Mechanical pump with integrated flame arrester

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.

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.

It is known to incorporate flame arrestors into mechanical fluid pumps as described in US-A-3 135 211 (which is considered the closest prior art); US-A-3 658 444; US-A-5 007 806; and US-a-5 591 019.

It is an aim of the present invention to provide a mechanical pump according to claim 1 having an inlet and spaced therefrom an outlet for the passage of fluid therethrough and incorporating within the mechanical pump at least one flame arrestor, characterised in that the flam arrestor comprises a flame arresting element removably mounted within a housing having a rectangular box section body (10) with opposite ends, the housing forming part of the pump and said ends being closed by removable cover plates for enabling replacement of the flame arresting element without disturbing any process pipework to which the pump is attached.

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 spheroidal 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 arresters.

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 includes 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 has 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.

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:

• Figure 1 is a perspective view of a mechanical pump according to the present invention; and
• Figure 2 is an exploded detail of the mechanical pump of Figure 1 illustrating a flame arrester incorporated within the pump.

As shown, 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 spheroidal 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 place 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.