CA1194339A - Sampler - Google Patents

Abstract

ABSTRACT

A fluid sampler is disclosed which operates so as to trap a liquid sample and then eject to. To achieve this, a piston (18) and sleeve (14) are displaced together downwardly to move a pair of port-holes (10, 11) in the piston out of register with a pair of ports (2, 3) in the sleeve wall to as to trap the liquid sample in an internal space in the piston interconnecting the two portholes (10, 11). In this position the sleeve (14) is restrained against further downward movement.
On continuing downward advancement of the piston, the trapped liquid sample is ejected out of the internal space through a passageway (21) in the piston for analysis.
The sampler is ideally suited for taking oil sample from a pipeline and can be designed for isokinetic sampling.

Description

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Il SAMPLER ~

Thls invention relate~ to a 3ampler for the extractlon Or fluid sample~ in rlowlng or static ~tate.
There 13 a ereat need to 3ample liquid, ror examp~e, crude oil undzr sub~tantially isokinetic condltlons. Many devices exl~ts but they do not take representat~ve ~amples becau3e they do not operate ln accordance with ~okinetic principle3. Somel for example, use c~mplex bypass loop~ with mot~r drlven circulating pumps. Some lack racilities ror po~sible eJection Or the sample and have a loneer and complex rlow path to the sample receptacles. Others are not bi-directional and others are e~tremely complex unit~ with ~any component parts. Some have nD racilities ror chan~ing the quantity of sample~.
For 3ampling under non-isokinetic condition~, samplers are known which are Or relati~ely simple construction~ One such sampler employs a block Or rubbery material with a cavity therein in which a liquid sample is trapped by an advancing piston and then expelled through a passage way ~n the piston as the piston s~uashes the cavity and the rubbery block ~lat~ However, with sufriciently prolonged u~e, the rubbery material deteriDrates and eventually rails and, ln any case, is generally unsuitable for high temperature use which can for example be encountered when sampling North Sea oil. In another samyler, a closed-ended cylinder is used in place Or the rubbery block but the hydraulic shock-waves produced when the piston enters the open end Or the cylinder, ]particularly at high ~ampling rates9 can rupture the internal seals and even cau~e severe internal damage.

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Another known ~a~pline device, which i8 not s~bJect to the dl~advantage Ju~t mentloned, operates wlth rotary action to trap a llquid sa~ple in a cylindrical sample cup by rotatlng a cylindrlcal sleeve intD a ~ir~t position, and then causing a pi3ton ln the ~ample chamber to e~ect the trapped ~ample through a pa~sageway leading rrom the sample chamber. This sampler, ho~ever, surfers from a number of drawbacks9 viz., constructional complexity, large bearing 3urraces in ~liding contact leading to increased wear and ri~k Or ~amming caused by dirt, practical sealing difficultieq, and lim~tation on the sampling rate caused by the piston displacement speed during sample expulsion being governed by the line pressure Or the pipe line or similar into which the ~ampler iq fitted.
The present inYention i~ concerned with proYiding a sampling device which is of ~imple con~truction, has a long and trouble ~ree ~er~ice lifeJ is ~ultable for high temperature use and can be ~dapted for isokinetic sampling.
In ~ummary, the invention provide~ a fluid sampler comprising a casing having two ports in the wall thereof 90 that the casing can be arranged in com~un~cation with a pipeline. One Or the ports enables fluid in the pipeline to flow into the sampler and the other port enables fluid in the sampler to rlow out Or it. A sleeve is reciprocably ~ounted wlthin the casing and a piston is reciprocably mounted within the sleeve.

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Actuator means are provided which are operable for ~electlvely c~anelne the relatlve positlons Or the caslng, sleeve and plston ~uch that in a firAt relative po~ltlon comml~nication is provlded through a chamber between the two port~ ~o that the chamber becomes charged with llqu1d ln the pipeline. In a second relative po~ition a sample Or the rluid is i301ated from khe rluid flow wlthln a space bounded by the piston, sleeve and caslng. In a thlrd relative po3ition9 the volume Or the space i~
reduced ~or discharging rluid in the space through a passageway in communlcation with ~pace. ThiS rluid sampler is simple ~n con~truction, comprising essentially only three main components, viz., the casing, its sleeve and the p~ton, these being provided with the actuator means which can be sited at any convenient location. Becau~e none o~ the components need3 to consist Or a rubbery material, they can-be made of materials such as metal which are resistant to the temperature of hot liquids and can be designed to have a very long service llre. Furthermore, because Or the reciprocating, a3 opposed to rotary9 action of the sleeve and pi~ton, sliding ~riction can be produced, and the likelihood of ~amminB due to inBreq~ Or dirt i~ lessened. Because both the piston and sleeve have a reciprocating movement, the design o~ the actuator mean9 i9 simpler than ir it were to have to reciprocate the piston but rotationally oscillate the sleeve. ~nother advantage over the prior art rotary action sampler where the piston is displaced under`
tbe action Or line pressure is that because the piston is reciprocated by the action Or the actuator means, the sampler can be desiKned ror much hi~her ~ampling rates.

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Prerer~bly~ the sampler ~9 ~ dc ~en~d ~at lt c~n b~ Ir,~(:r~d through an aperture in the plpellne and ~u~pended there ~o tha~ f~uid can flow lnto one port and can also rlow out throueh the oth~r port.
Thls arran~ement makes the rluld sampler e~pecially ~ultable ror sampllng oil rlowing in an oll pipeline.
In one convenient arrangement, a compresslon ~prln~, located between the p~ston ~leeve and a shoulder, formed within the casing, and acting at its lower end on a top part o~ the sleeve, ls provided ror bia~-ing the sleeve toward~ a position in which the fluid sample is isolated within said space, the spring being in it3 state Or greatest compression when the casing, sleeve and the piston are in their first relative positionsO This ~rrangement is compact ~nd utllises the spring force to assi~t in rapidly di3placing the sleeve relative to the casing during changeover of the relative positlons Or the ca~ing~ sleeve and piston away from the first relative position.
Suitably, the body, 3ieeve and pi~ton are of circular cross-section and the two port~ are diametrically opposite one another. Thi~
assists in providin~ simplicity of manufacture and asse~bly and linear flow of liquid in the pipeline through the ~luid sampler.
For achieving isokinetlc flow coDditions, the shape and design Or the ports and the chamber are chosen 90 that the ~low *hrouEh the rluid sampler, when the casing, sleeve and piston are in their rirst relative po3ition, is substantially isokinetic. Ihis can be achieved in a ~luid sampler in which the'casing and piston provide flat sur~aces which are sub3tantially at right angles to the longitudinal axis of the sleeve and de~ine opposite wall~ Or the chamber when the casing, sleeve and piston are in thelr ~lrst relative po.sition, the planes of the flat ~urface~ lining up w:lth the ports at the perimeters thereor such that rluid flowing throuKh one port and out through the other port has a substantially uninterrupted path and wlthout there being substantially any cavities in the chamber.

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ln onc particular arraneemcnt, bo~h ror is~kinc~c ~nd rJ~n-1s~klnetlc ~ampllne, the ~all Or the 31eeve 1~ rorm~d with t~ port~oles whlch alien one wlth each Or the two pvrt~ when the caslng~ sleeve and plston are ln their rirst relative po~itlon, each p~rt 1~ the ~ame 3ize as the porthole with which lt register~, and the arrangement Or the sleeve and piston i9 such that they are moved together by the actuator mean~ relatlve to the ca3ing during the chang~over from the fir3t to the second relatlve positions of the casin~, sleeve and pi~ton b~t the pi~on alone i9 moved further, in the Longitudinal directlon Or the sleeve, durinK changeover rrom the second to the third relatlve positions.
This arrangement is advantageouq in that it merely requires the actuator means to take the ~rm of a double-acting actuat~r and a lost-motion device which becomeq operative after the ~leeve ha~ been arrested in the second relative poqition Or the casing, sleeve and piston. To assist in achieving isokinetic ~ampling with such a sampler, the ~leeve can be made cylindrical and the-chamber bounded by two tran~verse circular plates fixed to the inside Or the sleeve and meeting the inner ~urface of the sleeve at the extremities of the porthole.
The caslng ~ay include a plug unted in the botkom region of the casing and having a flat ~urface constituting a b~undary wall o~ the chamber. The plug is advantageous in that it can be removed for enabling the interior Or the chamber and the neighbouring internal regions to be inspected.
A stop can be provided ~or arresting the sleeve rrom further movement in the same direction after arriving in the ~econd relative position Or the casing, 31eeve and piston ~rom the first relat~ve position.
The stop constitutes a simple and e~reotive way of arre~ting the motlon Or the sleeve.

One way Or handlin~ and collecting the sample e~ected from the chamber i~ ror the said paA~a~eway to be rormed ln the plston and the piston provid2d with a p~ston rod which extends to the inner ~leeve~ the pas~age~ay beine extended to pa~ within the piston rod in the lonei-tudlnal dlrection thereof and communicatlne vla a rlexible tube or plpe with a receptacle for receiving rluid di~charged from the sampler.
One prererred embodiment, ~hich iY specially de~iened for lsokinetic ~ampling, comprlses a ca~ing having two port~ in the wall thereo~, the casing being capable in communlcation with the pipeline 90 that fluid in the pipeline can rlow into one port and out of the other port, the axis of the pipeline being substantially at right angles to the axis of the casing. A sleeve is reciprocatable within the caslnB and i9 provided with two portholes capable of aliening wlth the port~ in the casing/ each porthole being substantially no greater in ~ze than it~
ad~acent port. The slee~e haq a chamber formed th~rein, at least ~hen the port~ and portholes are aligned, the boundary Or the chamber comprising a pair Or wall~, the plane~ Or which are sub~tantially at right angles to the longitudinal axis o~ the ~lee~e and which when the portholes are aligned with the ports of the casing meet at the portholes at the perimeter~ thereof so that rluid ~lowing through one aligned port and porthole ~Id out through the other aligned porthole and port has a substantially uninterrupted path and without there being substantially any cavities in the chamber. Finally, means are provided for removing ~rom the chamber fluid which has been collected there.

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In U91n~ ~he sa~pler the sleeve 1~ ralsed or lowered ~ that both p~rta and porthole~ ~re aligned. At thls ~taee rluid i~ flo~lng through the sampler, enterlng throueh one p~rt Or the casing and leavin~ by the other port. ~his rlOw i9 ~t constat ~elocity and at the same velocity as the flow of fluid pas~in~ around the ca~ing.
Therearter~ the sleeve i~ ~hifted 90 that there i8 no l~n~r any pa3sage of fluld through the sampler i~e. 7 the ports ln the casine are blocked by the walls Or the sleeve. A sample of fluld is thererore trapped ln the chamber and it can be removed rrom this chamber by the mean~ proYided and 1t can then be analysed, lr de~ired.
In its simple~t rorm the casing and sleeve are of circular cross-section and the ports and portholes are circular or oval. U~ually the ports and portholes are dlametrically opposite one another. There should be means to prevent relative rotation Or the ca~ing and the sleeve 30 a~ to prevent the posslbility that the ports and portholes are misaligned radially. - Qne such means comprise~ a protru~ion in tbe ca~ing mating with a longitudinal channel in the slee~e. Alternatively the easing can have a longitudinal ~lot or channel and the casing can have a protruslon.
It is especially convenient i~ the sleeve i~ cylindrical and the chamber rormed by two transverse circular plates fixed to the inside Or the ~leeve and meetlng the inner ~ur~ace Or the sleeve at the extremities Or the portholes, i.e., tanEentially. In thi~ manner, there is no ~pread Or the fluid in the longitudinal direction of the sleeve as the fluid ~lows straight throueh the chamber in a direction which ~ at right angles to the longitudinal axi~ of the casin~ and 3~

~leeve. Also th~ rluld ha~ an unlnterrupted flo~ throueh the ca~ing and sleeve. Finally there are the m~ans for removlng ~rom the cha~ber fluid whlch has been collected ln the ehamber. ~he simple~t form would be a tap in the bottom Or the chamber whlch could be ~hut when the chamber is being u~ed to collect f`luld and opened when fluid no loneer rlows ~nto the chamber and it is desired to collect the fluld .
Although the above brie~ly de~crlbed sampler can be used for var~ouq applicationq, in practice lt has been found necessary to use a rather more sophisticated design Or 3ampler. Accordingly such a fluid sampler comprises a casine havine a stop on the internal ~urrace thereof and havin~ two ports in the wall thereor, the casing being capable Or be~nB in communication with the pipeline so that fluid in the pipeline can ~low into one port and out Or the other port, the axis of the pipeline being substantially at right angles to the axi~ Or the casing, the pi~ton sleeve having a base and in slidable contact with the inner ~urface of said casing and having porthole~ therein adjacent to the base thereof capable of aligning ~ith the ports of the casing, each porthole beiDg substantially no greater in ~ize than its aligned port, a piston in ~lidable contact ~ith the inner surrace of ~aid sleeve moYable therein from a po~ition ~ust clear Or the portholes9 past the porthole~ to a po~it~on in contact with the ba~e Or the piston sleeve, a piston~having a passageway therein extending the length thereof, and resllient means enabling pressure on the piston to move the sleeve and piston past the ports in the oasing until the base Or the piston sleeves cDntact~ the stop of the caslng when ~urther pressure on the plston ~orces the piston into contact with the base Or the piston ~leeve..

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g When depres31n~ the pl~ton and sle~ve in us1rlg the prererred sampler o~ the lnventlon, the ports Or the easlng are elo~ed by the plston ~leeve and a ~ample Or rluld is i~olated in the volume bounded by the base Or the piston sleeve, the inner ~urface Or the c~sing and the lower end Or the piqton. On rurther depre~sine the plqton 90 that it contacts the base Or the piston sleeve the fluid is fvrced up through the passageway in the pi~ton when it can be collected in a recepta~le~
In thi~ manner only a sinele do~nward short ~troke is required.
I~ is preferred but not es~ential khat the casing, sleeve and piston are circular in cross-section. Thi~ ~orm is cheaper to make and less likely to result in ~am~ing than if the cross-section were square or rectangular. However, when the cross-section is circular there are means to ensure that there is no relative rotati~n between the sleeve and the casinB so that the ports and portholes can always be aligned by shi~ting the ~leeve relatlve to the casing along their longitudinal axis. Generally a mating longitudinal channel and protrusion achieves this result.
Generally the casing should be elongate, i~e., be Or a length considerably greater than lts diameter lr cylindrical or lts greatest cross-~ectional dimension i~ not circular in cro~ sectlon.

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The two port3 ~re u~ually near but not at the end o~ the ¢a31ng 9~ that there i~ ~pace ror the ~leeve to be depre~sed so a~ to close the ports in the cas~ng. The casin~ has a ~top on the lnternal wall thereor 30 as to preYent the pl3ton sleeve rrom ~liding pa~t the end o~ the ca~ing and to enable rurther pre~ure on the piston to force the plston lnto contact wlth the ba~e Or the piston sleeve. Thl~ stop c~n be ~y lug or lnternal protru~ion, prererably at least two, but the mo~t prererred 3top 1~ a ~eat collar, the outer dimensions Or which are qubstantially the same a~ the ~nternal dimenslon~ of the ca~ing. A particularly preferred form when the casing i~ cylindrical is a collar with an external screw thread capable of` ~crewing into the base of the ca-qing. It is essential that the stop does not close the end Or the casing completely because it is necessary to permit displacement o~ any fluid trapped below the base o~ the piston sleeYe ~hen the plston sleeve descends. Hence a seat collar ls particularly suitable.
The two ports are prererably aligned i.e., diametrically opposite one another ir the ca~ing is cylindrical. HoHever this is not ab~olutely necessary and the ports could be located ~o that they co-operate ~ith two ends of a pipeline which are at rlght aneles to one another. It is particularly desirable however that the axis of the pipeline is substantially at right angles to the axls o~ the casing, the ax~s Or the casing being the direction in which pi~ton and piston sleeve reciprocate.

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Il de~ired ~ch port cnn be provided with B flan~e ~ that they can be bolted to.flRngeD.on the end6 of the p;peline. Pre~erably a ~al i6 interpDsed between the flange on ~ port and on-the pipeline.
. It is preferred however for the ~pler to be design~d so that ~t can be inserted through a~ aperture in the pipeiine and suspended in the pipeline.so that fluid ean llow through one port and out throu~h the other port; Ihi~.can be achieved by fixing a socket to the-aperture, the inner surfac~ of the socket having a screw thread. I~e upper portion of the casing of the.sampler can be provided with a.screw thread which co-operates with that of t~e ~ocket. AltPrnativeiy the upper end Df the sampler can screw into a block, the upper end of the ~lock having the yoke of a pneumatic actuator attached thereto.
. The piston sleeve must be capable of sliding within the casing and there should be only the ~inimum gap between the outer surface of the sleeve and.*he inner surface of the casi~g. I'he sleeve serves as a valve to block the ports.of the casing and at the same time trap a sa~ple of flui~ flowing-~hrough~he pipeline.
There are porthol~es in the s~eeve designed to be capable-of aligning or Tegistering wi~h the ports i~.the cas;ng. This alignment is-achieved by shifting the:sleeve longitudi~ally ~ithin.the casing l~ntil.the ports aod porthDles are level with each other~ Each porthole should preferably be the same ~ize as the port with which it registers. Prefersbly all portholes and ports should be oval~ the longer axis being transverse to the lon~itudinal.axes~.of the sleeve and casing~ Less desirably the por~s aDd portholes are circular, ~uare or rectangular.

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The lower end of the ~leeve a6 provided with a bnse. Pre~rnbly thi6 i8 ~chievea by thre~din~ internally the lower end of the slePve and fitting it with ~ ~ealing plug.
Slidea~le with;~ the piston ~ieeve is a pi~ton. There i~ preferably also a pi~ton rod ~lso havin~ a p~ssageway extending the length thereof.
~referably the pistoD ~leeve i6 provided with an end section opposite the base thereof:so that this piston rod can pass through an aperture in the top end section of the piston sleeve. In order to equalise press~re pi~tDn ~leeves with end member~ should be provided with one or more apertures, the~e preferably being located in the member itselfO
The passage~ay WithiD the p;ston (and piston rod) and extending the length thereof is preferably`located centrally of the cross-section of the piston i.e. along the axis ~hen ca6ing, piston sleeve and pis~on have circular cross-~ection. The ~urpose of thi~ passageway is to allow the ~ample of fluid to.be forced.out of ~he sampler when the-pistoR is forced.i~to.-con~a~ with the base of ~he sleeve.
. The passageway i~ the piston or ~i.s~o~ rod is preferabl~ provided with.a Don-return valve ~or ex~mple ball ~nd ~pring ~o ~hat there îs no ~low o~ ~he fluid being sampled passing ~o a receptacle or drnin back of ~ample.~luid.from.a.receptacle ~hen the ~ampler.is no~ being used.
The ~ilien~.means are preferably a compression sprin~ ~hi.oh m~y be located:between.the pistoD sleeve aDd a shoulder formed on the pi6ton Iod or..a.shoulder formed withi~ the casing. ~he shoulder formed on.the piston rod if of the same diameter as the inDer diameter o~ the casing ~an also act ~s a guide disc.for the pisto.n ~od. If ~he should2r ~ormed on the.piston rod ;c i~ ~lideable contact ~i~h the interior o~

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the ~a~ing then it ~hould.be pr~vided with ~ne lDr ~re ~pertures ~o a~
tv equslise the pressu~e both ~ides of the ~houlder.
~ he pass~geway should communicate with ~ receptacle ~or the Is~mple.
Since the piæton .move6 / the connecting tobe or pipe between the pas~ageway and receptacle will usually be flexible. Alternatively it i~ possible to haYe.an elongated aperture from the passageway in communication with the connecting tube ~r pipe such that w;th the further move~eDt of the piston after the piston sleeve has contactea the closed end there is s~ill communication between the passageway and said tube or pipe.
..To.obtain a sample rom fluid flowiDg in a pipeline after the sampler has been positioned in the pipeline with the portholes of the sleeve aligned.~ith the ports of . the casing, pressure is exerted on the piston ~ia the piston.Tod. .~his force~ down the piston a~d piston slee~e, the latter clos;ng the ports o~ the casingS the pistGn sleeve eveDtually contacting the stop of the casi~ urther pressure on the piston forc~s.the piston do~n.f~lrther until it contacts the base o~ the piston sleeve~ Ae ~he.~ame time the Isample of ~luid.originally;-trapped ~ithin.the con~ines ~f.the piston ~leeve i~ fDrced out of the ~aMpler ~hrough the passageway within:the piston and pi~ton rod.
Usually.the fluid will be a liquid, for example oil, but it can be .a gas. I~ he case where ~ases are sampled it is preferred that the wall of ~he piston be ~rovided with nn "O-ring" seal so ~hat ~here is no leaka~e between the pisto~.and piston ~eeve and also for "O-ri~gi' seals tu.be provided ~etween the piston rod n~d sleeve to prevent leakage near the outlet ~ro~ the passageway.to the tube or pipe connected to the receptaele. .In ~nct ~he presence of ~D O-ri~ ~eal~could be desirable even when aampliDg 1;quids.
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The ~ampler may be operated by a re1AtiYely s1mple c~n~rol ~ystem involvlne the u3e o~ compres~ed alr, a d1aphragm and solenoid Yalves as wlll be descrlbed later.
The advantaees o~ the sampler are manifold. It can ensure that it operate~ in accordance with lsokinetic princ~ple~ and there are very rew moving parts or ~mall complex components. ~here 18 unlimlted compression po~er for po~itive in~ection. Al~o there i9 bi-directional operation~ and the quantity cr samp1e may be ad~u~ted on-line~ Furthermore the sampler may be ea~ily coupled to a ~imple pneumatic pulse integrator to log the number o~ samples taken~
A preferred rorm Or the fluid ~ampler Or the invention i3 now de~cribed, by way o~ example, with reference to the drawings in which :
Fig. 1 show~ a vie~ in part ~ection, o~ the top portlon Or a sampler ;
Fig. 2 hows a ~ection throu~h the bottom port~on ~r the sampler Or Fig. 1 ;
Fig. 3 to 5 ~ho~ di~grammatically the various positions of the pi9$0n and p~3ton sleeve within the ca~inB as the piston and piston ~leeve are depressed;
Fig, 6 to ~ show the sequence o~ operations wher~in the sample Or rluid is automatically collected from a pipeline and discharged from the ~ampler of Fig. 1 to 5.
Rererrine to Fig. 1 to 5 the cylindrical casing 1 is provided with two oval port~ 2 and 3. The ca~ing 1 i9 provided with a ~eat ring 7 ~crewed into the bottom thereof.

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Slldeable withln casing 1 i9 the pl~qton ~leeve 14, the lower end of which ~s internally thr~aded and ~itted w'Lth a seallng plu~ 9. The ~sleeve 14 ha~ tw~ apertures 15 and '16 and to equali~e pres~ure each slde Or the 31eeve and a central apert~re 17 to accommodate the piston rod 19.
The ~leeve 14 al90 has two diametrically opposed oval porthol~ 10 and 1~ the ~ame size as the ports 2 and 3 and capable o~ registering therewith. Relative rotation bet~en casing 1 and ~leeve 14 i8 prevented by a protru~ion pin 68 communicating with a longitudinal channel in sleeve 14.
The piqton 18 into which piston rod 19 is ~crewed is provided with an 0-ring ~eal 20 and an axially located passageway 21 ~hich extends the length Or the pi~stoD 18 and plqton rod 19 . ~here are 0-rir~ ~seals 38 making a fluid-tight ~eal when the pi~ton rod ~lide~s in the block 35 form'Lng a shoulder 40.
Located within the pa~ssageway 21 i9 a non-return Yalve compri~qing a ball 25 and a compression spring 26. Between the top Or the pl~ton sleeve 14 and the shoulder 40 formed in the ca~sing 1 i~ a compression spring 27. Aperture~s 28 ~nd 29 are ~or ~qualis~ng pressur~.
Further up the casing there iB an lnspection plug 41 and there are also some ~urther O~ring seals 39 at the top of thç casing.
Surmounting the casing 1 is a sa~pler tran~qrer block 45 which is ~crewed onto casing 1 by mean~ of ~screw thread 46. A standard pneumatic actuator (includinK yoke 33) is indicated in Fi~. 1 generally as 44 and i~
~crewed into ~ampl~er tran~rer block 46 by thread 47.
~ here iB also an Lsolatlon Yalve 50 whereby when the ~ampler i~
removed ~rom the piLpeline 6 the aperture at the top Or the pipeline can be sealed Orr.

The fi~mple ~f ~luid which i6 col~ec~ed em~r~e~ fro~ the top of th~
passa~eway 21 by means of nn e~ongated ~perture 42 which i~ ~lway6 in CO~DUniCatiOn with ~onduit 43 which i~ connected to pipe-line 57.
Leakage of fluid in transferring from pass3g~way 21 to condu;t 43 i~
prevented by the 0-ring sea~s 39.
The stroke adjustment whereby the volume of sample can be altered is by means ~f the nut6 48 and 49 indicated in ~ig. lo Referring.t~ ~ig. 3 to ~ to obtain a sample it is necessary to move the piston 18 and piston slee~e 14 upwards so ~hat the portholes 10 and.ll register with.the ports.2 and 3~ respectively9.as shown in ~ig. 3.
The presence ~f the compre~sion spring 27 located ~etween the shoulder 40.and the top of piston sleeve 14 ~eans that wheD the piston rod 1~ is moved upwards~ both piston 18 ~nd sleeve 14 asceDd together.
Likewnse when the piston rod 1~ is.depressed b~th piston 18 ~nd sleeve 14 descend to~ether. Therea~ter it is necessary ~o exert further force, forciDg down the pist~ 18 aDd piston sleeve 14 until the sealing plug 9 o~ the latter.contacts the seat ~ing 7 o~ the caslng 1 as shown i~ Fig.
4.
. .The sample is trapped between the-bottom o~ the pis~on 18 and the plug 9 of the piston sieeve 14. Further pressure on the pis~on ~od 19 results lD t~e piston 18 being .~orced down ln~o contact with the plug 9 af the sleeve lb as.shown iD ~ig. S, thereby forcing`the sample up the passageway 21, ~hrou~h aperture 4~, conduit 43, p;pe-line 57 a~d to the sample ~ceptacle.

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R~errin~ ~ow to ~ig. 6 ~ sigllal ~rom contro]ling e~emcn~L via short ~ime de~ay unit.(not shown) eonnec&ed to li~e 51 immediately eneJ~i~es so~eno;d S~. Tbi~ energi~in~ of the ~olenoid 52 cause~ ~pply air ~rom reservDir 53 to pass to the di~p~ragm 549 this diaphra~m 54 and a compression spring 58 forming part of a stan~ard pneumatic aet~lator~
Since this diaphragm 54.is.pressurised this causes the pi~ton rod 19~
piston 18 and piston s~eeve 14 to move downwards togethe~, compressing compression spring 58~
Referxing t~ ~ig. 7:when the pressure in the diaphrag~ 54 ~eaches.
the region o~ 0;85 kg/cm2 the sealing plug 9 of the sleeve 14 will be firmly seated on the seat ring 7 of the casing 1~ the sleeve holding the ~aptive sample.
Referring to Fi~. 8 as the pressure of the diaphra~m S4 rises the pistoD 14 is DOW driveD down~ards, compressin~ the fluid and transferring it through line 57 ~o the sample receptacle~
Just as full air pressure is applied to the diaphragm 54 the short tim~ delay unit.has come to the end ~f ~he ti~e cycle and the eleetrical sigDai is removed from .the s~leDoia valve`S2. The de-energising of the soleDoid 52 vents the air.from diaphra~m 54 via the vent (Y~ on the solenoid valve 52 and the compression sprin~ 58 causes the piston rod l9,..piston 18 aDd piston sleeve 14 ~o mo~e upward.

Claims (16)

1. The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-l. A fluid sampler comprising a casing having two ports in the wall thereof so that the casing can be arranged in communication with a pipeline, one of the ports enabling fluid in the pipeline to flow into the sampler and the other port enabling fluid in the sampler to flow out of it, a sample isolating sleeve linearly reciprocably mounted within the casing, a sample ejecting piston linearly reciprocably mounted within the sleeve, and actuator means operable for selectively changing the relative axial positions of the casing, sleeve and piston such that in a first relative axial position, the sleeve allows communi-cation between the two ports, in a second relative axial position the sleeve cuts off communication between the two ports and thereby isolates a sample of the fluid from the fluid flow within an internal space bounded by the piston, sleeve and casing, and in a third relative axial position the volume of said space is reduced for forcibly discharging fluid in said space from the fluid sampler through a passageway in communication with said space.
2. 2. A fluid sampler according to claim 1, wherein a compression spring, which is located between said sleeve and a shoulder, formed within said casing, and acts at its lower end on a top part of said sleeve, is provided for biasing the sleeve towards a position in which the fluid sample is isolated within said space, the spring being in its state of greatest compression when the casing, sleeve and piston are in their first relative position.
3. 3. A fluid sampler according to claim 1 or 2, which is so designed that it can be inserted through an aperture in the pipeline and suspended in the pipeline so that fluid can flow into one port and can also flow out through the other port.
4. 4. A fluid sampler according to claim 1, wherein said casing, sleeve and piston are of circular cross-section and the two ports are diametrically opposite one another.
5. 5. A fluid sampler according to claim 1, 2 or 4, wherein the casing and piston provide flat surfaces which are substantially at right angles to the longi-tudinal axis of the sleeve and define opposite walls of said chamber when the casing, sleeve and piston are in their first relative position, the planes of said flat surfaces lining up with the ports at the perimeters thereof such that fluid flowing through one port and out through the other port has a sub-stantially uninterrupted path and without there being substantially any cavities in the chamber.
6. 6. A fluid sampler according to claim 1, 2 or 4, wherein the shape and design of said ports and said chamber is such that the flow through the fluid sampler, when the casing, sleeve and piston are in their first relative position, is substantially isokinetic.
7. 7. A fluid sampler according to claim 1, 2 or 4, wherein the wall of the sleeve is formed with two portholes which align one with each of said two ports when the casing, sleeve and piston are in their first relative position, each port is the same size as the porthole with which it registers, and the arrangement of the sleeve and piston is such that they are moved together by the actuator means relative to the casing during the changeover from the first to the second relative positions of the casing, sleeve and piston, but the piston alone is moved further, in the longi-tudinal direction of the sleeve, during changeover from the second to the third relative position.
8. 8. A fluid sampler according to claim 1, 2 or 4, wherein the wall of the sleeve is formed with two portholes which align one with each of said two ports when the casing, sleeve and piston are in their first relative position, each port is the same size as the porthole with which it registers, and the arrangement of the sleeve and piston is such that they are moved together by the actuator means relative to the casing during the changeover from the first to the second relative positions of the casing, sleeve and piston, but the piston alone is moved further, in the longi-tudinal direction of the sleeve, during changeover from the second to the third relative position, and wherein the sleeve is cylindrical and the chamber is bounded by two transverse circular plates fixed to the inside of the sleeve and meeting the inner surface of the sleeve at the extremities of the portholes.
9. 9. A fluid sampler according to claim 1, 2 or 4, wherein the casing includes a plug mounted in the bottom region of the casing and having a flat surface constituting a boundary wall of said chamber.
10. 10. A fluid sampler according to claim 1, 2 or 4, wherein a stop is provided for arresting the sleeve from further movement in the same direction after arriving in the second relative position of the casing, sleeve and piston from the first relative position.
11. 11. A fluid sampler according to claim 1, 2 or 4, wherein said passageway is formed in the piston and the piston is provided with a piston rod which extends within the sleeve, said passageway being extended to pass within the piston rod in the longitudinal direction thereof and communicating via a flexible tube or pipe with a receptacle for receiving fluid discharged from the sampler.
12. 12. A fluid sampler comprising a casing having two ports in the wall thereof, the casing being capable of being in communication with a pipeline so that fluid in the pipeline can flow into one port and out of the other port, the axis of the pipeline being substan-tially at right angles to the axis of the casing, a sleeve linearly reciprocable within the casing pro-vided with two portholes capable of aligning with the ports in the casing, each porthole being substantially no greater in size than its adjacent port, said sleeve having a chamber formed therein, at least when said ports and portholes are aligned, the boundary of the chamber comprising a pair of walls, the planes of which are substantially at right angles to the longitudinal axis of the sleeve and which when the portholes are aligned with the ports of the casing, meet the port-holes at the perimeters thereof so that fluid flowing through one aligned port and porthole and out through the other aligned porthole and port has a substan-tially uninterrupted path and without there being substantially any cavities to create dead fluid flow areas in the chamber, and means for removing from the chamber fluid which has been collected in the chamber.
13. 13. A sampler according to claim 12, wherein the sleeve is cylindrical and the chamber is formed by two transverse circular plates fixed to the inside of the sleeve and meeting the inner surface of the sleeve at the extremities of the portholes.
14. 14. A fluid sampler comprising a casing having a stop on the internal surface thereof and having two ports in the walls thereof, the casing being capable of being in communication with a pipeline so that fluid in the pipeline can flow into one port and out of the other port, the axis of the pipeline being substantially at right angles to the axis of the casing, a piston sleeve having a base and in axially slideable contact with the inner surface of said casing and having portholes therein adjacent to the base thereof capable of aligning with the ports of the casing, each port-hole being substantially no greater in size than its aligned port, a linearly reciprocable piston in slideable contact with the inner surface of said sleeve movable therein from a position just clear of the portholes, past the portholes to a position in contact with the base of the piston sleeve, the piston having a passageway therein extending the length thereof and resilient means enabling pressure on the piston to move the sleeve and piston past the ports in the casing until the base of the piston sleeve contacts the stop of the casing when further pressure on the piston forces the piston into contact with the base of the piston sleeve.
15. 15. A sampler according to claim 14 wherein the piston has an end section opposite the base thereof and the piston is connected to a piston rod having a passageway therein extending the length thereof and in communication with the passageway in the piston, said piston rod passing through an aperture in the end section of the sleeve.
16. 16. A sampler according to claim 14 or 15, wherein the passageway in the piston rod terminates in an elongated aperture which through-out the stroke of the piston is always in communication with a conduit capable of being connected to a receptacle for the sample.