulator 34 of about 1.6 cu. ft. water volume. The receiver 36 is connected to the filling line l8 by a valve 35.

A pressure responsive shut-off valve R acts to prevent excessive pressure on the apparatus 33 with the

valves

23 and 25 closed. This apparatus 33 acts to shut oil gas flow so that all of the racks may be filled to a definite predetermined pressure. The cylinders C are connected to the racks i6 and l I by means of flexible tubing or pigtails Z, which terminate in quick connectors.

Suitable means are provided for automatically closing the filling

control valves

23 and 25 when the rack pressure is increased to the desired predetermined value. The apparatus 33 is a well known type sensitive pressure responsive mechanism in which the high pressure in the line is proportionally reduced before being applied to a mercury column so that such a mercury column need not be excessively high. The mercury in the apparatus 33 is adapted to close an electrical contact when it reaches a predetermined level to energize a solenoid G by a battery 36 and initiate the closing of the proper

filling control valve

23 or 25 when the cylinders connected thereto are filled. The filling

control valves

23 and 25 are connected to a shaft P having a handle H and a semi-circular disc-like cam I. When the

valves

23 and 25 to both racks are closed, the handle H extends downward and the cam I is above the shaft P. When the valve 23 is opened to the right-hand rack IS the valve handle H is horizontal, extending from the shaft P to the right, as shown. In this position an operating spring J, attached to the valve handle H, is extended. Also, a. solenoid K is energized by a battery 31 in circuit with normally-closed contacts 38 of the solenoid G, and pulls upward on its armature L (urged downwardly by a spring 33), keeping a dog M at the right-hand end of a pivoted lever N engaged with an edge of cam I, thus preventing the spring J from pulling the handle H back to a verical or valve shut-off position. The regulator 20 in each embodiment illustrated functions in the same way as a cut-oil valve responsive to a predetermined pressure. Since such pressure in the Fig. 7 apparatus is a predetermined high pressure on the more sensitive pressue responsive apparatus 33, this valve must effect a pressure drop on starting the filling operation, such drop decreasing as the pressure in the cylinder or cylinders rises. Inasmuch as the pressure responsive apparatus 33 and trip mechanism of Fig. 7 function together as a pressure responsive shut-oil mechanism, the pressure responsive shut-oil regulator 20 is set to close at a pressure above that at which the apparatus 33 and trip mechanism function because otherwise the pressure responsive shut-off regulator 20 and not the apparatus 33 with its trip mechanism would do the cutting off when filling had been completed.

When the pressure in the right-hand bank of cylinders reaches a predetermined desired value, an electrical contact is made by the mercury column in the apparatus 33, energizing the solenoid G which opens the contacts 38, and the solenoid K is de-energized. The dog M is then lifted off the edge of the cam I by the spring 33, and the spring J pulls the valve handle H downwardly to the vertical position, closing valve 23 and thereby shutting off the fiow of gas to the right-hand rack !6. The operator then swings the handle H to the left of the shaft P and, as the left-hand valve 25 opens, the pressure in the apparatus 33 falls. The dog M then engages with the other edge of the cam I, holding the valve 25 in this new position until it is released; this taking place, as before, when the pressure in the new rack reaches the predetermined desired value.

The racks l3 and I! of gas from the full rack back through the filling control valve into the new rack about to be filled,

when the filling valve is being closed to one rack and opened to the other. The blowdown valves B are opened after the filled cylinders have been closed, the valves B being closed when these cylinders are replaced with empty cylinders.

Time studies have been made using the tworack multi-cylinder system shown in Fig. '7 to determine the relative capacities of this system when different numbers of cylinders C are connected to the racks l6' and I1. In the first time study, four cylinders were used on each rack. The time to change four cylinders was about half the time to evacuate four cylinders. Therefore, if one rack is being filled while the alternate rack is being changed and evacuated, the capacity of the two-rack four cylinder system is a certain number of cylinders an hour. A two-rack fivecylinder system was then tried and the capacity was increased to a greater number of cylinders an hour. A further change was tried in which eight cylinders were placed on each rack. This further increased the capacity to a still greater number of cylinders an hour, but still equivalent to a pumping rate within the capacity of the mobile pumping unit.

The operating cycle of the system shown in Fig. 7 is substantially like that of the system shown in Fig.3. The batteries 36 and. 31 may be the battery of the trunk I, Fig. 1, or any other suitable source of electrical energy, such as a generator connected to the engine of the truck I.

Among the advantages of this invention may be mentioned not only the saving through elimination of having to ship containers to and from the factory for filling but also the expeditious filling of available cylinders at any place where the tank truck I0 may stop. Where the charging pump in prior factory practice was operated only while charging the cylinders the charging pump of the present invention may be operated substantially continuously while the truck is stopped at a particular station, due to the accumulator being able to receive additional gas while cylinders are being disconnected and replaced. The entire operation including'the manipulation of a number of valves may be semi-automatic in response to time for operation of a cycle controller by manually starting and manually initially opening the first rack evacuating valve. The cycle of operations may be terminated manually or are preferably provided with check valves 0 to prevent any reverse flow otherwise. the reason two cylinders of different pressures may be evacuated at the same time without equalizing the pressures in them is that the vacuum pump is of a size correlated to the orifices in the valves in the top of each cylinder to accomplish the desired result. The racks mounted on the truck provide a portable and easily accessible, quick detachable connecting means for the cylinders. The racks being extensible take up little space and the lowered tail gate provides additional space for the cylinders being filled, all accessible for efiicient operation by one man.

What is claimed is:

1. Apparatus for first evacuating and then charging gas storage cylinder with gas material such as oxygen in the gas phase, comprising, in combination, a manifold, a vacuum pump, means including a valve connecting said vacuum pump to said manifold, a container for low boiling point liquefied gas, such as liquid oxygen, a liquid pump and vaporizing device connected to said container, means including a valve connecting said liquid pump and vaporizin device to said manifold, an automatic pressure actuated shut-01f mechanism for said charging valve disposed in the connnecting means between said vaporizing device and said manifold, and a gas accumulator disposed in the connecting means between said automatic pressure actuated shut-01f valve and said liquid pump for preventing an excessive rise of pressure by said pump when said shut-off valve automatically operates to stop the fiow of gas material to said manifold.

2. Apparatus for charging gas storage cylinders with oxygen in the gas phase, comprising, in combination, a liquid oxygen supply tank, a liquid oxygen pump and vaporizer connected to said supply tank, means connecting said liquid oxygen pump and vaporizer to said manifold, an adjustable regulator disposed in the connecting means between said pump, vaporizer and said manifold for closing said connection when a gas storage container connected to said manifold reaches a predetermined gas pressure, and a gaseous oxygen accumulator disposed in the connecting means between said regulator and said liquid oxygen pump for preventing an excessive rise of pressure when said regulator automatically operates to stop the flow of vaporized oxyen to said manifold.

3. Apparatus for evacuating and charging gas storage cylinders with oxygen in the gas phase, comprising, in combination, a plurality of manifolds through each of which at least a plurality of gas storage cylinders are adapted to be evacuated and charged wi h oxygen in the gas phase, a single vacuum pump having a connection to each of said manifolds, a valve in each such vacuum pump connection, a liquid oxygen supply tank, a single liquid oxygen pump and vaporizing device connected to said supply tank and having a connection to each of said manifolds, a valve in each such charging connection, and control means for opening and closing saidvalved connections in sequence so that gas storage cylinders connected to each of said manifolds are first evacuated and then charged with oxygen in the gas phase in a cycle moving from one manifold to another, whereby the charged gas storage cylinders connected to each manifold may, in turn, be replaced with empty cylinders while gas storage cylinders connected to one manifold are being evacuated and cylinders connected to an- 10 other manifold are being charged with oxygen in the gas phase, the number of cylinders connected to each manifold, and the number of manifolds being such that the effective operation of said pumps is substantially continuous.

4. Apparatus for evacuating gas storage cylinders and charging them with valuable gas material such as oxygen in the gas phase from a source of liquid oxygen comprising, in combination, a source of low boiling point liquefied gas, a liquid pump and vaporizing device for said low boiling point liquefied, a vacuum pump, a plurality of gas storage cylinder manifolds, means connecting each of said manifolds to said liquid vaporizin device and to said vacuum pump, said connecting means comprising a normally-closed vacuum valve located between each manifold and said vacuum pump, a normally-closed filling valve located between each manifold and said.

liquid vaporizing device, and control means for operating said valves in sequence so that gas storage cylinders connected to said manifolds are first evacuated by said vacuum pump and then charged with gas material by said liquid vaporizing pump in a predetermined cycle such that charged cylinders may be replaced by empty cylinders without interfering with the substantially continuous effective operation of said pumps.

5. The method of continuously charging groups consisting of not less than two and not more than five gas storage cylinders, each having a valve with an orifice therein, with valuable gas material such as oxygen in the gas phase at high pressure, which comprises connecting a group of gas storage cylinders to a vacuum pump and when said group of cylinders is only partiallyevacuated connecting a second group of cylinders to said vacuum pump without equalizing the degree of vacuum in the groups by maintaining a higher vacuum between the vacuum pump and each cylinder than exists inside the cylinders up to the valve and orifice of each; when said first.

group of cylinders are sufiiciently evacuated, connecting them to a supply tank containing such gas material in the liquid phase, through a liquid pump and vaporizing device; while said cylinders are being charged with said gas material, connecting another group of gas storage cylinders to said vacuum pump; charging said first group of cylinders with said gas material until the gas pressure therein reaches a predetermined value; closing said first group of charged cylinders and disconnecting them from said liquid vaporizing pump; when said second group of cylinders are sufficiently evacuated, connecting them to said supply tank through said liquid vaporizing device, and repeating this cycle of steps with any desired number of additional groups of gas storage containers; said filling and evacuating steps being timed so that at least one group of cylinders is'being evacuated at all times.

6. The method of continuously handling cylinclers comprising evacuating gas storage cylinders each provided with a valve and orifice therein from a single vacuum pump and charging them with a valuable gas material such as oxygen in the gas phase from a single liquid vaporizing device connected to a tank containing a low boiling point liquefied gas such as liquid oxygen, which comprises establishing and maintaining communication between said vacuum pump and a gas storage cylinder until the latter is suitably evacuated, closing the communication between said vacuum pump and said evacuated cylinder, establishing and maintaining communication between inder has said evacuated cylinder and said liquid vaporizing device until said cylinder is charged with such gas material to a predetermined pressure, and establishing communication between said vacuum pump and another cylinder after said first cylbeen partly evacuated without equalizing pressures in said cylinders by'maintaining the vacuum between the vacuum pump and said cylinders at closer to zero vacuum than is the vacuum in said cylinders up to the valve and orifice of each.

7. Apparatus for evacuating and charging cylinders with gas such as oxygen, rapidlyand without having to ship them to the factory for such charging, said apparatus comprising in combination a portable liquid tank, a vacuum pump, a connecting passage between said vacuum pump and a cylinder to be evacuated, a valve in said passage, a liquid charging pump and vaporizer for pumping liquid from said tank and changing the same into gas, a passage from the vaporizer to said cylinder, an accumulator in said passage, a valve between said accumulator and said cylindex, a portion of the first and second mentioned passages between their valves and said cylinder being in common and adapted to function as a rack or header whereby after the cylinder has been evacuated it may be filled by said charging pump, said vacuum pump being of a size capable of evacuating at least two cylinders under different degrees of evacuation without equalization of pressures in the cylinders, and the charging pump being of a size to fill a cylinder in less time than is required to exhaust it and also capable of being operated continuously, there being a second rack to which a second cylinder may be connected, a connection between said secondrack and each of the exhaust and supply passages, and a valve in each such connection, whereby one cylinder may be receiving gas while another is being evacuated andwhen one cylinder has been filled it may be removed and replaced by another to be evacuated.

8. Apparatus for filling groups of cylinders with gas comprising at least two racks to each of which a group of cylinders is adapted to be connected for evacuating and filling, vacuum pump means for evacuating a group of cylinders, pressure pump means for filling a group of cylinders with gas r under pressure, valve connections whereby the cylinders connected-to each rack may be connected to said vacuum pump means and then connected to said pressure pump means, a valve means responsive to a predetermined pressure on its downstream side, an accumulator between saidpressure pump means and said valve means whereby said pressure pump means may continue operation after the valve means has closed, a trip mechanism for closing a rack filling valve, and a pressure responsive means between said valve means and rack filling valve for tripping said mechanism in response to a predetermined pressure lower than that to which said valve means is responsive whereby said valve means may function as a safety cut off in event of failure of either the trip mechanism or the pressure responsive means to function.

9. A mobile unit comprising, in combination, a transport truck having an extension platform adapted to be opened to provide a temporary floor upon which gas storage cylinders to be filled with a gas material such as oxygen may be placed, and means mounted on said truck for charging said cylinders with said gas material and including a substantially rigid and extensible manifold adapted to be moved out over said platform, when the latter is in open position, for connection to gas storage cylinders placed on said floor.

10. The method of continuously handling cylinders comprising evacuating gas storage cylinders and charging them with valuable gas material such as oxygen in the gas phase from a source of liquid oxygen, which comprises connecting a first group of gas storage cylinders to a first manifold that is connected through a normally-closed first vacuum valve to a vacuum pump and througha normally-closed first filling valve to a liquid vaporizing pump, and opening said first vacuum valve to start the evacuation of said first group 01 cylinders; connecting a second group of gas storage cylinders to a second manifold that is connected through a normallyclosed second vacuum valve to said vacuum pump and through a normally-closed second filling valve to said liquid vaporizing pump, and opening said second vacuum valve to start the evacuation of said second group of cylinders before the first group of cylinders are fully evacuated without equalizing the vacuums in each group of cylinders by maintaining a highervacuum in said manifolds than exists in said cylinders; closing said first vacuum valve when said vacuum pump has completed the evacuation of said first group of cylinders and opening said first filling valve to start thecharging of said first group of cylinders with gas material by said liquid vaporizing pump; connecting a third group of gas storage cylinders to a third manifold that is connected through a normally-closed third vacuum valve to said vacuum pump and through a normally-closed third filling valve to said liquid vaporizing pump, and opening said third vacuum valve to start the evacuation of said third group of cylinders before the second group of cylinders are fully evacuated; closing said second vacuum valve when said vacuum pump has completed the evacuation of said second group of cylinders, and opening said second filling valve to start the charging of said second group of cylinders with gas material by said liquid vaporizing pump; closing said first filling valve when said liquid vaporizing pump has completed the charging of said first group of cylinders with said gas material, disconnecting said first group of gas charged storage cylinders from said first manifold, connecting another group of gas storage cylinders to said first manifold, and opening said first vacuum valve; andrepeating the cycle until the desired number of gas storage cylinders has been filled.

ODD A. HANSEN.

GEORGE H. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 19,458 Heylandt Feb. 12, 1935 1,103 4'74 Bickford July 14, 1914 1,304,965 Hammarstrom May 27, 1919 1,629,174 Patton May 17, 1927 1,786,858 Merrell et a1. Dec. 30, 1930 2,075,408 Sholes Mar. 30, 1937 2,075,678 Vonlangen Mar., 30, 1937 Certificate of Correction Patent No. 2,469,434 May 10, 1949 ODD A. HANSEN ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 3, line 4, for exepnse read expense; line 7, for the Word he read The; column 7, line 13, before such strike out and; line 64, for pressue read pressure; column 8, line 54, for trunk read truck; column 9, line 1, for the read The; line 16, for cylinder read cylinders; column 10, line 12, after liquefied and before the comma, insert gas; and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 20th day of December, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommz'ssioner of Patents.