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MMC INTERNATIONAL CORP
OPERATING AND MAINTENANCE
INSTRUCTIONS
OXYGEN LEVEL SENSOR
GAUGING TAPE
CLOSED AND RESTRICTED APPLICATIONS
MODEL D-2615-11
APPROVED BY:
BASEEFA AS
INTRINSICALLY SAFE FOR USE IN
CLASS I, DIVISION I, GROUPS C & D
HAZARDOUS ENVIRONMENTS
MMC INTERNATIONAL CORP.
60 INIP DRIVE
INWOOD, NEW YORK 11096
OCTOBER 2022
DRAWING FILE NO. A-2615-60
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Summary of Contents for MMC D-2615-11
- Page 1 MMC INTERNATIONAL CORP OPERATING AND MAINTENANCE INSTRUCTIONS OXYGEN LEVEL SENSOR GAUGING TAPE CLOSED AND RESTRICTED APPLICATIONS MODEL D-2615-11 APPROVED BY: BASEEFA AS INTRINSICALLY SAFE FOR USE IN CLASS I, DIVISION I, GROUPS C & D HAZARDOUS ENVIRONMENTS MMC INTERNATIONAL CORP.
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Page 2: Table Of Contents
TABLE OF CONTENTS PAGE NUMBER GENERAL SPECIFICATIONS SPECIAL FEATURES INTRODUCTION III. THEORY OF OPERATION 5, 6 REQUIRED CONDITIONS AND RECOMMENDED USAGE REQUIRED CONDITIONS RECOMMENDED SAFE USAGE CONDITIONS FLUID LEVEL (ULLAGE) OF TANK OR OTHER VESSEL OPERATION FAMILIARIZATION WITH OPERATING CONTROLS & FEATURES LOCATED ON THE TAPE REEL HUB BEZEL NAMEPLATE OXYGEN LEVEL MEASUREMENT 8, 9... - Page 3 CONTINUED FROM PREVIOUS PAGE VII. CALIBRATION PROCEDURE METHOD OF CALIBRATION VIII. FAULT FINDING 14, 15 APPENDIX LIST OF APPLICABLE DRAWINGS...
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Page 4: General
SECTION I 1. GENERAL: 1.1 SPECIFICATIONS: Oxygen Sensor Measurement Range 0% to 25% Accuracy over the 1% to 25% Range ±0.2% Batteries for Intrinsically Safe Operation Duracell #MN1604 Only (supplied) Battery Life Approximately 1000 Hours (Depends on night light use) Battery Drain (Display Night Light off) 1.0 MA (IN AIR) 0.7 ma with <8% Oxygen... -
Page 5: Special Features
SPECIAL FEATURES: Simple Automatic Push-Button Calibration in Air Audible (Horn) and visual (Red LED) indication is provided to designate that the gaseous mixture within a particular tank or vessel contains an oxygen concentration greater than 8%. Note: For the intended application area of this device, oxygen content percentages of 8% or less are considered non-explosive. -
Page 6: Introduction
The MMC system uses a sensor suspended at the end of a fluoropolymer covered gauging tape, wound on a reel assembly. The plastic covered steel gauging tape contains two isolated side conductors to carry the signal and ground from the electronic circuit within the sensor barrel to conditioning electronics in the reel hub. - Page 7 To minimize the danger of fire and explosive discharge within the tanks on petroleum carrying vessels, the U.S. Coast Guard has specified that the gaseous environment abo ethe fluid levels in petroleum cargo tanks be maintained with sufficient inert gas to reduce oxygen levels below an 8% level.
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Page 8: Theory Of Operation
SECTION III THEORY OF OPERATION: Drawing S-2615-OCX illustrates the main components of the oxygen sensor. A tape reel crank is used by the operator to raise and lower the oxygen sensing head assembly, which is attached to the reel via the tape. In the stored position, the reel lock prevents the sensor and tape from unreeling due to weight. - Page 9 Normally, and if left unattended in air after power is applied, timing circuits within the hub assembly will permit the system to remain on for approximately 5 minutes and then will automatically turn the power off. However, when lowered into a gaseous environment containing less than 18% oxygen, an internal voltage comparator senses this condition and prevents the unit from turning off until it is once again exposed to a normal air environment, Thereafter, approximated one minute of additional on power is permitted before the unity automatically turns...
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Page 10: Required Conditions
SECTION IV REQUIRED CONDITIONS AND RECOMMENDATIONS FOR SAFE USAGE: The attention of the user of this apparatus is drawn to the possible hazards of oxygen sensing within flammable environments normally found above confined petroleum liquids, which are known to be generators of static electricity, and which are not covered with an inert gas blanket. The following is a general guidance to safe usage, drawn from the advice and experience of various industry sources. -
Page 11: Fluid Level (Ullage) Of Tank Or Other Vessel
SECTION V FLUID LEVEL (ULLAGE) OF TANK OR OTHER VESSEL WHICH IS TO BE GAUGED FOR OXYGEN PERCENT LEVEL: 4.3.1 Before entering the free space above a liquid level, the level of the fluid contained within the tank or vessel should be known. If the location of fluid level is not known, it should be determined by suitable and reliable means. - Page 12 FlGURE .1 OXYGEN SENSOR HUB FACEPLATE � UCENCE j E�ia M0635 II 8. T-4 EN 50. E.x9.3CZ0.37X 014 & 020 POWER ON/OFF DISPlA Y LIGHT i,.uro"""°"' � "'lSH -..:ui ;m,t,:;-TO CAUB. .lT 1'0e4I �- w,\ ""€5:S � (70• � .lllOW ::0 UCS. HC>IJJ lalH1' ua>rr@ AT Tt<II WA- UP.
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Page 13: Care And Maintenance
6.0.3 Make sure before lowering the sensor into a tank, that the tank product level is known, so that the sensor is not immersed int the product. Before lowering the oxygen sensor, always obtain an accurate ullage reading by using an MMC ullaging tape or similar device. (See Section 5.0). -
Page 14: Oxygen Cell Replacement
OXYGEN CELL REPLACEMENT 6.2.1 The oxygen cell, located within the sensor barrel, has a life expectancy of at least one year. The cell is similar to a battery except unlike a battery, it produces a current which is directly proportional to the level of oxygen it senses in a gaseous environment. In normal air, the current generated by a live cell is approximately 0.8 milli-amperes, which produces a conditioned reading on the display of 20.9% ±0.2. - Page 15 6.3.9 Detach the tape at the hub removing the grounding machine screw and unsoldering the spliced connections between gauging tap and PCB connection wires. 6.3.10 Note on the tape reel which way the tape scale is facing. 6.3.11 Pull the tape away to the hub by reverting hub reel through the tape wiper housing, and out through the slot in the side of the reel hub.
- Page 16 SECTION VII CALIBRATION PROCEDURE: 7.0.1 The Oxygen Sensor and associated electronics have been accurately calibrated at factory. The oxygen cell used, and the electronic circuits are extremely stable and in general require calibration only when the 9-volt battery or the oxygen cell is replaced. 7.0.2 A simple way to perform push button calibration has been incorporated in the design which permits the operator to quickly bring the system into calibration using the oxygen content of normal air (20.9%) ±0.2% as standard.
- Page 17 SECTION VIII FAULT FINDING The following section covers only simple faults that may occur. No attempt has been made in this section to cover highly technical faults. PROBLEM NO. 1: Unit does not turn on when power “On/Off” switch is depressed. PROCEDURE &...
- Page 18 PROBLEM NO. 7: Alarm circuit (Red LED or horn) does not function properly. PROCEDURE & EXPLANATION: Unit requires factory calibration. Horn may be badly corroded. Comparator is not functioning properly. Return to MMC or authorized service center for repair.
- Page 19 CAUTION This equipment is an approved intrinsically safe device. The factory of approved service centers may only make circuitry repair. Unauthorized repairs will void any guarantee or warranty given elsewhere in this manual. In addition to the above statement, it is equally, if not more important to understand that repairs by unqualified persons may endanger the intrinsically safe construction of this device.
- Page 20 APPENDIX PAGE NUMBER A. MMC Warranty Statement B. Oxygen Sensor Gauging Tape Warranty Addendum C. Glossary of Approvals D. BASEEFA Certificate of Conformity Ex93C2037X 25-28...
- Page 21 No other warranty period, in excess of one year, may be expressed or implied by sub-agents or others, unless authorized in writing by MMC. The liability of the seller under this warranty is limited, at seller’s option, solely to repair or replace with equivalent equipment.
- Page 22 OXYGEN SENSOR GAUGING TAPE WARRANTY ADDENDUM: Warranty for MMC Oxygen Level Sensor Tapes is One (1) year from the ship date of shipment against defects in the material or workmanship, excluding oxygen cell assembly. Warranty for Oxygen Cell Assembly is six (6) months from the date of shipment.
- Page 23 GLOSSARY OF APPROVALS MAJOR APPORVAL STANDARDS & GOVERNEMNT SPECIFICATIONS ADOPTED BY MMC INTERNATIONAL CORP. FOR CERTIFICATION, MANUFACTURE, INSPECTION CALIBRATION AND TESTING INTRINSICALLY SAFE APPROVALS CAS (CAN.) Sira Certification Service Canadian Standards Association EECS Electrical Equipment Certification Service (U.K.) CSA Group Testing UK Limited...
- Page 24 LIST OF DRAWINGS DRAWING NUMBER REV. DESCRIPTION A-2615-17 Oxygen Sensor Cell Outline Drawing B-2615-14 Tape Reel Hub Electronics Module Assembly S-2615-OCX “Flexi-Dip” Portable Tape Assembly, Oxygen Sensor, Closed Gauging DB-2615-1FRX “Flexi-Dip” Portable Tape Assembly, Oxygen Sensor, Restricted Gauging...
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