Abstract:
An apparatus and method for mounting a sensor with strict orientation and insertion depth requirements in a process vessel or pipe section. The apparatus includes a lock block having a socket for receiving a plug disposed around a sensor inserted through an inner bore of the lock block. Reception of the plug in the socket controls insertion depth of the sensor in the process vessel. The lock block also includes a cam bore for receiving a cam used to rotationally orient the sensor and the attached plug. The cam is locked into position within the cam bore of the lock block by inserting a retaining pin through a retaining pin bore in the cam. During insertion and removal of the sensor through the sensor mounting apparatus, process isolation is maintained by an integral seal mechanism of the lock block and an internal isolation valve that fits within the lock block.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of and priority to U.S. Provisional Patent Application No. 61/228,862, filed Jul. 27, 2009. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a sensor mounting apparatus and method for sensor probes requiring specific orientation and insertion depth such as optical flow meter and ultrasonic flow meter probes. 
     BACKGROUND OF THE INVENTION 
     Many sensors require specific orientation and insertion depth of the sensor probe for accurate measurements. These requirements apply to optical flow meters based on laser-two-focus (L2F) particulate velocimetry and optical flow meters based on laser-two-beam (L2B) particulate velocimetry. In L2F particulate velocimetry, an optical flow meter probe measures the velocity of gas particles by measuring the time delay between light scattering occurrences in two active sheets that are perpendicular to the gas flow direction and separated by a fixed distance. In L2B particulate velocimetry, an optical flow meter probe measures the velocity of gas particles by sensing the scintillation of light beams caused by flow turbulence. Both L2F and L2B types of optical flow meters require that the optical probe be positioned within a system with a specific orientation in relation to the direction of gas flow. Ultrasonic flow meters have multiple probes that have extremely tight tolerance insertion-depth requirements. 
     Other sensors such as temperature and pressure sensors require periodic removal for replacement, cleaning, and troubleshooting. The removal and subsequent reinstallation of these sensors occurs during operations requiring a method to remove the probe while maintaining process isolation. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a sensor mounting apparatus that efficiently orients a sensor to a specified rotational position. 
     It is a further object of the present invention to provide a sensor mounting apparatus that efficiently positions a sensor at a predetermined insertion depth. 
     It is a further object of the present invention to provide a sensor mounting apparatus that maintains process isolation during insertion and removal of a sensor. 
     These and other objects and advantages are achieved by the novel sensor mounting apparatus and method described herein. The sensor mounting apparatus may include a lock block, a locking cam assembly, an internal isolation valve, and a base plate. The lock block may have a first end surface, a second end surface, and two pairs of opposing side surfaces interconnecting the first and second end surfaces. The lock block may also have a socket in the first end surface, an inner bore extending from the socket to the second end surface, a cam bore extending through one of the pairs of opposing side surfaces, and an integral seal mechanism capable of sealing the inner bore. The locking cam assembly may be capable of being inserted through the cam bore in the lock block. 
     The internal isolation valve may be removably disposed within the lock block. The internal isolation valve may have an inner bore aligned with the inner bore of the lock block. The internal isolation valve may be capable of sealing its inner bore. The base plate may have an inner bore aligned with the inner bore of the internal isolation valve and the inner bore of the lock block. The internal isolation valve and the lock block may be operatively connected to the base plate. 
     The sensor mounting apparatus may also include a plug having a first end surface, a second end surface, and a side surface interconnecting the first and second end surfaces of the plug. The plug may also have a plug groove disposed on the side surface and an inner bore extending from the first end surface to the second end surface. The plug may be capable of being inserted into the socket of the lock block. Insertion of the plug into the socket of the lock block may position a sensor probe at a predetermined insertion depth within a process vessel. 
     The locking cam assembly may include a locking cam, a spring pin stop, and a retainer pin. The locking cam may have a head with a groove and an elongated portion with a recess and a retainer pin bore extending laterally through the elongated portion. The elongated portion of the locking cam may be capable of being inserted through the cam bore in the lock block. The spring pin stop may be positioned within the recess of the elongated portion and may engage the groove in the head of the locking cam when the head is rotated into an engaged position. The retainer pin may be capable of being inserted through the retainer pin bore in the elongated portion to secure the locking cam in position within the cam bore of the lock block. 
     An aperture may be formed on the lock block by an intersection of the cam bore with the socket. The plug may have an aligned position in which the sensor probe is positioned at a predetermined rotational orientation within the process vessel. The plug groove may be rotationally aligned with the aperture in the aligned position of the plug. The insertion of the elongated portion of the locking cam through the cam bore of the lock block when the plug is in the aligned position may lock the sensor probe in the predetermined rotational orientation and the predetermined insertion depth within the process vessel. 
     The internal isolation valve may include a ball valve. The integral seal mechanism may include one or more O-rings disposed around the inner bore of the lock block. 
     In another embodiment, the present invention includes a sensor mounting apparatus including a lock block, a plug, an internal isolation valve, a base plate, a locking cam, a spring pin stop, and a retainer pin. The lock block may have a first end surface, a second end surface, and two pairs of opposing side surfaces interconnecting the first and second end surfaces. The lock block may also have a socket in the first end surface, an inner bore extending from the socket to the second end surface, a cam bore extending through one of the pairs of opposing side surfaces, and an integral seal mechanism capable of sealing the inner bore. 
     The plug may have a first end surface, a second end surface, and a side surface interconnecting the first and second end surfaces of the plug. The plug may also have a plug groove disposed on the side surface and an inner bore extending from the first end surface to the second end surface. The plug may be capable of being inserted into the socket of the lock block. The internal isolation valve may have an inner bore aligned with the inner bore of the lock block. The internal isolation valve may be capable of sealing its inner bore when activated and may be removably disposed within the lock block. The base plate may include an inner bore aligned with the inner bore of the internal isolation valve and the inner bore of the lock block. The internal isolation valve and the lock block may be operatively connected to the base plate. 
     The locking cam may have a head with a groove and an elongated portion with a recess and a retainer pin bore extending laterally through the elongated portion. The elongated portion of the locking cam may be capable of being inserted through the cam bore in the lock block. The spring pin stop may be positioned within the recess of the elongated portion of the locking cam and may engage the groove in the head of the locking cam when the head is rotated into an engaged position. The retainer pin may be capable of being inserted through the retainer pin bore in the elongated portion to secure the locking cam in position within the cam bore of the lock block. The internal isolation valve may include a ball valve. The integral seal mechanism may include one or more O-rings. 
     In yet another embodiment, the present invention includes a method of mounting a sensor to a process vessel. The method may include providing a sensor mounting apparatus having a lock block, a locking cam assembly, an internal isolation valve, and a base plate. The lock block may include a first end surface, a second end surface, two pairs of opposing side surfaces interconnecting the first and second end surfaces, a socket in the first end surface, an inner bore extending from the socket to the second end surface, a cam bore extending through one of the pairs of opposing side surfaces, and an integral seal mechanism capable of sealing the inner bore. The internal isolation valve may have an inner bore aligned with the inner bore of the lock block. The internal isolation valve may be removably disposed within the lock block. The base plate may have an inner bore aligned with the inner bore of the internal isolation valve and the inner bore of the lock block. The internal isolation valve and the lock block may be operatively connected to the base plate. 
     The method may also include attaching the sensor mounting apparatus to a process vessel by connecting the base plate to the process vessel, and inserting a sensor through the sensor mounting apparatus and into the process vessel while maintaining isolation of a process within the process vessel. 
     The step of inserting the sensor into the process vessel through the sensor mounting apparatus while maintaining process isolation may include sealing the inner bore of the internal isolation valve by activating the internal isolation valve and inserting the sensor through the inner bore of the lock block to a semi-inserted position in which the sensor is disposed between the integral seal mechanism and the internal isolation valve. The inner bore of the lock block may then be sealed with the integral seal mechanism so that the inner bore of the internal isolation valve may be unsealed by deactivating the internal isolation valve. The sensor may then be inserted through the inner bore of the internal isolation valve, through the inner bore of the base plate, and into the process vessel. 
     The method may also include removing the sensor from the process vessel through the sensor mounting apparatus while maintaining process isolation within the process vessel. This step may include sliding the sensor out of the process vessel to the semi-inserted position, sealing the inner bore of the internal isolation valve by activating the internal isolation valve, and sliding the sensor out of the inner bore of the lock block. 
     The sensor mounting apparatus may further include a plug having a first end surface, a second end surface, a side surface interconnecting the first and second end surfaces of the plug, a plug groove on the side surface, and an inner bore extending from the first end surface to the second end surface. The locking cam assembly may include a locking cam, a spring pin stop, and a retainer pin. The locking cam may have a head with a groove and an elongated portion with a recess and a retainer pin bore extending laterally through the elongated portion. The spring pin stop may be positioned within the recess of the elongated portion. The retainer pin may be capable of being inserted through the retainer pin bore in the elongated portion of the locking cam. The sensor may include a sensor probe having a proximal end and a distal end. 
     The step of inserting the sensor into the process vessel through the sensor mounting apparatus while maintaining process isolation may include sealing the inner bore of the internal isolation valve by activating the internal isolation valve. The sensor probe may be inserted through the inner bore of the plug to secure the plug on the sensor probe at a predetermined position corresponding to a predetermined insertion depth of the distal end of the sensor probe in the process vessel. The sensor probe may be inserted through the inner bore of the lock block to a semi-inserted position in which the distal end of the sensor probe is disposed between the integral seal mechanism and the internal isolation valve. The inner bore of the lock block may then be sealed with the integral seal mechanism and the inner bore of the internal isolation valve may be unsealed by deactivating the internal isolation valve. The sensor probe may be inserted through the inner bore of the internal isolation valve, through the inner bore of the base plate, and into the process vessel such that the distal end of the sensor probe is positioned at the predetermined insertion depth. The predetermined insertion depth may be reached when the plug slides into the socket of the lock block. 
     The method may further include rotationally orienting the sensor probe in the process vessel. An aperture may be formed in said lock block by an intersection of said cam bore with said socket. The step may include aligning the plug groove with the aperture in the lock block by rotating the plug in the socket of the lock block, completely inserting the elongated portion of the locking cam through the cam bore of the lock block, rotating the head of the locking cam into an engaged position in which the spring pin stop engages the groove in the head, and locking the locking cam in the cam bore by inserting the retainer pin through the retainer pin bore in the locking cam. 
     Alternatively, the process of rotationally orienting the sensor probe in the process vessel may involve positioning the elongated portion of the locking cam in the cam bore; retaining the elongated portion of the locking cam in the cam bore by inserting the retainer pin in the retainer pin bore; aligning an aperture in the elongated portion of the locking cam with an aperture in the socket of the lock block so that the elongated portion of the locking cam is flush with the socket; sliding the plug within the socket; and rotating the locking cam to a position indicative of the plug being in a correct rotational orientation. 
     The method may further include removing the sensor probe from the process vessel while maintaining process isolation. 
     These and many other objects and advantages will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims and the following detailed description of the preferred embodiments and read in conjunction with the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a sensor mounting apparatus. 
         FIG. 2  is a perspective view of a sensor that may be mounted through the sensor mounting apparatus shown in  FIG. 1 . 
         FIG. 3  is a perspective view of the sensor mounting apparatus shown in  FIG. 1  mounted on a pipe section. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the figures where like elements have been given like numerical designation to facilitate an understanding of the present invention, and particularly with reference to the embodiment of the present invention illustrated in  FIG. 1 , sensor mounting apparatus  10  may include lock block  12  having socket  14 . Socket  14  and plug  16  may allow for a specified insertion depth and orientation of a sensor. For insertion type sensors, plug  16  may be attached to a sensor shaft using a compression pin. For process sensors (e.g., temperature or pressure sensors), plug  16  may be incorporated into the sensor housing or the sensor may be threaded directly onto plug  16 . Plug  16  may be inserted into socket  14  of lock block  12 . 
     Locking cam  18  may include head  19  having groove  20 . Locking cam  18  may also include elongated portion  21  having recess  22  and retainer pin bore  23 . Spring pin stop  24  may be disposed within recess  22  of locking cam  18 . Locking cam  18  may be capable of being inserted through cam bore  26  in lock block  12 . Cam bore  26  may intersect with socket  14  at aperture  28 . Locking cam  18  may orient plug  16  in socket  14  of lock block  12 . After sliding plug  16  into socket  14 , locking cam  18  may be inserted into cam bore  26 . Plug  16  may be rotated such that plug groove  30  is aligned with aperture  28  of lock block  12 . In this position, locking cam  18  may extend completely through cam bore  26  due to the space created by the alignment of plug groove  30  with aperture  28 . With locking cam  18  extending completely through cam bore  26 , plug  16  is rotationally aligned with and locked into socket  14 . Locking cam  18  may be rotationally locked by rotating head  19  until spring pin stop  24  engages groove  20  in head  19 . Locking cam  18  may be locked into cam bore  26  by inserting retainer pin  32  through retainer pin bore  23  in locking cam  18 . Insertion of retainer pin  32  through retainer pin bore  23  may prevent locking cam  18  from slipping or being removed from cam bore  26 . 
     Alternatively, and more preferably, locking cam  18  is inserted into cam bore  26  and retained therein by retainer pin  32  before plug  16  is slid into socket  14 . Aperture  22  in locking cam  18  is aligned with aperture  28  by rotating locking cam  18  so there is no obstruction to prevent plug  16  from being inserted into position within socket  14  of lock block  12  (i.e., cam  18  is flush with socket  14 ). Locking cam  18  is then rotated. If plug  16  is correctly rotationally oriented in socket  14  (i.e., plug groove  30  is aligned with aperture  28 ), locking cam  18  is able to rotate to a position where a portion of locking cam  18  extends outward of aperture  28  and is no longer flush therewith. In this configuration, plug  16  is oriented in the desired rotational position. Locking cam  18  (and plug  16 ) are held in place by actuation of spring pin stop  24  and engagement with groove  20  in head  19 . 
     Sensor mounting apparatus  10  may also include one or more seal mechanisms. The seal mechanisms may include integral pressure seals  34  in lock block  12  and internal isolation valve  36 , which may fit into lock block  12 . Integral pressure seals  34  may be O-rings. Internal isolation valve  36  may isolate a process when actuated. Internal isolation valve  36  may be a ball valve. Lock block  12  and internal isolation valve  36  may be mounted on base plate  38  such that sensor mounting apparatus  10  may be mounted onto process equipment, such as a process vessel or a section of pipe. Lock block  12  and internal isolation valve  36  may be mounted on base plate  38  by any mounting means, such as by bolt or screw. Inner bore  39  may extend through lock block  12 , internal isolation valve  36 , and base plate  38 . 
       FIG. 2  illustrates sensor probe  40  which may be any type of sensor probe or process sensor designed to be inserted into a process vessel or pipe section. In a preferred embodiment, sensor probe  40  may have specific rotational orientation and insertion depth requirements and/or may require process isolation during insertion and removal of sensor probe  40 . Sensor probe  40  may be an optical probe for a gas flow meter functioning based on L2F or L2B particulate velocimetry. Alternatively, sensor probe  40  may be one of multiple probes of an ultrasonic flow meter that requires a specific insertion depth of each probe. Sensor probe  40  may be oriented and positioned at a specified insertion depth within a system using sensor mounting apparatus  10 . Sensor probe  40  may contain proximal end  42  and distal end  44 . Distal end  44  may be designed to be positioned within a process vessel or pipe section. 
     As shown in  FIG. 3 , sensor mounting apparatus  10  may be mounted onto process equipment such as pipe section  46 . Base plate  38  of sensor mounting apparatus  10  may be operatively connected to mounting plate  48  of pipe section  46  by any mounting means, such as by bolt or screw. Alternatively, base plate  38  may be mounted directly onto a process vessel. Sensor probe  40  may be positioned through plug  16 , inner bore  39  of sensor mounting apparatus  10 , and a bore (not shown) through mounting plate  48  such that distal end  44  of sensor probe  40  is positioned within pipe section  46  at the required rotational orientation and insertion depth. Proximal end  42  of sensor probe  40  may be covered by probe sleeve  50  and probe cap  52  to protect sensor probe  40  from surrounding environmental conditions. 
     Referring now to  FIGS. 1-3 , sensor probe  40  may be mounted onto process equipment (e.g., pipe section  46 ) using sensor mounting apparatus  10 . Lock block  12  and internal isolation valve  36  may first be connected to base plate  38 . Base plate  38  may then be connected to mounting plate  48  on pipe section  46  thereby mounting sensor mounting apparatus  10  to pipe section  46 . Internal isolation valve  36  may be placed in an activated position such that inner bore  39  is sealed at internal isolation valve  36 . 
     Plug  16  may be connected to sensor probe  40  and secured at a predetermined position on sensor probe  40  using a compression pin. Distal end  44  of sensor probe  40  may then be inserted into socket  14  and inner bore  39  until distal end  44  is disposed between integral pressure seals  34  and internal isolation valve  36  (sometimes referred to as a semi-inserted position). Integral pressure seals  34  may form a seal around sensor probe  40  so that internal isolation valve  36  may be deactivated while maintaining process isolation. With internal isolation valve  36  in the deactivated position, distal end  44  of sensor probe  40  may be inserted further through inner bore  39  and through the bore in mounting plate  48 . Lock block  12  may stop the insertion of sensor probe  40  when attached plug  16  slides into socket  14  as sensor probe  40  reaches the predetermined insertion depth within pipe section  46 . The predetermined position of plug  16  on sensor probe  40  may be manipulated to achieve the required predetermined insertion depth for the type of sensor probe  40  used. 
     To rotationally orient sensor probe  40 , locking cam  18  may then be partially inserted through cam bore  26  of lock block  12 . If plug groove  30  on plug  16  is not aligned with aperture  28  of lock block  12 , locking cam  18  will be unable to be completely inserted through cam bore  26 . Plug  16  and sensor probe  40  may be rotated within socket  14  and inner bore  39  until locking cam  18  is able to be inserted completely through cam bore  26  indicating to a user that plug groove  30  and aperture  28  are aligned. In this position, sensor probe  40  is locked into the required rotational orientation within pipe section  46 . The rotational position of plug  16  on sensor probe  40  may be manipulated to achieve the required rotational orientation of sensor probe  40  in pipe section  46 . Head  19  of locking cam  18  may then be rotated into an engaged position in which spring pin stop  24  engages groove  20  in head  19 . In the engaged position, head  19  of locking cam  18  is rotationally locked in place. Retainer pin  32  may be inserted through retainer pin bore  23  in locking cam  18 . Retainer pin  32  may lock plug  16  in socket  14  to maintain the proper insertion depth of distal end  44  of sensor probe  40  in the system. 
     Alternatively, and more preferably, locking cam  18  is inserted into cam bore  26  and retained therein by retainer pin  32  before plug  16  is slid into socket  14 . Aperture  22  in locking cam  18  is aligned with aperture  28  by rotating locking cam  18  so there is no obstruction to prevent plug  16  from being inserted into position within socket  14  of lock block  12  (i.e., cam  18  is flush with socket  14 ). Locking cam  18  is then rotated. If plug  16  is correctly rotationally oriented in socket  14  (i.e., plug groove  30  is aligned with aperture  28 ), locking cam  18  is able to rotate to a position where a portion of locking cam  18  extends outward of aperture  28  and is no longer flush therewith. In this configuration, plug  16  is oriented in the desired rotational position. Locking cam  18  (and plug  16 ) are held in place by actuation of spring pin stop  24  and engagement with groove  20  in head  19 . 
     To remove sensor probe  40  from pipe section  46  while maintaining process isolation, locking cam  18  may be removed from cam bore  26  by removing retainer pin  32  from retainer pin bore  23  in locking cam  18 , rotating head  19  out of the engaged position, and sliding elongated portion  21  of locking cam  18  out of cam bore  26 . Sensor probe  40  may be extracted from pipe section  46  and through inner bore  39  until distal end  44  of sensor probe  40  is disposed between internal isolation valve  36  and integral pressure seals  34  (i.e., the semi-inserted position) such that integral pressure seals  34  continue to seal around sensor probe  40 . Internal isolation valve  36  may then be activated to seal inner bore  39 . Sensor probe  40  may then be completely removed from inner bore  39  while maintaining process isolation with internal isolation valve  36 . 
     Alternatively, and more preferably, to remove sensor probe  40  from pipe section  46  while maintaining process isolation, spring pin stop  24  is disengaged and locking cam  18  rotated to a position wherein aperture  22  is aligned with aperture  28  (cam  18  is flush within socket  14 ). This releases plug  16 , which, together with probe  40 , may be removed from socket  14 . Probe  40  is then extracted from pipe section  46 . 
     While preferred embodiments of the present invention have been described, it is to be understood that the embodiments described are illustrative only and that the scope of the invention is to be defined solely by the appended claims when accorded a full range of equivalence in view of the many variations and modifications naturally occurring to those skilled in the art from perusal hereof.