Abstract:
It comprises, in addition to a sampling system ( 3 ), at the outlet of a vat ( 1 ) containing the liquid to be sampled, a selector ( 4 ) that establishes switching on an array of similar vats ( 1 ), and especially a suction unit ( 5 ) that operates by releasing compressed air into a nozzle ( 28 ); the airflow direction is controlled by a valve ( 29 ) between a direction directed toward the outlet ( 6 ), causing the suction of the liquid from the vat ( 1 ), and an opposite direction when the valve ( 29 ) is closed, feeding the liquid back into the vat ( 1 ) and cleaning the pipe ( 2 ).

Description:
FIELD OF THE INVENTION 
     The invention relates to a device for collecting liquid samples from a vat, and even from a plurality of vats. 
     BACKGROUND OF THE INVENTION 
     Such devices are common in the nuclear industry in order to analyse certain liquids loaded with irradiating materials. The corresponding devices are generally placed in shielded units, and they are manipulated through the use of remote manipulators. The liquid to be analysed is first present in a vat. It undergoes a suction through a pipe exiting into the top of the vat, which carries it toward a sampling holder whereon a small container, generally called a jug, has been installed, and it partially fills this jug. The excess liquid is evacuated toward an outlet or returns to the vat by flowing through the pipe, which is inclined, as soon as the suction has stopped. 
     A disadvantage with these devices is that the return to the vat is not complete and that droplets of liquid remain on the pipe, and then crystallise: this can be considered as a pollutant, and limits the quality of the following measurements by mixing with the samples sucked thereafter when the original liquid of the vat has been replaced with another. Another disadvantage with these devices is that it is difficult to join them to an array of vats in order to sample by choice samples from any one of them. 
     The invention has for object to eliminate these disadvantages, and above all to allow for a sufficient cleaning of the pipe and of the pipes leading to the vats without substantially complicating the device or having it lose its faculty to be able to be actuated via remote handling. 
     BRIEF SUMMARY OF THE INVENTION 
     In a general form, it relates to a device for collecting liquid samples from at least one vat, comprising at least one pipe connecting to a respective vat and ending at an outlet at an end opposite the vat, a sampling jug holder of samples arranged on the pipe, and a suction unit of the contents of the vat in the pipe, characterised in that the suction unit comprises a nozzle arranged on the pipe, a compressed air inlet exiting in the nozzle, and the device further comprises a valve for sealing off the pipe, arranged on the pipe between the nozzle and the outlet. 
     This arrangement makes it possible to use compressed air to produce the suction by releasing pressure in the nozzle, then, as soon as the valve is closed, to clean the pipe by reversing its circulation toward the vat, which rejects the droplets of the liquid that are still contained therein. 
     The pipe advantageously comprises a small reservoir and the sampling jug holder is able to be connected to the small reservoir by the intermediary of a self-sealing quick-coupling in two portions, a first of said portions belonging to the small reservoir and a second of said portions comprising a needle which penetrates inside the small reservoir by passing through the first portion: this arrangement makes it possible to have a jug holder that can be manipulated easily via a remote manipulator in order to be installed on the device for collecting, then withdrawn to remove the jug and replace it without difficulty away from the device. 
     The pipe is advantageously wider on the side of the nozzle which leads from the outlet than toward the opposite side, which leads toward the vat. This device facilitates the proper direction of the compressed air when it arrives at the nozzle, toward the outlet when the valve is open, thanks to the lower resistance that it encounters from this side. 
     In order to facilitate the maintenance of the device although only remote manipulations are possible, it is recommended that the nozzle and the valve form a single and removable unit with a portion of the pipe and a portion of the compressed air inlet, said portions being connected to main portions of the pipe and of the compressed air inlet by capstan connectors. 
     According to a perfected embodiment, the device comprises a plurality of vats and pipes, the pipes connecting in turn to a selector, and then comprising a joint portion toward the outlet, whereon the nozzle and the valve are arranged. 
     The device can then serve several vats and several pipes. A favourable embodiment comprises a rotating selector which comprises a cylindrical mobile element provided with an external member for manoeuvring, the mobile element comprising an axial piercing directed toward the outlet and a radial piercing directed toward the vats and connections of the pipes arranged on a portion of a turn of the selector. 
     The invention shall now be described more completely and for the purposes of illustration in liaison with the figures. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a general view of the invention, 
         FIG. 2  is a general view of the sampling ( 2 A as a unit,  2 B as an exploded view), 
         FIG. 3  is a view of the selector, 
         FIG. 4  a view of the nozzle and 
         FIG. 5  a view of the capstan connector. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference shall first be made to  FIG. 1 . The liquid to be sampled is initially located in storage vats  1 . Pipes  2  for sampling exit at the top of the vats  1 , pass through a sampling installation  3 , respective, are connected to a joint selector  4 , then pass through a suction unit  5 , and finish toward an outlet  6  which is a reservoir for collecting the excess sucked liquid. The main elements of the device shall now be described successively. The pipes  2  rise first from the vats  1 , to the sampling installations  3 , then fall little by little toward the outlet  6 , opposite the vats  1  and therefore separate from them. 
     The sampling system  3  is shown in detail in  FIG. 2 . It first comprises a mobile portion constituted of a manual valve  7  of which the top is occupied by a cylindrical case  8  open at the top comprising an upper needle  9  whereon can be installed the jug  10  and a pivoting portion  17  making it possible to imprison the jug  10  in its housing, and the base via a needle  11  whereon is fixed a female self-sealing quick-coupling  18  and through which the sampling will be carried out. In the case of a plurality of vats to be sampled, this mobile portion is displaced and is provided with a new jug. 
     The unit further comprises a fixed portion comprising a small reservoir  12  closed by a male self-sealing quick-coupling  13  and wherein exit a lower surface  14  of the pipe  2  leading to the vat  1 , a second surface  15  of the pipe  2  leading to the selector  4 . In order to take a sample, the mobile portion is installed on the fixed portion, through the insertion of the needle  11  in the coupling  13  to connexion of the female quick-coupling  18  on the male quick-coupling  13 . A new jug  10  was installed beforehand in the mobile portion on the needle  9 , the manual valve  7  being in closed position. These jugs are hermetic and the vacuum therein is created at the onset. Their septum  16  is made of rubber and can be pierced by the needle  9  when the jugs  10  are pressed onto it. This is done when a suction has made it possible to fill the small reservoir  12  with the liquid to be sampled: the manual valve  7  is open and the vacuum present in the jug  10  then sucks a portion of the liquid via the needle  11 , the manual valve  7  and the needle  9 . After which, the manual valve  7  can be closed, and the mobile portion can be withdrawn through disconnection of the quick-couplings  13  and  18 . The jug  10  can be withdrawn, and the piercing made in the septum  16  closes itself. 
     Reference is again made to  FIG. 1 , and to  FIG. 3 , for the description of the selector  4 . It comprises a casing  19  occupied by a cylindrical plug  20 , provided with a member for manoeuvring in the form of a square shaft tip  21  protruding out of the casing  19 . To the casing  19  is connected connectors  22  extending the second surfaces  13  of the pipes  2  and which extend in a radiating direction from the casing  19  over a portion of the turn. Another connector  23  is connected to the casing  19 , but this time in the axial direction, opposite the square shaft tip  21 . This connector  23  is connected to the suction unit  5 . The plug  20  contains a piercing  43  leading to the connector  23  by an axial portion and, according to the rotation of the square shaft tip  21 , to one or the other of the connectors  22  via a radial portion. The selector  4  makes it possible to select the vat  1  from which the liquid is sampled, according to its manoeuvre and by means of the arrangements described now. 
     The suction unit  5  comprises a removable portion of the pipe  2 , a removable portion  25  of a compressed air inlet  26  connected to a source of compressed air  27 , and, installed on the removable portion  24 , a nozzle  28  and a valve  29 . The nozzle  28 , shown in  FIG. 4 , comprises a venturi  30  and the removable portion  25  of the compressed air inlet  26  exits therein. The compressed air with a release of pressure in the venturi  30  acquires a supersonic speed able to carry out the suction of the liquid by the pipe  2 . The valve  29  comprises an actuator  31  extending above the removable portion  24  and controlling a valve to open or close the removable portion  24  by the intermediary of a rod  33 . 
     The suction unit  5  can be withdrawn from the rest of the device and then put back into place, being connected via three capstan connectors  34  to the compressed air inlet  26 , to the connector  23  at the outlet of the selector  4  and to a third surface  35  of the pipe  2  after the valve  29  which leads to the outlet  6 . The capstan connectors  34 , shown more completely in  FIG. 5 , include a case  36  and an end  37  to be assembled together, the seal being formed by a double-cone seal  38  placed between them. The case  36  carried a container  39  in the shape of a trough receiving and maintaining the end of the tip  37 . In addition, a capstan nut  40 , engaged on an external threading of the tip  37 , is also maintained by an external lip  41  of the container  39 . A rotation applied to the capstan nut  40  displaces the tip  37  axially in the container  39  and compresses it against the case  36  by crushing the double-cone seal  38 . 
       FIGS. 1 and 3  further show a discharge pipe  42  connecting the interior of the casing  19  to the outlet  6 , and intended for the evacuation of the humidity in the selector  4 . 
     When the compressed air is supplied, with the valve  29  open, the liquid is sucked from the chosen vat  1  toward the suction unit  5  and the outlet  6  fills the small reservoir  12  where it can be sampled. Note that the air inlet exits perpendicularly in the venturi  30 , but the proper direction of air circulation is guaranteed by selecting the surfaces  14 ,  15  and  35  of the pipe  2  with diameters which become successively wider from the vat  1  to the outlet  6  (without considering the diameters at the nozzle  28 ), which can also be in a vacuum in relation to the vat  1 : the resistance to the flow of the compressed air is therefore less substantial toward the outlet  6 . But when the suction stops, the closing of the valve  29  has for effect to close the removable portion  24  and to inverse the direction of the flow of the compressed air toward the vat  1 , by feeding back therein the liquid which may have stagnated in the device and in particular in the small reservoir  12  and the pipe  2 . No other manoeuvre is required. 
     All of these movements are easy to accomplish through ordinary remote manipulators, with limited dexterity.