More about Triark Pumps

Critical components

AODD pumps benefit from their simplicity of operation. The key components in the pump are the air valve (which is usually a shuttle valve to route the compressed air alternatively to each diaphragm), the valves, and of course, the diaphragms themselves. The position of the various components of an AODD pump is shown in the cutaway figure.

The air valve is an important part of the pump and in the early days of AODD pumps these were prone to stalling, causing the pump to stop. This was due to icing of the valve, caused by sudden expansion of air to the atmosphere and consequent rapid cooling, which instantly freezes any moisture contained in the air. The ice formed on the moving parts of the air valve caused them to stick.

Naturally manufacturers have addressed this problem in different ways and each has its own particular designs to eliminate the problem. In general, therefore, stalling is no longer a significant problem for this type of pump. Moreover, many pumps are designed to have the air valve serviceable without the need to dismantle the rest of the pump. The diaphragms are another key component for AODD pumps.

Diaphragm selection

The key factors that determine the suitability of the diaphragm for a particular application are: flex life, the chemical composition of the fluids to be pumped and their effect on the diaphragm; the temperature range that the pump must operate in, including extremes; and the abrasive nature of the media being pumped, including the size of any particulates. Most pump manufacturers can supply chemical resistance guides to assist in the selection of suitable diaphragms.

However, since the diaphragm is continually being stressed, stress corrosion can result. Information on the previous practical performance of a particular material used for the diaphragm is therefore also important.

Diaphragm materials

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