Abstract:
A medical infusion pump is disclosed which provides for greatly improved accuracy in the delivery of medicaments to a patient. Among the various features included in the instant invention is a pumping body which serves to deform and reform a tube so as to maintain the initial cross-section thereof and thereby preserve the output accuracy of the pump. Also disclosed with regard to the pumping body is a wholly mechanical synchronization of the pumping body and valves associated therewith and coactive with the aforementioned synchronization a mechanical linearization of output of the pumping body per each pumping cycle. Additionally, several features which serve to enhance the utility of the instant invention are also included therein among which is an associated assembly operative to automatically load or disload a tube or IV set into or out of the pumping body. Associated with the assembly operative to automatically load or disload a tube and disclosed herein is an assembly operative to selectively open or close a slide clamp associated with the tube in such a way as to ensure that the tube is occluded such that in combination with the valves associated with the pumping body, a condition of free-flow of medicament is never realized. Additionally disclosed are sensor housings adapted to measure various quantities associated with fluid flowing through the tube wherein the housings are with associated components adapted to achieve a substantially normal orientation with respect to the sidewall of the tube and in the achieving of such normal orientation, expressing an essentially zero elastic stress gradient across the tube.

Description:
This is a divisional of application Ser. No. 08/672,367, now U.S. Pat. No. 5,892,841 filed on Jun. 24, 1996. 
    
    
     FIELD OF THE INVENTION 
     The instant invention relates to volumetric infusion pumps for parenteral delivery of fluids in a medical environment. 
     BACKGROUND OF THE INVENTION 
     Previous medical infusion pumps have comprehended a wide variety of methods for pumping fluids into a patient. The most common of these methods has been a peristaltic pump. In a peristaltic pump, a plurality of actuators or fingers serve to massage a parenteral fluid delivery tube in a substantially linear progression. The primary problem associated with peristaltic pumping technology is that the tube is repeatedly deformed in an identical manner, thereby over the course of time destroying the elastic recovery properties of the tube so that the tube maintains a compressed aspect. This destruction of the elastic recovery properties of the tube results in the volumetric output of the pump changing markedly over time. Another common type of pump used in the volumetric delivery of medical fluids is commonly known as a cassette pump. Although cassette pumps do not display the fairly rapid degradation of performance as evidenced in a peristaltic pump, they require a fairly elaborate pump cassette to be integrated with the IV tube. This added expense of having to change a cassette along with an IV set every time an operator wishes to change the medicament delivered to the patient, significantly raises the cost of patient care. Additionally, as both peristaltic and cassette pumps, as well as other infusion devices present in the market, require a fairly elaborate knowledge of the specific pumping device to ensure that the IV set is loaded appropriately, generally medical infusion pumps were purely the purview of the nursing or medical staff in a hospital environment. 
     The necessity of manually loading a set into an IV pump is universal in the art. Generally when a standard IV set is used, in addition to the rapid degradation of accuracy mentioned above, great difficulty is encountered in correctly loading the set into those pumps presently in the art. The state of the art of loading technology as it relates to medical infusion pumps has progressed only to the state of enclosing the IV tube between a pumping device and a door or cover and adding progressively more elaborate sensors and alarms to assure that the tube is correctly loaded into the pump. Even so, loading errors occur with regularity requiring great efforts on the part of hospital staffs to ensure that critical errors are minimized. 
     The state of the art in infusion pumps also includes the requirement of manually assuring that a free-flow condition of medicament does not occur when an IV set is installed or removed from a pump. Although hospital staffs exercise great care and diligence in their attempts to assure that free-flow conditions do not occur, a demonstrable need for additional precautions directed to the prevention of a free-flow condition has been a continuous concern of healthcare workers. 
     U.S. Pat. No. 5,199,852 to Danby discloses a pumping arrangement including a squeezing device for deforming a length of pliant tubing first in one direction locally to reduce its volume, and in another direction tending to restore its original cross-section and on either side of the squeezing device, inlet and outlet valves which operate by occluding the tubing. The control of the valves is by a plurality of motors controlled by a microprocessor. 
     U.S. Pat. No. 5,151,091 to Danby et al. discloses a pumping device which alternately compresses and reforms a section of tubing. 
     U.S. Pat. No. 5,055,001 to Natwick et al. discloses an infusion pump with spring controlled valves designed to open at a specific predetermined pressure. 
     U.S. Pat. No. 3,489,097 to Gemeinhardt discloses a flexible tube pump having a unitary fixture operative to act as an inlet and outlet valve and a pumping body located therebetween, driven off an eccentric. 
     U.S. Pat. No. 2,922,379 to Schultz discloses a multi-line pump having an inlet and an outlet valve mechanism and a pumping body located therebetween wherein both the inlet valve mechanism and the outlet valve mechanism are driven from a single cam. 
     U.S. Pat. No. 3,359,910 to Latham discloses a cam driven pump having inlet and outlet valves driven from a single cam and a pump body driven by an eccentric co-rotating with the single cam. 
     U.S. Pat. No. 4,239,464 to Hein discloses a blood pump having an inlet and outlet plunger serving as valves and a displacement plunger located therebetween. 
     U.S. Pat. No. 5,364,242 to Olson describes a drug pump having at least one rotatable cam and a reciprocally mounted follower engaged with the cam in a tube which is compressed by the follower during rotation of the cam. In the embodiment disclosed there are three cams. 
     U.S. Pat. No. 5,131,816 to Brown et al. discloses a infusion pump containing a plurality of linear peristaltic pumps and includes a position encoder mounted on the pump motor shaft to determine when the shaft has reached the stop position in the pump cycle. 
     U.S. Pat. No. 4,950,245 to Brown et al. discloses a multiple pump which is individually controlled by a programmable controller within the pump. 
     U.S. Pat. No. 4,273,121 to Jassawalla discloses a medical infusion system including a cassette and a deformable diaphragm and inlet and outlet windows which are occludable to pump the fluid contained in the cassette. 
     U.S. Pat. No. 4,936,760 to Williams discloses a infusion pump adapted to use a special tube wherein the tube has diametrically opposed handles extending longitudinally thereon and wherein the handles are adapted to be gripped by pump actuators so as to deform the tube transversely by pulling or pushing on the handles. 
     U.S. Pat. No. 5,092,749 to Meijer discloses a drive mechanism for actuating the fingers of a peristaltic pump having a jointed arm pivotally attached at one end to a drive member and at the other end to a fixed point on the base of the pump and a rotary cam actuator mounted on the base to urge against the arm and reciprocate the drive member. 
     U.S. Pat. No. 4,950,817 to Nason et al. discloses a mechanical drive system for a medication infusion system comprising a cassette pump wherein inside the cassette a single cam drives the inlet and outlet valves as well as the pump mechanism. 
     U.S. Pat. No. 5,252,044 to Raines discloses a cassette pump. 
     U.S. Pat. No. 3,606,596 to Edwards discloses a drug dispensing pump. 
     U.S. Pat. No. 3,518,033 to Anderson discloses an extracorporeal heart. 
     SUMMARY AND OBJECT OF THE INVENTION 
     The instant invention provides for an infusion pump wherein the pump has a pumping body which consists of a v-shaped groove extending longitudinally along a pump assembly and has associated therewith a fixed, and a moveable jaw and a plurality of valves located at either end of the v-shaped groove or shuttle. 
     In operation, an operator such as a nurse or patient would commence infusion of a medicament by inserting a standard IV set tube into a tube loading orifice located on the front of the pump. Additionally, the operator would simultaneously insert a slide clamp which is associated with the tube into a appropriate slide clamp orifice located upstream, i.e. more toward the fluid source, of the tube loading orifice. The operator would then actuate a tube loading sequence in which a series of pawls and a moveable upper jaw would serve to seize the tube and draw it into a tubeway, part of which is comprised of the v-shaped groove and valves. As the loading cycle progresses the jaws and pawls close about the tube capturing the tube within the tubeway. Sequentially as the valves close to occlude the tube, the slide clamp would be moved to a position such that the slide clamp would no longer occlude the tube. Upon receipt of appropriate signals from associated electronics which would determine the pumping speed, allowable volume of air, temperature and pressure, the pump is actuated wherein fluid is drawn from the fluid source and expelled from the pump in a constant and metered amount. 
     Should the tube be misloaded into the tubeway or the tubeloading orifice, appropriate sensors would determine the existence of such a state and effect an alarm directed thereto. 
     At the end of the infusion, actuation by an operator would serve to automatically close the slide clamp and release the tube from the pump. 
     The pump comprehends a variety of sensors directed to improve the safety of the infusion of medicament in addition to the sensors recited previously which provide information on the state of the fluid passing through the pump, the pump comprehends a variety of sensors operative to provide information regarding the state of various mechanical subassemblies within the pump itself. Among the sensors are devices directed to providing positional location of the shuttle or v-shaped slot aforementioned, valve operation, slide clamp location, misload detection, and manual operation of the tubeloading assembly. 
     The sensors relating to the state of the fluid being passed through the pump have themselves been improved with regard to accuracy. This has been accomplished by the development of the method of making contact between the sensor and the tube such that the contact is normal to the tube and the tube is placed in contact with the various sensors in such a way that there is neither a volumetric nor a stress gradient across the tube. 
     Therefore, it is a primary object of the invention to provide for an infusion pump capable to delivering an accurate volume of medicament using a standard infusion set. 
     It is another object of the invention to provide an infusion pump having a pumping shuttle and valves associated therewith, wherein the pumping shuttle and valves are mechanically synchronized. 
     It is a further object of the invention to provide an infusion pump having greatly improved accuracy whereby the output of the pumping member is linearized over the course of a pumping cycle. 
     It is another object of the invention to provide for a plurality of valves in an infusion pump such that the valves are adapted to occlude an infusion set tube while having a shape adapted to promote the elastic recovery of the tube when the valve is release therefrom. 
     It is an additional object of the invention to provide an infusion pump having enhanced resistance to medication errors by providing for an automatically loaded slide clamp associated with the infusion set. 
     It is a further object of the invention to provide, in the aforementioned infusion pump having a resistance to medication errors, a slide clamp sensor operative to sense whether the slide clamp aforementioned is opened or closed. 
     It is an additional object of the invention to provide for a synchronized, automatic closure of the slide clamp at all times when a free flow of medicament is possible. 
     It is an additional primary object of the invention to provide for an infusion pump capable of automatically loading a standard IV set therein. 
     It is a further object of the invention to provide for an infusion pump capable of sensing an incorrectly automatically loaded IV set and further capable of releasing the set from the pump in a state operative to prevent free flow of medicament through the set. 
     It is another object of the invention to provide an autotubeloader assembly operative to automatically load and unload a standard IV set from an associated infusion pump. 
     It is an additional object of the invention to provide for a synchronization of the slide clamp state and the valve state such that when one of the valves is in an open state, the second of the valves is in a closed state and when both valves are in an open state, the slide clamp is in a closed state. 
     It is an additional object of the invention to provide for a partial cycle of the pumping member immediately subsequent to the tubeloading cycle, so as to ensure that the tube is properly seated in the pumping member aforementioned. 
     It is another object of the invention to provide a cam associated with the pumping member wherein the cam is operative to linearize the output of the pump. 
     It is a further object of the invention to provide for a variability of pumping speed over the course of a pumping cycle. 
     It is another object of the invention to provide a further linearization of pump output by varying the speed of the pumping member. 
     It is an additional object of the invention to provide a variability in pumping output over the course of an infusion by varying the speed of the pumping member. 
     It is a further object of the invention to provide for a hydrodynamic assistance in the elastic recovery of the tube during the fill portion of a pumping cycle. 
     It is another object of the invention to provide a pumping body having an aspect adapted to be assembled with other pumping bodies into a multiple channel pump having a single controller. 
     It is a further object of the invention to provide for a tubeloading assembly having pawls adapted to capture and restrain an IV tube within the pump. 
     It is another primary object of the invention to provide for a sensor housing and an actuation assembly associated with the housing adapted to place a sensor in substantially normal contact with the tube. 
     It is an additional object of the invention to provide for a sensor housing and an actuation assembly operative to place a sensor in contact with a tube such that the volumetric gradient across the tube beneath the sensor is essentially zero. 
     It is a further object of the invention to provide for a sensor housing and an actuation assembly operative to place a sensor in contact with a tube such that the stress gradient of the tube beneath the sensor is essentially zero. 
     It is another object of the invention to provide for a single datum body operative to fix the relative location of the various elements within the pump. 
     It is a further object of the invention to provide for a plurality of shafts associated with the single datum body and cooperative therewith to fix the relative location of the various elements of the pump. 
     It is an additional object of the invention to provide a compact means for pumping a medicament. 
     It is a further object of the invention to provide for a fluid seal barrier operative to prevent fluid ingress to various electrical components of the pump. 
     It is another object of the invention to provide for a case having a geometry operative to enforce a downward orientation of the tube in those areas exterior to the pump. 
     It is a further object of the invention to provide for manual means for actuating the automatic tube loading feature. 
     These and other objects of the instant invention will become apparent in the detailed description of the preferred embodiment, claims and drawings appended hereto. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of the complete pump assembly. 
     FIG. 2 is an exploded view of the pump sub-assembly. 
     FIG. 2A is an exploded view of the motor mounts and pump drive motor. 
     FIG. 3 is an isometric view of the chassis or datum body with the associated datum shafts. 
     FIG. 4 is an isometric view of the index wheel and the associated sensor. 
     FIG. 5 is a face-on plan view of the pump drive cam. 
     FIG. 6 is an isometric view of the valve cam lands on the main drive cam. 
     FIG. 7 is a graph showing the relation between linear displacement of the shuttle and volumetric displacement of the tube when there is no linearization of the fluid output. 
     FIG. 8 is an isometric view of the downstream platen. 
     FIG. 9 is a graph of displaced volume of the tube versus cam angle when the cam provides a linearizing correction to the pump displacement. 
     FIG. 10 is a cross-sectional view substantially along line A—A of FIG.  1 . 
     FIG. 11 is an isometric view of the rear of the shuttle platen and shuttle. 
     FIG. 12 is an exploded view of the pump motor encoder. 
     FIG. 13 is an isometric view of the valve sub-assembly. 
     FIG. 14 is an exploded view of the valve sub-assembly as shown in FIG.  13 . 
     FIG. 15A is an isometric view of substantially the rear and side of one of the valves. 
     FIG. 15B is an isometric view showing substantially the bottom or tube-facing side of one of the valves. 
     FIG. 16 is an exploded view of the tubeloader sub-assembly. 
     FIG. 17 is an isometric view of the upstream platen showing the tube-present sensor in contact with a tube. 
     FIG. 18 is an assembled view of the tubeloader sub-assembly. 
     FIG. 18A is a plan view of the downstream platen showing a pawl in engagement with a tube. 
     FIG. 18B is a plan view of a tubeloading pawl. 
     FIG. 19 is an exploded view of the tubeloader camshaft. 
     FIG. 19A is an assembled view of the tubeloader camshaft and tubeloader motor. 
     FIG. 20 is an exploded view of the tubeloader motor and encoder. 
     FIG. 21 is a plan view of the sensor housings wherein shadow-views of the open and closed positions thereof are included. 
     FIG. 22 is an exploded view of the downstream sensor housings. 
     FIG. 23 is an exploded view of the upstream pressure sensor housing. 
     FIG. 24 is an isometric view of the air detector housing as connected to the pressure sensor housing. 
     FIG. 25 is an isometric view of the slide clamp loader sub-assembly. 
     FIG. 26 is an exploded view of the slide clamp loader sub-assembly. 
     FIG. 27 is an isometric view of the slide clamp. 
     FIG. 28 is an isometric view of the slide clamp sensor and the associated upstream platen. 
     FIG. 29 is an isometric view of the downstream platen with the temperature sensors in an exploded view therebeneath. 
     FIG. 30 is an isometric view of the pump housing. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the preferred embodiment of the instant invention, pump assembly  10  consists of a plurality of sub-assemblies as shown in FIG. 1, which perform various associated functions in concert with the pump sub-assembly  12 . 
     THE PUMP SUB-ASSEMBLY 
     The pump sub-assembly, as seen in FIG. 2, comprises a housing  14  to which various associated elements are affixed. Housing or chassis  14  is preferably made of a molded plastic so as to speed assembly and fabrication thereof. Chassis  14  further comprises an aft plate  16  formed integral with chassis  14 , wherein aft plate  16  has defined therein a plurality of apertures. 
     Motor shaft aperture  18  is substantially centrally located in aft plate  16  and is operative to allow pump motor shaft  20  to pass therethrough. Aft plate  16  further has defined therein pump motor mounting holes  22  which are spaced radially outwardly from pump motor shaft aperture  18 . These holes serve to locate accurately pump motor  24  in combination with the motor bearing boss with respect to the chassis  14 . Abaft of the aft chassis plate  16  are a plurality of mounting wings  26  which are operative to securely fix the chassis to the downstream platen  500  located on the downstream side of the chassis  14  and the upstream platen located on the upstream side of the chassis  14 ; wherein upstream denotes the side of the assembly  10  which is located closer to the fluid inlet thereto and downstream denotes that side of the assembly  10  which is located closer to the fluid outlet therefrom. 
     As seen in FIGS. 2 and 3, chassis  14  further defines a plurality of apertures substantially transverse to the pump motor axis  32  which is defined as being coaxial with pump motor shaft  20 . 
     Set before wings  26  is an upstream fluid barrier tab  27 A and a downstream fluid barrier tab  27 B which are cooperative with the slide clamp actuator support and downstream platen aft plate  580  to provide a fluid shield between the fluid source (IV tube or set) and the associated electrical apparatus located abaft of the combined fluid stop assembly composed of the three elements aforementioned. 
     These transverse ports or apertures serve to allow access to various mechanisms interior to the chassis as shall be subsequently described and also provide a single datum point to fix the relative locations of the various sub-assemblies which depend from the various parts associated with these apertures. This style of manufacture provides an accurate and robust means of fabricating the pump assembly  10  whilst providing an economy of measured points requiring adjustment to ensure correct operation of the device. These apertures are reproduced on both the upstream sidewall  32  and downstream sidewall  34  of the chassis  14 . 
     The first such aperture set is the valve pivot shaft ports  36 ,  38  which serve to support and locate the valve pivot shaft  410  relative to the chassis  14 . 
     The second such aperture set supports the tubeloader camshaft  510  and is denoted as the tubeloader camshaft ports  40 ,  42 . 
     The third such aperture serves to support and locate, relative to the chassis  14 , the tubeloader layshaft  512  and is denoted the tubeloader layshaft apertures  44 ,  48 . 
     The fourth such aperture set serves to allow access of the pump valve cam actuators  422 , to the interior of the chassis  14 , and is denoted valve actuator ports  46 ,  50 . 
     The chassis defines a cavity  52  therein which serves to house the pump drive sub-assembly as shown in FIG.  2 . 
     The pump motor  24  is the aftmost element of this sub-assembly. This motor is preferably a variable speed d.c. motor having an internal speed reduction gearbox  54  which in the preferred embodiment provides a 64 to 1 reduction of motor speed. 
     The output of the pump motor gearbox  54  is pump shaft  20 . Pump shaft  20 , as aforedescribed, extends axially into cavity  52  via pump shaft aperture  18 . 
     Interior to cavity  52  and in circumferential engagement with pump shaft  20  is drive collet  56 . Drive collet  56  has a further mechanical engagement with pump shaft  20  via a combination of a plurality of collet flats  58  which are impressed on shaft  20  so as to provide a polygonal surface operative to engage grubscrews  60  which thread through collet  54  via threaded grubscrew holes  62  which are situated radially and transversely to shaft axis  32  though drive collet  56 . Drive collet  56  further has defined therein a drive pin aperture  61  which is longitudinally parallel and radially outwardly from pump shaft axis  32  and is operative to support and drive fixing pin  63  in concert with movement of collet  56  and motor shaft  20 . 
     Surmounting drive collet  56  and coaxial therewith, is the pump index wheel  64 , as shown in FIG.  4 . 
     Index wheel  64  is operative, with associated sensors, to determine the location of the pump elements. The index wheel has defined therein a first radial slot  66  and a second radial slot  68 , which are about the periphery of index wheel  64 . These two slots are located 180 degrees away from each other. 
     The index wheel  64  is comprised of a wheel disc portion  70  and a hub portion  72  wherein the hub portion  72  is radially interior to and substantially forward of the wheel disc portion  70 . The hub portion  72  of the index wheel  64  is connected to the wheel disc  70  by a plurality of webs  74  extensive from the hub  72  to the disc  70 . The hub portion further comprehends a cylindrical longitudinally extensive portion  76  and a transverse annular portion  80 , wherein the cylindrical portion  76  extends forward of disc plate  70  and the annular portion  80  extends radially inwardly from the cylindrical portion  76  to the motor shaft  20 . 
     Annular portion  80  further defines a motor shaft port  82  which is coextensive with the motor shaft  20  and a fixing pin port  84  located outward from the motor shaft port  82  and parallel therewith. The motor shaft port  82  allows the motor shaft  20  to pass through the index wheel  64  while the fixing pin port  84  enforces co-rotation of the motor shaft  20  and the index wheel  64  when fixing pin  63  is inserted therethrough. 
     Hub portion  72  has defined therein two access ports  86 ,  88  which allow access to the collet grub screws  60 . These hub access ports  86 ,  88  are accessible from the exterior of the chassis  14  via set screw access port  90 . 
     Surmounting the index wheel  64  and forward of the annular portion  80  thereof, resides the pump drive cam or cam body  100  shown in FIGS. 5 and 6. Pump cam  100  consists of a front face area  102  and a rear face area  104 . 
     The front face area  102  further comprises an exterior cam land  106  and an interior cam land  108 . The exterior and interior cam lands  106 ,  108  are cooperatively formed so as to provide positive actuation of pump cam follower  110 . The shape and aspect of the two lands  106 ,  108  are non-linear with respect to the variation of distance of various parts of the lands  106 ,  108  from the pump shaft axis  32 . 
     The rotary to linear motion conversion, as realized by cam  100 , introduces non-linear error, as shown in FIG. 7, in the volumetric output of the pump with respect to time (as measured in shaft encoder counts). The aspect of the interior land  108  and the exterior land  106  act cooperatively to achieve a first order correction of this error so as to linearize the output of the pump with respect to volume. This is achieved by an alteration of the change in radial displacement of the cam lands  106 ,  108  with respect to the motor shaft axis  32  as aforedescribed so as to minimize the effects of angular error on the accuracy of the pump. 
     Specifically, to a first approximation the cam executes a sine function as determined by the radial distance of the lands  106 ,  108  from the shaft axis  32 . 
     As can be seen in FIG. 7, the characteristic volumetric output of a tube between two v-grooves executing a relative motion is a non-linear function of displacement of the grooves. This shuttle  200  structure is recited in the Patent to Danby et al, U.S. Pat. No. 5,151,019 corresponding to U.K. Pat. No. 2,225,065 as aforerecited. 
     As seen in FIG. 5, the alteration of the cam profile, as herein described, provides a markedly more linear output by increasing the shuttle speed during the middle of the stroke (between 30 degrees and 60 degrees of cam angle) and decreasing the speed of the shuttle  200  at the beginning and end of the stroke. 
     As seen in FIG. 9, this variable linear velocity provides a significantly more linearised volumetric output wherein output is essentially linear between 30 degrees and 70 degrees of cam angle. The variation between upward and downward strokes being due to use of simple radii within the cam. 
     Referring now to FIG. 5, which depicts cam lands  106 ,  108  in face on aspect, shows the various cam positions clearly. As shown, there are two primary pumping portions  110 ,  112  corresponding to downward and upward movements of the shuttle  200 . Also seen are dwell portions  114 ,  116  which allow the inlet and outlet valves to be actuated as shall be subsequently described. 
     Further linearization of output is controlled electronically via a position sensitive speed control which shall be subsequently described. 
     Referring now to FIG. 6, the reverse side  118  of cam  100  is shown. As can be seen, there are two concentric valve cam lands  120 ,  122 . In this embodiment, the inner valve cam land  120  drives the upstream (inlet) valve and the outer valve cam land  122  drives the downstream (outlet) valve. As can be seen, at no time are the inlet and outlet valves simultaneously operated, thereby positively preventing a free flow condition of medicament. The duration and dwell of the valve cam lands  120 ,  122  are arranged to provide for proper valve synchronization although the inner valve cam race  120  and the outer valve cam race  122  are at differing radii as measured from the pump shaft axis  32 . 
     The rear hub  118  of the drive cam  100  also defines a cam fixing in port  124  which serves to lock the relative location of the drive cam  100  to that of the drive collet  56 , via fixing pin  63  and, therefore, to that of motor shaft  20 . 
     Motor shaft  20  is capped by nosebearing  126  which is located immediately afore cam  100 . The motor shaft  20  passes through cam  100  via cam motor shaft port  127  defined centrally in the cam  100 . Surrounding cam motor shaft port  127  is the forward cam annulus  128  which serves as a lash adjustment for cam  100  float along motor shaft  20  between collet  56  and nosebearing  126 . 
     In the preferred embodiment of the instant invention, nosebearing  126  is a roller type bearing. Nosebearing  126  fits into the nosebearing race  132  in the rear side of the shuttle platen  130 . 
     Shuttle platen  130  is affixed to the forward chassis surface  53  by a plurality of fasteners which connect shuttle platen  130  to forward chassis surface  53  via a plurality of fastener ports  134  defined in the shuttle platen  130  and a second plurality of fastener ports  136  defined in the forward surface  53  of chassis  14 . The relative location of the shuttle platen  130  with respect to the chassis  14  is defined by register pins  138  in the forward chassis surface  53  for which corresponding shuttle platen register ports  140  are defined in the back surface of shuttle platen  130 . 
     Shuttle platen  130  additionally has defined therethrough a shuttle drive cam follower throughport  142  which is defined to allow the shuttle actuating cam follower  144  access to the shuttle drive cam  100 . The front surface of the shuttle platen  146  defines a plurality of channels  148  in which the shuttle  200  resides. These shuttle platen channels  148  are of a low friction finish so as to allow free movement of the shuttle  200  thereacross. The front shuttle platen surface  146  further defines side rails  150 ,  152  which are operative to limit torsional movement of the shuttle  200  as the shuttle  200  performs its motion. 
     Throughport  142 , as aforementioned, allows passage therethrough of cam follower  144 . Cam follower  144  is an annular roller bearing of such dimension as to allow motion thereof between the pump drive cam lands  106 ,  108 . The shuttle drive cam follower  144  rides on the shuttle drive pin  154  which resides in the shuttle drive pin recess  156  so as to be flush with the front surface  201  of the shuttle  200 . The drive pin  154  further comprises a head  158  which is operative to spread drive forces evenly to the shuttle  200  and furthermore, provides an adequate peripheral area for effective press-fit connection thereof to the shuttle  200 . 
     The shaft portion  160  of the shuttle drive pin  154  extends through the shuttle  200  via drive pin port  202  defined therein, and is sufficiently extensive to pass through the shuttle platen  130  and engage shuttle drive cam follower  144 . 
     The shuttle platen  130  completes the datum or register point set based on measuring locations throughout the pump  10  from the chassis  14  and associated components. 
     The shuttle platen side rails  150 ,  152  have forward surfaces  162 ,  164  upon which are located a plurality of datum surfaces  168 ,  170 . These datum pads  168 ,  170  are operative to fix the distance from shuttle  200  to that of the upper jaw  220  of the pump assembly. This distance, experiment has found, must be maintained at 0.2 mm. This distance is critical due to the pump geometry wherein, as shown in FIG. 10, the initial deformation of the tube section acted upon by the pump is dependent upon the lateral distance between the moving shuttle indent  204  and the fixed, or non-moving, indent  206  so as to provide a deformation of the initially circular tube cross-section to an equiangular quadrilateral cross-section. This initial deformation bears on the amount of closure of the pump tube lumen  6  as the pump cycles through its stroke; as the stroke throw is fixed by the lift of the drive cam lands  106 ,  108 . The amount of deformation of the pump tube lumen fixes the volumetric output of the pump, per stroke or cycle thereof. 
     The lower portion of the side rails  150 ,  152  are laterally extensive beyond the shuttle  200 . The forward surfaces of the lower lateral extension  172 ,  174  have associated therewith a second set of datum pads  176 ,  178  which are operative to fix the distance of the lower fixed jaw  222  from the shuttle  200 . The function of these lower jaw datum pads  176 ,  178  are similar to the function of the upper datum pads  168 ,  170  as aforedescribed. 
     Shuttle  200  further comprises, as shown in FIG. 11, a rear side  207  of the shuttle  200 . The rear shuttle side  207  further has defined therein a plurality of slide rails  206 . The slide rails  206  are operative to provide for a minimization of friction betwixt the shuttle  200  and the shuttle platen  130 . The slide rails  206  are in substantially full face engagement with the channels  146 A of the shuttle platen  130 , and provide a fixation of both longitudinal and lateral lash between the shuttle  200  and the shuttle platen  130 . 
     The front surfaces  201  of the shuttle  200  defines a pump groove aperture  204 . This aperture, or indent  204 , is of a substantially v-shaped cross-section and has a rounded interior corner  211  so as to provide for a conformation of the tube  5  and the groove aperture  204  when the tube  5  is loaded therein. 
     The rear surface  207  of the shuttle  200  further has defined therein a plurality of pockets  203  arranged in a substantially vertical array. These pockets  203  are adapted to contain a plurality of magnets which are cooperative with a magnetic sensor  322  to sense the linear position of the shuttle  200 . 
     SENSORS ASSOCIATED WITH THE PUMP SUB-ASSEMBLY 
     The pump sub-assembly, as previously described, has associated therewith a plurality of sensors which are operative to provide information as to the function and location of the various elements thereof. 
     The aftmost of the sensors is the drive motor shaft encoder  300 . This sensor comprises an encoder flag wheel  302  which is attached to the armature shaft  303  of motor  24 . The pump motor flag wheel  302  has, in the preferred embodiment of the instant invention, twelve flags  304  extending radially outward from the hub  306  thereof. 
     These flags  304  act in concert with two optical switches  308 ,  310  to fix the location of the armature shaft  303  of the pump drive motor  24 . The switches  308 ,  310  further consist of a light emitting diode and a photocell as shown in FIG.  12 . The arrangement of the optical switches  308 ,  310  allows for a first switch  308  to sense the edge  311 E of flag  304 , and the second switch  310  to sense the middle  311 M of a subsequent flag  304 . This arrangement allows for greater resolution of motor shaft position and direction as read by the encoder  300 . 
     In this presently preferred embodiment, the resolution of encoder  300  is 1/3072 of a rotation of motor shaft  20 . The encoder assembly  300  resides in a pump motor encoder support collar  313  which is a sliding fit over motor housing  24  and is affixed thereto by pinch clamp  313 . 
     The motor encoder  300  senses armature shaft  303  rotation directly. However, as there are mechanisms resident between the armature shaft  303  and the shuttle  200 , further sensors are desired. 
     Moving forward along motor shaft axis  32 , one returns to index wheel  64 . As aforementioned, index wheel  64  has a plurality of circumferentially coextensive radially disposed slots  66 ,  68 . Associated with these slots is an index wheel optical sensor  314 . This sensor comprises a light emitting diode  315  and an optical sensor or switch  316 . 
     The index wheel sensor  314  is cooperative with the index wheel  64  and the slots  66 ,  68  therein to provide positional information of the rotational location of the pump motor shaft  20 . 
     In operation, the index wheel sensor  314  acts in concert with the pump encoder  300  to provide this positional information as well as directional information of the motor shaft  20 . The index wheel sensor times the passage of each of the slots  66 ,  68  past the index wheel switch  314 . The two slots  66 ,  68  are of differing widths so as to provide information as to whether the shuttle  200  is beginning the upstroke thereof or the downstroke thereof, where a first width indexes the upstroke and a second width indexes the downstroke. 
     Associated with the shuttle  200  itself is a linear gross position sensor  320 . This sensor comprises a linear position Hall effect sensor  322  and a plurality of magnets  324 ,  326 . Shuttle position sensor magnets  324 ,  326  present opposite poles to the shuttle Hall switch  322 , so as to provide a field gradient operative to provide an indicium of the linear position of the shuttle  200 . 
     The combination of the encoder  300  and the other associated sensors aforementioned, provide inputs to a control mechanism, which may operate more than one pump so as to accurately control the speed of variable speed motor  24 , the primary feature provided by such speed control is a temporal variability of the output of the pump  10 . Additionally, such speed control allows for an electronically controlled linearization of the pump output per individual stroke as well as improving the time integrated output of the pump  10 . In the preferred embodiment the per stroke linearization of output is realized in combination with the drive cam  100  as aforementioned. The time integrated output of the pump is made more accurate by the pump speed being markedly increased at such points as would provide for a discontinuity in the output profile as measured with respect to time so as to minimize the effects of such discontinuities in output. 
     As a manufacturing convenience, both the shuttle linear position sensor  320  and the index wheel sensor  314  are electrically connected to the associated signal processing electronics by a shared printed circuit strip denoted as the pump sensor circuit strip. 
     THE VALVE SUB-ASSEMBLY 
     The valve sub-assembly is shown, removed from the associated pump sub-assembly, in FIGS. 13 and 14. The valve sub-assembly consists of a valve pivot shaft  410  which is carried by chassis  14  by being supported thereby in pivot shaft ports  36 ,  38 . Valves  412 ,  414  pivot about this shaft  410  and are supported thereon by valve pivot bearings  416 ,  418  which are clearance fit onto pivot shaft  410  and into valves  412 ,  414 . 
     The two valves  412 ,  414  are denoted individually as the upstream valve  412  and the downstream valve  414 . The upstream valve  412  comprises a pivot hearing aperture  420  adapted to accept thereinto the upstream value pivot bearing  416  and hereby pivot about valve pivot shaft  410 . The upstream valve  412  further comprises an upstream valveshaft aperture  422  which is located axially parallel to the pivot shaft  410  and substantially vertically displaced therefrom. The upstream valveshaft aperture  422  is adapted to slidingly receive the upstream valveshaft  424  therein. The upstream valveshaft  424  extends laterally from the upstream valve  412  and is disposed to enter into the chassis  14  via upstream valveshaft aperture  48 . The upstream valve actuator shaft  424  is substantially cylindrical and has defined therein an outer cam race cutout  426 . The outer cam race cutout  426  is operative to allow the upstream valve actuator  424  to clear the outer or downstream valve race  122  defined on cam  100 . The upstream valve actuator  424  terminates in a cam follower nub  428 , which is adapted to support the upstream valve roller cam follower  430 . The upstream cam follower  430  is, in the preferred embodiment, a roller bearing so as to provide following contact between the valve cam land  120  and the upstream valve actuator  424 . 
     Returning to valve  412  or  414 , the valve further comprises a valve blade  432 , as shown in FIG. 15B, which is of a substantially v-shaped cross-section wherein the first side of the valve blade  434  and the second side of the valve blade  436  subtend an angle of approximately 90 degrees therebetween and also define a 0.5 millimeter rounded vertex  438 . The combination of the included angle and the rounded vertex  438  provide for an optimal arrangement between the conflicting necessities of ensuring that the tube  5  is sealed during the appropriate part of the pump cycle while simultaneously ensuring that the tube will reform into an accurate approximation of its initial shape when the valve blade  432  is lifted from the tube  5 . 
     The rounded vertex  438  of the valve blade  434  defines a 0.5 mm curvature. This curvature, in combination with the 0.7 mm distance between the valve blade  434  and the valve anvil  570 , to be discussed subsequently, provide for an optimization of the two necessities of ensuring sealing while providing for elastic recovery of the tube during the appropriate part of the pump cycle. 
     Additionally, the tube  5 , due to its deformation by the shuttle  200  in combination with the upper and lower jaws  220 ,  222 , comprehends a partial vacuum within that portion of the tube lumen  6  located adjacent to shuttle  200 , and the opening of the inlet valve  412  with the positioning of the shuttle  200  providing conditions conducive to assist hydrodynamically the elastic recovery of the tube section below the inlet valve  412 . 
     The upstream valve body  412  further comprises a valve lifting tang  440  which is cooperative with a valve loading cam to raise the valve during the tube loading operation. The valve body  412  comprehends a valve spring seat tang  442  which extends upwardly from the distal end  444  of the valve blade arm  435 . The valve spring tang  442  defines a valve spring retainer port  446  which is operative to provide support for the distal end  448  of the valve spring retainer  450 . The valve spring retainer  450 , in combination with valve spring tang  442 , serves to completely capture the valve spring  452  therebetween. The valve spring retainer  450  comprises a substantially c-shaped base  454  which is operative to slidingly fit about the tubeloader layshaft  512 , to be described subsequently. The valve spring retainer base  454  is designed to permit oscillary motion of the retainer  450  about the aforementioned tubeloader layshaft so as to accommodate the motion of the valve  412 ,  414 . 
     The downstream valve  414  is resident on the valve pivot shaft  410  adjacent to the shuttle  200 . The downstream valve  414  is essentially a mirror image of the upstream valve  412  about a plane transverse to the pivot shaft  410  and displays all of the associated elements of the upstream valve  412  in a reversed orientation as seen in FIG.  14 . The downstream valve actuator arm  456  is shortened to align the downstream valve cam follower  458  with the outer valve cam land  122 . 
     The action of the two valves  412 ,  414  is such that at no time during the pump cycle are both valves open at the same time. Furthermore, as both the valves  412 ,  414  and the shuttle  200  are driven by a single motor  24  and off to a single drive cam body  100 , exact synchronization of the valves  412 ,  414  and the pump shuttle  200  is positively achieved by wholly mechanical means. 
     SENSORS ASSOCIATED WITH THE VALVE SUB-ASSEMBLY 
     Associated with each of the valves  412 ,  414  is a valve motion sensor  328 ,  330 . Each of these valve motion sensors  328 ,  330  is actuated by a magnet  332 ,  334  which is inserted into a valve sensor magnet port  332 A,  334 A in the outboard end  444  of the valve blade tang  435 . Located therebelow, in the associated valve anvil and outwardly located therefrom is the valve motion sensor Hall switch  329 ,  330  which, with associated software, linked to the output of the valve sensor switches  328 ,  330  to that of the drive motor encoder  300 , serves to stop the pump  10  and activate an alarm if a valve  412 ,  414  is not operating correctly. This is essentially accomplished by comparing the expected output of the appropriate valve sensor  328 ,  330  with the expected signal therefrom at a specific motor  24  and drive cam location. 
     Residing outwardly from each valve  412 ,  414  and separated therefrom on valve pivot shaft  410  by tube present arm spacers  460  is the tube present sensor arm  340 . The upstream tube present sensor, in conjunction with the downstream tube present sensor, serves to determine the actual physical presence or absence of the IV tube in the pump  10 . Each of the tube present sensors  332 ,  334  comprises an annular bearing or tube sensor pivot  336  which surrounds and rides on the valve pivot shaft  410 . The tube sensor arm web  338  extends outwardly from the tube sensor pivot  336  and serves to support the tube sensing blade  340  which extends forwardly from the sensor arm web  338  and the tube sensor flag  342  which extends substantially rearwardly from the sensor arm web  338 . The sensor blade  340  comprises a downward extension thereof so, when installed, the sensor blade tip  344  resides on the appropriate valve anvil. The insertion of a tube  5  between the blade tip  344  and the valve anvil will, therefore, serve to raise the blade  340  away from the anvil  570  and cause the sensor arm to pivot about the valve pivot shaft  410 . This serves to lower the rearwardly extending valve sensor flag  342  thereby interrupting the tube present sensor optical switch  346  by the flag  342  moving into the interstice  348  of the tube present sensor optical switch  346  and interrupting the light beam extending thereacross, as shown in FIG. 17. A return spring  350  serves to bias the tube sensor arm to a position wherein, should the tube  5  not be present, the tube sensor blade tip  344  rests on the associated valve anvil. 
     THE TUBELOADER SUB-ASSEMBLY 
     As shown in FIGS. 18 and 19, the tubeloader sub-assembly utilizes two shafts associated with chassis  14 . These two shafts are the tubeloader camshaft  510  and the tubeloader layshaft  512 . These two shafts  510 ,  512 , in conjunction with the valve pivot shaft  410 , provide the primary datum points for the relative locations of the various assemblies and associated elements thereof, throughout the pump. The locations of these three shafts is shown in FIG.  3 . By referencing all points in the pump to these shafts, and thereby to the chassis  14 , the pump structure can be indexed without the necessity of a wide variety of precision machined parts, whilst maintaining the requisite accuracy of the completed assembly. 
     The tubeloader layshaft  512  provides an axis about which all parts which are driven by camshaft  510  rotate save the valves and slide clamp. Moving upstream along layshaft  512 , the most outboard of the elements associated therewith are the downstream tubeloaders pawls  514 . The downstream tubeloader pawls each consist of an annular body  516  which is adapted to ride on the tubeloader layshaft  512  and is fixed thereto by the associated helical pin  518  which extends through the pawl annulus  516  and the layshaft  512  and into the opposed area of the annulus, thereby positively fixing the associated pawl  514  to the layshaft  512 . Extending forward of the pawl annulus or collect  516  is the pawl arm  518 . The pawl arm has a substantially linear section  520  and an arctuate section  522  extending outwardly and downward from the pawl collet  516 . 
     The shape of the arctuate section  522  of the pawl  514  is such that when the pawl  514  is fully lowered, the tube  5  is firmly wedged against the downstream platen  500 , thereby encircling the tube  5  between the pawl  514  and platen  500 . 
     In greater detail, the interior angled surface  526  of the pawl tip  524  intersects the tube  5  at an approximately 45 degree angle with respect to horizontal and is thereby operative to urge the tube  5  downwardly and inwardly against the tube detent  501  in the downstream platen  500 . 
     The pawl tip  524  encompasses a plurality of areas. The interior side of the tip defines a horizontal tube engaging surface  525 , an angled tube engaging surface  526 , a vertical tube capture surface  528 , a horizontal tube misload activating surface  530  and an externally facing tube rejection surface  532  on the exterior side thereof; and the aforementioned surfaces are disposed on the periphery of the pawl tip. These surfaces operate in concert with the downstream platen  500 . 
     The design comprehended by tubeloader pawl tip  524  is repeated on the lower edge of the upper pump jaw  220  and serves an identical function as shall be described herein. 
     When an operator is loading a tube into pump  10  and actuates the tubeloading cycle by means of an appropriate actuator, or a control button or switch, the tubeloader pawl tips  524  are lowered over tubeway  8  which, in combination with the lowering of the upper jaw  220 , serves to completely close off the longitudinal slot or opening on the outboard side of tubeway  8 . Should a tube be partially inserted into the pump  10 , yet remain wholly outside the tubeway  8 , the tube reject surface  532  will operate in combination with nesting slots  582 , which are also resident on lower jaw  222 , to expel the tube  5  from the pump. In the event of a tube  5  being loaded partially within the tubeway and partially exterior thereto, the misload activating surface  530  will serve to pinch the tube  5  between the misload activating surface  530  and the associated section of either the downstream platen  500 , the upstream platen  500 , or the lower jaw  220  and thereby actuate a misload detection as described herein. Another possibility contemplated in the design of the pawl tip  524  is wherein the tube  5  is inserted into the tubeway  8  yet has not been fully drawn into contact with the tubestops  576 . In this event, the tube capture surface  528  will serve to draw the tube  5  rearwardly and into contact with the tubestops  576  and thereby execute a correct loading of the tube. The combination of the tube reject surface  532 , the misload activating surface  530  and the tube capture surface  528  provides for a sharp discontinuity between the various possibilities for loading scenarios aforementioned. 
     The vertical tube capture surface  528  additionally works in combination with the angled tube engaging surface  526  and the horizontal tube engaging surface  525  to hold the tube  5  securely against the tube stops  576  and to provide for a deformation of the tube  5  by co-action of the angled surface  526 , the horizontal surface  525  and the tube stop  576  to lock the tube securely into the tubeway  8  when the longitudinal tubeway aperture is closed as well as to provide substantially full face engagement of the tube  5  with the associated sensors. 
     The downstream platen  500 , or the corresponding upstream platen  800 , are preferably constructed of a molded plastic such as glass filled polyphenylsulfide. The downstream platen  500  serves a variety of functions. 
     The tubeloader bearing cup  502  provides for a mounting area for the tubeloader powertrain. 
     Gearbox sidewalls  503 A serve to house the tubeloader gearset  560  which comprises two helical gears  562 ,  564  in a perpendicular arrangement so as to transfer rotation from a fore and aft mounted tubeloader motor  550  to the transverse tubeloader camshaft  510 . The downstream platen  500  gearbox housing further comprehends a camshaft bushing race  566  which serves to support the downstream camshaft bushing  568  in which the camshaft moves. The forward section of the downstream platen  500  comprises the downstream valve anvil  570  as well as the temperature sensors ports  572  and the lower air sensor transducer housing  574 . Abaft of these areas are a plurality of tube stops  576  which serve to support the tube  5  rearwardly so as to provide controlled conformation of the tube  5  when in the loaded condition. 
     Abaft of the tube supports  576 , the downstream platen  500  further provides for the downstream sensor pivot slot  578  which, in concert with associated apparatus, serves to correctly locate the downstream sensor array as shall be described. The rear barrier wall  580 , cooperative with chassis  14 , serves as a fluid barrier between tube  5  and the electrical components behind the rear barrier wall  580 . The rear barrier wall  580  is affixed to the chassis  14  by fasteners and additionally serves a fastening point for the downstream tube present sensor switch  346 . 
     Returning to the foreward edge of the downstream platen  500 , a plurality of tubeloader pawl nesting slots  582  are seen. These pawl slots  582 , in combination with the tubeloader pawls  514  and the chamfered forward edge  584  of the downstream platen  500 , serve to promote a correct loading of the tube  5  into the pump  10  by allowing the pawls  514  to lift and push the tube rearwardly against the tube stops  576 . Outward of the outermost of the pawl nesting slots  582 , a tube retaining detent  584  serves to retain the rube  5  in a position adapted to be captured by the pawls  514  during initial placement of the tube  5  within the tubeway  8  defined by the raised pawls  514  and the downstream platen  500  when the tubeloading assembly is in a state allowing the tube  5  to be loaded. 
     As aforedescribed, the tubeloader motor  550  drives, by means of a plurality of gears, the tubeloader camshaft  510 . The tubeloader motor  550  is a d.c. motor. The tubeloader motor  550  further comprises a speed reduction gearset  534  operative to provide sufficient torque to rotate camshaft  510  against the drag placed thereon by the components in contact therewith and resident on layshaft  512 . 
     The tubeloader motor shaft  536  extends forwardly from the tubeloader motor  550  and passes through the tubeloader motor mount  538  by way of a central aperture  540  therein. 
     The tubeloader motor shaft  536  has a flat  542  defined therein which is operative to provide a seat for the tubeloader drive gear setscrew  544  which is inserted through a threaded setscrew aperture  546  in the tubeloader drive gear  562  and thereby fix the rotation of the tubeloader drive gear  562  to that of the tubeloader motor shaft  536 . 
     The tubeloader drive gear  536  is a helical cut gear wherein the teeth thereof are about the circumferential periphery thereof. These teeth engage corresponding teeth on the face of the tubeloader camshaft gear  564 , thereby allowing perpendicular actuation of the transversely mounted camshaft  510  by the longitudinally mounted tubeloader motor  550 . 
     The tubeloader camshaft gear  564  is releasably engaged with the camshaft  510  by means of a slideable engagement pin  588 . 
     The camshaft clutch pin  588  is cooperative with a clutch slot  590  on the rear or inboard facing face of the camshaft gear  564 . The clutchpin  588  resides transversely to the camshaft  510  in a longitudinal clutchpin slot  592  defined through the camshaft  510 . A longitudinal actuator pin  594  coaxially emplaced within the camshaft  510  and in endwise contact with the clutchpin  588  serves to selectively insert and allow the withdrawal of the clutch pin  588  from engagement with the clutch slot  590  on camshaft gear  564 . A biasing spring  596  is located within the camshaft  510  and in opposition to the longitudinal actuator pin  594 . The outboard end  598  of the actuator pin  594  is rounded to allow sliding contact therewith by the associated component. 
     Handwheel  600  provides a housing for a pivoting clutch tab  602  which comprises on its inboard facing surface a clutch cam  604  which is in sliding engagement with the outboard end  598  of actuator pin  594 . The clutch tab  602  is interior to handwheel  600  and is hinged thereto by a clutch tab pivot pin  606 . In operation, actuation of the clutch tab  602  by tilting same about clutch tab pivot pin  606  will cause the clutch cam  604  to impinge on and depress the outboard end  598  of the actuator pin  594  causing the actuator pin  594  to move inwardly against clutch biasing spring  596  and moving clutch pin  588  inwardly and out of contact with the clutch slot  590  in camshaft gear  564 , thereby allowing the camshaft  510  to be freely rotated manually by means of handwheel  600  without rotating the camshaft gear  564 . 
     The camshaft  510  is one of the three primary datum shafts resident in the pump  10 . The camshaft supports two compound cams denoted as the downstream cam  610  and the upstream cam  620 . 
     The downstream and upstream cams  610 ,  620  comprise, moving outwardly from chassis, a camshaft deadstop  612 ,  622 , a tubeloaded pawl cam  614 ,  624  which is itself a compound cam, and valve loading cam  618 ,  628 . 
     The camshaft deadstops  612 ,  622  work in cooperation with the chassis rotator stops  28 ,  30  to provide a positive stop for camshaft rotation. Associated electronics sense the stall condition of the tubeloader motor  550  and interrupt power thereto when the camshaft deadstops  612 ,  622  are in contact with the chassis rotator stops  28 ,  30  during an initial indexing cycle of the tubeloader assembly, thereafter the tubeloader  550  in combination with the tubeloader encoder  702 ,  704 ,  705  will back-count from the rotator stops  28 ,  30  and under control of associated software interrupt power to the tubeloader motor  550  prior to the deadstops  612 ,  622  making contact with the chassis rotator stops  28 ,  30 . 
     Moving outwardly from the camshaft deadstops  612 ,  622 , the tubeloader pawl cams  614 ,  624  serve to actuate the tubeloader pawls  514 . Additionally, each of the tubeloader pawl cams  614 ,  624  has a locking surface  616 ,  626  which serves to activate a second, rigidly affixed lifting follower associated with the tubeloader layshaft  512  so as to provide a positive fixation of the associated elements when the layshaft  512  reaches the end of its travel. 
     Outward of the pawl cams  614 ,  624  are the valve loading cams  618 ,  628 . These cams serve to lift the valves  412 ,  414  out of the tubeway  8  during the loading operation. The valve loading cams accomplish this lift in cooperation with the valve loading tangs  440  as aforedescribed. 
     Outermost on the camshaft  510  reside the sensor arm cams  630 ,  632 . The downstream sensor arm cam  630  comprises a single surface and is operative to raise or lower the downstream sensor arm. 
     The upstream sensor arm cam  632 , however, is a compound cam having a sensor arm actuating surface  634  and, located outwardly therefrom and integral therewith, the slide clamp loader crank  650 . 
     All of the cams associated with a camshaft  510  are fastened thereto by helical pins driven transversely through the hubs of the various cams and through the camshaft  510 . 
     The tubeloader layshaft  512  supports all of the loading members associated with placing the tube  5  in the tubeway  8 . Additionally, the layshaft serves to pivotally support other elements which are driven at differing rates than the tubeloader pawls  514 . Innermost along layshaft  512 , wherein innermost defines that area closer to chassis  14 , are the upper jaw pawls  652 ,  654 . 
     The upper jaw pawls are biased in an upward position by means of helical pre-load springs  656  which are wound about layshaft  512  and are hooked to and have one end hooked to the torsion spring stops  45  and  47 , associated with the tubeloader layshaft apertures  44 ,  46 . The other end of the preload spring  656  being hooked onto the respective upper jaw carrier  652 ,  654 . Each of the upper jaw carriers  652 ,  654  further comprises a forwardly extending arm portion  658  which has a downwardly aimed terminus  660 . Forwardly extending arm portion  658  is adapted, in combination with upper jaw tie rod  662 , to support the upper pump jaw  220 . 
     The downwardly extending termini  60  of the upper jaw carrier  652 ,  654  further define a distinctive tubeloading tip shape, as mentioned in the description of the tubeloader pawls  514 . 
     Located rearward of the forwardly extending arm portion  658 , a spring slot  664  is formed in the upper jaw carrier  652 ,  654  and is operative to retain the associated torsion springs  656  therein. The upper jaw carrier  652 ,  654  have further defined a bifurcated central portion  667  which is adapted to retain the upper jaw carrier locking tangs  668  in the interstice of the bifurcated central portion  667  of the associated upper jaw carrier  652 ,  654 . 
     Extending rearwardly of the central area  667 , an upper jaw carrier cam follower arm  670  has defined therein an upper jaw cam follower port  672  which is adapted to receive the upper jaw carrier arm cam followers  674 . The upper jaw cam followers  674  are slidingly retained in the upper jaw cam follower ports  672  and are biased against tubeloader pawl cam  614 ,  624  by preload-spring  675 . The purpose behind this being that should a tube  5  be misloaded beneath the upper jaw  220  or pawls  514 , a sensor associated with the position of the upper jaw  220  and in combination with a tubeloader encoder  702 ,  704 ,  705 , associated with the tubeloader motor armature shaft  701 , will detect that the upper jaw  220  and layshaft  514  have ceased their motion while the tubeloader motor continues to rotate as the clearance between the upper jaw carrier cam follower arm  670  and the radially extensive seat  676  of the upper jaw cam follower  674  is closed. An electronic detection circuit will record this differential motion and cause the tubeloader motor  550  to reverse its rotation, opening the upper jaw  220  and tubeloader pawls  514  thereby expelling the tube  5 . 
     To assure a final fixed registration of the upper jaw  220  and the other assemblies driven by layshaft  514 , the locking follower  668  rides up on the locking surfaces  616 ,  626  of the tubeloader pawl cam or layshaft drive cam  614 ,  624 , and is adjustably fixed relative to the upper jaw carrier cam  652 ,  654  by means of adjustment screws  680 . The upper jaw carriers are fixed to layshaft  512  by means of spiral pins so as to actuate a co-rotation thereof. 
     As seen in FIG. 16, moving outwardly from the upper jaw carrier arms are the valve spring retainers  450 . Outward of the valve spring retainers  450  resides the innermost of the tubeloader pawls  514  as aforedescribed. 
     Associated with, and pivotal about layshaft  512 , are the upstream and downstream sensor carrier arms  690 . As it is necessary for the tube  5  to be completely loaded in the tubeway  8  before the application of the associated sensors, the sensor carrier arm  690  is actuated by a separate and delayed cam with respect to action of the rest of the components affixed to layshaft  512 . Associated with each of the sensor carrying arms  690  is a downwardly extending sensor arm cam follower  692  having a downward biased spring  694  associated therewith. Affixed to a central portion of the sensor carrying arm  690  and in substantially opposing contact with the sensor arm cam  630 ,  632  is the sensor arm opening spring  696  which, in the preferred embodiment is a leaf spring. This arrangement allows for both the opening of and the closure of the sensor array associated with the upstream or downstream sensor carrier arm  690  by a single cam respectively. 
     As can be seen in FIG. 16, the sensor arm  690  further comprises a forward forcipate end  698  which is operative in combination with a sensor handle pin  799  inserted thereacross, to support the associated sensor sub-assembly. 
     SENSORS ASSOCIATED WITH THE TUBELOADER SUB-ASSEMBLY 
     As recited previously, there are a plurality of sensors associated with the sensor arm  690  of the tubeloader sub-assembly. The most downstream of these sensors is the ultrasonic air detection apparatus or transducer  728  as shown in FIG.  22 . The ultrasonic transducer  728  acts in concert with a second transducer element located in the downstream platen  500 , as aforedescribed. The ultrasonic transducer  728  is housed in a compoundly pivotal housing  720 . This sensor housing  720  comprises a vertically split housing body including a transducer cavity  724 . The housing  720  further comprises a substantially horizontally axially extensive suspension slot  722  which, itself, comprehends an oval joining ring  725 , which is defined by a substantially oval and longitudinally extensive sensor arm pin retainer  723 . The suspension slot  722  serves to capture the sensor handle pin  799 , while allowing the sensor assembly  720  to move in fore and aft relation thereto. The sensor assembly  720  is further retained by the vertically disposed sensor arm pivot slot  578  in combination with sensor housing lift pin  721 , which is retained in lift pin ports  726  and  746  allowing vertical axial motion thereof, to allow the sensor  720  to roll over or tilt against the top of tube  5  when the sensor arm cam  630  actuates the substantially downward motion of the forward forcipate end of the sensor arm  690 . This ability to roll over, or conversely execute a rocking motion with respect to the tube  5 , allows the sensor housing  720  to come into a substantially vertical compressive contact with the tube  5 . This allows the tube to be extended or stretched equally across the face of the associated sensor, thereby eliminating either a volumetric or stress gradient in the tube  5  beneath the associated sensor so as to improve the accuracy of response of the sensor associated with, or connected to, housing  720 . Essentially all of the sensors associated with, or actuated by, sensor arm  690  execute the above described motion so as to achieve the above described result. 
     The next sensor located inboardly of the ultrasonic air detection transducer  720  is the downstream pressure sensor which resides in housing  734 . The sensor itself comprises a fairly standard, full bridge array on a deflection beam  740 . The deflection beam  740  is actuated by a sensing foot  730  which includes a substantially hemispherical tip  738 . The hemispherical tip  738  is surrounded by a conical extension of the housing  734 . The deflectability of the deflection beam  740  is controlled by seat pin  742  and stiffener  744  in conjunction with sensor foot fastener  743 . The hemispherical foot tip  738 , in combination with a conical circumferential enclosure thereof has, to achieve maximum accuracy, the requirement that the combination of the foot tip  738  and the conical enclosure be emplaced on the tube  5  in an essentially normal orientation thereto which is achieved by use of a compound rocker arrangement, as previously described, associated with the transducer housing  720  as shown in FIG.  21 . In this sensor, being contiguous with the ultrasonic detector  720 , the compound rocking motion thereof is actuated by the lift pin  721  and oval rocker slot  722  of the transducer housing  720 . 
     The corresponding upstream pressure sensor resident in housing  750 ,  760  provides an essentially similar layout save that the rocker assembly is unitary with the housing halves  750 ,  760  and the rocker slot associated herewith is denoted as upstream slot  758  defined in the upstream rocker handle  756  which includes oval inserts  754  and further comprises a separate lift pin  752  riding in an associated vertical slot  810  in the upstream platen  800 . Also associated with the tubeloader assembly is the tubeloader motor encoder as aforementioned. The encoder comprises an encoder flag wheel  702  which, in the preferred embodiment, comprehends a tubeloader encoder flag wheel hub  702 A and a plurality of flags  702 F, resident therebehind is the tubeloader encoder support collar  702  which serves to support the tubeloader encoder optical switches  704 ,  705  and is affixed to motor  550  via pinch clamp  706  and further supports the optical switch printed circuit board  707 . 
     The downstream platen  500  also serves to support a plurality of temperature sensors which consist of thermistors  754 T and  755 T which are gasketed to the downstream platen  500  by means of gaskets  760 T and are supported from below by the thermistor support  762 T. 
     THE SLIDE CLAMP LOADER SUB-ASSEMBLY 
     The slide clamp loader sub-assembly and its related sensors are generally associated with the upstream platen  800 . The upstream platen  800  comprises a rearward facing fluid barrier wall  801  which is connected by fasteners to chassis  14 . The fluid barrier wall  801  serves with the rear wall of the chassis and the rear wall of the downstream platen  500  to effectively seal the electronic assemblies from fluid ingress. Mirroring the downstream platen  500 , the upstream platen  800  further has defined thereon a tube sweep chamfer  812 . With the substantially identical chamfer resident on the shuttle facing interior side of the downstream platen  500 , the upstream tube sweep chamfer  812  accounts for forward shift of the tube therefor. The forward facing edge of the upstream platen  800  future defines a plurality of tubeloader pawl nesting slots  803  which are identical functioning to the tubeloader pawl nesting slots  582 . Furthermore, the upstream platen further has defined therein a similar forward facing chamfer as the downstream platen chamfer  584 . 
     The upstream platen further has defined thereon the upstream valve anvil  805  and a plurality of tube stops  809  of similar function to the tube stops  576  associated with the downstream platen  500 . The upstream platen further receives support from the upstream end of the valve pivot shaft  410  residing in carrier  807 . The upstream-most end of the upstream platen  800  further has defined on the exterior peripheral edge thereof a upstream tube retaining detent  842  which is identical in function and cooperative with the corresponding downstream tube retaining detent  584 . The base of the upstream platen  800  further has defined thereon a slide clamp loading groove  856 . This groove, in combination with the upper slide clamp channel  824  resident in slide clamp carrier  814 , serves to capture the slide clamp  895  through which passes tube  5 . Additionally, present in the slide clamp channel  824  are a plurality of slide clamp locating pins  824 A,  824 B which serve to provide, in combination with an asymmetric slide clamp  895 , a preferred orientation of the slide clamp  895  and thereby as the slide clamp  895  is already resident on the tube  5 , a preferred loading direction of the tube  5  into the pump  10 . 
     The slide clamp loader assembly is driven by camshaft  510  and is actuated by the slide clamp loading crank  650 . The slide clamp loading crank  650  has inserted therein a slide clamp loading crank pin  804  upon which rides a slide clamp actuator bushing  802 . The rotation of this crank is converted into a substantially linear motion by cooperative movement of the slide clamp actuator bushing  802  and the slide clamp traveler  815  by means of motion of the slide clamp actuator bushing  802  and the slide clamp traveler bushing race  813 . The slide clamp traveler  815 , in cooperation with the slide clamp clam pin  826 , provides substantially fore and aft motion of the slide clamp clams  820 ,  830 , which are operative to grasp and releasably retain the slide clamp  895 . The slide clamp clams  820 ,  830  are in a substantially scissorlike arrangement with respect to each other and reside in the slide clamp clam shell  832 , which is operative to allow fore and aft motion of the slide clamp clams  820 ,  830  therein. The tubeloader pawls further serve to raise the slide clamp shield  811 . This ensures that the slide clamp  895  will not be accidentally removed from the pump  10  as the position of the slide clamp traveler  815  provides that shield or visor  811  will be in a lowered position at such time as the pump  10  is in operation, thereby precluding removal of the slide clamp from the slide clamp groove  856 . 
     As aforementioned, slide clamp  895  is adapted to be gripped by the slide clamp clams  820 ,  830 . This is achieved by a cooperation between the slide clamp  895 , having detents or grippable elements impressed therein, and the slide clamp loader clam tips  820 ,  822  which are essentially barblike so as to ensure retention of the slide clamp  895  when the clams are engaged. 
     In operation the slide clamp loader functions in concert with the tubeloader assembly to ensure correct loading of the tube  5  and the associated slide clamp  895 . After the tubeloader pawls  514  close about the tube  5 , the slide clamp loading assembly, specifically the slide clamp clams  820 ,  830 , close onto the slide clamp resident about the tube  5  and within the slide clamp groove  856 . As the pawls  514  close, and the upper jaw  220  lowers into its operating position, and subsequent to the valves  412 ,  414  lowering to close off the tube  5 , the clams  820 ,  830  draw the slide clamp  895  into the slide clamp groove  856 , thereby opening the slide clamp as it slides past tube  5  which is being retained by the upstream tube stops  844 . 
     The cam arrangement between the valve loading cam races  120 ,  122  and the tube loader cams assures that the slide clamp will be closed by a reverse of the aforerecited motion of the slide clamp  895  with respect to the tube  5  prior to the tube being in a condition allowing removal thereof from the tubeway  8 . 
     SENSORS ASSOCIATED WITH THE SLIDE CLAMP LOADER 
     The slide clamp loader has two primary sensors associated therewith. The first of the these sensors is resident in the upstream platen  800  about the slide clamp groove  856 . This sensor is denoted the slide clamp positioning sensor. The slide clamp positioning sensor is located on sensor base  880 . Resident on sensor base  880  are two light emitting diodes  872  and  876  which are positioned in a fore and aft arrangement on a first side of the slide clamp groove  856 . Diametrically opposed to the light emitting diodes  872 ,  876  across the slide clamp groove  856 , are a corresponding pair of photocells  870 ,  874 . The photocells  870 ,  874  are also arranged fore and aft to align with the diodes  872 ,  876 . The diodes  872 ,  876  emit light into a first or transmitting pair of light pipes  864 ,  868  which extend upwardly above the upstream platen  800  on one side of the slide clamp groove  856 . The light pipes  868 ,  864  terminate in 45 degree internal reflecting surfaces  863  which serve to bend the output of the diodes  872 ,  876  into horizontal beams transverse to the slide clamp groove  856  at a height suitable for intersection of the beams with a slide clamp  895  present in the groove  856 . A corresponding set of receiving light pipes  860 ,  862  across from the transmitting light pipes  864 ,  868  serve to receive the light beam emitted by the diodes  872 ,  876  and transmit same down to the receiving photocells  870 ,  874  thus putting the light sources and sensors in photonic communication. The receiving light pipes  860 ,  862  also comprehend 45 degree internal reflecting surfaces  863  in opposing relation to those of transmitting light pipes  864 ,  868 . 
     In operation the slide clamp sensors serve to identify both the position and presence of a slide clamp  895  in the slide clamp loader sub-assembly. The two sensor sets corresponding to the outer photocell  874  and the inner photocell  870  work in concert to accurately display the location of the slide clamp  895  within the loader sub-assembly. Specifically, the two sensors  874  and  870  determine the location of the slide clamp  895  according to the following truth table wherein high denotes a beam transmitted across the slide clamp groove  856  and low denotes a condition wherein reception of a specific beam is absent. 
     
       
         
               
               
               
             
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Outer Beam 
                 Inner Beam 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 No Slide Clamp 
                 High 
                 High 
               
               
                   
                 Clamp Present &amp; Open 
                 Low 
                 Low 
               
               
                   
                 Clamp Present &amp; Closed 
                 High 
                 Low 
               
               
                   
                 Clamp Not Fully Home 
                 Low 
                 High 
               
               
                   
                   
               
             
          
         
       
     
     As can be seen from this table, the duality of the sensor array allows not only a detection of the presence or absence of the slide clamp  895 , but also detection of the position thereof within the slide clamp groove  856  and, therefore, as the tube  5  is in a fixed location within the tubeway  8 , an indication of the state of the slide clamp  895 , namely opened or closed, is also provided. 
     Also associated with the slide clamp loader sub-assembly, a micro switch  882  in combination with an actuator  882 A, which is operated by crank pin  804 , serves to detect operation of the tubeloader camshaft  510  by means of handwheel  600  and with associated electronics will register an alarm when handwheel  600  is rotated. 
     THE PUMP HOUSING 
     The last of the major sub-assemblies associated with the pump  10  is the pump housing  900 . In general aspect, the housing  900 , as well as the pump assembly  10 , is adapted to be stackable vertically so as to allow, in an alternative embodiment, a plurality of pumps  10  to be driven off of a single associated control module. 
     The pump housing  900  provides for an attachment and fixation point for the motor mount strap  955  which serves to support the pump motor  24  and the tubeloader motor  550 , which are supported in resilient grommets  960 ,  965 , which have associated therewith rotation-suppressing indents  970 ,  972  which serve to hold securely the two motors  24 ,  550  and suppress torsional vibration thereof with the co-action of the indents  970 ,  972  and the corresponding indent-engaging keys  972 A,  972 B. 
     The case  900  further consists of a tubeway access slot  904  which has an upstream end  902  and a downstream end  901 , wherein both the upstream end  902  and the downstream end  901  are geometrically adapted to form drip loops in the tube  5  by means of a downwardly angled orientation of each of the tubeway access slot ends  901 ,  902 . This geometric adaptation of the tubeway slot ends  901 ,  902  serves to ensure a conformation of the tube  5  which serves to prevent fluid ingress of the pump  10  from leaks associated with fluid delivery components exterior to the pump  10 . The housing  900  further has defined therein an access port  906  adapted to receive therein the tubeloader camshaft handwheel  600  so as to provide access thereto by an operator. 
     CONCLUSION 
     This description of the preferred embodiment of the instant invention is indicative of that embodiment presently preferred and should not be deemed to restrict the scope of the instant invention in any way more restrictive than the scope of the Claims appended hereto, and other and equivalent embodiments of the instant invention are to be deemed as expressly included in the claimed elements of the instant invention.