Diaphragm position

Fig. 9 Pressure-loaded diaphragm actuators, (a) Planar diaphragm. Positive piessme causes bulge in active region. Foam can replace fluid pressure, (b) Diaphragm actuator showing large out-of-plane motion in response to an applied voltage. Diaphragm actuators can be used for loudspeakers or pumps, (c) Array of diaphragm actuators (each 5.5 mm in diameter) made from a single elastomer...

An expandable anode involves compression of the anode stmcture using cHps during cell assembly so as not to damage the diaphragm already deposited on the cathode (Eig. 3a). When the cathode is in position on the anode base, 3-mm diameter spacers are placed over the cathode and the cHps removed from the anode. The spring-actuated anode surfaces then move outward to bear on the spacers, creating a controlled 3-mm gap between anode and cathode (Eig. 3b). This design has also been appHed to cells for the production of sodium chlorate (22). 

Because indirect-heat calciners frequently require close-fitting gas seals, it is customaiy to support aU parts on a selFcontained frame, for sizes up to approximately 2 m in diameter. The furnace can employ elec tric heating elements or oil and/or gas burners as the heat source for the process. The hardware would be zoned down the length of the furnace to match the heat requirements of the process. Process control is normaUy by shell temperature, measured by thermocouples or radiation pyrometers. When a special gas atmosphere must be maintained inside the cyhnder, positive rotaiy gas se s, with one or more pressurized and purged annular chambers, are employed. The diaphragm-type seal ABB Raymond (Bartlett-Snow TM) is suitable for pressures up to 5 cm of water, with no detectable leakage. 

Lube oil pumps are typieally heavy-duty eentrifugal or positive displaeement type with a design eapaeity that eovers the full range of antieipated operation. They ean be either direet-driven by eleetrie motors or eoupled with disk or diaphragm-type eouplings. Experieneed turboexpander manufaeturers will supply motors and eouplings that are at least 25% oversized. 

The mean tensile stress aeting on the eross-seetional area of the diaphragm eoupling-equipped shaft depends on how far the diaphragm is displaeed axially from its neutral rest position and the axial spring rate of the diaphragm. 

The internal passages are formed by a set of diaphragms. Figure 5. 2 depicts a typical multistage barrel compressor. Refer to this figure lo locale the relative position of the various parts that are described in the following section. 

Other positive displacement pumps, such as rotary, gear, and diaphragm pumps, normally require PR valve protection for both the pump and downstream equipment. PR valves for all positive displacement pumps should have a capacity at least equal to the pump capacity. 

These special throttling valves use an elastomer diaphragm to restrict or stop flow (Figure 15-7). They are suitable for slurry service and make an excellent valve for sand drains. Unfortunately, they do not provide a reliable, positive shut-off and should be installed in series with a ball or other on/off valve if positive shut-off is required. 

It consists of a spring-loaded cut-off valve which is held open in the open position under normal conditions. Should the pressure deviate sufficiently, the diaphragm will move and disengage the trigger mechanism, releasing the latch on the valve, which will close under the force of the spring. 

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