Pumps diaphragm

The valves are arranged in such a way that during the phase where the volume of the pumping chamber increases it is open to the intake line. During compression, the pumping chamber is linked to the exhaust line. 

Due to the limited elastic deformability of the diaphragm only a comparatively low pumping speed is obtained. In the case of this pumping principle a volume remains at the upper dead center - the so called dead space - from where the gases can not be moved to the exhaust line. The quantity of gas which remains at the exhaust pressure expands into the 

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Any commercially available vacuum pump is perfectly fine for the underground chemist s needs but the best kind to buy is a diaphragm pump, which is more resistant to the often-harsh chemical vapors that are sucked through it. Most vacuum pumps cost about 100- 200. However, the stronger the vacuum the better. If a chemist is looking to pull 1mm of Hg (don t ask) like the girls in the chemistry papers do then she can be looking at a turbovac that can run well over 5000. 

Fig. 12. Diaphragm pump (a) suction cycle, and (b) discharge cycle.

Reciprocating Pumps There are three classes of reciprocating pumps piston pumps, plunger pumps, and diaphragm pumps. 

Pnettmatically Actuated Diaphragm Pumps (Fig. 10-53) These pumps require no power source other than plant compressed air. They must have a flooded suction, and the pressure is, of course, limited to the available air pressure. Because of their slow speed and large valves, they are well suited to the gentle handling of liquids for which degradation of suspended solids should be avoided. 

A major consideration in the apphcatiou of diaphragm pumps is the realization that diaphragm failure will probably occur eventually. The consequences of such failure should be reahstically appraised before selection, and maintenance procedures should be established accord-ingly. 

FIG. 10-53 Pneumatically actuated diaphragm pump for slurry service. (Coutiesy of Dotr-Olvier Inc.)... 

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. 

There are trade-offs for magnetic drive and canned pumps versus centrifugal pumps with double-mechanical seals. The former have no seals to leak, but need active interlocks to prevent high temperature for temperature sensitive materials. Similarly, diaphragm pumps, that have... 

DATA nOUNDARY Dual-diaphragm pumps in uranium solution service. 

This paper describes a reliability analysis of dual - diaphragm pumps in uranium solution service. It is part of the output from a failure modes and effects analysis of the design for a system to be installed at the Oak Ridge Y-12 plant. The study involved collecting data on pumps with Viton and Teflon diaphragms at 10 gpm and 15 gpm. 

If the duty is metering, piston or diaphragm pumps should be selected. 

By virtue of their construction, diaphragm pumps cannot be used for high pressure applications. In the Mars pump, there is no need for a diaphragm as the working fluid (oil), of lower density than the liquid to be pumped, forms an interface with it in a vertical chamber. The pump, which is used extensively for concentrated slurries, is really a development of the old Ferrari s acid pump which was designed for corrosive liquids. 

Positive displacement pumps, such as reciprocating and diaphragm pumps. 

In a review of incidents involving explosive reactivity of liquid chlorine with various organic auxiliary materials, two involved hydrocarbons. A polypropylene filter element fabricated with zinc oxide filler reacted explosively, rupturing the steel case previously tested to over 300 bar. Zinc chloride derived from the oxide may have initiated the runaway reaction. Hydrocarbon-based diaphragm pump oils or metal-drawing waxes were violently or explosively reactive [8], A violent explosion in a wax chlorination plant may have involved unplanned contact of liquid chlorine with wax or chlorinated wax residues in a steel trap. Corrosion products in the trap may have catalysed the runaway reaction, but hydrogen (also liberated by corrosion in the trap) may also have been involved [9],... 

A cryogenist does not usually need a general purpose mass spectrometer, but the cryogenist cannot work without an LD which is made up of a small vacuum system (rotary pump or diaphragm pump in series with a turbo pump) and a mass spectrometer for the detection of light gases (H2,3He and 4He). 

FIGURE 7.11 Schematic of double-diaphragm pump controls. 

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