Pressure valve

Another solution is to eliminate the air exiting the unit on the assumption that if no air goes in, no flue gas comes out to drive the expander. Again, this is not very effective because the unit acts as a large surge bottle and the large flue gas valves are relatively slow. Before the flue gas back-pressure valves have acted, excessive acceleration may result. 

On high pressure valves, the reactive forces during relief are substantial and external bracing may be required. See equations in API RP 520 for computing this force. 

Increase the absorber pressure, if needed. This may require the installation of a back pressure valve. 

Vessel is final scrubber in a flare, relief, or vent system, is designed to withstand maximum built-up back-pressure, and has no internal or external obstructions, such as mist extractors, back-pressure valves, or flame arrestors. 

IMAS has a facility called EXPLORE allows the analyst to specify which indicators (e.g., temperatures, pressures, valve settings) are present, and which are absent in a particular scenario. EXPLORE then traverses the various links in the mental model representation network and generates a report that simulates the worker s thinking processes. This form of simulation provides useful information to the analyst with regard to the worker s capability to achieve correct diagnoses. Embrey (1985) gives an example of these simulations for the mental model in Figure 4.13. 

Figure 13.5 Schematic presentation of the procedure involved in coupled-column RPLC AS, autosampler C-1 and C-2, first and second separation columns, respectively M-1 and M-2, mobile phases S-1 and S2, interferences A, target analytes HV, high-pressure valve D, detector. Reprinted from Journal of Chromatography, A 703, E. A. Hogendoom and R van Zoonen, Coupled-column reversed-phase liquid cliromatography in environmental analysis , pp. 149-166, copyright 1995, with permission from Elsevier Science.

Another required safety feature on water heaters is a temperature and pressure relief valve. This is mounted near or on top of the tank. The temperature and pressure valves are designed to vent water if the temperature or pressure in the tank becomes too high. If there is no relief valve and the controls fail to limit water temperature, there is a danger of a powerful explosion from superheated, pressurized water flashing to steam as the water heater bursts. 

Figure 12-143 shows the curves for identical fans. When unlike fens are placed in series, the individual static and total pressure curves are placed on the graph. The individual curves for assumed fans No. 1 and No. 2 and the system resistance curve define the system. The combined total pressure curve is the sum of the individual values at the same capacity. Then total combined pressure curve = Pft (No. 1) + Pft (No. 2). The new combined operating static pressure curve is the sum of the individual static pressure valves at the same capacity and exists only at the oudet of the second fan then, the total combined static pressure = Pfti + Pftg — Ps. Any losses in connections between the fans will reduce the values of the total static and system total pressures. 

Stable Foam. When a well is drilled with stable foam as the drilling fluid, there is a back pressure valve at the blooey line. The back pressure valve allows for a continuous column of foam in the annulus while drilling operations are under way. Thus, while drilling, this foam column can have significant bottom-hole pressure. This bottomhole pressure can be sufficient to counter formation pore pressure and thus control potential production fluid flow into the well annulus. 

Row control valves, such as back pressure valves, will not necessarily be the same nominal size as the pipe in which they are fitted. Manufacturers data for selection of their products is usually very comprehensive, and their guidance should be sought in case of any doubt. 

Batch Experimental Apparatus and Methods. The activity of the rhodium catalyst was tested in a 125 mL reactor with a pressure rating of 3000 psi at 350°C and a pressure relief valve that is rated for 1500-2200 psi. If the pressure valve releases, the gaseous contents of the autoclave are safely vented through a 1/4" stainless steel line and the liquid/vapor content in the autoclave is collected in a metal container and the vapor vented out through the hood. The reactor was heated in a silicone oil bath with a digitally controlled heat/stir plate. 

Fig. 5.1a shows the slurry packing system that 1 use. This operates at a fairly low pressure, as I am not especially interested in producing columns with very high efficiencies, but rather in saving on the cost of commercial columns. The pump and high pressure valve are rated for pressures of 500 bar (7500 psi) and 400 bar (6000 psi) respectively. The slurry reservoir is a stainless steel tube 85 cm long, with a capacity of about 50 cm3. The method is not hazardous unless there is air trapped in the high pressure line nevertheless it is advisable to use a safety screen. 

Figure 5-P62 illustrates two relief valves. The valve disk is designed to lift when the upstream pressure in the vessel (Pi) reaches the valve set pressure. Valve A has a disk that diverts the fluid leaving the valve by 90° (i.e., to the horizontal direction), whereas the disk in valve B diverts the fluid to a direction that is 60° downward from the horizontal. The diameter of the valve nozzle is 3 in., and... 

Too much flow through valve Both internal pressure valves fail open Operation Excessive chlorine flow to Tower Water Basin - high chlorine level in cooling water - potential for excessive corrosion in cooling water system Rotameter Daily testing of cooling water chemistry Relief valve on Pressure check valve outlet III None... 

Chlorine flow to environment Internal relief valve sticks open Both internal pressure valves fail open and relief valve opens Operation Potential low chlorine flow to Tower Water Basin -see above Chlorine released to environment - potential personnel injury due to exposure Distinctive odor Pressure check valve located outdoors -unlikely to accumulate significant concentration III Action Item Consider venting relief valve above ground level... 

High pressure valves, manual, 13 415 High pressure vessel suppliers, 13 412 High production volume (HPV) chemicals, 24 186... 

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