Critical flow check

Check for Critical Flow. From Table 2-8 it is determined that k = 1.299. Checking the pressure ratio, Equation 2-67, gives... 

Often, if both high and low pressure relief valves need to relieve simultaneously, parallel high and low pressure headers terminating at the flare knockout drum are the economical choice. Be sure to check for critical flow at key points in the high pressure header. 

Note In practice, these coordinates should be checked against the flow conditions of the chosen dimensions of the Parshall flume. If the flumes are shown to be submerged forcing them not to be at critical flows, other coordinates of the parabolic cross sections must be tried until the flumes show critical flow conditions or unsubmerged. 

MCFEARIN, L NAIR, V. Control-flow checking using assertions. In CONFERENCE ON DEPENDABLE COMPUTING FOR CRITICAL APPLICATIONS, Urbana-Champaign, USA Proceedings... Washington, USA IEEE Computer Society, 1995, pp. 103-112. 

For gas service, if the program predicts critical flow for the engineer s first choice, a noise check almost certainly would be run to find out whether the proposed installation will conform with OSHA specifications. If it will not, various low-noise valve designs are available the engineer may choose one and rerun the program. 

In order to avoid the need to measure velocity head, the loop piping must be sized to have a velocity pressure less than 5% of the static pressure. Flow conditions at the required overload capacity should be checked for critical pressure drop to ensure that valves are adequately sized. For ease of control, the loop gas cooler is usually placed downstream of the discharge throttle valve. Care should be taken to check that choke flow will not occur in the cooler tubes. Another cause of concern is cooler heat capacity and/or cooling water approach temperature. A check of these items, especially with regard to expected ambient condi-... 

If the control valve size is critical to the overpressure protection of the downstream equipment, and must not be increased, then this is clearly noted in all relevant documentation (specification sheets, flow diagram, operating manual, etc.,) and a warning notice plate is welded to the valve body. In such cases, an actual check of the valve installed or purchased should be made during the startup review. 

In heterogeneous systems AP must be critically reviewed, especially if the reaction involves a two-phase mixture of liquid and gas, or if the gas flows through a deep bed of catalyst particles as in the FCC systems. AP should be checked early in the design process to assess its influence on the overall plant integrity. 

Tlic heat duty is best calculated with a process simulation program hi will account for phase changes as the fluid passes throiigli ilic ctioke. It will balance the enthalpies and accurately predict the change m tcnipcrature across the choke. Heat duty should be checked for vanoits combinations of inlet temperature, pressure, flow rate, and outlet temper ature and pressure, so as to determine the most critical combination. 

The heat duty may have to be checked for various combinations of inlet temperature and pressure, flow rate, and outlet temperature and pressure to determine the most critical combinations. 

An opportimity for error recovery would have been to implement a checking stage by a supervisor or independent worker, since this was a critical maintenance operation. However, this had not been done. Another aspect of the unforgiving environment was the vulnerability of the system to a single human error. The fact that the critical water jacket flow was dependent upon a single pump was a poor design that would have been detected if a hazard identification technique such as a hazard and operability study (HAZOP) had been used to assess the design. 

For most vapor discharges through spring reliefs the flow is critical. However, the downstream pressure must be checked to ensure that it is less than the choked pressure computed using Equation 4-49. Thus for an ideal gas Equation 4-50 is valid ... 

Vibration interference is a common problem with dissolution equipment (23). Careful leveling of the top plate and lids is critical. Within the spindle assembly, the bearings can become worn and cause vibration and wobble of the shaft. The drive belts should be checked for wear and dirt. The tension adjustments for the belt should be optimized for smooth operation. Surging of spindles, though difficult to detect without closely scrutinizing the tester operation, can cause spurious results. Vessels need to be locked in place so that they are not moving with the flow of water in the bath. 

Process validation entails firstly the definition of both the critical and non-critical parameters. Qnce they are defined, emphasis can be directed to designing a program to validate these parameters. Some established steps involve the evaluation of process consistency over at least three batches, via the consideration of the processing steps and yield and comparing these with predetermined specifications. Some input parameters that may be considered as critical are temperature, flow rate, and stirring speed, and they are varied and checked against output variables such as yield, purity, and crystallization rate. 

Laminar Flow Location Samples ID on Grid Condition at Rest/ at Work Actual Counts Actual Counts Most Critical Location Performed by/Date Checked by/Date... 

The utilities check is used to verify that the utility supplied fulfills the chamber requirements as specified by the manufacturer. During IQ, the as found parameters are verified against the as specified parameters on the checklist. If the as found results are significantly different from the as specified parameters, it will be necessary to determine the cause of this discrepancy and to implement corrective actions. The utilities check is a part of the site preparation for the installation of the chamber and should include verification of the power supply, such as the voltage, amperage, and wire size and the quality, pressure, and flow rate of the feed water supply. The quality of the feed water supply is a critical component of proper operation of the chamber. Experience has shown that if the quality of the feed water does not meet the manufacturer s specifications, this will lead to premature corrosion within the humidification and/or dehumidification system and subsequent problems with maintaining the humidity in the chamber within the specified limits. 

When the line containing the jbursting disc is short and the disc itself has low frictional resistance after burst (total equivalent length to diameter ratio less than about 40), the friction associated with the inlet contraction from the vessel will dominate the overall frictional effect on flow capacity. Also, the critical pressure ratio can be reasonably approximated to that for a nozzle (see Annex 8, Figure A8.2). This is needed to check that flow is choked. 

It should now be checked whether or not the flow is choked. Reading from Figure A8.7, with G/Gc=0.6 and =4.13 gives value of the critical pressure ratio, , of 0.45. 

Water-level and cooling control. When a water thermostat bath is operated for long periods, it is subject to loss of water by evaporation to a point that will interfere with its normal operation unless the water is replaced. Therefore the tank should have an overflow drain and should be provided with a continuous supply of cold water that can be controlled from a few drops per minute to a small, steady stream. This supply of water also performs an important control fimctiott A -hp motor delivers constantly about 37 W of mechanical energy to the bath, and on days when the room temperature is not far below the desired bath temperature, this amount of energy is itself sufficient to maintain the bath temperature above the desired level. A stream of cold water may compensate largely or entirely for the stirring heat. The adjustment of the water flow is often critical and must be checked frequently. 

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