Small volume prover

A small volume prover, comprising:

• a closed cylindrical outer housing having a fluid inlet in a wall near an inlet-side end thereof, and a fluid outlet in said wall near an opposite outlet-side end thereof;
• a cylindrical measuring conduit of a constant inside diameter coaxially mounted within the housing, said conduit being open at an inlet-side end thereof and coaxially supported at an outlet end thereof by an inner end wall of the housing and having two axially apart spaced rows of ports radially in a wall of said conduit, one of said rows of ports being inlet-side ports and the other of said rows of ports being outlet-side ports;
• an annular wall sealably dividing an annular passage formed between the measuring conduit and the outer housing into two sections, one section including said open conduit inlet-side end and the other section including said inlet-side ports;
• a slide valve having a valve rod sealably extending through the inlet-side end of the outer housing and being slidable within the measuring conduit near the open inlet-side end thereof to open and close the inlet-side ports;
• a piston having a piston rod sealably extending through the outlet-side end of the housing and being movable within a downstream portion of the measuring conduit rearwardly of the inlet-side ports to displace a base volume of fluid a certain amount between the inlet-side ports and the outlet-side ports;
• a valve actuator for driving the valve rod to control the slide valve to close the inlet-side ports only during a proving pass;
• a piston actuator for actuating the piston rod to hold the piston at a starting position rearwardly of the inlet-side ports in the measuring conduit during a proving preparation, to render the piston movable during a proving test and to return the piston to the starting position;
• a position sensor provided in the piston actuator for detecting that the piston passes a defined portion of the measuring conduit;
• and
• the inlet-side end of the housing includes:
• a clutch door comprising a liquid-tightly rotatable outer ring affixed to the inlet-side end of the housing and a stationary inner ring removably engaged with the rotatable outer ring and integrally mounting therein-the slide valve and the valve actuator;
• a linear driving means for moving the stationary inner ring in an axial direction of the measuring conduit;
• and
• a turning means for horizontally turning the slide valve and the valve actuator when the slide valve and the valve actuator have been moved apart from the movable ring by means of the linear driving means.

A small volume prover, comprising:

• a closed cylindrical outer housing having a fluid inlet in a wall near an inlet-side end thereof, and a fluid outlet in said wall near an opposite outlet-side end thereof;
• a cylindrical measuring conduit of a constant inside diameter coaxially mounted within the housing, said conduit being open at an inlet-side end thereof and coaxially supported at an outlet end thereof by an inner end wall of the housing and having two axially apart spaced rows of ports radially in a wall of said conduit, one of said rows of ports being inlet-side ports and the other of said rows of ports being outlet-side ports;
• an annular wall sealably dividing an annular passage formed between the measuring conduit and the outer housing into two sections, one section including said open conduit inlet-side end and the other section including said inlet-side ports;
• a slide valve having a valve rod sealably extending through the inlet-side end of the outer housing and being slidable within the measuring conduit near the open inlet-side end thereof to open and close the inlet-side ports, the slide valve having a cylindrical form with a row of radially arranged ports corresponding in form and spacing to the inlet-side ports of the measuring conduit and being rotatable bidirectionally by 1/2 of the spacing between the ports therein;
• a piston having a piston rod sealably extending through the outlet-side end of the housing and being movable within a downstream portion of the measuring conduit rearwardly of the inlet-side ports to displace a base volume of fluid a certain amount between the inlet-side ports and the outlet-side ports, said piston having a thickness;
• a valve actuator for driving the valve rod to control the slide valve to close the inlet-side ports only during a proving pass;
• a piston actuator for actuating the piston rod to hold the piston at a starting position rearwardly of the inlet-side ports in the measuring conduit during a proving preparation, to render the piston movable during a proving test and to return the piston to the starting position;
• a position sensor provided in the piston actuator for detecting that the piston passes a defined portion of the measuring conduit;
• and
• a row of pressure relieving ports, each of which is smaller than the outlet-side ports, and radially arranged in the wall of the measuring conduit at a downstream position apart from the outlet-side ports by a distance corresponding to the piston thickness.