Double-diaphragm pumps
A double-diaphragm pump includes a pair of axially spaced apart pumping chambers, each chamber having a pumping diaphragm which divides each chamber into an inner and outer compartment. Inner ends of both pumping chambers are closed by a central element, and fluid is supplied to the outer compartments to cause the diaphragms to oscillate and vary the capacities of the inner compartments. I Each of the inner compartments having an inlet and an outlet port leading to unidirectional valves to allow fluid to be drawn into one of the compartments when the appropriate diaphragm moves outwardly and expelled from that compartment when the diaphragm moves inwardly. The unidirectional valves are located in inlet and outlet manifolds in the central element and are accessed and fitted through the inlet and outlet ports in the inner compartments.
1. A double-diaphragm pump comprising a pair of axially spaced apart pumping chambers, each chamber having a pumping diaphragm which divides each chamber into an inner and an outer compartment, the inner ends of both pumping chambers being formed by a central element, a mechanism supplying fluid to the outer compartments to cause the diaphragms to oscillate and vary the capacities of the inner compartments and each of the inner compartments having an inlet port leading to an inlet manifold in the central element and an outlet port leading to an outlet manifold in the central element, and wherein unidirectional valves are located inside of the inlet and outlet manifolds to allow fluid to be drawn into one of the compartments through the inlet port of that compartment from the inlet manifold of that compartment when the appropriate diaphragm moves outwardly and to allow the fluid to be expelled from that compartment through the outlet port of the compartment into the outlet manifold of that compartment when the diaphragm moves inwardly, and in which the unidirectional valves are accessed and fitted through the inlet and outlet ports in the inner compartments when the diaphragms are absent, and wherein the inlet and outlet manifolds within the central element extend away from their respective chambers at an acute angle relative to the plane of the rim of said respective inner chamber.
2. A double-diaphragm pump as claimed in claim 1 in which the unidirectional valves are ball valves the balls of which act as valve seatings which are fitted into said inlet and outlet manifolds through the inlet and outlet ports.
3. A double-diaphragm pump as claimed in claim 2 in which the valve seatings are screw threaded into said manifolds.
4. A double-diaphragm pump as claimed in claim 2 in which the valve balls are located in cages located inside said inlet and outlet manifolds.
5. A double-diaphragm pump as claimed in claim 1 in which said central element is provided in a pump body formed from a block of material in which the inner walls of the inner compartments and the inlet and outlet manifolds are formed.
6. A double-diaphragm pump as claimed in claim 5 in which the pump body is formed from a synthetic plastics material.
7. A double-diaphragm pump as claimed in claim 6 in which the pump body is formed from P.T.F.E.
8. A double-diaphragm pump as claimed in claim 1 in which the diaphragms must be removed to access the unidirectional valves.
9. A double-diaphragm pump as claimed in claim 1 in which the diaphragms are held in place and the outer compartments are closed by end covers.