DB1 Liquid Level Measurement Sensor Revision: 12/07 C o p y r i g h t © 1 9 9 3 - 2 0 0 7 C a m p b e l l S c i e n t i f i c , I n c .
Warranty and Assistance The DB1 LIQUID LEVEL MEASUREMENT SENSOR is warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
DB1 Table of Contents PDF viewers note: These page numbers refer to the printed version of this document. Use the Adobe Acrobat® bookmarks tab for links to specific sections. 1. Overview.......................................................................1 2. Specifications ..............................................................2 3. Installation....................................................................2 4. Wiring............................................................................
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DB1 Liquid Level Measurement Sensor 1. Overview The double bubbler is a self-calibrating system for liquid level measurement. This manual focuses on water level measurement in stilling wells or open channels, but the information applies to other liquids as well. The system detects water level by measuring the pressure required to force a nitrogen gas bubble from a submerged tube. The nitrogen pressure in the tube is equal to the hydrostatic pressure created by the exiting bubble.
DB1 Liquid Level Measurement Sensor 2. Specifications Measurement Range: Option - 5 Option - 15 Option - 30 (0 to 5 psi/0 to 11.5 ft.) (0 to 15 psi/0 to 34.5 ft.) (0 to 30 psi/0 to 69 ft.) Maximum Overpressure Range: Option - 5 Option - 10 Option - 15 20 psi 45 psi 60 psi Transducer Accuracy: ± 0.05 % Full Scale Temperature Range: -25° to + 50°C Supply Voltage: 12 Vdc System Current Drain: 75 mA (Activated) 0.
DB1 Liquid Level Measurement Sensor fluctuates between 5 and 15 ft (2.2 and 6.5 psi), set the pressure regulator above 7 psi (read 10 psi) to ensure adequate pressure. Open the nitrogen bottle valve, set the pressure regulator, and adjust the nitrogen flow by adjusting the two needle valves. The suggested bubble rate is 1 to 3 bubbles/seconds. The nitrogen gas bottle, regulator, and tubing (Campbell P/N 7567) are available from any welding supply store.
DB1 Liquid Level Measurement Sensor FIGURES 1 and 2.
DB1 Liquid Level Measurement Sensor CR10(X) CR1000, CR800, CR850, 21X FIGURE 3.
DB1 Liquid Level Measurement Sensor 5. Programming Every 60 seconds, the following program examples calculate the pressure transducer multiplier, measure the offset, and measure the liquid level. The average liquid level is stored in final memory every 15 minutes. 5.
DB1 Liquid Level Measurement Sensor Case 3 PortSet(3,1) EndSelect 'Open valve to atmosphere Delay(0,150,MSEC) Sum = 0 For j = 1 To 25 'Take 25 pressure readings for each tube and atmosphere BrFull(mV, 1, mV25,4, VX1, 1, 2500, true, true, 0, _60Hz, 1, 0) Sum = Sum + mV Next j Valve(i)= Sum/25 'Average the 25 readings from upper and lower tube and atmosphere PortSet(1,0) 'Close valve to lower tube PortSet(2,0) 'Close Valve to upper tube PortSet(3,0) 'Close Valve to atmosphere Next i Delta_mV = Valve(2) - V
DB1 Liquid Level Measurement Sensor 3: Excitation with Delay (P22) 1: 1 EX Chan 2: 0 Delay w/EX (units=.01sec) 3: 150 Delay after EX (units=.01sec) 4: 0 mV Excitation Subroutine 1 measures the pressure in the tubing connected to the second value: 4: Do (P86) 1: 1 Call Subroutine 1 5: Do (P86) 1: 52 Set low Port 2 The following instructions convert the mV readings to engineering units: 6: Z=X*Y (P36) 1: 8 2: 4 3: 1 X Loc AVG LEVEL Y Loc MULT.
DB1 Liquid Level Measurement Sensor 2: Z=F (P30) 1: 0 2: 0 3: 7 F Exponent of 10 Z Loc [:SUM ] 3: Beginning of Loop (P87) 1: 0 Delay 2: 25 Loop Count 4: Full Bridge (P6) 1: 1 Rep 2: 23 25 mV 60 Hz rejection Range 3: 1 IN Chan 4: 1 Excite all reps w/EXchan 1 5: 2500 mV Excitation 6: 6 Loc [:mV/V ] 7: 1 Mult 8: 0 Offset 5: Z=X+Y (P33) 1: 7 2: 6 3: 7 X Loc SUM Y Loc mV/V Z Loc [:SUM ] 6: End (P95) 7: Z=X*F (P37) 1: 7 2: .
DB1 Liquid Level Measurement Sensor 13: Do (P86) 1: 1 Call Subroutine 1 14: Z=X (P31) 1: 8 2: 9-- X Loc AVG LEVEL Z Loc [:mV/V #1 ] 15: Do (P86) 1: 51-- Set low Port 1 16: End (P95) 17: Z=X-Y (P35) 1: 10 X Loc mV/V #2 2: 9 Y Loc mV/V #1 3: 12 Z Loc [:DELTA V ] Note: On the next command, enter the measured Delta h value for F, using the units (e.g. inches, cm, etc.) you want the data to be in on your printout.
DB1 Liquid Level Measurement Sensor 6.1 Periodic Maintenance • Inspect submerged bubbler tubes for sediment or other debris. Remove debris and clean tubes as required. • Replace submerged bubbler tubes if cracked or damaged. • Replace nitrogen bottle every 2 to 3 months depending on bubble rate. • Inspect valves for leaks every 2 to 3 months and tighten or replace as required (refer to discussion on valves below). • Inspect fittings for leaks every 2 to 3 months and replace as required.
DB1 Liquid Level Measurement Sensor 7. Replacement Parts 12 Part # Description Qty. in DB1 5199 SWAK THREAD SEALANT 1 7397 TUBE FITTING ELL 1/4 O.D.x 1/8NPT 4 7558 NEEDLE VALVE ASSEMBLY 2 7561 2-WAY NC SOLENOID VALVE 3 7571 PLUG PIPE 1/8NPT TEFCOAT 2 6078 MOUNTING SCREW (6/32 x 2.
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Campbell Scientific Companies Campbell Scientific, Inc. (CSI) 815 West 1800 North Logan, Utah 84321 UNITED STATES www.campbellsci.com info@campbellsci.com Campbell Scientific Africa Pty. Ltd. (CSAf) PO Box 2450 Somerset West 7129 SOUTH AFRICA www.csafrica.co.za cleroux@csafrica.co.za Campbell Scientific Australia Pty. Ltd. (CSA) PO Box 444 Thuringowa Central QLD 4812 AUSTRALIA www.campbellsci.com.au info@campbellsci.com.au Campbell Scientific do Brazil Ltda.
