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3.8 

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 

off during a measurement cycle. 

 

3.9 

The alarm circuit within the hub consists of 18% oxygen level comparator described above, an 

8% comparator, a red lamp (LED) and horn as visual and audible alarm indicators, with other 

ancillary electronic circuits. 

 

3.10  When the sensor is powered in a normal air environment, the oxygen level is well above the 8% 

level and the red LED lamp on the faceplate will flash slowly. The horn is silent. If the sensor is 

now lowered into a tank which contains an oxygen level below 18% but above 8%, the horn will 

now emit a pulsating audible tone and the red lamp will then begin to flash at a rapid rate. Below 

8% the horn will be silent, and the red LED will extinguish. 

 

 

To Summarize: 

 

Above 18% 

 

 

Lamp slowly Flashes, Horn Silent (Power on indicator) 

From 8% to 18% 

 

Lamp Rapidly Flashes, Horn Sounds 

 

Below 8% 

 

 

Lamp off, Horn Silent 

 

3.11  As can be seen from the above table, during an above acceptable level of oxygen contents, both 

red LED and horn are off. In addition, the action of the red LED is explained as follows: 

 

3.12  The red LED lamp served two purposes. 

 

3.13  The first purpose is to act as a simple power on indicator in normal air during day and nighttime 

use. This feature is important at night since an operator may not be aware that automatic shut-off 

has occurred and attempt a gauging procedure. 

 

3.14  The second purpose is to provide an additional indication that an unsafe in-tank oxygen level 

exists. In the event that an operator has difficulty in hearing the alarm horn, the rapidly flashing 

red LED can be clearly seen. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Summary of Contents for D-2615-11

Page 1: ...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...

Page 2: ...S 7 4 2 RECOMMENDED SAFE USAGE CONDITIONS 7 4 3 FLUID LEVEL ULLAGE OF TANK OR OTHER VESSEL 8 V OPERATION 5 1 FAMILIARIZATION WITH OPERATING CONTROLS FEATURES LOCATED ON THE TAPE REEL HUB BEZEL NAMEPLA...

Page 3: ...CONTINUED FROM PREVIOUS PAGE VII CALIBRATION PROCEDURE 7 1 METHOD OF CALIBRATION 12 VIII FAULT FINDING 14 15 IX APPENDIX 16 X LIST OF APPLICABLE DRAWINGS 24...

Page 4: ...1000 Hours Depends on night light use Battery Drain Display Night Light off 1 0 MA IN AIR 0 7 ma with 8 Oxygen Night Light Battery Drain 9 0 ma use Storage Temperature 20 C to 40 C Tape Length Standar...

Page 5: ...ape Reel Position Lock Watertight Electronics Housing with Sealed Switches Stainless Steel Fasteners Nylon Coated Aluminum Frame for lightweight portability Low Battery Indicator Liquid Crystal Displa...

Page 6: ...replacing oxygen cells WARNING This equipment is solely intended for use in determining the percent by volume of the oxygen that may be present in a protective blanket of inert gas It is not claimed o...

Page 7: ...an 8 level 2 6 A single 9 volt battery contained within the hub assembly powers the oxygen sensor tape and sensor assembly Battery drain is extremely low approximately 0 75 milli amperes and if the un...

Page 8: ...may be used to give instant push button calibration of the system in air See section 7 0 3 5 When the oxygen sensor is powered in a normal ambient environment the reading of the digital will show an...

Page 9: ...flash slowly The horn is silent If the sensor is now lowered into a tank which contains an oxygen level below 18 but above 8 the horn will now emit a pulsating audible tone and the red lamp will then...

Page 10: ...CONDITIONS 4 2 1 The apparatus sensor should preferable be entered into a tank or vessel within an earthed sounding tube or pipe where such devices are provided and are normally used for temperature...

Page 11: ...liable means 4 3 2 With the fluid level known the oxygen sensor can be entered into the tank and unreeled to the mid point position of free space above and between the liquid level and tank top CAUTIO...

Page 12: ...NTIFICATION FUNCTION IDENTIFICATION FUNCTION DIGITAL DIS LAY PERCENT OXYGEN DISPLAYED LO EAT LOW EATI ERY INDICATOR L E D RSD RAPIDLY FT ASHES WHEN OXYGEN 0 LEVEL IS ABOVE 8 SLOWLY FLASHES AT LEVEL AB...

Page 13: ...turning 6 0 6 Never permit tape and sensor head to unwind freely control speed of descent by use of a restraining force on tape reel crank 6 1 BATTERY REPLACEMENT In Safe Area Only The battery should...

Page 14: ...he cell assembly Replace screen and retaining cap Then follow procedure given for cell calibration in Section 7 0 6 3 GAUGING TAPE REPLACEMENT In case of damage the gauging tape may be replaced by fol...

Page 15: ...aking sure that the tape numerals face in the same direction as the previous tape numerals faced 6 3 13 Use a silicone rubber sealant to re seal area around slotted tape entrance to reel hub Re wind t...

Page 16: ...ned look at the upper left corner of the display If LO BAT appears indicating a low battery condition replace the 9 volt battery contained in the hub following the procedure given in Section 6 Note Wh...

Page 17: ...is symptom is usually indicative of a faulty power On Off push button switch Check the switch with an Ohmmeter as explained in Problem No 1 above PROBLEM NO 3 When turned on in normal air unit does no...

Page 18: ...Hold the cell housing so that the V notch in the center ring of the connector is up See drawing A 2615 17 Connect the positive lead of a digital voltmeter capable of reading millivolts to pin from th...

Page 19: ...ay 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 understa...

Page 20: ...APPENDIX PAGE NUMBER A MMC Warranty Statement 21 B Oxygen Sensor Gauging Tape Warranty Addendum 22 C Glossary of Approvals 23 D BASEEFA Certificate of Conformity Ex93C2037X 25 28 20...

Page 21: ...upon discovery of the defects B Upon receipt of written authorization from the seller the equipment is to be returned as directed transportation prepaid by the buyer C Buyer is to disclose the use of...

Page 22: ...reements with the above mentioned approval agencies and yet accommodate our customers as much as possible we have developed four modules which can be purchased as units installed by the owners of the...

Page 23: ...SPECTION BODIES APPORVALS ABS American Bureau of Shipping CCS China Classification Society DNV Det Norske Veritas Norway LLOYD S Lloyd s of London U K BV Bureau of Veritas GAUGING TAPE AND OTHER MEASU...

Page 24: ...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...

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