House vacuum systems

Three vacuum systems are commonly used in modern aseptic manufacturing facilities (1) house vacuum systems, (2) vacuum systems dedicated to lyophilization equipment, and (3) vacuum systems dedicated to autoclaves or other sterilization equipment. 

A modest vacuum source (about 20 - 50mmHg) should be available at each bench and is sufficient for rotary evaporation of most solvents, filtering under vacuum, distillation of relatively volatile oils, and similar tasks. This level of vacuum is sometimes provided by a house vacuum system. Alternatively, a water aspirator or small diaphragm pump can be used. 

A high volume house vacuum system was used for this step. 

Nucleic acids are traditionally fixed to membranes in a vacuum oven (a conventional oven can be used for nylon membranes). The house vacuum system is usually adequate and baking of most membranes is at 80°C. UV crosslinking is an attractive alternative although it is only recommended for specific membranes. Special equipment is available for sophisticated, well-controlled UV irradiation (e.g., Stratalinker from Stratagene). However, conventional transilluminators available in the laboratory perform equally well. 

The CAMS units consist of monitors that continuously sample air for gross beta (P) activity. These instruments require either portable vacuum pumps or connection to a house vacuum system. Like RAMS, CAMS are located in Zone 2 where routine manned operations are conducted. CAMS units also have alarm set points that are determined and established to provide an indication of an abnormal airborne condition. CAMS units detectors and flowrates are calibrated and tested in compliance with the SNL RPPM Chapter 12. 

A laboratory worker was conducting a routine filiation using a standard Erlemneyer flask with a sidearm connected to a house vacuum system. The flask imploded and dispersed a spray of shards of glass and the solution being filtered. Fortunately, the filtration was in a chemical hood with the shield lowered and there were no injuries. 

Low-pressure operations are common in many laboratories. Laboratories are often equipped with a house vacuum system, vacuum pumps, rotary evaporators, water aspirators, vacuum concentrators, vacuum ovens, and other apparatus that operate under reduced pressure. Some labs build elaborate vacuum racks... 

A common use of vacuums involves their utility for removing volatiles from reactions or filtering materials. It is common to use house vacuum systems, water aspirators, or vacuum pumps for these purposes. Besides the risks of implosions, there can be potential hazards from exposures to toxic products released from the vacuum exhaust. Maintenance workers have been exposed to toxic chemicals that were allowed to enter into a house vacuum system. Others have been exposed to toxic products from unventilated vacuum pumps used to evaporate volatile organics. It is important to use techniques to set up traps to prevent these kinds of releases of hazardous materials. 

While the oxidation is proceeding, set up a vacuum filtration apparatus using a 125-mL filter flask (should be clean and dry). Prepare a 1.27-cm Hirsch funnel to filter the reaction mixture (Technique 8, Section 8.3 and Figure 8.5 A). Place a moist (with water) piece of Whatman 2 filter paper into the Hirsch funnel. Weigh out 0.5 g of Celite (filter aid) in a beaker and transfer the solid to the Hirsch funnel. Using a bent spatula, adjust the Celite (filter aid) so that it covers the filter paper as evenly as possible. Weigh out 1 g of silica gel and add it on top of the filter aid to create as uniform a layer as possible. Turn on the aspirator or house vacuum system. 

Low-pressure operations are common in many laboratories. Laboratories are often equipped with a house vacuum system, vacuum pumps, rotary evaporators, water aspirators, vacuum concentrators, vacuum ovens, and/or other apparatus that operate under reduced pressure. Some labs build elaborate vacuum racks for special purposes (see Figure 5.3.4.1). All glass vessels under vacuum should be considered potential risks for implosions with the result being flying glass shards, chemical splashes, and fires. The violence of implosions is limited due to the fact that the pressure differential between inside and outside the vessel cannot be more than 1 atmosphere (unlike pressure vessels, where the pressure differential can be much greater). 

The Mass Spectrometer Module houses the vacuum system, capillary interface assembly, and ion-trap mass spectrometer in approximately half of the module. Also included are the reagent gas and calibration gas subassembly (a temperature-controlled housing that ensures consistent gas pressures). The other half contains the electronic printed circuit boards, power supplies, and instrument control computer. 

Example The vacuum system of non-benchtop mass spectrometers consists of one to three rotary vane pumps and two or three turbo pumps. Rotary vane pumps are used for the inlet system(s) and as backing pumps for the turbo pumps. One turbo pump is mounted to the ion source housing, another one or two are operated at the analyzer. Thereby, a differentially pumped system is provided where local changes in pressure, e.g., from reagent gas in Cl or collision gas in CID, do not have a noteworthy effect on the whole vacuum chamber. 

The LC column can operate for several weeks without any loss of separation efficiency. The flow rate of solvent into the mass spectrometer is 2-3 pL/min under normal conditions. The pressure in the ion source housing is 10 Pa and 10 Pa in the analyzer. No deterioration of the vacuum system during two years of operation has been observed. 

What the foundations are to a house, the bench and frame are to a vacuum line, and as with the siting of any building, the location of a vacuum system is important. 

In the initial development of LC-MS, the gas load to the vacuum system was a serious concern. A mobile-phase flow of 1 ml/min corresponds to a gas flow between 0.3 and 2.1 Pa mVs, depending primarily on the molecular mass of the solvent used. The effective pumping speed at the El ion-source housing of a differentially pumped MS system is between 0.3 and 0.7 mVs, which allows the introduction of ca. 2 pl/min of water, which is oidy ca. 0.2% of the typical flow-rate of a conventional 4.6-mm-ID LC column. In order to introduce the complete effluent of a 4.6-mm-ID LC column into the ion-source housing, a substantial increase of the effective pumping efficiency at the ion-source housing is required. This can be done in various ways ... 

The apparatus consists of a flask containing balls which is connected by flexible bellows to the ion-source vacuum housing. The flask is vibrated by a motor drive outside the vacuum system. Volatile compounds evolved from the sample pass through the flexible bellows connection into the ion source. 

---