User manual FLUKE MOLBOX RFM

[. . . ] Operation and Maintenance Manual molboxTM RFMTM (Ver 1. 10 and Higher) Reference Flow Monitor © 1998-2007 DH Instruments, a Fluke Company 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. © 1998 - 2007 DH Instruments, a Fluke Company All rights reserved. No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, for any purpose, without the express written permission of DH Instruments, a Fluke Company 4765 East Beautiful Lane Phoenix AZ 85044-5318 USA. [. . . ] In automatic microrange mode, use of the microrange option to improve flow measurement is optimized in a manner that is transparent to the user. In particular, the transition between the two different types of differential pressure measurement is smoothed out by weighted averaging of the differential values in a transition zone between 10 and 12. 5 kPa differentials (1. 5 to 1. 8 psi). The MICRO function turns ON and OFF the microrange option's automatic mode. With automatic microrange OFF, the microrange option differential pressure RPT measurements are not used at all (unless manual microrange is ON, see Section 3. 6. 7). With automatic microrange option ON, the differential pressure value used to calculate mass flow can come from the difference between the upstream and downstream RPTs, the microrange differential RPT or a combination of the two during the transition from one method to the other. The microrange option can also be operated in a manual mode (see Section 3. 6. 7). OPERATION The MICRO function can be operated at any time from the main run screen. Pressing [MICRO] causes automatic microrange to turn ON if it is OFF and to turn OFF if it is ON. When [MICRO] is pressed, the molbox RFM displays a 3 second message indicating whether it is turning automatic microrange ON or OFF and then returns to the main run screen in the new condition. Automatic microrange ON is indicated by an <m> in the microrange status character of the main run screen. If molbox RFM is not equipped with the microrange option, a 5 second message indicates that the microrange option is not installed. Don't confuse this message with <Access denied> which displays when the security level setting restricts [MICRO] key access (see Section 3. 6. 2). Turning microrange OFF may reduce the accuracy of flow measurements below 10 % of the molbloc flow measurement range and lead to unexpected results. Automatic microrange option ON is indicated by an "m" in the microrange option designator character of the main run screen (top line, 6th character from the right). Microrange option OFF is indicated by a blank designator (see Section3. 2). Use of the MICRO function overrides the current setting of manual microrange option made by pressing [SPECIAL] and selecting <7micro> (see Section 3. 6. 7). If manual microrange is ON, pressing [MICRO] turns OFF manual microrange and turns ON automatic microrange. Page 69 © 1998-2007 DH Instruments, a Fluke Company molboxTM RFMTM OPERATION AND MAINTENANCE MANUAL 3. 4. 8 [MOLBLOC] PURPOSE To initialize and/or rapidly identify a molbloc that is connected to molbox RFM. PRINCIPLE molblocs carry an EEPROM on which are stored the molbloc identification header, molbloc specific flow calibration coefficients and the zero offset of the molbloc platinum resistance thermometers. molbox RFM must have this information to accurately identify the molbloc to which it is connected and to correctly calculate flow through the molbloc. molbox RFM does not continuously read the information off the molbloc EEPROM. It reads and loads the information on the molbloc EEPROM each time it powers up. However, if the molbloc connected to the molbox is changed without turning the molbox RFM OFF and back ON, the new molbloc and the previous molbloc's calibration information will continue to be used. The [molbloc] function key provides a rapid and simple way of causing the molbox RFM to load the molbloc to which it is connected and display a summary of its characteristics. This is useful when changing molblocs or to identify the molbloc that is currently in service. [. . . ] The gas for which a device under test is to be characterized or calibrated. The gas that will actually flow in the device under test when it is used in a process. The element used in molblocs to measure Critical flow Clean Deviation Differential Downstream DUT FA (Flow Adder) FM (Flow Multiplier) Freeze Full Mod Calibration FS Gauge Head Hi/Lo K Factor Microrange Operating Pressure PA (Pressure Adder) Perfect Mass Flow Units PM (Pressure Multiplier) Process Gas PRT Psia Psig Pressure unit "pounds per square inch absolute". Pressure expressed relative to atmospheric pressure. Page 161 © 1998-2007 DH Instruments, a Fluke Company molboxTM RFMTM OPERATION AND MAINTENANCE MANUAL Rate Ready/Not Ready Reynolds Number A DISPLAY function in which the current rate of change of the flow in flow units/second is displayed. [. . . ]