User ManualTable of ContentsIntroduction71.1 Safety guidelines71.2 Specific gravity measurement81.3 Functional description91.3.1 Meter sensing element101.3.2 Installation101.4 Definition of terms111.4.1 Specific gravity111.4.2 Standard (base or normal) density121.4.3 Relative density121.5 Physical properties of gas compounds131.6 Applications131.6.1 Supplementary gas supply131.6.2 Wobbe index measurement141.6.3 Consumer gas costing14Installation Procedure152.1 Installation procedure152.2 Contents152.3 Installing the 3098 enclosure152.3.1 Important precautions152.3.2 Connections162.3.3 Coalescing filter162.4 Electrical connections and safety barriers / galvanic isolators162.5 Reference chamber pressure determination172.6 Set-up procedure – purge cycling and calibration18Purge cycling193098 specific gravity meter calibration using two known gases192.7 Outline dimensional drawings20Electrical Connections253.1 Introduction253.2 EMC cabling and earthing263.3 Certificate conditions for hazardous areas263.4 Use with signal converters and flow computers273.5 System connections (7950/7951)283.5.1 7950 2-wire configuration283.5.2 7950 3-wire configuration293.5.3 7951 2-wire configuration303.5.4 7951 3-wire configuration323.6 System connections (customer’s own equipment)333.6.1 Non-hazardous areas333.6.2 Hazardous areas333.6.3 Customer's equipment, 2-wire configuration333.6.4 Customer's equipment, 3-wire configuration343.7 Post-installation checks34Accuracy Considerations354.1 Accuracy considerations354.1.1 Example 1354.1.2 Example 2354.1.3 Calculating parameters36Density range at 20°C36Density meter temperature coefficient error36Gas compressibility error36Velocity of sound error36Example 137Example 2374.2 Calibration (for non-natural gas applications)374.3 Operation at low reference pressure levels384.4 Calibration certificate example39Maintenance and Fault Finding415.1 Introduction415.2 Calibration check415.3 Fault finding415.3.1 Instrument over-reads415.3.2 Instrument under-reads42(i) Reference chamber to sample gas path42(ii) Reference chamber to atmosphere42(iii) Erratic instrument readings425.4 Maintenance43General notes435.4.1 Main meter (3098 specific gravity meter) removal (Figure 5-1)445.4.2 Density meter removal (Figure 5-2)455.4.3 Reference chamber diaphragm removal (Figure 5-3)465.4.4 Re-assembly procedure475.4.5 3098 specific gravity meter filter change procedure475.4.6 Further servicing of the density meter (Figure 5-5)485.4.7 Leak testing the 3098 specific gravity meter495.4.8 Post-maintenance tests495.4.9 Worked example of calibration certificate49Specifications516.1 3098 specific gravity meter specifications516.1.1 Performance516.1.2 Electrical526.1.3 Mechanical526.1.4 Safety52Performance Optimization53A.1 Introduction53A.1.1 Density sensor53A.1.2 The non-ideal behaviour of gases54A.1.3 Selection of reference chamber pressure54A.1.4 Selection of calibration gases54A.2 Recommended calibration methods55A.2.1 General calibration method55Selection of reference chamber gas55Selection of reference chamber pressure55Calibration and sample gases55A.2.2 Specific calibration method55Selection of reference chamber gas55Selection of reference chamber pressure55Calibration55Velocity of sound effect56Compressibility factor57Combination of VF and ZF58Total factor calculations58Legend for Table A159Summary59Example Calculations62Principles of Operation67B.1 Theory of specific gravity measurement67Return Policy69C.1 General guidelines69C.2 New and unused equipment69C.3 Used equipment69Certified System Drawings71D.1 General71Size: 3.49 MBPages: 78Language: EnglishOpen manual