User manual FLUKE MOLBOX

[. . . ] molbloc/molboxTM Low Mass Flow Calibration System AFMETCAL Configurations Installation and Operation Manual Supplement ©2000-2008 DH Instruments, a Fluke Company MOLBLOC/MOLBOXTM CONFIGURATIONS INSTALLATION AND LOW MASS FLOW CALIBRATION SYSTEM AFMETCAL OPERATION MANUAL SUPPLEMENT High pressure liquids and gases are potentially hazardous. Energy stored in these liquids and gases can be released unexpectedly and with extreme force. High pressure systems should be assembled and operated only by personnel who have been instructed in proper safety practices. © 2000-2008 DH Instruments, a Fluke Company All rights reserved. Information in this document is subject to change without notice. [. . . ] Remember that a molbloc's true usable range may be different from its nominal range designation due to the pressure-dependent calibration performed on the molbloc or due to the gas being used. It is also important that the molbloc is used at the correct pressure for the stated usable flow range and measurement specifications to be valid. A silver label on each AFMETCAL configuration system molbloc displays the calibrated usable flow range and proper inlet pressure for that molbloc. The flow range stated on this label, not the nominal range designation referenced on the black label, should be observed. The arrow on the silver label indicates molbloc flow direction. Figure 4. AFMETCAL Configuration molbloc Label MOLBLOC PRESSURE AND Flow ranges molbloc ranges are traditionally described according to the flow ranges they would have if they were calibrated in nitrogen for standard low pressure use. Since the usable range of a molbloc can differ from this nominal value depending on the gas and pressure used, newer molblocs are defined by a size designation instead to avoid confusion about the molbloc's true usable range. The size designations for each molbloc in the AFMETCAL system are included in Table 3 along with their nominal ranges. The black labels on the back of newer molblocs will display both the molbloc size designation, as part of the model name, and the nominal N2 flow range. Older molblocs display only the nominal flow range as part of the model name. To accommodate elevated DUT back pressure applications, molblocs in AFMETCAL configuration systems have special, high pressure calibrations. The result is that the each molbloc's usable flow range is shifted upward from its nominal flow range. For example, a 500 sccm (5E2) molbloc with a high pressure calibration has a usable flow range up to 1 000 sccm (1 slm). For most range designations, the usable range of the molbloc is double the nominal range as in the previous example. An exception is the 30 slm (3E4) molbloc, which becomes a 40 slm range when given a high pressure calibration. molblocs are calibrated over their entire usable range; usable flow range = calibrated flow range. The maximum flow and minimum flow at which molblocs can be most accurately used are both changed by a high pressure calibration. molbloc flow measurements have an uncertainty of ± 0. 2 % of reading, or ± 0. 02 % of full scale, whichever is greater (see note). This means that flow can be measured with ± 0. 2 % of reading uncertainty from 10 to 100 % of the molbloc's range. A high pressure calibration shifts both the 10 and 100 % value. For example, measurements with a 500 sccm (5E2) molbloc can be made with ± 0. 2 % of reading uncertainty from 100 to 1 000 sccm. This does not mean that molblocs should not be used below their 10 % value. Below 10 % of a molbloc's full scale range, uncertainty is calculated as a percentage of its full scale range (± 0. 02 % FS). [. . . ] The default command set in the RPM3 hardware configuration does not change the current measurement range used by the RPM3. Whatever range is manually selected before a test will be used to supply pressure readings for the test. If you would like your RPM3 hardware configuration to set the RPM3 to the same pressure range each time it is used by COMPASS, add the following command to the Initialization Commands: CONFIGURE1 HI. This command will put the RPM3 into its highest range, 100 psia. [. . . ]