Pumping apparatus

Abstract

A conduit supplies a flow of gas to a sealed chamber surrounding the swept volume of a pump. The conduit comprises a flow impedance for limiting the rate of flow of the gas to the sealed chamber. Signals output from pressure transducers provided on either side of the flow impedance are used to detect leakage of gas from the sealed chamber into the pump swept volume, thus indicating the state of the seal surrounding the swept volume.

1 . A pumping apparatus comprising a pump adapted to form a swept volume and a sealed chamber surrounding the swept volume, the apparatus further comprising a conduit for supplying fluid to the chamber, the conduit comprising a flow impedance for limiting the rate of flow of fluid to the chamber, and means for determining a pressure difference across the flow impedance.  
     
     
         2 . The pumping apparatus as in  claim 1 , wherein the impedance is provided by a restriction within the conduit.  
     
     
         3 . The pumping apparatus as in  claim 1 , wherein the rate of flow of fluid across the impedance is such that fluctuations in fluid pressure on one side of the impedance are not rapidly transmitted to fluid on the other side of the impedance.  
     
     
         4 . The pumping apparatus as in  claim 1 , wherein the impedance is provided by one of the group of a porous, sintered material, a capillary formed within a non-porous blockage, and a valve.  
     
     
         5 . The pumping apparatus as in  claim 1 , wherein the means for determining the pressure difference comprises at least one pressure transducer.  
     
     
         6 . The pumping apparatus as in  claim 5 , wherein said at least one pressure transducer comprises a first pressure transducer configured to output a signal indicative of a fluid pressure in the conduit upstream of the impedance and a second pressure transducer configured to output a signal indicative of a fluid pressure in the conduit downstream of the impedance.  
     
     
         7 . The pumping apparatus as in  claim 6 , comprising a controller for receiving the signals from the first pressure transducer and the second pressure transducer and for generating an alert depending on the difference in the fluid pressures indicated by the signals.  
     
     
         8 . The pumping apparatus as in  claim 7 , wherein the alert is generated when the pressure difference across the impedance exceeds a predetermined value.  
     
     
         9 . The pumping apparatus as in  claim 1 , wherein the conduit is connected to a reservoir for supplying fluid thereto.  
     
     
         10 . The pumping apparatus as in  claim 9 , wherein the reservoir is configured to supply a purge gas to a pump of the pumping apparatus.  
     
     
         11 . The pumping apparatus as in  claim 1 , wherein the sealed chamber is formed by two adjacent stator components and a first O-ring seal and a second O-ring seal therebetween.  
     
     
         12 . The pumping apparatus as in  claim 11 , wherein the O-ring seals are formed from an elastomeric material.  
     
     
         13 . A method for detecting a leak of fluid from a chamber surrounding a swept volume of a pump, the method comprising the steps of supplying the fluid to the chamber through a flow impedance, and monitoring a pressure difference in the fluid across the flow impedance.  
     
     
         14 . The method according to  claim 13 , wherein the pressure difference across the flow impedance is monitored subsequent to a pressure equilibrium being established between the fluid downstream of the flow impedance and the fluid upstream of the flow impedance.  
     
     
         15 . The method according to  claim 13 , wherein the monitored pressure difference is compared with a predetermined value, and an alert is generated if the monitored pressure difference exceeds the predetermined value.  
     
     
         16 . The method according to  claim 13 , wherein the fluid is supplied from a reservoir.  
     
     
         17 . The method according to  claim 16 , wherein the reservoir is configured to supply a purge gas to the pump.  
     
     
         18 . The method according to  claim 13 , wherein the chamber is defined in part by two O-ring seals.  
     
     
         19 . The method according to  claim 18 , wherein the O-ring seals are formed from an elastomeric material.