User manual FLUKE E-DWT-H

[. . . ] E-DWT-H Electronic Deadweight Tester Operation and Maintenance Manual © 2009 DH Instruments, a Fluke Company E-DWT-H OPERATION AND MAINTENANCE MANUAL W Warning · 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. This instrument is not to be operated in any other manner than that specified by the manufacturer. · © 2009 DH Instruments, a Fluke Company All rights reserved. Information in this document is subject to change without notice. [. . . ] PRINCIPLE AutoZ Purpose and Principle The RPM4-E-DWT AutoZero function (AutoZ) is used to achieve gauge measurement mode with the RPM4-E-DWT's intrinsically absolute Q-RPTs and to eliminate the influence of zero drift on measurement uncertainty. AutoZ can also tare out fluid heads between the E-DWT-H and the device under test. The AutoZ functions provides full on-board support for regular zeroing including determination, application and storage of offset values as well as dynamic compensation for changes in atmospheric pressure between zeroing opportunities. The operator initiates Q-RPT zeroing by pressing the [AutoZ] key from the main run screen when zero (atmospheric pressure) is applied to the RPM4-E-DWT Q-RPT. Pstd, 0: Zero (atmospheric pressure) which is supplied by definition when the Q-RPT is active, the reservoir shut off valve is close, the TEST shut off valve is open and the TEST port is disconnected and filled with oil to the weep hole (reference level). Page 57 © 2009 DH Instruments, a Fluke Company E-DWT-H OPERATION AND MAINTENANCE MANUAL 2. Pu, 0: The absolute pressure reading of the Q-RPT, with no AutoZ offset, at the time [AutoZ] is pressed. Poffset, G: The difference between the reading of the Q-RPT with no AutoZ offset when [AutoZ] is pressed (Pu, 0), and zero gauge pressure (atmospheric gauge pressure) (Pstd, 0): Poffset, G = Pu, 0 - Pstd, 0 4. Patm: The difference between atmospheric pressure (absolute) as measured by the RPM4-E-DWT's on-board barometer when [AutoZ] was last pressed and the current measured value. Patm is used to compensate real time for the evolution of atmospheric pressure between updates of Poffset, G by [AutoZ]. Patm is dependent only upon the ability of the barometer to measure small changes in atmospheric pressure over short time periods, not upon the barometer's absolute accuracy or long term stability. The gauge pressure measured by the RPM4-E-DWT Q-RPT at any given moment is: Pgauge = Pu - Poffset. G - Patm The AutoZ function can be turned ON and OFF. When the AutoZ function is OFF, the [AutoZ] function to rezero the RPT is no longer available and dynamic compensation for changes in atmospheric pressure using the RPM4-E-DWT's on-board barometer is no longer active. AutoZ should be left on at all times unless the RPM4-E-DWT's on-board barometer is inoperable. OPERATION Note · · The AutoZ function and values are Q-RPT specific. To RUN the AutoZ routine that rezeroes the Q-RPT, use [AutoZ] (see Section 3. 7. 10). To access the RPM4-E-DWT AutoZ function press [SPECIAL], <1AutoZ>. Indication of active measurement mode (always <gage> for gauge in this RPM4-E-DWT model) Indication of whether AutoZ is currently ON or OFF for this Q-RPT. 1off 2view 3edit Hi gage ON Select <1off> (or <1on>) to change the AutoZ status for the current Q-RPT and measurement mode from ON to OFF or vice versa. Note AutoZ ON is indicated by a <z> in the MAIN RUN screen, top line, third character from the right. AutoZ should always be left ON in RPM4-E-DWT unless the on-board barometer becomes inoperable. Select <2view> to view the current value of Poffset for the active Q-RPT. Note The value of Poffset is always displayed and entered in Pascal (Pa). Select <3edit> to edit the value of Poffset for the active Q-RPT and measurement mode. Press [ESC] to abandon changes. © 2009 DH Instruments, a Fluke Company Page 58 3. OPERATION Note There is no reason to edit Poffset during normal RPM4-E-DWT operation or maintenance. Poffset should only be adjusted using [AutoZ] (see Section 3. 7. 10). 3. 9. 2 <2REMOTE> PURPOSE To configure the RPM4-E-DWT COM1 and COM2 communication ports. [. . . ] Measurement mode in which the Q-RPT indicates gauge pressure (difference from atmospheric pressure), but only in the positive direction (above atmosphere). A difference in height between the RPM4-E-DWT reference level and the DUT. A DISPLAY function in which the highest and lowest pressure measurements since reset are recorded and displayed. The designation of a single Q-RPT in an RPM4-E-DWT, or, if there are two, the one that has the highest full scale default range. [. . . ]