US3044300A

US3044300A - Liquid sampling apparatus

Info

Publication number: US3044300A
Application number: US793514A
Authority: US
Inventors: George E Eden; Kenneth V Melbourne
Original assignee: National Research Development Corp UK
Current assignee: National Research Development Corp UK
Priority date: 1958-02-20
Filing date: 1959-02-16
Publication date: 1962-07-17
Anticipated expiration: 1979-07-17
Also published as: GB854811A

Description

y 1962 G. E. EDEN ETAL 3,044,300

LIQUID SAMPLING APPARATUS Filed Feb. 16, 1959 2 Sheets-Sheet 1 l/ /7 2 AI 34 B/ O\ 33 r f/gl.

July 17, 1962 G. E. EDEN ETAL 3,044,300

LIQUID SAMPLING APPARATUS Filed Feb. 16, 1959 2 Sheets-Sheet 2 Fig.2

3,6443% LIQUE SAMPLING APPARATUS George E. Eden and Kenneth V. Melbourne, Stevenage,

Herts, England, assignors to National Research Development Corporation, London, England Filed Feb. 16, 1959, Ser. No. 793,514 Claims priority, application Great Britain Feb. 20, 1958 14 Claims. (Cl. 73-422) The purpose of the invention is to take samples automatically from a body of liquid such as a stream or river at relatively long intervals of time, say half or one hour over a. period of several hours, by means of apparatus which can be left unattended.

In its broadest aspect, apparatus for the purpose in View comprises as many evacuable sample vessels as may be required, a connection from each vessel adapted to be immersed at the point from which the respective sample is to be taken, a valve controlling the opening of each such connection, and clock controlled mechanism which opens the valves in a predetermined time sequence, the vessels being evacuated and the valves all closed before the sampling point connections are made and the mechanism is set in action.

The valves should remain open once opened by the mechanism and may conveniently be in the form of pinch cocks held closed each by a latch which can be set by hand to close the valve, and the latches are conveniently released by respective electromagnets to open the valve. Only a momentary energisation is needed to release each valve and as apparatus of the kind in question will usually need to be provided with its own source of electric current, a convenient way of deriving the impulses is to provide a condenser which is charged from an electric battery in the intervals between the momentary excitations of a receiving circuit through which the condenser discharges and which causes the electromagnets to be energised in turn.

The clockwork moves a change-over-switch at predetermined time intervals from its normal position in which the condenser is connected to the battery to a position in which it connects the condenser to the receiving circuit for a short period adequate for the condenser to discharge.

The invention will be further described with reference to the accompanying diagrammatic drawings:

FlGURE 1 illustrates a first circuit arrangement according to the invention,

FIGURE 2 illustrates a second circuit arrangement,

FIGURE 3 illustrates a convenient construction of the valve and the parts by which it is actuated,

FIGURE 4 is a detail of a modification of FIGURE 3, and

FIGURE 5 is a plan view of FIGURE 4 with certain parts in section.

artists Patented July 17, 19%2 momentary energisation of the magnet A releases the corresponding latch and the latch under spring. action then moves a contact A1 over from the position shown in which the line 17 from the condenser was connected to the electromagnet A through a lower contact 33 to an upper contact 34 which carries the connection to the next electromagnet B.

At the next impulse therefore the condenser 15 discharges through the electromagnet B which releases the corresponding latch and then prepares a path to the next electromagnet C and so on.

Referring first to FIGURE 1 a convenient device for determining the time intervals comprises a notched disc 11 driven by the clockwork 12. An arm 13, downwardly biased, cooperating with the disc 11 actuates a changeover micro-switch indicated generally at 14. When the arm 13 is riding on the periphery of the disc 11 the upper contacts of the switch 14 are closed thereby holding a condenser 15 connected to a charging battery 16. When the disc brings a notch under the arm 13 the lower contacts of the switch 14 are closed thus disconnecting the condenser from the battery but switching it to a line 17 leading to the electromagnets. As shown in FIGURE 1 the electromagnet A is in circuit. The condenser therefore discharges through this electromagnet and momentarily energises it. A short time after this happens the notched disc 11 restores the micro-switch to its original position thus causing the condenser to be recharged. The

For a self-contained apparatus, a convenient source of supply would be a 50 volt battery 16 made up of pocket-lamp cells and the condenser 15 may have a capacity of 3000 ,uf. The charge on such a condenser is adequate to release a latch for the purpose in view.

A disadvantage of the simple circuit shown in FIG- URE l is that each successive electromagnet has the supply carried to it through contacts in series, changed over by the latches of all the preceding electromagnets. Thus, if there is a poor contact anywhere in the chain, due e.g. to dust, this may cause a valve to fail to open. It may open on the next discharge but this still means that a particular sampling time has been missed and all the following samples are out of step. This can be avoided by the somewhat more complicated circuit illustrated in FIGURE 2, in which the clock operated micro-switch 11, 14, condenser 15, battery 16 actuate a uniselector indicated generally at 18. Since the condenser 15 can only give a single impulse to the uniselector when it discharges, it is directly connected to the driving magnet DM of the uniselector. A second condenser 19 the capacity of which may be the same as the condenser 15 is connected on one side to the wiper W of the uniselector and on the other to a common line to which the various electromagnets A, B, C, etc., are connected, this common line also going to the charging battery for this condenser which is conveniently the battery 16 which charges the condenser 15. The alternateoutgoing contacts 21 of the uniselector are connected to a common line leading back to the other side of the battery and to the respective electromagnets A, B, C, etc. Accordingly at each step forward of the uniselector the condener 19 is connected alternately to the battery and to the next electromagnet A, B, C, etc., to be energised.

, It will be seen that with this arrangement a latch magnet is only energised at each alternate impulse from the micro-switch 14 so that if it is required to collect samples at the same intervals as in FIGURE 1 the disc 11 will have to have notches at half the spacing. The arrangement could however be modified so that a latch magnet is energised at every step. This could be done for in stance by providing the usual driving magnet contacts dm of the uniselector with an extra contact to convert it into a changeover-switch which normally connects the condenser 19 to the charging battery and arranging the other contact of 'the switch to connect the condenser to the wiper W. As the uniselector only steps-on on the return movement of its armature during the attraction of the armature the changeover-switch dm disconnects the condenser 19 from the battery and through the wiper discharges it through the electromagnet which at that moment is connected to the outgoing contact 21 on which the wiper is at rest.

In the particular arrangement illustrated a second contact bank of the uniselector is provided with a homing arc and a switch S2 is provided e.g. a push button switch, normally biased to the position shown. If this switch is changed over manually the uniselector is energized through this bank with the contact dm in series in the usual way with. the magnet DM so that the uniselector will step on automatically and can thus be zeroised.

tacts

33, 34 in fixed position, one on each side.

- tain of the latch magnets instead of being connected to V the alternate contacts on the bank could be connected at greater intervals thus requiring more steps of the wiper W before being energised;

FIGURE '3 illustrates a convenient structure vof valve and the associated parts which control it. This valve is in the form of a pinch cock constituted by a piece of elastic tubing such as thick walled rubber tubing 22, pinched between a semi-cylindrical block 23 having'its axis at right angles to the tube, and a clamping arm 24 one end of which has a clearing hole over a threaded rod'25, this end being urged in the opening direction by a compression spring 26 against a pair of lock nuts 27 which provide an adjustment. The other end of the arm carries a hardened latch member 28 which engages in a hardenedrecess in an L piece 29 secured to a pivoted arm 31 forming the armature of the electromagnet here marked A corresponding'with FIGURE 1. Nothing more is required in the case of the uniselector circuit, but in the case of the simple circuit shown in FIGURE 1, a spring blade 32 to which the supply comes from the line 17, is secured to the arm 31. This blade carries the moving contact A1 cooperating with the two other con- The contact 33 nearer the electromagnet, which is closed when the latch is engaged is the lower contact similarly num! bored in FIGURE 1, which completes the circuit from the condenser to the electromagnet A. After release when the movement of the clamping arm has carried the latch clear of the arm 31, an armature return spring 35 moves the arm 31 and spring blade 32 until the contact A1 touches the other fixed position contact 34 which is the upper contact similarly numbered in FIGURE 1 which connects the blade and thus the supply to the next electromagnet B. a a 1 Conveniently the rubber tube 22 is joined to a plastic tube 36 of any convenient length to reach the liquidto and the lower end of the clamping arm 24a is bifurcated to clear the magnet winding A. As shown the upper end of the arm 24a is mounted in the same way as in FIGURE 3 but alternatively a fixed hinge may be used here and adjustment eifected entirely by adjusting the position of the permanent magnet 41.

The clockwork may conveniently be one which is electrically wound and the rewinding may conveniently be effected from the same battery which serves to charge the condenser. It will be understood that the disc 11 may be exchanged for one giving some other predetermined time sequence.

q 1. Apparatus for collecting samples automatically from a body of liquid at intervals of time, comprising a plurality of independent fluid conduits each having one end adapted to be immersed in said body or" liquid in at least one region from which said samples are to be collected and the other end to be connected to a respective evacuated vessel to receive a respective sample, a separate valve for each said conduit, means urging each said valve to its open position, a respective latch holding each valve closed, and automatic time-controlled mechanism for releasing said latches in sequenceat predetermined time intervals, so that each said valve opens and remains open when its respective latch is released.

2. Apparatus as set forth in claim 1 also including a plurality of sample receiving vessels, and means for be sampled. Usually all the samples will be wanted from the same point in which case the ends of the plastic tubes may be brought to a common location and surrounded by a strainer 37. But in any particular case the tubes may be carried to different points, each with an individual strainer or they may be grouped just as may be necessary. By slipping the rubber tubes 22 off the plastic tubes 36, connection can readily be made to an evacuating pump, whereafter the pinch cocks are latched and the rubber tubes slipped over the ends of the plastic tubes. The sample vessels may be bottles 38. For many purposes a bottle having a capacity of 1% litres is convenient. p

The latch arrangement shown in FIGURE 3 may suffer from wear. This is avoided'in the modification shown 1 in FIGURES 4 and 5 in which a mechanical latch is avoided and a magnetic latch is substituted. For this purpose a permanent magnet 41 is provided adjustable in position by a screw 42 and the clampingarm 24a which corresponds with that of FIGURE 3 and which pinches the elastic tube 226: carries an armature 4 3 The parts are arranged so that when the armature is close .tothe magnet 41 the pinch cock is closed. To release it the electromagnet winding such as A-is on the armature latter position the distance of the armature from the a permanent magnet is so great that the magnetic attraction of the magnet is not sufficient to close the cock again.

, The permanent magnetzis conveniently of horseshoe form evacuating the vessels, said vesselsbeing the vessels to which the other ends of said fluid conduits are adapted to be connected.

3. Apparatus for taking samples automatically from a body of liquid at intervals of time comprising a plurality of initially evacuated sample vessels, a separate fluid conduit leading from the interior of each vessel and adapted to have its remote end immersed at the point from which the respective sample is to be taken, a valve controlling each said conduit, means for holding all said valves closed, and clock controlled mechanism which opens the valves in sequence at predetermined time intervals.

4. Apparatus as set forth in claim 3 in which said mechanism includes a latch for each valve which can be set by hand to close the valve, and an eleot-romagnet which when momentarily energised releases the latch to open the valve.

5. Apparatus as set forth in claim 4 in which the clock controlled mechanism includes an electric battery, a condenser, a switch actuated by each latch which when the latch is released prepares a path from that switch to the electrom'agnet which releases the next latch to be released, a change-over-switch, a connection from the condenser to the battery controlled by said change-overswitch and normally closed, and means actuated at predetermined time intervals which operates said change- -over-switch to disconnect the condenser from the battery controlled mechanism includes a first condenser, charging means of electric battery form, a changeover-switch, a connection from the condenser to said charging means controlled by said changeover-switch and normally closed, a uniseleotor, means actuated at predetermined timeintervals which operates said changeover-switch to disconnect the condenser from said charging means and connect it to the driving magnet of the uniselector, a second condenser, and switching means actuated by the uniselector whereby said second condenser is alternately switched to said charging means for charging it and to the next electromagnet to be operated; 7. Apparatus as set forth in claim 6 wherein said charging means is constituted by a single electric battery.

8. Apparatus as set forth in claim 6 wherein said uniselector also comprises a homing are, a homing contact and a wiper co-operating with the homing arc and homing contact, the apparatus also including a biased switch whereby said charging means can be switched into circuit with the wiper cooperating with said homing arc and contact to bring the uniselecto-r to zero position.

9. Apparatus as set forth in claim 6 wherein said switching means is constituted by the Wiper and outgoing contacts of the uniselector, said second condenser being connected to the Wiper of the uniselector and said charging means being connected to some of the outgoing contacts of the uniselector while other outgoing contacts alternating with the first mentioned outgoing contacts are connected respectively to said electromagnets.

10. Apparatus as set forth in claim 6 wherein said switching means includes rmpeotive connections from the outgoing contacts of the uniselector to said electromagnets, and a change-over-switch actuated by the armature of the uniselector when its driving magnet'is energised, said changeover-switch normally connecting said second condenser to said charging means but when actuated con meeting said second condenser to the wiper of the uniselector. 1

11. Apparatus as set forth in claim 4 wherein each valve comprises a flexible elastic portion of the respective conduit, and clamping means constituting a pinch cock for said portion, said clamping means being held by the respective latch in a clamping position in which it pinches said portion to close it, said valve opening by the elasticity of said portion when the respective latch is released.

12. Apparatus as set forth in claim 11 in which said clamping means comprises a clamping arm extending across said portion, and said latch comprises a pivoted arm having a notch retaining said clamping arm in a position in which it pinches said portion to close it, and spring means urging the pivoted arm into its retaining position, said electromagnet cooperating with said pivoted arm to move it against the action of the spring means thereby to release the clamping arm when the magnet is momentarily energised.

13. Apparatus as set forth in claim 11 in which said clamping means and latch comprise a clamping arm extending across said portion, an armature carried by the clamping arm, a permanent magnet cooperating with the armature and positioned so that when the armature is close to the permanent magnet and held thereto by magnetic attraction the clamping arm is in a position in which it pinches said portion to close it, a winding upon the armature constituting with it said electromagnet, said electromagnet being of such polarity that when the winding is momentarily energised it polarises the armature in such direction as to cause its release from the permanent magnet.

14. Apparatus as set forth in claim 5 in which each valve and latch comprise a tube of elastic material forming part of the respective fluid conduit, a clamping arm extending across the tube, a pivoted arm having a notch retaining said clamping arm in a position in which it presses the tube to close it, spring means urging the pivoted arm into its retaining position, said electromagnet cooperating with said pivoted arm to move it against the action of the spring means thereby to release the clamping arm when the electromagnet is momentarily energised, the clamping arm then moving clear of the pivoted arm, and each said latch-actuated switch includes a moving contact carried by said pivoted arm, and a pair of fixed position contacts so located that when the clamping arm is retained by the pivoted arm the moving contact touches one of said fixed position contacts and after the electromagnet has been energised and the pivoted arm has been released and moves under the action of the spring means the moving contact touches the other fixed position contact, said moving contact being connected to said condenser in the case of the first electromagnet to be energised, said one fixed position contact being connected to the electromagnet and said other fixed position contact being connected to the moving contact belonging to the valve next to be operated. 7

References Cited in the file of this patent UNITED STATES PATENTS 1,025,498 White May 7, 1912 2,165,893 Gunion July 11, 1939 2,295,881 Wheelock Sept. 15, 1942' 2,477,513 'Fairbairn July 26, 1949 2,644,934 Grant July 7, 1953 2,674,265 Dennis Apr. 6, 1954 2,886,000 Clegg May 12, 1959