Curtain area

If the system passes the test in the preceding step, continue to film or take photographs while the smoke is generated the operator should open the curtained area to perform routine interventions. If the smoke backflows permanently to the critical working area at any point during this operation, procedures must be established to prevent cross contamination and re-entry into these areas. If the smoke resumes direction away from the critical surface, the unit passes. Proceed to the next step. 

Slot area As The total (for all open valves) vertical curtain area through which vapor passes in a horizontal direction as it leaves the valves. It is a function of the narrowest opening of each valve and the number of valves that are open. The slot area is normally the smallest area available for vapor flow on a valve tray. 

Low-lift PRV A PRV in which the actual discharge area is the curtain area. It will not necessarily lift open fully to its capadty and acts more or less proportionally to the pressure increase but is usually rdatively unstable during its relief cyde. 

Curtain area Effectively the area of the cylindrical or conical discharge opening between the seating surfaces created by the lift of the disc above... 

While we have different designs, one important constant is that the bottom of the guide must limit disc lift. This determines the valve lift or the curtain area and hence the flow capacity of the valve. 

The minimum seat plate lift to achieve rated capacity must be such that the annular curtain area around the periphery of the nozzle equals the nozzle area. 

Curtain area) ttDL = ttD2/4 (Nozzle area)... 

Another advantage in some pilot-operated designs is the possibility of having a customized orifice so that the valve fits the required flow exactly. By adjusting the bolt on top of the piston, the curtain area of the valve can be adjusted to accommodate for the perfect flow. 

The possibility of restricted lift, on the other hand, provides the opportunity to achieve smaller or customized API orifices. Here, the curtain area determines the capacity. Fater, if capacity needs to be increased, only one bolt need be adjusted to get a larger orifice valve. It is the valve manufacturer for details, as each has its own design. 

Too large an orifice recjuired for the available connection size Some manufacturers can offer full-bore POSRVs where a larger orifice can be obtained in a smaller size valve by increasing the curtain area. Also some spring valves can be equipped with customized nozzles. 

A graph of discharge coefficient ( m) plotted against dimensionless lift L/D) is known as a flow characteristic. Fig. 9 shows an example of flow characteristics plotted for various pressure ratios relieving from an air receiver, where Pb is the total backpressure at the valve exit port and Pq the reservoir total pressure.According to ideal one-dimensional compressible flow theory, choked flow should occur at pressure ratios below 0.528. In practice, choked flow will occur at lower pressure ratios because of friction losses upstream of the curtain area. Nevertheless, the curves in Fig. 9 are close-together at pressure ratios below 0.333, and have collapsed to almost a single curve for ratios less than 0.25. Other work shows a similar effect. 

Slot area, i.e., the total vertical curtain area throu which vapor passes in a horizontal direction as it leaves the valves or bubble caps, ft . 

One of the limitations of the curtain/slot draw process is that the amount of fiber attenuation is constrained due to the short distance generally allowed between the spinnerette and the venturi slot and the use of relatively low pressure air for drawing so as not to induce high turbulence in the area of the laydown. In practical terms this has made the process difficult to adapt for the production of polyester fabrics which inherently require much higher fiber acceleration to attain the desired polyester fiber properties. 

Ammonium Sulfamate. A number of flame retardants used for ceUulosic materials, including fabrics and paper products, are based on ammonium sulfamate (56). These products are water-soluble and therefore nondurable if treated fabrics are washed or exposed to weathering conditions. For most fabric and paper constmctions, efficient flame retardancy can be provided with no apparent effect on color or appearance and without stiffening or adverse effects on the feel of the fabrics. A wide variety of materials are treated, including ha2ardous work-area clothing, drapes, curtains, decorative materials, blankets, sheets, and specialty industrial papers (57). 

It is generally agreed that a shelter with a roof having ridge ventilation and with curtain walls not extending lower than 8 feet above the operating platform would be freely ventilated. Because a gas compressor would not be a source of hazard, except under abnormal conditions such as an equipment failure, this type of compressor shelter is usually classified as a Division 2 area. 

In the general area of medicine uses range from spare-part surgery, such as hip joints and heart valves, through catheters, injection syringes and other sterilisable equipment, to more mundane but nevertheless desirable uses such as quietrunning curtain rails. 

Air curtains are local ventilation devices that are used in industrial buildings to reduce leakage of airflow through apertures in building enclosures and process equipment. Their operation is based on the damping effect of air jets that are supplied into the area of the open aperture. The advantages of air curtains include... 

Building areas separated by air jets located on the same level (e.g., jet-assisted hoods, air curtains) (Fig. 7.107c). 

To control air and contaminant movement between zones, different construction, process-related, and ventilation techniques are used. Clean and dirty areas can be separated using solid walls, curtains, or partitions (Fig. 7.109(2). Ventilation techniques used to separate zones include... 

Air Curtain and Exhaust Off-Take Air curtain design and exhaust offtake location are very important considerations. The air curtain is applied on roof openings that are typically 2 to 3 m wide and used for crane rope access. The opening may extend over the length of the enclosure and should, therefore, be served by two sets of independently operated doors— one for tapping and one for charging. This feature minimizes the pen area when one of the two events occurs. 

Water curtains can also cool or eliminate available ignition source to a released vapor cloud. In this fashion they can also be a mitigating feature to prevent vapor cloud explosions. Hot surfaces, sparking devices and open flames in the immediate area of a vapor release can all be eliminated as a result of a directed water curtain where these sources exist. 

For water curtains to be highly effective they should be automatically activated upon confirmed gas detection for the area of concern. 

For a crack, w cm wide, to advance by dx cm in a solid, a ribbon (or curtain) of this solid, dx cm thick and w cm wide, must be extended to its greatest possible elongation. If the curtain of length L can extend freely, the work of extension is, see Eq. (44), 2 Lw dx/2E ergs. The cohesion is equal to the breaking stress <7m (g/cm sec2) of the theoretical solid, otherwise identical with the real, but free of all defects. rather than am should be used here because dx is so small that no defect can find place in the curtain. The work per unit area corresponds to the hypothetical 7 . Hence,... 

To assist in concentrating the flow, the hood may have a flange, or broad flat rim, around the expansion of the hood bell, or it may have baffles or curtains to reduce unwanted air currents. While often placed at the back of the work area, drawing contaminants away from the worker, it may also be placed over the work area where the natural flow of air is upwards as in hot conditions. 

Silence. Then a shrill wave of insect sound swept like a drawn curtain through the area. Silence again. There was jungle, river, and sky—nothing else. We were on our own now. 

---