VacTran 3 Manual (779748), страница 13
Текст из файла (страница 13)
Each pump station is an independent group of pumps andconductance elements that can start and stop independently of each other. Conductance elements are pipes,elbows, apertures, etc combined in series or parallel connections. All of the pump stations work against thecommon gas load on the system.© 2011 Professional Engineering ComputationsSystem models8.399System model dialog commandsData can be added to or deleted from one of the three lists, depending on which one is active. Activate a list byclicking on it once. If the conductance list is active, a dialog will appear offering a selection of conductanceelements. If the pump list is active, a dialog will appear allowing you to choose a pump model. If the gas load listis active, a dialog will appear offering a selection of gas load types to enter. After adding something, if the globalauto update option is selected, the most recent calculation will be redone.Editing commands for system models:Add (Ctrl+A): Adds an element to the list.
For gas loads or conductances you can also use thefloating palette or thebutton.The Delete, and Get Info commands are available only if there is data in the list.Delete (Ctrl-D): Deletes the highlighted element from the list.Get Info (Ctrl-I): Displays an information box describing the element in detail.Double-click on any conductance, pump model, or gas load element to change its values.© 2011 Professional Engineering Computations1008.4VacTran 3Output from system modelsPowerful analysis functions are available as soon as minimum data is entered into a VacTran system model.
Forexample, addition of a single pipe element to a new, empty model enables the commands for graphing conductanceand throughput.Build the system model using the functions and procedures in the previous chapter. System model editing andanalysis are interactive activities that can be updated at any time. The design of VacTran encourages you tochange any parameter to see immediate cause and effect results.The following output is available from the Graph menu. Some options will be available only when the model hasenough content to support the calculation.
For example, "Pump Speed vs Pressure" will be available only afterpumps have been added to the model.For whole model:For each pump station:Comparing pump stations:Conductance vs pressureGenerate pump model...Conductance vs pressureThroughput vs pressureCompare conductances in stationThroughput vs pressurePump speed vs pressureCompare conductance throughputPump speed vs pressurePump throughput vs pressureCompare pump speeds in stationPump throughput vs pressureDelivered speed vs pressureCompare pump throughput in stationDelivered speed vs pressureDelivered throughput vs pressureStation conductance vs pressureDelivered throughput vs pressurePump down timeStation throughput vs pressurePump down time, no lossesStation pump speed vs pressureCompare gas loadsStation pump throughput vs pressureGas load vs timeStation delivered speed vs pressureStation delivered throughput vspressure© 2011 Professional Engineering ComputationsSystem models8.5101System model graphing optionsThe following commands are available under the Graph menu.
Any command that is dimmed is not active becausesome type of data is missing from the model. Use the Defaults menu or the Main Graph Window buttons tochange graph settings.See also:System:Compare StationsThis Station:Pump down timePump down time, no lossesGas throughput vs. timeCompare gas loadsGas load vs timePressure rise vs timeConductance vs pressureThroughput vs. pressurePump speed vs.
pressurePump throughput vs. pressureDelivered speed vs. pressureDelivered throughput vs. pressureConductance vs pressureThroughput vs pressurePump speed vs pressurePump throughput vs pressureDelivered speed vs pressureDelivered throughput vs pressureCompare conductance vs pressureCompare throughput vs pressureCompare pump speeds vs pressureCompare pump throughput vs pressureConductance vs pressureThroughput vs pressurePump speed vs pressurePump throughput vs pressureDelivered speed vs pressureDelivered throughput vs pressureGenerate Pump Model...Generate Raw Conductance Model...© 2011 Professional Engineering Computations1028.5.1VacTran 3System: Pump down timePressure vs time is calculated for the system model, starting at the global start pressure and ending at the globaltarget pressure.
Only active stations are used in this calculation. If the gas load gate valve is open, gas loads inthe gas load list are included in the pump down calculation. If he two curves overlap, the gas load may be too smallto have a significant effect on pump down time.recommended axis settings:Y log-X linearwhen dimmed:No station active© 2011 Professional Engineering ComputationsSystem models8.5.2103System: Pump down time, no lossesVessel pressure vs time is calculated with no conductance losses, starting at the global start pressure and endingat the global target pressure. Only active stations are used in this calculation.
If the gas load gate valve is open, agas-loaded curve is calculated separately.recommended axis settings:Y log-X linearwhen dimmed:No station active© 2011 Professional Engineering Computations1048.5.3VacTran 3System: Gas throughput vs. timeThe total gas load for the system is graphed along with the pump throughput for all combined pump stations duringa pump down cycle. Pump throughput will always be greater than or equal to the gas load curve, otherwise thesystem will not pump down to the target pressure and an error message will be displayed. The total time on the xaxis will equal to the gas load stop time setting.recommended axis settings:Y log-X linearwhen dimmed:No station active© 2011 Professional Engineering ComputationsSystem models8.5.4105System: Compare gas loadsCalculate gas load vs time for each of the gas load elements in the gas load list.
The graph will be bounded by thetime values of Gas Load Start Time and the Gas Load Stop Time.recommended axis settings:Y log-X linear, orY log-X logwhen dimmed:Less than two gas loads in the gas load list© 2011 Professional Engineering Computations1068.5.5VacTran 3System: Gas load vs timeCalculate the combined gas load vs time for all the gas load elements in the gas load list. The graph will bebounded by the time values of Gas Load Start Time and the Gas Load Stop Time.recommended axis settings:Y log-X linear, orY log-X logwhen dimmed:No gas load elements in the gas load list© 2011 Professional Engineering ComputationsSystem models8.5.6107System: Pressure rise vs timeCalculate the vessel pressure rise in the absence of an active pumping system. The graph will be bounded by theRate of Rise start and stop time values and the initial vessel pressure setting.recommended axis settings:Y log-X linear, orY log-X logwhen dimmed:No gas load elements in the gas load list© 2011 Professional Engineering Computations1088.5.7VacTran 3System: Conductance vs pressureTotal conductance vs pressure for the system is calculated based on adding conductances in series.
The pressurerange of the calculation will be based on the global Start and Target Pressures. to change these values, click onthe Vacuum Vessel icon.recommended axis settings:Y linear- X logY log-X logwhen dimmed: No conductances in current pump station, no station active© 2011 Professional Engineering ComputationsSystem models8.5.8109System: Throughput vs.
pressureTotal conductance throughput vs Pressure for the pump station is calculated for conductances in series. For eachpressure increment, total conductance is multiplied by the current pressure to obtain throughput. For example, ifthe conductance is 1000 liters/second at 10 torr, the throughput at this pressure will be 10,000 torr-liters/second.The pressure range of the calculation will be based on the global Start and Target Pressures.recommended axis setting:Y log-X logwhen dimmed: No conductances in current pump station, or no station active© 2011 Professional Engineering Computations1108.5.9VacTran 3System: Pump speed vs.
pressurePump speed vs pressure is calculated for all active pump stations, to the extent that they are set to stop and start.Different results will occur if the start/stop settings are changed for one of the pump stations. If more than onepump station is active at a given pressure, the pump speeds will add together. The total range of pressure for thisgraph is governed by the global Start and Target pressure.Recommended axis settings:Y linear- X logY log-X logwhen dimmed: No station active, no pumps in station© 2011 Professional Engineering ComputationsSystem models1118.5.10 System: Pump throughput vs. pressurePump throughput vs pressure is calculated for all active pump stations, to the extent that they are set to stop andstart. Different results will occur if the start/stop settings are changed for one of the pump stations.
If more thanone pump station is active at a given pressure, pump throughput will add together. The total range of pressure forthis graph is governed by the global Start and Target pressure.recommended axis settings:Y log-X logwhen dimmed:No station active, no pumps in station© 2011 Professional Engineering Computations112VacTran 38.5.11 System: Delivered speed vs. pressurePump delivered vs pressure is calculated for all active pump stations, to the extent that they are set to stop andstart.
Delivered speed shows the effect of the conductance elements in each pump station. The total range ofpressure for this graph is governed by the global Start and Target pressure.recommended axis settings:Y linear- X logY log-X logwhen dimmed:No station active© 2011 Professional Engineering ComputationsSystem models1138.5.12 System: Delivered throughput vs. pressurePump delivered throughput vs pressure is calculated for all active pump stations, to the extent that they are set tostop and start.
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