Abstract:
A mechanical pump having an inlet and spaced therefrom an outlet for the passage of fluid therethrough and incorporating at least one flame arrester.

Description:
FIELD OF THE INVENTION 
     The present invention relates to mechanical pumps, and in particular, to mechanical pumps for use in the chemical and process industries where there are inherent risks of explosions and /or fires due to the properties of the fluids to be pumped. 
     BACKGROUND OF THE INVENTION 
     Currently commercial flame arresters are separate costly devices which are bolted or otherwise fitted to mechanical pumps to mitigate against or inhibit the chances of an explosion or a fire arising from the pumping of hazardous fluids. These known flame arresters are made from expensive stainless steel since they are conceived as ‘cold pipework’ and are susceptible to corrosion. They also require considerable mechanical support. 
     SUMMARY OF THE INVENTION 
     It is an aim of the present invention to provide a mechanical pump which incorporates at least one flame arrester. 
     By effectively integrating the flame arrester within the mechanical pump, the flame arrester is kept hotter and less susceptible to corrosion. Furthermore, the flame arrester can safely be made from a cheaper material than stainless steel, for example spheriodal graphite iron. 
     According to the present invention, a mechanical pump having an inlet and spaced therefrom an outlet for the passage of fluid therethrough incorporates at least one flame arrester. 
     Preferably, the flame arrester is located immediately adjacent the pump inlet. 
     In one embodiment, two flame arresters are incorporated in the pump, one being located immediately adjacent the pump inlet and the second being located immediately adjacent the pump outlet. 
     The or each flame arrester may include a flame arresting element removably mounted within a housing. This feature allows for the flame arresting element to be removed or replaced without disturbing any process pipework to which the pump is attached. 
     The housing may have a rectangular box section body the opposite ends of which are closed by one or more removable cover plates which facilitates the removal of the flame arresting element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An embodiment of the invention will now be described, by way of example, reference being made to the Figures of the accompanying diagrammatic drawings in which: 
         FIG. 1  is a perspective view of a mechanical pump according to the present invention; and 
         FIG. 2  is an exploded detail of the mechanical pump of  FIG. 1  illustrating a flame arrester incorporated within the pump. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the figures, a mechanical pump  1  includes an inlet  2  and an outlet  3  spaced from the inlet  2  for the passage therethrough of a fluid to be pumped. 
     Immediately adjacent the inlet  2  there is located a flame arrester  4  which includes a flame arresting element  6  made, for example, from mesh material, removably mounted within a housing  8 . The housing  8  has a rectangular box section body  10  opposite ends of which are closed by removable cover plates  12  (only one shown). Since the body  10  and cover plates  12  form part of the pump  1  and attain high temperatures when the pump  10  is running they can be made from relatively cheap material such as grey or spheriodal graphite iron without the risk of corrosion. 
     In use, with one or both cover plates  12  removed, the flame arresting element  6  is slid in place within the body  10  of the housing  8 . The or each cover plate  12  is then bolted to its respective end face of the body  10  to seal the flame arresting element within the housing  8 . 
     Finally, the flame arresting element  6  is clamped in place by for example a plurality of bolts  14  or other mechanical means in the housing  8 . The bolts  14  are sealed within the housing to make them leak-tight. 
     The flame arrester  4  is bolted to the pump casing between the casing and the pump inlet  2  and is thereby incorporated within the body of the pump  1 . 
     It will be apparent that the flame arresting element  6  can be removed from the pump  1  for cleaning or replacement by removing one of the cover plates  12 , releasing the bolts  14 , and sliding the flame arresting element  6  out from the body  10  of the housing  8 . 
     In this manner, the flame arresting element  6  can be removed without disturbing any process pipework to which the pump  1  is attached. 
     It will be evident that a second flame arrester can be incorporated within the pump  1  immediately adjacent the outlet  3  of the pump in a similar manner to that described with respect to flame arrester  4  and the pump inlet  2 . 
     Although the housing  8  is described and shown having a rectangular box section body  10 , other shapes could be used, for example oval or circular. 
     While the present invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be apparent to by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.