Vacuum diaphragm

A heated female die is used with a vacuum diaphragm, as in vacuum forming... 

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. 

Gauges. Because there is no way to measure and/or distinguish molecular vacuum environment except in terms of its use, readings related to gas-phase concentration ate provided by diaphragm, McCleod, thermocouple, Pitani gauges, and hot and cold cathode ionization gauges (manometers). 

Fig. 7. Sohds content of sludges dewatered by C, soHd bowl centrifuge VF, vacuum filter BP, belt press FP, filter press, and DFP, diaphragm filter press...

Strain-gauge pressure transducers are manufactured in many forms for measuring gauge, absolute, and differential pressures and vacuum. Full-scale ranges from 25.4 mm of water to 10,134 MPa are available. Strain gauges bonded direc tly to a diaphragm pressure-sensitive element usually have an extremely fast response time and are suitable for high-frequency dynamic-pressure measurements. 

Bourdon and diaphragm gauges that show both pressure and vacuum indications on the same dial are called compound gauges. 

The most used mechanical vacuum pumps or compressors are reciprocating, liquid-ring, rotary-vane, rotary blower, rotary piston, and diaphragm. 

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). 

The DLI interface became the second commercially available LC/MS interface in 1981. The liquid eluent is introduced into the ion source through a capillary or a pinhole diaphragm. As the name implies, the analyte in DLI LC/MS is introduced from solution into the MS ion source.When sufficient energy is given to the solution, the preformed ions in solution such as protonated molecules, deprotonated molecules, cationized molecules and solvated ions can be desorbed into a mass spectrometer while the bulk solvent is vaporized and eliminated by the vacuum system. 

The best-known design of a diaphragm vacuum gauge is a barometer with an aneroid capsule as the measuring system. It contains a hermetically sealed, evacuated, thin-walled diaphragm capsule made of a copper-beryllium alloy. As the pressure drops, the capsule diaphragm expands. 

---