The design characteristics of a Convoluted Diaphragm allow it to travel twice as deep as a non-convoluted design.
The maximum recommended stroke length for deep draw diaphragms is determined by keeping the height of the diaphragm less than, or equal to, the diameter of the bore.
A standard deep draw diaphragm can be augmented with a second taper. By adding this second taper, the main sidewall angle is greatly reduced thereby reducing the circumferential compression and increasing life.
Gallagher engineers approach the design and manufacturing of diaphragms through a step-by-step process that results in the best diaphragm design, with the most appropriate material, constructed in a manner that optimizes manufacturability and cost.
An elastomeric diaphragm is a versatile dynamic seal that eliminates many of the limitations of other sealing methods. They do not leak, offer little friction and can be constructed for low pressure sensitivity. With proper material consideration, diaphragms can seal over a wide temperature and pressure range without maintenance or lubrication.
Diaphragm Design Check-List
1: Environmental, Functional and Material Considerations
What are the environmental conditions? Specifically what temperature, humidity and media is the diaphragm exposed to? What is the basic function of the diaphragm? Is it acting as a regulator with pressure from one side, or as a pump with pressure from both sides? Very important distinctions distinguish diaphragms for control, switching, accumulation or pumping applications. Material selection typically requires the expertise of the supplier. Specifying the best choice of materials not only ensures the longest possible life of the diaphragm, but can often avoid unnecessary costs by not “overdesigning.”
2: Construction and Shape Elements
A primary goal of the design process is to consider the construction method of the diaphragm at the earliest stage possible. A layer of reinforcing material molded to the elastomer, or a layer of coating on one or both sides of the diaphragm can clearly add significant cost to the component. The decision to use a coating on one or both sides of the diaphragm is dependent on the pressure, media, and stroke length of the piston.
3: Application Properties and Hardware Considerations
Cycle rate and expected cycle life of the diaphragm must be established. These values are tested for confirmation during the prototype phase. Requisite hardware is made from either injection molded plastic, stamped or formed metal or a machined plastic or metal. Additional hardware considerations include the presence of return springs, positive stops, the piston design, and care over time of the diaphragm. Each of these considerations eliminates various design options, and the optimal diaphragm design begins to emerge.