Patent Publication Number: US-2020284636-A1

Title: Reciprocating fluid meter

Description:
FIELD OF INVENTION 
     The field of the invention is flow meters. 
     BACKGROUND 
     The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art. 
     Currently the flow control and metering industries are limited in their ability to accurately measure and concurrently control rates of flow across a broad spectrum with a single device. Consequently, the rate of flow in which the customer must operate any given meter, must be inside of a given rate of flow envelope (as published by the manufacturer) in order to receive accurate rate, velocity and volume information. This operating envelope can be narrow. This restriction can hinder the customer in choosing the appropriate metering device for a given application, as quite often the rate of flow will exit this accuracy envelope, be it on the low or high side. 
     When a manufacturer of a metering device publishes operating statistics for their product, the term “turndown ratio” or “rangeability” is always very high on the list of questions asked by a potential buyer. Turndown ratio is the maximum rate of flow, divided by the minimum rate of flow put forward by the manufacturer. If the rate of flow exits this given range, the accuracy of the meter will degrade sharply, this is the operating envelope referred to in the previous paragraph. For example, if a meter has a published turndown ratio of 50 (or 50:1), it would mean that the meter would be capable of accurately measuring down to 1/50 th  of its maximum operating range. Given this example, a meter with a turndown ratio of 50, with a maximum range of 20 GPM, will accurately measure down to 0.4 GPM. Flow exceeding this high/low range will not be measured or recorded with a high degree of accuracy. 
     Predominantly we see turndown ratios of 50 or less available in today&#39;s market place. To combat this, some manufacturers will pair mechanical meters of different capabilities together to create a new metering product. The meters which make up this new product will have a high rate of flow envelope, say 10 to 200 GPM, and the other, a low flow envelope, 0.5 to 15 GPM. The manufacturer of this meter can now measure across a broader range, expanding the accuracy envelope to the highest and lowest ranges of each meter, in this example 0.5 GPM to 200 GPM, giving it a turndown ratio of 400. This is called a compound meter. 
     Previous versions of piston/cylinder meters do exist, but all have faults which detract from their accuracy, throughput and reliability. For example, U.S. Pat. No. 3,459,041 to Hippen describes a complex metering device that lacks a timing mechanism, along with an external valve. These drawbacks hindered the meter in 3 ways. First the lack of a timing mechanism eliminated its ability to measure rate of flow (the device only measures total volume). Second, it cannot start and stop flow in conjunction with user input. And last, its reliability was hindered by a large number of moving parts. 
     The Hippen invention was designed to address two problems associated with a piston/cylinder metering device. These problems were the inability to detect very low rates of flow (this resulted in fluid passing previous piston/cylinder meters undetected), and backpressure created by two or more valves being closed inside of the device simultaneously. While the Hippen patent aimed to solve these issues, there were in fact additional problems associated with a piston/cylinder metering device which were not addressed by the Hippen patent. 
     All publications identified herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply. 
     SUMMARY OF THE INVENTION 
     The inventive subject matter provides apparatus, systems and methods in which A reciprocating piston fluid meter assembly comprises a cylinder housing (ref  FIG. 1 a   ,  150 ) separated by a piston (ref  FIG. 2 a   ,  260 ) into two chambers (ref  FIG. 5 b   .  525 ,  528 ) and measures the flow rate and volume of a fluid by tracking the distance traveled by the piston along a pushrod ( 210 ) running through a cylinder. It is contemplated that the reciprocating piston fluid meter can be used to measure the flow rate of any fluid, including gas, liquid (including water, solution, and oil), and any mixture thereof. 
     In preferred embodiments, the reciprocating piston fluid meter assembly has two inlets (ref  FIG. 2 a -2 b   ,  310 ,  320 ), two outlets ( 330 ,  340 ), two end-caps ( 300 L,  300 R), and four passages each coupling one inlet or outlet to a chamber. A perforated spindle valve ( 230 L,  230 R) at each end of the pushrod ( 210 ) is positioned at a junction between two passages inside of each endcap ( 300 L,  300 R), and can simultaneously control the two passages by shutting them both or allowing only one in each endcap to be open. Since fluid cannot pass through the system without triggering the travel of piston  260 , which is tracked by a tracking device (e.g., linear encoder), the reciprocating fluid meter is highly sensitive and can detect very small flow volumes and velocities. 
     The pushrod ( 210 ) comprises an elongated member that travels inside the cylinder housing ( 150 ). In preferred embodiments, spring catches ( FIG. 3 a - b   ,  235 L,  235 R) are rigidly coupled to pushrod  210 , along with rigidly coupled perforated spindle valves  230 L and  230 R, and engaging elements  220 L and  220 R. Two sealing members ( FIG. 5,6   a - e ,  400 L,  400 R) are disposed outside of endcaps  300 L and  300 R. Each have magnets ( FIG. 6 c - d   ,  420 L,  420 R) that interact with the engaging elements ( 220 L,  220 R), which provides magnetic force sufficient to counteract the elastic force created by springs  250 L and  250 R ( FIG. 3 a   ). 
     The reciprocating fluid meter assembly has one or more mechanisms to provide damping force that at least partially reduces the travel speed of pushrod assembly  200  ( FIG. 3 b   ). First, the sealing members ( FIG. 7 a - b   ,  400 L,  400 R) contain damping pins ( 410 L,  410 R) which can be transitioned inside bores ( FIG. 7 a   ,  211 R) on either end of the pushrod ( 210 ). Second, pushrod  210  has bores ( 211 L,  211 R) with a thru-hole ( 212 L,  212 R) through a longitudinal wall of the pushrod. Third, the sealing members ( 400 L,  400 R) have receptacles that can interact with engaging elements  220 L and  220 R. Third, the engaging elements ( 220 L,  220 R) have through holes ( FIG. 3 b   ,  FIG. 7 b - c   ,  221 - 226 ) that can be either open or blocked by screws (e.g.,  FIG. 7 a - c   ,  466 L,  466 R). It is contemplated that one or more sources of damping force can be adjusted, and one or more elements described above have tapered or non-tapered walls. It is also contemplated that one or more O-rings can be used to seal one or more holes or receptacles. 
     Because the reciprocating piston fluid meter (e.g. RPM, reciprocating piston meter, or reciprocating fluid meter) relies on the positive displacement of piston  260  to measure flow, it enables the system to detect and measure flow rates which other meters are not capable of detecting, this is especially true at very low rates and velocities. Because the position of the piston (in conjunction with time) is used to calculate rate, it allows the invention to hold accuracy across a very large range, and allows the system to produce repeatable volume/mass accuracies which rival Coriolis meters at 0.05 to 0.1%. 
     In some embodiments, the RPM can be configured to measure flow rates from 0.0004 GPM to 60.0 GPM, giving it a turndown ratio of 150,000. 
     Such embodiments can also be configured to measure flow velocities as low as 0.0001 FPS up to 25 FPS. 
     Various meter configurations can be constructed to target the specific high or low ranges required by the customer&#39;s application. For example, high flow velocity or rate applications will require a larger cylinder diameter ( FIG. 150 ), in which case the meters high end may be 250 GPM, but the resolution will diminish in accordance with the larger tube diameter. 
     The RPM can detect flow rates as small as 5 ml over a 60-minute time period. In other embodiments, it can be stated that a variety of applications would benefit from a smaller tube diameter. As such, the resolution of the invention increases, making the device more accurate, but decreasing the maximum rate/velocity of flow, through the device. Applications which may benefit from a smaller tube diameter may include laboratory environments in the petrochemical, pharmaceutical and food industries. 
     The high turndown ratio, in combination with the inventions accuracy, will provide the end user with a metering solution which could be beneficial in flow control, batching, dosing, compounding, custody transfer and leak detection operations. 
     The RPM solves a multitude of problems not only seen in the Hippen device, but in other previous piston/cylinder metering devices. These problems appear in 4 categories: 
     1) Rate of Flow—The Hippen invention, and previous inventions, could only record the total volume which passed through them. They did not record/report rate of flow, as the devices could not measure time in accordance with flow. Ex: If 5 gallons passed through the meter in 1 minute, the Hippen device would only display 5 gallons, not the rate of 5 gallons per minute, as it did not contain an internal clock. 
     2) External Valve—The Hippen invention cannot start or stop flow in conjunction with programmed user input, as it does not have an external valve. Ex: The RPM can be used for batching/dosing (filling multiple containers repeatedly with an identical quantity of fluid). Custody transfer (the transfer of a specific amount of fluid for purchase), compounding (making another product using an exact fluid volume) and leak detection (the valve allows the RPM to shutoff all flow, should a leak be detected. 
     3) Accuracy
         The RPM can precisely track piston position through the use of a linear encoder.   The solid pushrod ensures that the valves inside of either endcap switch at exactly the same time, in perfect unison with one and other. The use of a solid pushrod, as opposed to a pushrod which actuates individual spring-loaded valves through a lever, as the Hippen device does, eliminates numerous parts, and makes the device significantly more reliable.       

     4) Simplicity of Build
         Magnet—The RPM uses a magnet to oppose the energy created by the piston compressing the pushrod spring. Once the spring is fully compressed, the magnet is forced to release the pushrod, allowing the compressed spring to thrust the valve to its new position, engaging the magnet on the opposite side, and reversing flow. This action reverses the pistons direction. This simple action eliminates numerous parts, making the device reliable and simple.   Piston Tracking—The RPM tracks the position of the piston by embedding a magnet inside of the piston and tracking the position of the piston through the movement of another magnet which sits outside of the cylinder (directly on top of the piston magnet). When the piston moves, the external magnet which sits outside of the cylinder moves with it.   Linear Encoder—The RPM uses a linear encoder in conjunction with magnets embedded in the piston to measure the position of the piston along its longitudinal track. This allows us to report and record the position of the piston.   Internal Valve Simplicity—The RPM uses a more efficient valve configuration. This is achieved by allowing fluid to flow through the same channel, in either direction (these channels begin at the six large holes inside the fluid chambers in the cylinder and run through each endcap to the center of the valve). The device can change direction of flow through the valves in either endcap, in unison, by moving the solid pushrod assembly a short distance when the piston reaches its full range of travel, reversing the direction of the piston.       

     Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components. 
     Alternate Embodiment (A) FIG.  1   d    
     In alternate embodiment (A), the power needed to drive pushrod assembly  750  ( FIG. 3 k   ) is provided by an air cylinder or electric motor  712  ( FIG. 1 d   ). The air cylinder or electric motor  712  has a shaft that is rigidly attached to pushrod  706 . The air cylinder/electric motor  712  has a body that is rigidly attached through stand-offs ( FIG. 1 d , 3 e   ,  712 ) to right sealing member  700 R ( FIG. 1 d   ). Perforated spindle valves  702 R and  702 L are also rigidly attached to pushrod  706  ( FIG. 2 c , 3 k   ). 
     Alternate embodiment (A) simplifies the primary embodiment by both eliminating the spring/magnet drive mechanism, and making the remaining parts less complex. 
     The following parts are eliminated from the primary spring/magnet embodiment: Engaging elements  220 L and  220 R, spring catches  235 L and  235 R, springs  250 L and  250 R, damping pins  410 L and  410 R and magnets  420 L and  420 R (Reference  FIGS. 2 a , 2 b  and 3 a   ). 
     The following parts are unique to the primary embodiment: Piston  260 , perforated spindle valve  230 L and  230 R, pushrod guide  240 L and  240 R, pushrod  210  (Reference  FIGS. 2 a , 2 b  and 3 a   ). 
     The following parts are unique to alternate embodiment (A): Piston  710 , perforated spindle valve  702 L and  702 R, pushrod guide  704 L and  704 R and pushrod  706  (Reference  FIG. 2 c   ). 
     Alternate Embodiment (B) RPM Pump FIG.  1   e    
     Alternate embodiment (B) is a highly accurate, positive displacement piston pump. It combines the accuracy of the primary embodiment and alternate embodiment (A) with a linear actuator that can precisely control rate of flow. Alternate embodiment (B) is a standalone piston pump, and can start, stop or alter flow rates based on input from the user through the interface. 
     Alternate embodiment (B)  FIG. 1 e    depicts a subassembly framework which is built in conjunction with the primary embodiment ( FIG. 1 a   ), or alternate embodiment (A) ( FIG. 1 d   ). This framework, which incorporates a stepper motor and linear actuator, allows piston  846 ,  FIG. 2 f , 2 h    to be precisely moved back and forth along the same track as the primary or alternate embodiment (A). 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1 a    is a front, left, top perspective view of an embodiment of A reciprocating fluid meter. 
         FIG. 1 b    is a front, right, top perspective view of the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 1 c    is a rear, right, top perspective view of the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 1 d    is a front, right, top perspective view of an alternate embodiment (A) of the reciprocating fluid meter of  FIG. 1   d.    
         FIG. 1 e    is a front, right, top perspective view of an alternate embodiment (B). 
         FIG. 2 a    is an exploded perspective view of the reciprocating fluid meter of  FIG. 1 a   , without the display. 
         FIG. 2 b    is an exploded top plan view of the reciprocating fluid meter of  FIG. 1 a   , without the display. 
         FIG. 2 c    is an exploded perspective view of the alternate embodiment (A) of the reciprocating fluid meter of  FIG. 1   d.    
         FIG. 2 d    is a front, right, top perspective view of the alternate embodiment (B) of the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 2 e    is a front, right, top perspective view of the alternate embodiment (B) of the reciprocating fluid meter of  FIG. 1   d.    
         FIG. 2 f    is a front, right, top cutaway view of the alternate embodiment (B) of the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 2 g    is a front, right, top cutaway/exploded view of the alternate embodiment (B) of the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 2 h    is a front, right, top cutaway view of the alternate embodiment (B) of the reciprocating fluid meter of  FIG. 1   d.    
         FIG. 2I  is a front, right, top cutaway exploded view of the alternate embodiment (B) of the reciprocating fluid meter of  FIG. 1   d.    
         FIG. 3 a    is an exploded view of pushrod assembly  200  and related components in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 3 b    is a perspective view of pushrod  210 , engaging elements  220 L,  220 R, perforated spindle valves  230 L,  230 R, spring catches  235 L,  235 R, and pushrod guide  240 L,  240 R in the reciprocating fluid meter  001  of  FIG. 1   a.    
         FIG. 3 c    is a vertical cross-sectional view (along line A-A in  FIG. 3 b   ) of the pushrod, engaging elements, perforated spindle valves, spring catches and pushrod guides in the reciprocating fluid meter  001  of  FIG. 1   a.    
         FIG. 3 d    is a horizontal cross-sectional view (along line B-B in  FIG. 3 b   ) of the pushrod, engaging elements, perforated spindle valves, spring catches and pushrod guides in the reciprocating fluid meter  001  of  FIG. 1   a.    
         FIG. 3 e    is a perspective view of alternate embodiment (A) pushrod assembly and power source. It includes pushrod  706 , perforated spindle valves  702 L and  702 R, pushrod guides  704 L and  704 R, sealing members  700 L and  700 R, standoffs  714 , the air cylinder/motor mounting block  708  and the 3 position air cylinder/motor part  712 . 
         FIG. 3 f    is a horizontal cross-sectional view (along line B-B in  FIG. 3 b   ) of alternate embodiment (A) pushrod assembly. The parts consist of pushrod  706 , perforated spindle valves  702 L and  702 R, pushrod guides  704 L and  704 R, sealing members  700 L and  700 R, along with the 3 position air cylinder/motor part  712 . 
         FIG. 3 g    is a left side view of endcap  300 R, depicting pushrod guide  240 R disengaged from endcap  300 R, with fasteners  237 ,  238  and  239  also disengaged. 
         FIG. 3 h    is a left side view of endcap  300 R, depicting pushrod guide  240 R fully seated and affixed in place by fasteners  237 ,  238  and  239 . 
         FIG. 3 i    is a left side view of endcap  300 R, depicting pushrod guide  704 R fully seated and affixed in place by fasteners  237 ,  238  and  239 . 
         FIG. 3 j    is a perspective cross-sectional view of alternate embodiment (A) of  FIG. 1 d   .  FIG. 3 j    depicts pushrod assembly  750  (Ref.  FIG. 3 k   ) in a second position. 
         FIG. 3 k    is a perspective view of alternate embodiment (A) pushrod assembly. 
         FIG. 4 a    is a multi-angle sectional view of an end-cap ( 300 ) in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 4 b    is a left side view of the right end-cap in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 5 a    is a perspective cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line A-A of the right end-cap in  FIG. 4 b    showing two of six channels ( 302 L,  302 R and  305 L,  305 R) in each end-cap. 
         FIG. 5 b    is a side cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line A-A of the right end-cap in  FIG. 4 b    showing two of six channels in each end-cap. 
         FIG. 5 c    is a perspective view of a cross section of the reciprocating fluid meter of  FIG. 1 a   , along line B-B of the right end-cap showing two of six channels ( 301 L,  301 R and  306 L,  306 R) in each end-cap. 
         FIG. 5 d    is a side cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line B-B of the right end-cap showing two of six channels in each end-cap. 
         FIG. 5 e    is a perspective cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line D-C (in  FIG. 4 b   ) of the right end-cap and line C-D (in  FIG. 4 b   ) of the left side, showing a portion of the first and third passages. (Note the orientation of  FIG. 4 b    differs from the orientation of  FIG. 5 e   ) 
         FIG. 5 f    is a side cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line C-D (in  FIG. 4 b   ) of the left end-cap, showing a portion of the first and third passages, and along line D-C (in  FIG. 4 b   ) of the right end-cap showing a portion of second and fourth passages. (Note the orientation of  FIG. 4 b    differs from the orientation of  FIG. 5 e   ). 
         FIG. 5 g    is a perspective cross-sectional view of alternate embodiment (A) of  002   FIG. 1 d   , along line D-C (in  FIG. 4 b   ) of the right end-cap and line C-D (in  FIG. 4 b   ) of the left side, showing a portion of the first and third passages. 
         FIG. 5 h    is a side cross-sectional view of alternate embodiment (A) of  002   FIG. 1 d   , along line B-B of the right end-cap showing two of six channels in each end-cap (ref  FIG. 4 b   ). 
         FIG. 6 a    is an outside perspective view of the right sealing member ( 400 R) in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 6 b    is an inside perspective view of the right sealing member in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 6 c    is a vertical cross-sectional view of the right sealing member along line A-A in  FIG. 6   b.    
         FIG. 6 d    is a vertical cross-sectional view of the sealing member along line B-B in  FIG. 6   c.    
         FIG. 6 e    is a vertical cross-sectional view of the sealing member along line C-C in  FIG. 6   c.    
         FIG. 6 f    is a perspective view and cross-sectional views along lines D-D and E-E of the right sealing member in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 6 g    is a cross-sectional side view (along line D-D in  FIG. 6 f   ) of the sealing member in  FIG. 6   f.    
         FIG. 6 h    is a cross-sectional side view (along line E-E in  FIG. 6 f   ) of the sealing member in  FIG. 6   f.    
         FIG. 7 a    is a side cross-sectional view of the right sealing member interacting with the pushrod in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 7 b    is a perspective cross-sectional view of the right sealing member interacting with the pushrod in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 7 c    is an exploded view of the right sealing member in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 8 a    is an exploded view of the encoder housing in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 8 b    is an exploded perspective view of the encoder alignment with the piston in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 8 c    is a cross-sectional view of the encoder alignment magnets ( 263 ,  264 ) with the piston and piston encoder magnets ( 261 ,  262 ) in the reciprocating fluid meter of  FIG. 1   a.    
         FIG. 9 a    is a partially exploded cross-sectional view of the left end-cap and sealing member in the reciprocating fluid meter of  FIG. 1 a   , with the engaging element ( 220 L) disengaged from sealing member  400 L. 
         FIG. 9 b    is a partially exploded cross-sectional view of the left end-cap and sealing member in the reciprocating fluid meter of  FIG. 1 a   , with the engaging element ( 220 L) partially entering sealing member ( 400 L), half-way across its total travel length. 
         FIG. 9 c    is a partially exploded cross-sectional view of the left end-cap and sealing member in the reciprocating fluid meter of  FIG. 1 a   , with the engaging element ( 220 L) completely engaged with the sealing member ( 400 L). 
         FIG. 9 d    is a partially exploded cross-sectional view of right end-cap  300 R in alternate embodiment (A) of reciprocating fluid meter  002  of  FIG. 1 d   . Note position of perforated spindle valve  702 R in a third position, allowing fluid to exit the device, while entering the device from the opposite side. 
         FIG. 9 e    is a partially exploded cross-sectional view of right end-cap  300 R in alternate embodiment (A) of reciprocating fluid meter  002  of  FIG. 1 d   . Note position of perforated spindle valve  702 R in a center second position, closing both inlet port  310 , and outlet port  330 . 
         FIG. 9 f    is a partially exploded cross-sectional view of right end-cap  300 R in alternate embodiment (A) of reciprocating fluid meter  002  of  FIG. 1 d   . Note position of perforated spindle valve  702 R in a first position, allowing fluid to enter the device, while exiting the device from the opposite side. 
         FIG. 10 a    is a cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 200 ) in a first position where the first passage ( 310 ) (between first inlet and first chamber  528 ) is open, the second passage ( 320 ) (between second inlet and second chamber  525 ) is closed, the third passage ( 330 ) (between first chamber  528  and first outlet) is closed, the fourth passage ( 340 ) (between second chamber  525  and second outlet) is open. 
         FIG. 10 b    is a cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 200 ) in the first position as in  FIG. 10 a   , where the piston ( 260 ) has traveled further to the left side and spring  250 L has made contact with spring catch  235 L on the left side. 
         FIG. 10 c    is a cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 200 ) in the first position as in  FIG. 10 , spring  250 L is fully compressed between piston  260  and spring catch  235 L, and piston  260  has made contact with catch  235 L at point  241  (point  241  is the face of the piston and the face of spring catch  235 L, see  FIG. 3 c   ,  245 L,  245 R and  FIG. 9 a   ). 
         FIG. 10 d    is a cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 200 ) in a second position, where the first passage ( 310 ) (between first inlet and first chamber  528 ) is closed, the second passage ( 320 ) (between second inlet and second chamber  525 ) is closed, the third passage ( 330 ) (between first chamber  528  and first outlet) is closed, the fourth passage ( 340 ) (between second chamber  525  and second outlet) is closed. 
         FIG. 10 e    is a cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 200 ) in a third position, where the first passage ( 310 ) (between first inlet and first chamber  528 ) is closed, the second passage ( 320 ) (between second inlet and second chamber  525 ) is open, the third passage ( 330 ) (between first chamber  528  and first outlet) is open, the fourth passage ( 340 ) (between second chamber  525  and second outlet) is closed. Engaging element  220 L is seated against surface  453 L ( FIG. 6 c   ), adjacent to magnet  420 L, and the piston has reversed direction. 
         FIG. 10 f    is a cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 200 ) in the third position as in  FIG. 10 e   , showing the piston is disposed just left of the center position and is moving towards the right. 
         FIG. 10 g    is a cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 200 ) in the third position as in  FIG. 10 e   , showing the piston is disposed right of center and spring  250 R is in contact with spring catch  235 R. 
         FIG. 10 h    is a cross-sectional view of alternate embodiment (A) reciprocating fluid meter of  FIG. 1 d   . Along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 750   FIG. 3 k   ) in a first position where the first passage ( 310 ) (between first inlet and first chamber  528 ) is open, the second passage ( 320 ) (between second inlet and second chamber  525 ) is closed, the third passage ( 330 ) (between first chamber  528  and first outlet) is closed, the fourth passage ( 340 ) (between second chamber  525  and second outlet) is open. 
         FIG. 10 i    is a cross-sectional view of alternate embodiment (A) reciprocating fluid meter of  FIG. 1 d   , Along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 750   FIG. 3 k   .) in a second position, where the first passage ( 310 ) (between first inlet and first chamber  528 ) is closed, the second passage ( 320 ) (between second inlet and second chamber  525 ) is closed, the third passage ( 330 ) (between first chamber  528  and first outlet) is closed, the fourth passage ( 340 ) (between second chamber  525  and second outlet) is closed. 
         FIG. 10 j    is a cross-sectional view of alternate embodiment (A) reciprocating fluid meter of  FIG. 1 d   , Along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 750   FIG. 3 k   ) in a third position, where the first passage ( 310 ) (between first inlet and first chamber  528 ) is closed, the second passage ( 320 ) (between second inlet and second chamber  525 ) is open, the third passage ( 330 ) (between first chamber  528  and first outlet) is open, the fourth passage ( 340 ) (between second chamber  525  and second outlet) is closed, and the piston has reversed direction. 
     
    
    
     DETAILED DESCRIPTION 
     In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. 
     As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. 
     Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints, and open-ended ranges should be interpreted to include only commercially practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary. 
     The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value with a range is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention. 
     Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims. 
     The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus, if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed. 
     As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously. 
     Unless specified otherwise, the left side of the reciprocating fluid meter is symmetrical to its right side. The letter “R” designates the on the right side; the letter “L” designates the left side. 
       FIGS. 1 a - c    show an embodiment of a reciprocating fluid meter  001 .  FIG. 1 a    is a front, left, top perspective view of an embodiment of a reciprocating fluid meter  001 .  FIG. 1 b    is a front, right, top perspective view of the reciprocating fluid meter  001  of  FIG. 1 a   .  FIG. 1 c    is a rear, right, top perspective view of the reciprocating fluid meter  001  of  FIG. 1   a.    
       FIG. 1 d    shows alternate embodiment (A) of a reciprocating fluid meter  001 .  FIG. 1 d    is a front, right, top perspective view of the alternate embodiment (A) of a reciprocating fluid meter  002 . 
       FIG. 1 e    shows alternate embodiment (B). It is a front, right, top perspective view of alternate embodiment (B). 
     The reciprocating fluid meter  001  and alternate embodiment (A)  002  in  FIG. 1 a , 1 d    has a housing  150 , two end-caps (ref  FIGS. 1 a -1 d   )  300 L and  300 R, two sealing members  400 L,  400 R, and  700 L,  700 R in alternate embodiment (A), a display/computer housing  500 , a main inlet  101 , and a main outlet  199 . 
     The primary components which makeup the invention in its totality are depicted in  FIGS. 1 a , 1 b , 1 c  and 1 d   . The device is comprised of 8 primary parts, which include: 1) Inlet and outlet ports, 2) Endcaps, 3) Piston/cylinder housing, 4) Pushrod assembly, 5) Sealing components, 6) External valve (primary embodiment), Internal valve (alternate embodiment (A)), 7) Linear encoder, 8) RPM Computer.
         1. Inlet and Outlet Ports—Each endcap ( FIG. 2 a - b   ,  300 R,  300 L) contains one inlet port ( 310 ,  320 ) and one outlet port ( 330 ,  340 ). The media to be measured enters the device through a single orifice ( FIG. 1 c      101 ), continues through a short network of pipe, and enters the device through one of two open inlet ports ( 310 ,  320 ).   Each inlet and outlet port open and close in unison with one and other and will always act in opposition to each other. Example ( FIG. 2 b   ), when endcap  300 R has an open inlet port ( 310 ) and a closed outlet port ( 330 ), endcap  300 L will have a closed inlet port ( 320 ) and an open outlet port ( 340 ). Once the media flowing through the device has been measured, it exits the device through one of two outlet ports ( 330 ,  340 ). Note that the media being measured will always exit the same endcap in which it entered. When the valves shift position, the inlet and outlet positions shift from open to closed on both sides simultaneously. It is not possible for a given amount of fluid to enter the device through port  310  and exit the device through the opposite outlet ( 340 ) and vice versa. It will always exit from the same endcap in which it entered, in this case, outlet port  330 .   2. Endcaps—The two endcaps ( 300 R,  300 L) are identical to one and other. Each contain a 3-position valve which is rigidly coupled through a pushrod to the opposite endcap. The position of each valve inside of the endcaps operates in opposition to its counterpart. In other words, when the inlet port on endcap  300 L is closed, the inlet port on  300 R is open, the same is true for each outlet port. It is not physically possible for any two inlet or outlet ports to be open at the same time.   When the valve in each endcap is shifting to a new position, both valves will transition through a fully closed position (inlet ports  310 ,  320  and outlet ports  330 ,  340  will all be closed momentarily). By swiftly moving through this fully closed position, fluid is prevented from moving directly from an inlet to an outlet, which would impact the meters accuracy. The brief backpressure created by the closed valves is elevated through a hydraulic surge arresting device.   3. Piston/Cylinder Housing—The cylinder housing ( FIG. 2 b   ,  150 ) contains the piston ( 260 ), which moves longitudinally along the length of cylinder  150 . It is the pistons displacement, measured by the linear encoder, which allows the device to accurately measure rate and volume. When any given amount of fluid enters the device, it will always displace an equal amount of fluid exiting the device.   Rigidly attached to each face of the piston, about the pistons central axis, are springs ( FIG. 3 a   ,  250 R,  250 L). The springs, when compressed by the piston, provide the energy to shift the position of each valve inside of each endcap to its new position. This action causes a reversal in flow, forcing the piston to reverse direction at the end of its travel length.   Alternate embodiment (A) does not contain springs  250 L and  250 R. When the piston reaches its full travel length, the encoder which tracks the position of the piston will signal the RPM&#39;s computer to shift the position of the pushrod valve assembly ( FIG. 3 k   ,  750 ) to the opposite side. This action causes a reversal in flow, forcing the piston to reverse direction at the end of its travel length.   4. Pushrod Assembly—Running through the center of the device, along the longitudinal centerline is a solid pushrod ( FIG. 3 a   ,  210 ). Affixed to pushrod  210  are 6 parts, all of which are rigidly attached to pushrod  210 . The left and right sides of pushrod assembly  200  ( FIG. 3 b   ), are symmetrical to one and other.   Rigidly attached to pushrod  210 , are the spring catch ( 235 L,  235 R), the perforated spindle valves ( 230 L,  230 R), and the engaging elements, or plates ( 220 L,  220 R) see  FIG. 3   b.      Rigidly attached to endcaps  300 L and  300 R ( FIG. 3 e - f   ), is the pushrod guide ( FIG. 3 a - d   ,  240 L,  240 R). Pushrod  210  moves longitudinally through the central axis of the fixed pushrod guide when the pushrod shifts valve positions. The pushrod is sealed by an O-ring mounted inside the bore of part  240 L and  240 R ( FIG. 3 d    point  236 ). The pushrod guide serves to seal cylinder housing  150  from the valve in either endcap.   Pushrod assembly  750  ( FIG. 3 k   ) of alternate embodiment (A) differs from the primary embodiment. In alternate embodiment (A), engaging elements ( 220 L and  220 R) and spring catches ( 235 L and  235 R) are not required. Additionally perforated spindle valves  230 L and  230 R and pushrod guides  240 L and  240 R, while performing the same function, take a different shape.   Rigidly attached to pushrod  706  ( FIG. 3 e -3 f   ) of alternate embodiment (A), are perforated spindle valves  702 L and  702 R. Pushrod  706  moves longitudinally through the central axis of pushrod guides  704 L and  704 R, and sealing members  700 L and  700 R, both of which are rigidly attached to endcaps  300 L and  300 R (Reference  FIGS. 2 c  and 3 i   )   5. Sealing Components (Primary Embodiment)—Affixed to each end of the device, along the longitudinal centerline, are sealing components ( 400 L,  400 R). Each component serves three purposes.   1) It houses the magnet which directly opposes the energy created by springs  250 L and  250 R.   2) It serves to slow the velocity at which the pushrod, specifically part  220  L and R, make direct contact with surface  453 L and  453 R of part  450  ( FIG. 6 c , 7 b   ).   3) It houses damping pin  410 L and  410 R ( FIG. 7 a - b   ), which are used to provide fine adjustment to the damping mechanism.   Sealing Components (Alternate Embodiment (A)—Affixed to each end of the device, along the longitudinal centerline, are sealing components ( 700 L and  700 R). Each component serves to align pushrod  706  with the centerline of the device.   6. External Valve—Primary valve ( FIG. 1 a , 1 b   ,  205 ) starts and stops the flow of fluid exiting the invention. The valve can be programmed via the computer inside the encoder housing ( 501 ) to start and stop at specific volumes and time intervals.   Internal Valve—Alternate embodiment (A) does not require an external valve to start and stop flow. The air cylinder or motor ( FIG. 3 e   ,  712 ) can stop the motion of the pushrod assembly ( FIG. 3 k   ,  750 ) and rigidly attached perforated spindle valves ( 702 L and  702 R) at exactly ½ its travel length. This ½ way point, or second position, closes all 4 chambers, stopping the flow of media entering or exiting the device.     FIG. 10 i    is a cross-sectional view of alternate embodiment (A) of  FIG. 1 d   . Along line C-C in  FIG. 4 b   , showing the pushrod assembly ( FIG. 3 k   ,  750 ) in a second position, where the first passage ( 310 ) (between first inlet and first chamber  528 ) is closed, the second passage ( 320 ) (between second inlet and second chamber  525 ) is closed, the third passage ( 330 ) (between first chamber  528  and first outlet) is closed, the fourth passage ( 340 ) (between second chamber  525  and second outlet) is closed.   When the invention is used to measure specific quantities of fluid, (example—a batching or custody transfer application) or stop the flow of media when a specific flow rate has been exceeded (a leak detection application), the device can be programmed to automatically stop in this second position, as depicted in  FIG. 10   i.      7. Linear Encoder—The linear encoder, which is comprised of the encoder board ( FIG. 8 b      268 ), the encoder target ( 265 ), the encoder target/magnet housing ( 520 ), encoder wire guard ( 510 ), and the encoder magnets ( 261 ,  262 ,  263 ,  264 ).   The linear encoder tracks the position of piston  260  (or  710  for alternate embodiment (A) inside of cylinder housing  150 . Magnets  263  and  264  move in unison with magnets  261  and  262  ( FIG. 8 c   ). Magnets  263  and  264  are mounted inside of the encoder target/magnet housing ( 520 ). As the magnets move to track the position of the piston, housing  520  moves across the linear encoder board ( 268 ). Encoder board  268  is rigidly mounted to the base of the linear encoder housing ( 530 )   8. RPM Computer—The computer (ref  FIG. 8 a   ,  515 ) is housed inside of the linear encoder/display housing ( 500 ) and sits immediately below the 5-inch touch screen display ( 518 ). The computer displays, computes and stores data associated with input from the user, along with processing position information relayed to it from the linear encoder. It controls when, and in what time duration the external valve will open and close, allowing the device to function as a batching, dosing, custody transfer and leak detection system. Further its diagnostic function allows maintenance to be performed on the device both remotely (via Wi-Fi) and in person. This information is displayed to the user via the 5-inch touch screen display, or via a handheld tablet.       

     In reference to alternate embodiment (A), the RPM computer also serves to command air cylinder/motor  712  to a first ( FIG. 10 h   ), second ( FIG. 10 i   ) and third ( FIG. 10 j   ) position, in coordination with input from linear encoder target  520  ( FIG. 10 h -10 i   ), and/or a specific volume, leak or other condition which would require flow to stop. 
     It should be noted that both the primary and alternate embodiment (A) can employ the use of a hydraulic dampener or accumulator on the inflow and/or outflow sides of the device to mitigate the effects of hydraulic shock. 
     Primary Embodiment (Spring/Magnet) Detailed Description 
       FIG. 2 a    is an exploded perspective view of the reciprocating fluid meter of  FIG. 1 a   , without the display  501 .  FIG. 2 b    is an exploded top plan view of the reciprocating fluid meter of  FIG. 2 a    of the primary embodiment. 
       FIG. 1 a - c   ,  FIG. 2 a - b    depict primary valve  205  of the primary embodiment rigidly coupled to the outlet manifold assembly ( FIG. 1 c      130 ,  140 ,  180 ,  185 ,  190 ,  199 ) between pipe elbow  190  and outlet pipe  199 . Primary valve  205  is a two position, open/closed valve which starts and stops the flow of fluid exiting the device. The valve can be controlled both manually and automatically. This valve does not appear on alternate embodiment (A). 
     Manual actuation of primary valve  205  is controlled in two ways, through the rotation of a dial atop valve  205 , or through the inventions interface. 
     Automatic operation of primary valve  205  is a direct function of the RPM computer. Valve  205  will start and stop the flow of fluid in accordance with a given set of commands programmed by the user of the invention. The valve will automatically open or close in conjunction with the following: 
     Leak detection—Primary valve  205  will stop the flow of fluid passing through the invention should the rate, mass or volume of said fluid exceed programmed parameters set by the user of the device. 
     Batching/Dosing/Compounding operations—Primary valve  205  will automatically open and close in conjunction with a predetermined volume or mass of fluid passing through the invention. The predetermined volume or mass can be determined using an output signal of the encoder tracking device. This operation will repeat, allowing the user to fill multiple containers with a specific volume or mass of metered fluid, or perform similar tasks associated with batching, dosing or compounding operations. The time interval between the closed position and open position can also be programmed. 
     Custody transfer—Primary valve  205  will automatically open and close in conjunction with a predetermined volume or mass of fluid passing through the invention. The valve can also be manually opened/closed and the same volume/mass data will be displayed to the user, along with other ancillary information such as flow rate, temperature and velocity. 
     In preferred embodiments, pushrod ( 210 ) comprises an elongated member that can travel inside housing  150 . 
       FIG. 3 a    is an exploded view of pushrod  200 , piston  260  and related components in the reciprocating fluid meter of the primary embodiment 001 of  FIG. 1   a.    
     In the primary embodiment, the components which are rigidly attached to pushrod ( 210 ) or move along the longitudinal centerline of the pushrod can be seen in  FIG. 3 a   . Piston  260  sits in the center of the pushrod ( 210 ). Both the ID and OD of the piston are sealed against the ID of the cylinder ( 150 ) and the OD of the pushrod ( 210 ). This prevents fluid from leaking to the opposite side of the piston, which would degrade the meters accuracy. Attached to each side of the piston, about the center of each face, are springs  250 L and  250 R. Each spring is compressed at the end of the pistons travel length between piston  260  and spring catch ( FIG. 3 b - c   ,  235 L,  235 R). 
     The spring catch ( 235 L,  235 R) is rigidly attached to pushrod  210 , and therefore moves in unison with pushrod  210 . When the piston approaches its maximum travel length, one of the two springs ( 250 L,  250 R) will be compressed between piston  260  and the internal face of  235 L or  235 R (refer to the cutaway view of part  235 L and  235 R in  FIG. 3 c   ,  FIG. 9 a   ). The piston will continue to compress the spring until the face of piston  260 , specifically surface  315  (ref  FIG. 5 a , 5 c   ), makes physical contact with the face of  235 L or  235 R, specifically surface  245  (ref  FIG. 3 c   ). Contact between these two surfaces will force the pushrod assembly ( 200 ) to break the magnetic union between  220 L or  220 R and the magnet ( 420 L,  420 R) (specifically surface  453 R ref  FIG. 6 c   ) in either sealing component. 
     When the pushrod (which was held stationary during spring compression by magnet  420 L or  420 R) is dislodged from magnet  420 L, the energy from the compressed spring will physically drive pushrod assembly  200  into its new seated position in the opposite sealing member, reversing flow and driving the piston in the opposite direction where the process will be repeated. 
     The rigidly attached perforated spindle valves ( 230 L,  230 R), both direct flow from an inlet port ( 310 ,  320 ) to a chamber ( 525 ,  528 ) or from a chamber to an outlet port ( 330 ,  340 ), allowing fluid to flow into the flood chamber inside of the cylinder, or flow out of the flood chamber and exit the device. At the same time the inflow or outflow port on the opposite side of each perforated spindle valves is sealed. 
     The perforated spindle valves allow media to flow through the plethora of holes in each valve without disengaging from the seal to which it is mated. 
     The rigidly attached engaging elements ( 220 L,  220 R) are mounted at the end of the pushrod assembly ( FIG. 3 b   ,  200 ). The purpose of the magnetic engaging elements is to hold the pushrod stationary against surface  453 L or  453 R, via the force generated by magnet  420 L or  420 R. During this time, when the piston approaches the end of its travel length, it will compress spring  250 L or  250 R. Once spring  250 L or  250 R is fully compressed, the piston will make direct physical contact with rigidly attached  235 L or  235 R at point  241  ( FIG. 9 a   ). The force of piston  260  pressing against spring catch  235 L or  235 R will break the magnetic union between the engaging element and the magnet at the opposite end of the device. Compressed spring  250 L or  250 R will then drive pushrod assembly  200  to its new seated position, shifting the valve positions and the piston will reverse. 
       FIG. 3 b    is a perspective view of pushrod assembly  200 ,  FIG. 3 c    is a vertical cross-sectional view along line A-A in  FIG. 3 b   , and  FIG. 3 d    is a horizontal cross-sectional view (along line B-B in  FIG. 3 b   ) of pushrod assembly  200 , engaging elements ( 220 L and  220 R), perforated spindle valves ( 230 L and  230 R), spring catches ( 235 L,  235 R) and pushrod guides ( 240 L,  240 R) It also depicts the cross section of engaging elements  220 L,  220 R inclusive of dampening holes  221 L,  224 L,  221 R and  224 R in the reciprocating fluid meter  001  of  FIG. 1   a.    
       FIG. 3 d    is a horizontal cross-sectional view (along line B-B in  FIG. 3 b   ). The pushrod ( 210 ) comprises an elongated member having a bore ( FIG. 3 c      211 L,  211 R) on each end. 
     Engaging elements ( 220 L and  220 R), perforated spindle valves ( 230 L and  230 R), and spring catches ( 235 L and  235 R) are rigidly coupled to pushrod  210 . In preferred embodiments, the engaging elements ( 220 L and  220 R) have through holes ( 221 - 226 ) that can be plugged or unplugged to adjust the damping force. 
       FIG. 3 g    is an exploded view of endcap  300 R showing pushrod guide  240 R separated longitudinally along the extended center-line of endcap  300 R, with bolts ( 237 R,  238 R,  239 R) displaced laterally about the center-line of endcap  300 R. Bolts ( 237 R,  238 R,  239 R) affix  240 R to  300 R. 
       FIG. 3 h    is a perspective view of assembled endcap  300 R depicting  240 R rigidly mounted inside of endcap  300 R. 
       FIG. 4 a    is a multi-angle sectional view of endcap  300  in the reciprocating fluid meter  001  of  FIG. 1 a   . Each endcap contains two ports, one inlet ( 310 ,  320 ) and one outlet ( 330 ,  340 ). 
       FIG. 4 b    is a view from the cylinder housing side of the right end-cap  300 R in the reciprocating fluid meter  001  of  FIG. 1 a   . The endcap ( 300 R) has inlet  310  and outlet  330 . Six channels ( 301 R- 306 R) lead from the center of the valve ( FIG. 5 b      326 ) inside endcap  300 R to chamber  528 , inside the cylinder, between the piston and the inner face of each endcap. 
     Two tapered pins ( FIG. 5 c , 5 d   ,  307 L,  307 R) protrude from the inner face of each endcap ( 300 L,  300 R). Each tapered pin fits directly into a similar size hole ( FIG. 5 c , 5 d   ,  308 L,  308 R) in the piston ( 260 ). The pin insures that the piston stays in longitudinal alignment and does not rotate about the axis of pushrod  210  while in motion. 
       FIG. 5 a    is a perspective cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line A-A of the right end-cap in  FIG. 4 b    showing two channels in each end-cap.  FIG. 5 b    is a side cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line A-A of the right end-cap in  FIG. 4 b    showing two channels in each end-cap. Channels  302 L and  305 L are visible in left end-cap  300 L. Channels  302 R and  305 R are visible in right end-cap  300 R. 
       FIG. 5 c    is a perspective view of a cross section of the reciprocating fluid meter  001  of  FIG. 1 a   , along line B-B of the right end-cap showing two channels in each end-cap.  FIG. 5 d    is a side cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line B-B of the right end-cap showing two channels in each end-cap. Channels  301 L and  306 L are visible in left end-cap  300 L. Channels  301 R and  306 R are visible in right end-cap  300 R. 
       FIG. 5 e    is a perspective cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line D-C (in  FIG. 4 b   ) of the right end-cap and line C-D (in  FIG. 4 b   ) of the left side, showing a portion of the first and third passages. (Note that the orientation of  FIG. 4 b    differs from that of  FIGS. 5   c, d, e  and  f ).  FIG. 5 f    is a side cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line C-D (in  FIG. 4 b   ) of the left end-cap  300 L, showing a portion of the first and third passages, and along line D-C (in  FIG. 4 b   ) of the right end-cap  300 R showing a portion of second and fourth passages. The first passage comprises inlet  320  and channels  301 L- 306 L ( 304 L visible) in the left end-cap  300 L. The third passage comprises outlet  330  and channels  301 R- 306 R ( 303 R visible). 
       FIG. 6 a    is an outside perspective view of the right sealing member  400 R in the reciprocating fluid meter  001  of  FIG. 1 a   . The sealing member ( 400 L,  400 R), which includes damping pin  410 L and  410 R, serve to dampen the movement of pushrod assembly  200  at the end of its travel length. This damping action slows the pushrod in its final phase of travel, preventing damage to the unit due to repeated high velocity contact between parts  220 L and  220 R ( FIG. 7 a - b   ) and surface  453 L and  453 R ( FIG. 6C ). In addition to damping the pushrods movement, each sealing member houses a magnet ( 420 L,  420 R) along with various components to secure the magnet into position. 
       FIG. 6 b    is an inside perspective view of the right sealing member ( 400 R) in  FIG. 6 a   , comprising a shell ( 450 R), a damping pin ( 410 R), a magnet ( 420 R), and a washer ( 430 R). 
       FIG. 6 c    is a vertical cross-sectional view of the right sealing member ( 400 R) along line A-A in  FIG. 6 b   . The right sealing member ( 400 R) comprises a shell ( 450 R), a damping pin ( 410 R), a magnet ( 420 R), a washer ( 430 R), a spring washer ( 441 R) and a retaining ring ( 442 R). These components mount in shell  450 L,  450 R around column  451 L,  451 R, where a retaining ring snaps into a given gland that can be seen in  FIG. 6C . In preferred embodiments, sealing member ( 400 R) comprises a receptacle or chamber ( 454 R), with either tapered or straight walls. 
     Damping pin  410 L,  410 R in  FIG. 6 c    contains 4 (or more) O-rings. 3 O-rings ( 412  L,  412 R), which are mounted in the three O-ring glands closest to the threaded shoulder of damping pin  410 L and  410 R, serve to seal the damping pin, preventing pressurized fluid from escaping the device. One or more O-rings ( 415 L,  415 R), are mounted in one or more O-ring glands closest to the tapered end of the damping pin ( 410 L,  410 R), serve to pressurize each bore (ref.  FIG. 7 a      211 L,  211 R) at the end of the pushrod ( 210 ). 
       FIG. 6 d    is a vertical cross-sectional view of sealing member  400 R along line B-B in  FIG. 6 c   , showing the right sealing member ( 400 R) comprising the shell ( 450 R), a damping pin ( 410 R), a magnet ( 420 R) and the central column ( 451 R) of shell  450 R. 
       FIG. 6 e    is a vertical cross-sectional view of sealing member ( 400 R) along line C-C in  FIG. 6 c   , showing the right sealing member ( 400 R) comprising a shell ( 450 R), a damping pin ( 410 R), and a washer ( 430 R). 
       FIG. 6 f    is a perspective view and cross-sectional views along lines D-D and E-E of the right sealing member shell ( 450 R) of the reciprocating fluid meter  001  of  FIG. 1 a   .  FIG. 6 g    is a cross-sectional side view along line D-D in  FIG. 6 f   .  FIG. 6 h    is a cross-sectional side view along line E-E in  FIG. 6 f   . Depicted in  FIG. 6 h   , detail  452 R is a thru hole. This hole allows a spanner wrench to tighten and loosen the sealing member ( 400 L,  400 R) inside of its respective endcap ( 300 L,  300 R). 
       FIG. 7 a    is a side cross-sectional view of the right sealing member  400 R along line A-A in  FIG. 6 b   , interacting with the pushrod  210  in the reciprocating fluid meter  001  of  FIG. 1 a    of the primary embodiment. The right engaging element  220 R is in contact with the right sealing member  400 R. The magnet  420 R can interact with the right engaging element  220 R. Washer  430 R is seated directly against magnet  420 R and serves to shield the magnet. The damping pin  410 R is inside the bore  211 R of the pushrod  210 . 
       FIG. 7 b    is a perspective cross-sectional view of the right sealing member  400 R along line A-A in  FIG. 6 b   , interacting with the pushrod  210  in the reciprocating fluid meter  100  of  FIG. 1 a   . The engaging element  220 R contains a plethora of through tapped holes surrounding the center of the part (ref.  FIG. 7 c   ), 3 of which are visible in  FIG. 7 b   . ( 221 R,  222 R, and  226 R), where thru hole  226 R is being blocked by a bolt  466 R. 
     The engaging element  220 R enters chamber  454 R ( FIG. 6 c   ) of sealing member  400 R and exerts pressure on the fluid trapped between the face of  220 R and surface  453 R. Pushrod assembly  200  slows to an acceptable velocity in accordance with the pressure exerted on the trapped fluid. The trapped fluid can exit chamber  454 R in three ways: 1) around the sides of chamber  454 R, between the OD of  220 R and the chamber walls of  454  (prior to O-ring  444 R  FIG. 7 a   , engaging the OD of  220 R), 2) through the holes in engaging element  220 R  FIG. 7 b   , which can be individually blocked by screws ( 466 R), and 3) through the thru-hole  212 R ( FIG. 7 b   ) inside of bore  211 R. It is contemplated that chamber  454 R and  454 L have tapered or straight walls. 
     It is contemplated that as engaging element  220 R approaches the magnet inside sealing member  400 R, the force exerted on the fluid trapped in chamber  454 R increases. In the primary embodiment, chamber  454 R and  454 L are tapered, therefore as the engaging element  220 R travels closer to magnet  420 R, the O-ring ( 444 R) which is mounted on the bore of chamber  454  eventually makes contact with the OD of engaging element  220 R. This forces more fluid to move through the plethora of holes ( 221 R- 226 R) of engaging element  220 R, and stopping the flow of fluid around engaging element ( 220 R), further slowing pushrod assembly  200 . 
     When pushrod assembly  200  is in transition, damping pin  410 R,  FIG. 7 a   , engages and enters the orifice at the end of pushrod  210 , and simultaneously exits the orifice at the opposite end of pushrod  210 . 
     It is contemplated that damping pin  410 R and  410 L is tapered, which gradually increases the pressure trapped inside of bore  211 R at the end of pushrod  210  (ref  FIG. 7 a   ). It is further contemplated that when pushrod  210  reaches O-ring  412 R while in transition, the pressure inside of bore  211 R will increase. 
     In preferred embodiments, a small diameter thru-hole ( FIG. 7 a      212 R) connects bore  211 R with the outflow side of endcap  300 R. This small diameter thru-hole relieves pressure inside of bore  211 R. The rate at which fluid exits the bore through thru-hole  212  is largely dependent upon the viscosity of the media being metered by the device. To compensate for this, the amount of fluid under pressure inside of bore  211 R can be adjusted by rotating damping pin  410  about its longitudinal axis through its threaded shoulder ( 411 ). 
     In conjunction with the depth sitting of damping pin  410 R, the pushrod ( 210 ), while in transition to its new seated position, will reach O-ring  412 R, trapping the remaining fluid inside bore  211 R, and forcing it to exit through thru-hole  212 R. The point at which O-ring  412 R seals bore  211 R is dependent upon the position of the damping pin, as adjusted by the rotation of its threaded base. 
       FIG. 7 c    is an exploded cross sectional view of the right sealing member ( 400 R) of the primary embodiment. The components included in sealing member  400 R, are the sealing member shell ( 450 R), a magnet ( 420 R), a washer ( 430 R) and a damping pin ( 410 R). Ancillary parts included in the assembly are O-ring  446 R, which seals sealing member  400 R inside of endcap  300 R, O-ring  444 R, which is mounted in the bore of chamber  454 R, and seals the chamber when the pushrod is in transition, washer  443 , a spring washer ( 441 R), and a retaining ring ( 442 R) which holds parts  420 ,  430 ,  443  and  441  inside of shell  450 . 
       FIG. 8 a    is an exploded view of the encoder/display housing ( 500 ) in the reciprocating fluid meter  001  of  FIG. 1 a   . The encoder/display housing ( FIGS. 8 a , 8 b  and 8 c   ) is synonymous with both primary embodiment and alternate embodiment (A). 
       FIG. 8 b    is an exploded perspective view of the encoder ( 500 ), less the display housing, in alignment with piston  260  in the reciprocating fluid meter  001  of  FIG. 1 a   . This view shows how small magnets inside the piston, and magnets outside of the cylinder housing ( 150 ) align and serve to track piston  260 . Embedded into the circumference of piston  260 , displaced left and right of the pistons lateral center, are a series of magnets ( FIG. 8 b , 8 c   ,  261 ,  262 ). When piston  260  is in motion along its longitudinal track inside of cylinder housing ( 150 ), the position of magnets  261  and  262  is physically tracked by a series of similar magnets ( 263 ,  264 ) attached magnetically to one and other outside of cylinder housing  150 . Magnets  263  and  264  are rigidly mounted inside encoder target housing  520 . Magnets  263  and  264  move in conjunction with piston magnets  261  and  262 . This action moves the linear encoder target housing ( 520 ). The linear encoder target ( 265 ) is rigidly attached to housing  520 , and when in motion with piston  260 , will draw the encoder target ( 265 ) across encoder board ( 268 ), producing position data relative to piston  260 . 
       FIG. 8 c    is a cross-sectional view of the encoder,  500 , less the display housing, in alignment with piston  260  in the reciprocating fluid meter  001  of  FIG. 1 a   . Note the alignment of piston magnets  261  and  262 , with the magnets ( 263 ,  264 ) contained inside of encoder target housing  520 . 
     Piston  260  ( FIG. 8 c   ) of the primary embodiment and piston  710  ( FIG. 10 h   ) of alternate embodiment (A) are identical in their functionality with the encoder. 
       FIG. 9 a    is a partially exploded cross-sectional view of the left end-cap  300 L and sealing member  400 L in the primary embodiment of the reciprocating fluid meter  001  of  FIG. 1 a   . Engaging element  220 L is disengaged from sealing member  400 L, and damping pin  410 L is disengaged with bore  211 L of pushrod  210 . Note the position of perforated spindle valve  230 L in a first position, outlet port  340  is open, allowing fluid to exit the device, and inlet port  320  is closed. Fluid is entering endcap  300 L internally through ports  301 L,  302 L,  303 L,  304 L,  305 L and  306 L ( 304 L is visible, reference  FIG. 4 b   ). Flowing through the plethora of holes in perforated spindle valve  230 L, and exiting the device from outlet  340 . Draining chamber  525 , on the opposite side, chamber  528  is flooding. 
       FIG. 9 b    is a partially exploded cross-sectional view of left end-cap  300 L and sealing member  400 L in the primary embodiment of the reciprocating fluid meter  001  of  FIG. 1 a   , with the engaging element  220 L entering chamber  454 L of sealing member  400 L. Pushrod assembly  200  is in transition to its engaged position inside of chamber  454 L in sealing element  400 L, and is half-way across its movement track. Note the position of perforated spindle valve  230 L in a second position, blocking flow to both inlet port  320  and outlet port  340 . Damping pin  410 L is half-way engaged with bore  211 L of pushrod  210 . 
       FIG. 9 c    is a partially exploded cross-sectional view of left end-cap  300 L and sealing member  400 L in the primary embodiment of the reciprocating fluid meter  001  of  FIG. 1 a   , with engaging element  220 L mated with sealing member  400 L, and the damping pin  410 L fully engaged with tapered bore  211 L of pushrod  210 . Note the position of perforated spindle valve  230 L in a third position, outlet port  340  is closed, and inlet port  320  is open. Fluid is entering the device through inlet port  320 , flowing through the plethora of holes in perforated spindle valve  230 L, and exiting the device internally through ports  301 L,  302 L,  303 L,  304 L,  305 L and  306 L ( 304 L is visible, reference  FIG. 4 b   ) flooding chamber  525 . On the opposite side, chamber  528  is draining. 
       FIG. 10 a - g    shows piston  260  moving longitudinally inside cylinder housing  150  to the left, reversing direction, and moving to the right, in conjunction with fluid flowing through the invention.  FIGS. 10 a -10 g    pertain to the primary embodiment only.  FIG. 10 a - c    show piston  260  in different positions as it moves right to left.  FIG. 10 a    is a cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line C-C in  FIG. 4 b   , depicting pushrod assembly  200  in a position where the first passage (between inlet  310  and first chamber  528 ) is open, the third passage (between first chamber  528  and first outlet  330 ) is closed, the second passage (between second inlet  320  and second chamber  525 ) is closed, the fourth passage (between second chamber  525  and second outlet  340 ) is open. Fluid flows into right chamber  528  through the first passage (comprising inlet  310 ), pushing piston  260  toward the left. The fluid in the left chamber,  525  exits through the fourth passage (comprising outlet  340 ). The right engaging element  220 R is coupled with magnet  420 R in the right sealing member ( 400 R), and the left engaging element  220 L is decoupled with the magnet  420 L in conjunction with the left sealing member, ( 400 L). 
       FIG. 10 b    is a cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing the pushrod assembly  200  in the same position as in  FIG. 10 a   .  FIG. 10 b    shows piston  260  has traveled further to the left, and spring  250 L has made contact with the internal base of spring catch  235 L. As the piston continues to travel left, spring  250 L compresses between spring catch  235 L and piston  260 , producing an elastic force that is passed through to pushrod assembly  200 . In opposition to this force, magnet  420 R is coupled with engaging element  220 R, counteracting the elastic force generated by spring  250 L, and the pushrod remains static. 
       FIG. 10 c    is a cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing pushrod assembly  200  in the same position as in  FIG. 10 a   . Piston  260  has made physical contact with spring catch  235 L at point  241  between the small diameter face of spring catch  235 L (surface  245 ,  FIG. 3 c   ,  FIG. 9 a   ) and the inner face of piston  260 , inside the ID of spring  250  (surface  315 ,  FIG. 5 a   ). In this position, spring  250 L is compressed to its target length and has enough potential energy to physically move pushrod assembly  200  to its new seated position against magnet  420 L. The contact at point  241  between piston  260  and spring catch  235 L, pushes spring catch  235 L further left, along with pushrod assembly  200 . Once the right engaging element  220 R breaks contact with surface  453 R (ref  FIG. 6 c   ) inside of sealing member  400 R, the magnetic force decreases allowing compressed spring  250 L to release its stored energy and drive pushrod assembly  200  to its new seated position inside of the opposite sealing member ( 400 L). 
       FIG. 10 d    is a cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing the pushrod assembly  200  in a second transitional position. Note that in this position, pushrod assembly  200  is in motion. Magnetic element  220 R is decoupled from magnet  420 R and is being driven toward its new seated position against magnet  420 L by the force produced by compressed spring  250 L. At this position, pushrod assembly  200  is half way through its motion to the opposite magnet. The perforated spindle valves ( 230 L and  230 R) momentarily close all passages, including the first passage (between inlet  310  and first chamber  528 ), the second passage (between second inlet  320  and second chamber  525 ), the third passage (between first chamber  528  and first outlet  330 ), and the fourth passage (between second chamber  525  and second outlet  340 ). In this position engaging element  220 L and  220 R are disengaged from both  420 L and  420 R. The pushrod assembly  200  is moving left, due to the elastic force exerted by spring  250 L on spring catch  235 L. Piston  260  is momentarily stopped and will reverse its direction and begin to travel to the right as soon as inlet  320  opens and outlet  330  opens, inlet  310  and outlet  340  will remain closed. 
       FIG. 10   e - g  shows piston  260  in different positions as it moves left to right.  FIG. 10 e    is a cross-sectional view of the reciprocating fluid meter of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing pushrod assembly  200  in a third position, where the first passage (between inlet  310  and first chamber  528 ) is closed, the second passage (between second inlet  320  and second chamber  525 ) is open, the third passage (between first chamber  528  and first outlet  330 ) is open, the fourth passage (between second chamber  525  and second outlet  340 ) is closed. The right engaging element  220 R is decoupled with the magnet  420 R. The left engaging element  220 L is coupled with magnet  420 L. Piston  260  is disposed on the left side and is moving towards the right side. 
       FIG. 10 f    is a cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing the pushrod assembly  200  in the third position as in  FIG. 10 e   , showing the piston  260  is disposed just left of the center position and is moving towards the right. 
       FIG. 10 g    is a cross-sectional view of the reciprocating fluid meter  001  of  FIG. 1 a   , along line C-C in  FIG. 4 b   , showing pushrod assembly  200  in the third position as in  FIG. 10 e   . Piston  260  is disposed right of center, compressing spring  250 R between piston  260  and the internal base of spring catch  235 R. When piston  260  contacts spring catch  235 R, it will force engaging element  220 L to decouple from magnet  420 L, allowing spring  250 R to drive pushrod assembly  200  to its new seated position against magnet  420 R. This will complete the reversal process. Piston  260  then moves in the opposite direction, and the process repeats. 
     Alternate Embodiment (A) Detailed Description 
       FIG. 2 c    is an exploded perspective view of alternate embodiment (A) of the reciprocating fluid meter of  FIG. 1 d   , without the display interface ( 501 ). This view calls out the specific parts which differ from the primary spring/magnet embodiment. 
     In alternate embodiment (A), pushrod  706  comprises an elongated member that can travel inside housing  150 . 
     In alternate embodiment (A) the components which are rigidly attached to pushrod  706 , or move along the longitudinal centerline of the pushrod can be seen in  FIG. 2 c    and  FIG. 3 e   . Piston  710  floats freely inside housing  150 , and travels along the length of the pushrod. Both the ID and the OD of piston  710  are sealed against the ID of the cylinder ( 150 ) and the OD of the pushrod ( 706 ). This prevents fluid from leaking to the opposite side of the piston, which would degrade the meters accuracy. 
     Adjacent to either side of piston  710 , mounted on pushrod  706  is pushrod guide  704 L and  704 R ( FIG. 2 c , 3 e , 3 f   ). Each pushrod guide is rigidly attached to endcaps  300 L and  300 R ( FIG. 3 i   ). Pushrod guides  704 L and R serve to seal chambers  525  and  528  ( FIG. 5 h   ) from each valve assembly inside endcaps  300 L and  300 R. 
     Perforated spindle valves  702 L and  702 R, are each rigidly attached to pushrod  706 . Unlike the primary embodiment, these are the only parts which are affixed to pushrod  706 . Perforated spindle valves  702 L and  702  R of alternate embodiment (A) are slightly wider than perforated spindle valves  230 L and  230 R of the primary embodiment. 
     The perforated spindle valves of alternate embodiment (A) serve two purposes.
         1) (Reference  FIG. 3 j   ) perforated spindle valves  702 L and  702 R, rigidly attached to pushrod  706  can start and stop the flow of media traveling through the invention by halting their movement half way through the travel length (note the position of  702 L and  702 R blocking both the inflow and outflow passages in either endcap at the same time), this is the second position. This is accomplished by the 3 position air cylinder or linear motor ( 712 ,  FIGS. 3 e  and  j   ) driving pushrod assembly  750  ( FIG. 3 k   ), which can stop in the center position depicted in  FIG. 3   j.      Because the position of pushrod assembly  750  ( FIG. 3 k   ) can start and stop the flow of media, the external valve ( 205 ,  FIG. 1 a , 1 b   ) associated with the primary embodiment is not necessary in alternate embodiment (A), and as such, has been eliminated.   2) Perforated spindle valves  702 L and  702 R, serve to guide the flow of media through the device, shifting positions at the end of piston  710 &#39;s travel length between a first ( FIG. 10 h   ) and third ( FIG. 10 j   ) position, thus reversing the internal flow of media, causing the piston to reverse direction and repeat this reciprocating motion.       

     Sealing member  700 L and  700 R ( FIG. 3 e   ), mounted rigidly to the end of endcaps  300 L and  300 R ( FIG. 2 c   ), serve to seal each endcap, guide pushrod  706 , and serve as mounting point for air cylinder/motor  712 . 
     4 standoffs ( 714 ,  FIG. 3 e - f   ) mount directly to sealing member  700 R, and mounting block  708  ( FIG. 3 e - f   ). Air cylinder/motor  712  is affixed to mounting block  708 , while the air cylinder/motor shaft screws directly into pushrod  706  (reference  FIG. 3 e - f   ). 
       FIG. 3 i    is a left side view of endcap  300 R, depicting pushrod guide  704 R fully seated and affixed in place by fasteners  237 ,  238  and  239 . 
       FIG. 3 j    is a perspective cross-sectional view of alternate embodiment (A) of  FIG. 1 d   .  FIG. 3 j    depicts perforated spindle valves  702 L and  702 R, which are rigidly attached to pushrod  706 , which is driven by, and rigidly attached to the central drive shaft of air cylinder/motor  712 . The pushrod assembly, consisting of pushrod  706  and perforated spindle valves  702 R and  702 L, are in a second position (Ref  FIGS. 3 j  and 10 i   ). In this position, the flow of media flowing through the device has stopped, as both the inflow and outflow passages of each endcap is blocked by perforated spindle valves  702 L and  702 R. This internal valve position serves to control the flow of fluid moving through the device, allowing the invention to stop the flow of fluid at specified volumes or masses, as programmed by the end user of the invention. 
       FIG. 3 k    is a perspective view of alternate embodiment (A) pushrod assembly. It includes pushrod  706  and rigidly attached perforated spindle valves  702 L and  702 R. 
       FIG. 5 g    is a perspective cross-sectional view of alternate embodiment (A) fluid meter  002  of  FIG. 1 d   , along line D-C (in  FIG. 4 b   ) of the right end-cap and line C-D (in  FIG. 4 b   ) of the left side, showing a portion of the first and third passages. (Note the orientation of  FIG. 4 b    differs from the orientation of  FIG. 5 g   ). 
       FIG. 5 h    is a side cross-sectional view of alternate embodiment (A) reciprocating fluid meter  002  of  FIG. 1 d   , along line B-B of the right end-cap showing two channels in each end-cap. Channels  301 L and  306 L are visible in left end-cap  300 L. Channels  301 R and  306 R are visible in right end-cap  300 R. 
       FIG. 9 d    is a partially exploded cross-sectional view of right end-cap  300 R in alternate embodiment (A) of the reciprocating fluid meter  002  of  FIG. 1 d   . Note position of perforated spindle valve  702 R in a first position. Outlet port  330  is open, allowing fluid to exit the device, and inlet port  310  is closed. Fluid is entering endcap  300 R internally through ports  301 R,  302 R,  303 R,  304 R,  305 R and  306 R ( 304 R is visible, reference  FIG. 4 b   ). Flowing through the plethora of holes in perforated spindle valve  702 R, and exiting the device from outlet  330 . Draining chamber  525  (not shown), on the opposite side, chamber  528  is flooding. 
       FIG. 9 e    is a partially exploded cross-sectional view of right end-cap  300 R in alternate embodiment (A) of the reciprocating fluid meter  002  of  FIG. 1 d   . Note position of perforated spindle valve  702 R in a second (centered) position, blocking flow to both inlet port  310  and outlet port  330 . 
       FIG. 9 f    is a partially exploded cross-sectional view of right end-cap  300 R in alternate embodiment (A) of the reciprocating fluid meter  002  of  FIG. 1 d   . Note the position of perforated spindle valve  702 R in a third position, outlet port  330  is closed, and inlet port  310  is open. Fluid is entering the device through inlet port  310 , flowing through the plethora of holes in perforated spindle valve  702 R, and exiting the device internally through ports  301 L,  302 L,  303 L,  304 L,  305 L and  306 L ( 304 L is visible, reference  FIG. 4 b   ) flooding chamber  525  (not visible). On the opposite side, chamber  528  is draining. 
       FIG. 10 h    shows piston  710  moving longitudinally inside cylinder housing  150  from right to left, in conjunction with fluid flowing through the invention. Note pushrod assembly  750  ( FIG. 3 k   ) in a first position, as defined by paragraph [0088]. 
       FIG. 10 h    is a cross-sectional view of the alternate embodiment reciprocating fluid meter  002  of  FIG. 1 d   , along line C-C in  FIG. 4 b   , depicting pushrod assembly  750  ( FIG. 3 k   ) in a first position where the first passage (between inlet  310  and first chamber  528 ) is open, the third passage (between first chamber  528  and first outlet  330 ) is closed, the second passage (between second inlet  320  and second chamber  525 ) is closed, the fourth passage (between second chamber  525  and second outlet  340 ) is open. Fluid flows into right chamber  528  through the first passage (comprising inlet  310 ), pushing piston  710  toward the left. The fluid in the left chamber,  525  exits through the fourth passage (comprising outlet  340 ). 
     As piston  710  moves left ( FIG. 10 h   ), its position is tracked through the movement of linear encoder target  520 . When piston  710  reaches the end of its travel length, the position of piston  710  will be relayed to the RPM computer via linear encoder target  520 . The RPM computer will then command air cylinder/motor  712  to shift from its present first position, through a second position ( FIG. 10 i   ), directly to a third position ( FIG. 10 j   ). In this third position, the media flow will reverse, and the piston will shift direction. 
       FIG. 10 i    shows piston  710  at its full left travel length inside cylinder housing  150 . Note pushrod assembly  750  ( FIG. 3 k   ) in a second position, as defined by paragraph [0089]. 
       FIG. 10 i    is a cross-sectional view of alternate embodiment (A) reciprocating fluid meter of  FIG. 1 d   , Along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 750   FIG. 3 k   .) in a second position, where the first passage ( 310 ) (between first inlet and first chamber  528 ) is closed, the second passage ( 320 ) (between second inlet and second chamber  525 ) is closed, the third passage ( 330 ) (between first chamber  528  and first outlet) is closed, the fourth passage ( 340 ) (between second chamber  525  and second outlet) is closed. 
       FIG. 10 i    depicts piston  710  at the end of its left travel length inside cylinder housing  150 , and shows pushrod assembly  750  ( FIG. 3 k   ) in a second position in transition to a third position. Linear encoder target  520  has relayed the position of piston  710  to the RPM computer and signaled air cylinder/motor  712  to transition to a third position. 
       FIG. 10 j    shows piston  710  moving longitudinally inside cylinder housing  150  from left to right, in conjunction with fluid flowing through the invention. Note pushrod assembly  750  ( FIG. 3 k   ) in a third position, as defined by paragraph [0090]. 
       FIG. 10 j    is a cross-sectional view of alternate embodiment (A) reciprocating fluid meter of  FIG. 1 d   , Along line C-C in  FIG. 4 b   , showing the pushrod assembly ( 750   FIG. 3 k   ) in a third position, where the first passage ( 310 ) (between first inlet and first chamber  528 ) is closed, the second passage ( 320 ) (between second inlet and second chamber  525 ) is open, the third passage ( 330 ) (between first chamber  528  and first outlet) is open, the fourth passage ( 340 ) (between second chamber  525  and second outlet) is closed. 
       FIG. 10 j    depicts alternate embodiment (A) with pushrod assembly  750  ( FIG. 3 k   ) in a third position. In this position fluid is moving through the device, displacing piston  710  from left to right. When piston  710  reaches the end of its travel length, the position of the piston will be relayed to the RPM computer via linear encoder target  520 . The RPM computer will then command air cylinder/motor  712  to shift from its present third position, through a second position ( FIG. 10 i   ), directly to a first position ( FIG. 10 h   ) and the sequence will repeat. 
     Alternate Embodiment (B) Detailed Description 
     Alternate embodiment (B) is a highly accurate piston pump. It combines the accuracy of the primary embodiment or alternate embodiment (A), with the force and precision of a linear actuator. Alternate embodiment (B) can start, stop and alter rate of flow, making it highly useful in a wide range of industrial applications. 
     Alternate embodiment (B)  FIG. 1 e    depicts a subassembly or framework which is built as part of the primary embodiment ( FIG. 1 a   ), or alternate embodiment (A) ( FIG. 1 d   ). 
     Alternate embodiment (B) incorporates a stepper motor ( FIG. 1 e   ,  804 ) a linear screw ( FIG. 1 e      800 ) and a gear box ( FIG. 1 e      806 ). These components attach directly through the linear actuators driveshaft ( 802 ) to coupling  840  ( FIG. 1 e   ) and driveshaft&#39;s  842  and  844  ( FIG. 1 e   ). Driveshaft&#39;s  842  and  844  are rigidly attached to piston  846  ( FIG. 2 f   ,  FIG. 2 h   ) of the primary embodiment or alternate embodiment (A) and run through endcap  880  ( FIG. 1 e   ). 
     These components are encapsulated inside a framework which allows the transmission of force to piston  846  of the primary embodiment or alternate embodiment (A). Piston  846 , ( FIG. 2 f , 2 h   ) moves back and forth along the same track, over the same distance as the primary or alternate embodiment (A). The starting, stopping points and rate of travel can be precisely controlled through stepper motor  804 , via the user interface. 
     The stepper motor ( 804 ) of alternate embodiment (B) drives piston  846  along the longitudinal centerline of cylinder  150  ( FIG. 2 a   ). In the primary embodiment, when piston  846  approaches the end of its travel length, the stepper motor will ramp down until valves in endcaps  880  and  300 R ( FIGS. 2 d  and 2 c   ) shift position, the linear encoder ( 265 ,  268   FIG. 8 b   ) will then signal the RPM computer to drive the stepper motor in the opposite direction, reversing the direction of the piston. 
     The stepper motor ( 804 ) of alternate embodiment (B) drives piston  846  along the longitudinal centerline of cylinder  150  ( FIG. 2 a   ). In alternate embodiment (A), when piston  846  approaches the end of its travel length, the RPM computer will detect the position of the piston via the linear encoder, and signal the pneumatic air cylinder or motor ( 712 ,  FIG. 2 c   ) to shift valve positions inside endcaps  880  and  300 R ( FIGS. 2 d  and 2 c   ), at the same time the RPM computer will signal stepper motor  804  to reverse direction, driving the piston in the opposite direction. 
     Assembly of alternate embodiment (B) consists of 3 subassemblies. 
     Subassembly  1 —The fully assembled linear actuator is comprised of linear screw  800 , stepper motor  804 , and gear box  806 . Two rectangular steel plates ( 820 ,  822   FIG. 2 g   ) are pinned ( 866 ,  868   FIG. 2 g   ) to each side of the linear actuator. Mounting blocks  834 ,  824  and  826  are bolted to the linear actuator, then plates  820  and  822  are bolted to mounting blocks  834 ,  824  and  826 . Coupling  840  is bolted to linear actuator driveshaft  802 . 
     Subassembly  2 —Six mounting feet ( 874 ) are bolted to the base plate ( 832 ) of alternate embodiment (B). 
     Subassembly  3 —Driveshaft&#39;s  842  and  844  are bolted to piston  846 . The opposite end of driveshaft&#39;s  842  and  844  slide longitudinally through sealed holes in endcap  880 . Piston  846  slides inside of cylinder  150  of the primary embodiment or alternate embodiment (A). The assembly process for either the primary embodiment or alternate embodiment (A) is then completed, ending with mounting plates  828  and  830  ( FIG. 2 g   ) being bolted to each other via tie rods  876 . Note driveshaft&#39;s  842  and  844  are now protruding out of endcap  880  of subassembly  3 . 
     Mounting plates  820  and  822  of subassembly  1  are bolted to the primary mounting plate ( 832 ) of subassembly  2 . 
     Subassembly  3  is placed on the primary mounting plate of subassembly  2 . Driveshaft&#39;s  842  and  844  are bolted ( 870 ) into coupling  840 . Mounting plates  828  and  830  are bolted to primary mounting plate  832 . Mounting plates  820  and  822  are bolted ( 872 ) to mounting plate  828 . 
     Communication wiring is run between the servo driver and the RPM computer. Assembly complete. 
     In Summary 
     To summarize the primary embodiment, when piston  260  reaches its full length of travel, pushrod assembly  200 , which is rigidly attached to perforated spindle valves  230 L and  230 R, shifts its position which causes the fluid to reverse direction, and in turn, piston  260  also reverses its direction. The movement of the encoder target housing ( 520 ) is an indication of the volumetric flow rate of fluid flowing through the invention. Flow rate is determined by tracking the position of piston  260  in conjunction with time (a function of the RPM computer  515 ), as it moves back and forth inside cylinder  150 . The reciprocating fluid meter  001  is highly precise as it is a 100% positive displacement mechanism, it is physically impossible for fluid to pass through the meter without displacing the piston. 
     Alternate embodiment (A) differs from the primary embodiment in that pushrod assembly  200  ( FIG. 3 b   ) of the primary embodiment is powered by a spring working in conjunction with a magnet. The spring is loaded through fluid pressure. Alternate embodiment (A) uses a motor or air cylinder to power pushrod assembly  750  ( FIG. 3 k   ). Alternate embodiment (A) shifts the position of pushrod assembly  750  with positional input of the piston via the linear encoder and RPM computer. The primary embodiment shifts pushrod assembly mechanically. 
     Alternate embodiment (B) incorporates the force and precision of a linear actuator to drive the piston of the primary embodiment, or alternate embodiment (A). The result is a very accurate pump capable of controlling rates of flow, along with starting and stopping flow. The RPM pump, or alternate embodiment (B) is a standalone unit, capable of delivering exact amounts of fluid product in the fields of compounding, dosing, batching, custody transfer and product transfer. 
     It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.