Vacuum set

Fignre 7.7b shows the fate of the filtrate as it is sucked from the filter cloth. Two tanks called vacuum receivers are provided for the two types of filtrates the filtrate removed while the segments are still submerged in the tank and the residual filtrate removed when the segments are already out of the tank. Vacuum receivers are provided to trap the filtrate so that the filtrate will not flood the vacuum pump. Also note the barometric seal. As shown, this is in parallel connection with the suction vacuum of the filter. The vacuum pressure is normally set up to a value of 66 cm Hg below atmospheric. Any vacuum set for the filter will correspondingly exert an equal vacuum to the barometric seal, on account of the parallel connection. Hence, the length of this seal should be set equivalent to the maximum vacuum expected to be utilized in the operation of the filter. If, for example, the filter is to be operated at 51 cm. 

Oxidize the cobalt(II) by bubbling a vigorous stream of air through the solution for 3 h. A water aspirator vacuum set-up is shown in Figure 2.3. 

Disposable microprizm and photodiode were placed on a rotary table (10 arc sec resolution). Before depositing metal layers, the glass surface of the microprizm was treated with a chromium mkture, rinsed in bi-distilled water and then dried in a dust-fiee airflow. Au layer (thickness 45 run) was deposited onto the quartz surface of microprizm in special vacuum sets equipped with oil pumps and nitrogen traps (pressure 10 Pa). Before deposition, the mikroprizm surface was ion-bombarded in a vacuum (pressure 1 Pa). In order to increase the chip stability in the aqueous environment, Au film was modified by covalent binding of the thiol contained 12-carbohydrate spacer. 

Pipet 1 mL of the stopped suspension onto the center of the Whatman GF/C filter and immediately filter under vacuum. Set aside the remainder (approx 80 pL) of the stopped suspension (do not discard see step 13). 

The difference of temperature between the shelves and the condenser results in a vapor pressure difference above the ice, also called driving force, which is an essential factor in the sublimation rate. The colder is the ice condenser, the higher is the driving force for the same shelf temperature and pressure (vacuum) set point. This also means that for an identical shelf temperature profile and pressure (vacuum) set point, the sublimation rate can vary in relation to the condenser temperature. 

To realize such a vacuum leak test, a vacuum set-up similar to the one used for the actual part manufacture is installed (described below), but without the part lay-up itself. Instead, only one or two plies of a glass fibre prepreg material are used. This dummy set-up is then evacuated and cured. Air leaks in the mould will cause porosities in the cured matrix. Thanks to the transparency of the glass fibres and the low thickness of the dummy... 

As soon as the lay-up of the component is completed, the material stack is wrapped up for cure. This operation is called bagging, or installing the vacuum set-up. The consumable materials used in this set-up are often referred to as ancillary materials, auxiliary materials or consumable materials. A typical vacuum set-up is depicted in Figs 6.9 and 6.10. Its... 

Vacuum infrastructure The evacuation of the vacuum bag is realized by vacuum pumps connected via tubes and hoses to intake valves in the vacuum set-up. The intakes can be positioned either in the vacuum bag, in which case the vacuum foil has to be perforated in order to provide a passage, or as part of circuitry integrated into the mould. For further distributing the airflow efficiently, it is usually necessary to install additional channels underneath the vacuum bag, e.g. by stacking up several narrow layers of breather fabric. 

Sensors For process control, thermocouples and pressnre probes are often integrated directly into the vacuum set-up (or are already in the mould structure itself). 

The airtightness of the vacuum set-up ean easily be verified. First, the set-up is evacuated. Then, the vaeuum pump is diseonnected. By monitoring the rise in pressure inside the set-up, the tightness of the system can be quantified and evaluated. The set-up would only be released for cure if the tightness complies with predefined requirements (e.g. loss in vacuum not exceeding 50 mbar during a leak test of at least 5 minutes). 

Vacuum set-up Configuration and sequence of ancillary materials configuration and sequence of caul plates, cores, pressure pieces leak test conditions (differential pressure, pass/no pass criteria)... 

Surface resin shrinkage Hindered resin flow due to inappropriate vacuum set-up configuration Deteriorated visual appearance... 

The reasons for such defects to occur can be related to any of the process steps described before, e.g. lay-up, vacuum set-up or mould design. Some more generic defects may also be related to inappropriate material choices (e g. insufficient adhesion strength of bonded assemblies due to the use of inappropriate peel ply). 

Shake em down. Between vacuuming and washing, beat and shake your curtains (while they re still on the rod) to loosen dust and debris, and to rid them of minute mites. Do this with the windows open or with your vacuum set to suction with no hose attached (see How to Vacuum, page 180). 

X-Pert MPD system with Cu Ka radiation. X-ray photoelectron spectroscopy (XPS) measnrements were carried out in an ultra-high vacuum set-up equipped with a Gammadata-Scienta SES 2002 analyzer. A flood gun was used to compensate for the charging effects. The binding energies were calibrated with the C Is peak (284.5 eV). Thermogravimetry was performed with a Calm TG-2131 thermobalance in pure O2 with a heating rate of 2 K/min. 

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