MMC D-2401-2 Manual

MMC INTERNATIONAL CORP
OPERATING AND MAINTENANCE
INSTRUCTIONS
INTRINSICALLY SAFE TRIPLE FUNCTION GAUGING TAPE
FOR
CLOSED (GAS-TIGHT) APPLICATIONS
LIQUID MEASURE OF ULLAGE, OIL/WATER INTERFACE
AND TEMPERATURE
MODEL D-2401-2
TECHNICAL APPROVED BY:
CSA/ATEX FOR CLASS I, DIVISION I, GROUPS C & D
AND
LLOYD’S REGISTER, BUREAU VERITAS “MED” APPROVED
IN ACCORDANCE WITH IMO RESOLUTION MEPC.5 (XIII)
FOR OIL/WATER DETECTION
MMC INTERNATIONAL CORP.
60 INIP DRIVE
INWOOD, NEW YORK 11096
SEPTEMBER 2022 DRAWING FILE NO. A-2401-60AC REV A

TABLE OF CONTENTS
PAGE NUMBER
NOTICES i
User instructions (in compliance with 2014/34/EU Directive, Annex II, 1.0.6) ii
MMC Atex/IECEx definition iii
I. GENERAL 1
1.0 SPECIFICATIONS 1
1.1 LINEAR ACCURACY SPECIFICATIONS 2
1.2 SPECIAL FEATURES 3
II. INTRODUCTION 4
III. THEORY OF OPERATION 5, 6
IV. REQUIRED CONDITIONS AND RECOMMENDATIONS FOR
SAFE USAGE 7
4.1 REQUIRED CONDITIONS 7
4.2 RECOMMENDED SAFE USAGE CONDITIONS 7
4.3 GROUNDING PRECAUTIONS 7, 8
V. GAUGING TAPE OPERATION 9
5.1 TANK ENTRY 9
5.2 PRODUCT GAUGING OPERATION 9
5.3 DETERMINING CARGO LIQUID LEVEL 9
5.4 USE OF THE SECONDARY TAPE SIGHT PORT 9, 10
5.5 TAPE OVER-WIND AND OTHER CONDITIONS 10
5.6 SIGHT PORT GLASS CLEANING 10
VI. OPERATION 11
6.1 FAMILIARIZATION WITH OPERATING CONTROLS
& FEATURES LOCATED ON THE TAPE REEL HUB COVER PANEL 11
CONTINUED ON NEXT PAGE

CONTINUED
6.2 ULLAGE/INTERFACE MEASUREMENTS 11, 12
6.3 TEMPERATURE MEASUREMENT PROCEDURE 13
VII. CARE AND MAINTENANCE 13, 14
VIII. CALIBRATION PROCEDURE 15
8.1 ULLAGE AND INTERFACE 15
8.2 TEMPERATURE SENSOR CALIBRATION 15, 16
IX. GAUGING TAPE REPLACEMENT 17, 18
X. HUB COVER AND P. C. BOARD REPLACEMENT 19
XI. FAULT FINDING 20, 21
XII. APPENDIX 22
XIII. WARRANTY 23
IVX. GLOSSARY OF APPROVALS 24
VX. TEMPERATURE CONVERSION CHART 25
XVI. LIST OF CHEMICALS 26
XVII. GUIDELINES FOR TAPE REPAIR 27
XVIII. LIST OF DRAWINGS 28

NOTICE TO ALL EQUIPMENT USERS
The triple functions of this sensor are to detect cargo surface level, Ullage, the Interface between two
immiscible products such as oil and water, and cargo Temperature.
The normal order of the gauging device, response to the products “Ullage level”, is a steady horn tone.
The normal response to an “Interface level”, (i.e., between a non-conducting and an electrically
conducting product such as a petroleum product and water, is a “steady” tone changing to a “beeping”
tone at the interface level.
A special note to our chemical customers, is the fact that some chemical cargoes may be
inherently conductive.
Therefore, at the surface of a conductive product’s Ullage level, a “beeping” tone will be the normal
response.
As a further note to the above, the change in detection of a non-conductive product Ullage level as a
steady tone to that of a conductive product’s ullage “beeping” tone, it is not to conclude that the sensor
is malfunctioning.
Best Regards,
MMC International Corp.
i

User instructions (in compliance with ATEX 94/9/EC Directive, Annex II, 1.0.6)
The following instructions apply to the Flexidip Portable Gauging Tape Type D-2401-2** covered by
certificate number BAS 02ATEX1274X. The information contained herein shall be included with every
batch of products sold, either as a separate sheet or incorporated as a discrete section in an instruction
manual.
WARNING: USE ONLY DURACELL/PROCELL MN1604 BATTERY REPLACEMENT.
DO NOT REPLACE BATTERY WHERE AN EXPLOSIVE GAS ATMOSPHERE MAY BE PRESENT.
BE AWARE OF POTENTIAL ELECTROSTATIC CHARGING HAZARD AFTER LOADING
DISTILLED PETROLEUM.
THIS DEVICE MUST BE GROUNDED.
Instructions for safe selection, installation, use, maintenance, and repair
1 The equipment may be used in zones 0, 1, or 2 with flammable gases.
2 The equipment may be used in the presence of flammable gases and vapors with apparatus
groups IIC or IIB or IIA and with temperature classes T1 or T2 or T3 or T4.
3 The equipment is certified for use in ambient temperatures in the range of –20°C to +40°C and
should not be used outside this range.
4 The equipment is to be installed by suitably trained personnel in accordance with the applicable
code of practice (typically IEC EN 60079-14).
5 The equipment does not require assembly or dismantling.
6 With regard to safety it is not necessary to check for correct operation.
7 No user adjustment is required.
8 Regular periodic inspection of the equipment should be performed by suitably trained personnel
in accordance with the applicable code of practice to ensure it is maintained in a satisfactory
condition.
9 The equipment is not intended to be repaired by the user. Repair of the equipment is to be
carried out by the manufacturer, or their approved agents, in accordance with the applicable
code of practice.
10 The equipment contains no other customer-replaceable parts.
11 The apparatus shall not be subjected to a prolific charge generating mechanism (such as might
occur in pneumatic transfer of powders or charge spraying in a powder coating process).
12 If the equipment is likely to come into contact with aggressive substances, e.g., acidic liquids or
gases that may attack metals or solvents that may affect polymeric materials, then it is the
responsibility of the user to take suitable precautions that prevent it from being adversely
affected thus ensuring that the type of protection is not compromised.
ii

SECTION I
1. GENERAL
1.0 SPECIFICATIONS:
Display Readable Temperature Range °F = -40° to 199.9°*
*Reading Limit Due to 3-1/3 Digit LCD Display on °F Range °C = -40° to 150.0°
Guaranteed Temperature Calibration Range 32°F to 190°F
(0°C to 88°C)
Accuracy Over Calibration Range ±0.5°F (±0.2°C)
Accuracy Linear Measurements ±1/8” (±2.0 MM), Plus ±0.1%
of Total Tape Length, worst case
Minimum Detectable Tank Bottom Liquid Level 3/8” (10MM)
Minimum Detectable Floating Product Level 1/8” (3MM)
Batteries for Intrinsically Safe Operation Only Duracell MN1604
(supplied)
Battery Drain (Temperature Mode) 1.3 ma (In Air)
2.6 ma (In Fluid)
Display 3-1/2 Digit Liquid Crystal
Display 1/2” Character Height
Operating Temperature Limit of Liquid Crystal Display, -40°F to 176°F
-40°C to 80°
Storage Temperature Limits -67°F to 185°F
-55°C to 85°C
Available Tape Length, *Single Face Scales 50 FT (15 Meters)
65 FT (20 Meters)
75 FT (25 Meters)
100 FT (30 Meters)
*100 FT (10ths & 100ths)
35M, 40M
Hazardous Environments Certified Intrinsically Safe
BASEEFA/SIRA,
Gas Groups C & D
1

1.1 LINEAR ACCURACY SPECIFICATIONS:
MMC PORTABLE ELECTRONIC GAUGING TAPE
STANDARD PRODUCTION
LINEAR MEASUREMENT ACCURACY
Applicable Equipment:MMC Models D-2401-2 (Trimode),
D-2401-2UI (Ullage/Interface)
Tape Lengths: 50FT., 65FT., 75FT., 100FT. and
15M, 20M, 25M, 30M, 35M, 40M.
Basic Gauging Tape Style: Steel, 0.375 wide x 0.006 thick,
yellow or white faced, black & red
graduation markings. Manufactured in
accordance with API Chapter MPMS 3.1A
industrial guideline.
System Linear Accuracy:English Reading, ±1/8" of reading
Metric Reading, ±2MM of reading
plus +/- 0.01% of total tape length.
GENERAL STATEMENT OF LINEAR ACCURACY
MMC warrants that the above listed, newly produced equipment models, incorporating the listed basic
gauging tape style and lengths, will perform to the stated system accuracy.
Certification of accuracy for new equipment is available at an extra cost. Certification costs to standards
of accuracy more precise than the stated system accuracy will be quoted upon request.
2

1.2 SPECIAL FEATURES:
Conductive Tape Surface to Drain Off any Static Charge
Grounding Cable with Heavy Alligator Clamp
Dual-Purpose Spring-Loaded Tape Crank and Tape Position Lock
Watertight Electronics Construction with Sealed Switches
All Stainless-Steel Fasteners
Nylon Coated Aluminum Reel Housing for Lightweight Portability
Low Battery Display Indicator
High Daylight Visibility with Liquid Crystal Display
Push-Button Night Light
Rapid Multiple Temperature Measurements
Easily Renewable Tape Wiper
Manually Operated Vacuum/Pressure Relief Valve
Primary and Secondary Tape Sight Glasses
Anti-Wind Internal Spring-Loaded Stop Lever Sensor
Internal Tape/Reel Confinement Springs
Gas Tight Construction
3

SECTION II
2.0 INTRODUCTION:
2.1 The MMC Tri-Mode portable ullage, temperature and interface tape described herein
incorporates extremely accurate instrumentation to provide three vital petroleum and
other liquid tank measurements.
•Measurement of surface ullage level of oil or other fluids to an accuracy and
repeatability of ± 1/8 inch.
•Determination of the exact location of the ullage level of the interface layer
exists when an oil-water mixture is contained within the same vessel.
•Measurement in either Degrees F or Degrees C of the temperature of the fluid
within a vessel, at any or several desired ullage levels, in rapid succession.
Measurement is given to the nearest 0.1 degree and is accurate to ±0.5°F over
the calibrated temperature ranges given in the specifications listed in
Section I.
2.2 The MMC system utilizes 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 power to the electronic
circuit within the sensor barrel with the steel tape, provides the ground return. The plastic
surface of the tape has been treated to make it sufficiently conductive to prevent the
build-up of static charges. Temperature indication is provided by a large digital liquid
crystal display (LCD), housed within a sealed reel driving assembly.
2.3 Ullage and interface detection is provided by an audible signal obtained from a horn
in the reel driving hub, when the bottom “U” gap in the sonic sensor is immersed in fluid.
The audible signal heard will be a continuous tone in a non-conductive fluid such as oil,
gasoline, kerosene, etc., but will change to an interrupted tone when immersed in a fluid
which is electrically conductive, such as water.
2.4 The system is certified as intrinsically safe for electrical equipment in hazardous
atmospheres by SIRA, CSA, BV, DNV.
2.5 The triple function temperature, interface, and ullage sensor is powered by a single 9-volt
battery contained within the hub assembly. Battery drain is extremely low,
(approximately 1-1/4 Milliamperes in either the ullage, interface, or the temperature
mode), ensuring very long operation, without battery replacement. Low battery warning
is provided at the upper left corner of the temperature display LCD, when the battery
voltage has dropped to a level that would, with further operation, cause excessive errors
in temperature readings.
4

SECTION III
3.0 THEORY OF OPERATION:
3.1 Drawing S-2562-1TR illustrates the main components of the closed Temperature, Ullage,
and Interface system. A tape reel contains the calibrated tape. The reel crank on the
driving hub is used by the operator to raise and lower the sensing head assembly which is
attached to the reel via the tape. Before lowering or raising the tape, the reel brass thumb
screw lock must be unlocked.
3.2 The sensor head assembly contains two piezo-electric crystals, a pair of interface or
conductivity pins and a temperature sensor, located in one of the conductivity pins and
electronic circuit board. The sensor is connected electrically to the driving hub
electronics by the two wires encased in the gauging tape plastic jacket, which covers and
hermetically seals these wires and centers graduated metallic gauging tape. The metallic
tape is used as a ground return conductor, which when including the two wires straddling
it, form a rectangular three conductor transmission cable.
3.3 The electronic circuits in the hub assembly are comprised of an LCD digital display
which provides temperature readings when the system is in the temperature mode; an
analog to digital converter, a power on-off switch, a mode switch which permits operator
to select the temperature mode or ullage/interface mode, a night light switch and ancillary
electronic parts all assembled on a printed circuit board. A 9-volt battery power source
and audio horn are located within the tape reel hub assembly below the P.C. board of the
modular hub cover assembly.
3.4 When the system is placed in the ullage/interface mode, and as the sensor is immersed in
a non-conductive fluid such as oil, a sonic signal originated by the sensor head circuits
freely crosses the sensor gap and is detected, amplified and then transmission tape to the
hub electronics board, which in turn drives a horn in the turning drum assembly. A high
pitched continuous audible signal is then emitted. When the sonic sensor is in air, the
sonic signal does not cross the sensor gap and therefore the horn is silent.
3.5 When the sonic sensor is immersed in a conductive fluid, such as the water layer side of
an oil/water interface, operation is as above except that the conductivity pins within the
sensor gap now permit a minute current to flow between the pins. This current flow is
detected by the sensor electronic circuitry with the sensor housing and suitably
conditioned to cause the sonic signal to be periodically interrupted, yielding a “beeping”
tone for operator identification.
3.6 When the system is placed in the temperature mode the ullage and interface circuits
within the sensor barrel are de-energized, also disengaging the audio signals associated
with the ullage/interface mode. The integrated circuit temperature sensor housed within
the grounded interface pin now functions as an extremely accurate linear temperature to
current transducer. As the temperature at the sensor rises, so does the temperature sensor
current. By passing the temperature sensor current via the transmission tape, through the
electronic component network, with the turning drum, input to an A to D converter is
5

caused to vary linearly with temperature. Span control (R18) is adjusted to provide a
fixed reference voltage, to scale for either, to scale for either a Centigrade or Fahrenheit
reading device. Coded digital output from the A to D converter to the LCD Display is
used to prove accurate and fast temperature readings.
The two potentiometer controls, R13 and R18, perform as a two-point temperature calibration
adjustment.
A complete temperature calibration procedure is later described in this manual. (See section
VIII).
Temperature recalibration is recommended at yearly intervals. Please note that units returned
for Temperature Calibration during standard or extended warranty periods are not covered by
warranty statement.
3.7 New Addition LED to existing PCB. When the electronic probe is lowered and senses a
hydrocarbon, a steady horn tone is sounded and LED illuminates. When sensing an oil-water
interface, or a heavier than water non-conductive liquid, and intermittent horn tone sounds, and
LED begins flashing.
6

SECTION IV
4.0 REQUIRED CONDITIONS AND RECOMMENDATIONS FOR SAFE USAGE:
The attention of the user of this apparatus is drawn to the possible hazards of ullage, interface,
and temperature measurements within flammable liquids, which are known to be generators of
static electricity.
Adhering to the specific safety directives of your company is the responsibility of the user.
The following is a general guideline to safe usage, drawn from the advice and experience of
various industry sources.
The specific safety standards or directives of your company are to be strictly adhered to, with the
general guidance given here being regarded as only a supplement to existing and established
operating safety procedures.
4.1 REQUIRED CONDITIONS:
This apparatus must be earthed (grounded) to the liquid tank containment vessel or tank,
before and during introduction into the vessel. The earthed conductor must not be
disconnected until the apparatus is completely withdrawn from the vessel being gauged.
A suitable grounding cable is provided as part of the gauging unit. Proper grounding of
this cable is the responsibility of the user.
4.2 RECOMMENDED SAFE USAGE CONDITIONS FOR THE TRIPLE FUNCTION
GAUGING TAPE:
As the word “Closed” implies, the Tri-Mode gauging assembly shown on drawing S-
256201TR has been carefully constructed to eliminate the escape of cargo vapors to the
atmosphere and to minimize exposure of operating personnel to these vapors. The sealed
construction utilized meets the current state and federal environmental requirements and
provides the operator with a tool which greatly reduces potential occupational hazards.
To assure that the above conditions will prevail, the “Closed” Tri-Mode gauging system
should be entered into a cargo tank by means of a deck station vapor valve.
4.3 GROUNDING PRECAUTIONS:
The “Closed” gauging tape assembly is to be hull grounded before and during its use for
cargo gauging. Grounding of the gauging unit with the provided coiled grounding
cable should be completed before the vapor valve is opened and any measurements
conducted. The unit must remain grounded during all measurement procedures and until
the sensor is fully wound back up into the case and the valve is closed.
4.3.1 The grounding of the unit and adhering to the specific company safety standards
or directives, is the sole responsibility of the operator.
4.3.2 Sensor entry into tanks or vessel immediately following a tank filling or loading
operation of known static accumulator type petroleum products or other such
flammable liquids, should not be attempted until, at least a period of 30 minutes
has elapsed since the cessation of filling.
7

4.3.3 Clean oil distillates are, in general, known to be accumulators of static electricity
due to their low conductivity (i.e., less than 100 Pica Siemens/Meter) and
therefore may require relaxation periods of longer than 30 minutes before gauging
is attempted.
4.3.4 The foregoing does not consider the use of anti-static additives to clean oils, as
generally easing the need for proper precaution, unless actual and specific product
testing has shown the product to have conductivity levels which eliminate the
danger of static electric charging.
4.3.5 Sensor entry into tanks or vessels that have been water washed and which
previously contained, or still partially contain petroleum products is not
recommended unless a sounding pipe is provided, and approved for such use, or
at least a period of five hours has elapsed since completion of the working
operation.
8

SECTION V
5.0 GAUGING TAPE OPERATION:
5.1 TANK ENTRY:
5.1.1. The closed tape is installed into a vapor control valve in the same was as a
restricted Flexi-Dip model. However, since the closed unit is sealed, an air
cushion may occur, preventing the “Closed” tape from easily seating into the
valve. BY depressing the vacuum/pressure relief valve located on the top of the
“closed” unit, the back pressure is release, allowing the unit to properly seat. The
securing collar on the storage tube barrel is then tightened on the valve.
5.1.2 In addition, the vacuum/pressure relief valve can be used to determine the
pressure within the case. Unscrewing the valve actuator cap exposes the actual
valve. This valve is similar to an ordinary bicycle tire valve and has its own
attached to the valve by means of the exposed threaded valve stem. After pressure
readings are complete, screw that valve actuator cap back onto the valve.
5.2 PRODUCT GAUGING OPERATION:
5.2.1 The tape sensor, lowered and raised by unwinding and rewinding the tape
crank/reel lock assembly, is located on the reel driving hub, which is spring-
loaded (perpendicular to the hub faceplate), the sensor can be freely lowered by
turning the reel hub clockwise
To lock the reel at a desired tank depth, pull the knurled knob up and out of its
hub socket and rotate it downward against the case. The reel is not locked. To
unlock the reel, reverse the above procedure.
5.3 DETERMINING CARGO LIQUID LEVEL:
Upon sonically determining the liquid level, (previously described), the gauging tape
scale is read through the primary gauging sight port, located on the bottom side of the
gauging assembly directly above the tape wiper housing. With a vapor valve properly
installed, the tape reading will be corrected to the “zero” ullage reference pane.
After completing a reading, re-wind the tape to its stowed position, being careful to
engage the spring-loaded tape wiper.
5.4 USE OF THE SECONDARY TAPE SIGHT PORT:
5.4.1 A secondary tape sight port is provided for two main purposes. This port is
located at the top of the unit, just below the carrying handle. With the carrying
handle rotated to the case cover side, the secondary port may be viewed directly.
5.4.2 When lowering or raising the tape, the motion of the gauging tape should be
observed through the secondary port. Viewing the tape through the secondary port
gives the operator an immediate sense of tape direction, and approximate pay-out
location of the sensor. When using a closed unity, as opposed to a restricted or
open mode, a sense of tape direction may not be obvious to new operators.
9

Therefore, the use of the secondary sight port becomes an important part of
normal operations.
5.4.3 When tape motion is stopped, the tape reading seen in the “secondary” sight port
is exactly 300MM above “zero” ullage reference level.
CAUTION:
If the gauging tape reading seen at the secondary sight port is to be used as a
recorded ullage, 300MM must be subtracted from reading to correct the
“zero” ullage reference plane.
5.4.4 In addition to the above functions, the secondary port provides an easy means of
determining oil-water interface layer measurements. Ince interface measurements
are only concerned with relative differences, the previously mentioned 300MM
corrective subtraction becomes unnecessary.
5.5 TAPE OVER-WIND AND OTHER CONSIDERATIONS:
The closed gauging tape is provided with an automatic anti-wind mechanism. The
purpose of this mechanism is to prevent the operator from re-winding the tape, after
having fully payed-out the tape length, in an opposite fold over sense. When a tape is
fully extended, a hard stop to further tape reel rotation will occur. Do not force this stop,
as tape damage may result. When a tape travel stop is encountered, please observe the
tape re-wind level for the proper re-wind direction.
Internally, spring band fingers have been positioned around the tape take-up reel, to
prevent the tape from coming out of the reel. However, in the event that the assembly is
inadvertently dropped a good distance with a tape not fully rewound, the gauging case
cover should be removed for an internal inspection.
5.6 SIGHT PORT GLASS CLEANING:
Occasionally, sight glass cleaning may become necessary. With reference to drawings A-
2562-146 and A-2562-147, cleaning may be easily accomplished. Cleaning may be most
easily accomplished by unscrewing the entire assembly and washing in a suitable
detergent.
CAUTION!
To maintain the sealed integrity of the gauging assembly, be sure that the case seal “O”
ring, Part No. 5 is in place upon re-installation of sight ports.
10

SECTION VI
6.0 OPERATION (Refer to Figure 1):
6.1 FAMILIARIZATION WITH OPERATING CONTROLS AND FEATURES ON
THE TAPE REEL HUB COVER PANEL:
6.1.1 Turn on power by momentarily depressing the “On/Off” push-button switch (1)
located at left of panel. The display should read 1XX.X* indicating that the
system is in the Ullage/Interface mode.
6.1.2 Looking at the top left-hand corner of the LCD display, notice if the symbol “LO
BAT” appears. If the symbol is displayed, the battery voltage is low, and the
battery should be replaced (see Section VII Paragraph 7.5). Always replace the
battery if “LO BAT” appears even though the digital display turns on.
Temperature readings with a low voltage batter (below 7.0 Volts) are unreliable.
6.1.3 Once again, momentarily depress the power “On/Off” switch. Note that the
display turns off. Always turn power off when the system is not in use to prolong
battery life.
Depress the “On/Off” switch once more. Display turns on and reads 1XX.X*
indicating the Ullage/Interface mode.
*NOTE: Due to an inherent digital uncertainty of the A to D converter, some
digital displays, whenever is the Ullage/Interface mode, will read 00.0
instead of 1XX.X.
6.1.4 Now momentarily depress the “Mode” switch at the right of the panel. The
display should now switch to the temperature mode as indicated by a reading on
the display indicative of the temperature of the sensor tip.
Once again depress the “Mode” switch and not that the display reads 1XX.X*
(Ullage/Interface Mode). Depressing the “Mode” switch alternately changes the
function from temperature to Ullage/Interface and vice versa. Depressing the
power “On/Off” switch alternately turns power off or on regardless of which
mode was in operation. However, when power is switched on again the system
will always come on in the Ullage/Interface mode.
6.1.5 Depress the night light switch (3) at upper center of panel when it is too dark to
see the display. The display background will illuminate, and the reading should
now be discernible.
6.2 ULLAGE/INTERFACE MEASUREMENTS:
6.2.1 If power is off, depress power “On/Off” push-button switch. The system comes
on in Ullage/Interface mode (display reads 1XX.X).
6.2.2 If the power was on and the system is in temperature mode, depress the “Mode”
switch at right of panel to alter function to Ullage/Interface.
11

6.2.3 Make sure “LO BAT” does not show at left upper corner of display.
6.2.4 After grounding the assembly, insert the barrel of the gauging unit into the valve.
Un-lock the tape reel lock by rotating the brass lock thumbscrew
counterclockwise turning position hub seat. Grasp the knurled reel crank hand and
lower the sensor head tape assembly, which contains the sonic sensor, into the
tank. Always exert a retraining force to prevent the sensor from descending too
rapidly or free falling.
CAUTION!
Under no circumstances should the reel and tape be permitted to unwind without
restraint. Permanent damage may be incurred to the sensor head or to the
calibrated tape if the head is permitted to fall freely.
6.2.5 Lower the sensor head slowly until a steady tone is heard. If the surface of the
fluids is oil or other non-conductive fluid, a continuous audible tone will be heard.
If the surface of the fluid is water of other conductive fluid, the audible tone heard
will be a “beeping” tone.
6.2.6 Define measurement by raising the sensor head until the sound just ceases. Lower
until sound is just heard again, to refine ullage level.
6.2.7 Place gauging tape against ullage referenced point and read ullage on tape. Note
this reading as the surface liquid ullage level.
6.2.8 To find the oil-water interface point, continue to lower the sensor into fluid,
noting that the audible tone is continuous. When the audible signal changes to a
“beeping” tone, the sensor has entered the water column underneath the oil.
6.2.9 Raise the sensor very slowly until the tone once again becomes continuous.
Repeat if necessary to refine water entry point (Interface level).
6.2.10 Again, read the ullage on the tape. By subtracting the first reading obtained (step
7) from this reading, the total product depth is thus determined. By subtracting the
second water level ullage from the maximum tank depth, water level innage is
determined.
6.2.11 When the measurement is completed, place the spring-loaded wiper knob in the
“On” position while rewinding the tape until sensor is stored with the vapor valve
entry barrel. Do not close the vapor valve until the fully “stowed” position is
confirmed, by noting that yellow pop-up button on top of the wiper housing is up.
6.2.12 Lock the reel by rotating the crank/reel lock thumbscrew down position parallel to
hub. Depress power “On/Off” switch to conserve battery power.
6.2.13 Close the vapor valve, disconnect the valve securing cap, remove the gauging
unit, disconnect the grounding cable. Replace the vapor valve cap.
12

6.3 TEMPERATURE MEAUREMENT PROCEDURE:
6.3.1 If power is off, turn unit on by depressing “On/Off” push-button switch. Unit
comes on in Ullage/Interface mode. Depress “Mode” push-button switch to select
temperature.
6.3.2 If unit was on and in Ullage/Interface mode, simply press the “Mode” push-button
to select temperature.
6.3.3 Make sure “LO BAT” does not show at left upper corner of display. If “LO BAT”
appears, replace battery even though the digital display turns on. The display may
continue to operate even though the battery voltage is below normal. Temperature
reading however, may be in error.
6.3.4 Ground the assembly, release the turn handle reel lock. Lower the sensing sensor
to the deepest reading desired. Make sure to exert restraining force while
lowering.
6.3.5 When the desired temperature ullage level is reached, allow the sensor to rest at
this point for at least two (2) minutes. Then joggle the sensing sensor up and
down, approximately 6” above and below the desired measurement level until the
displayed temperature reading settles. Record this reading. For heavy crude oil
products, the joggling procedure is a necessity to ensure accurate readings. The
viscous nature and low thermal conductivity properties of these petroleum
products makes the joggling procedure a necessity to ensure accurate temperature
in a minimum amount of time.
6.3.6 Raise the sensor to the next ullage level to be measured. Repeat step 6.3.5.
Continue raising sensor to all levels at which readings are desired.
6.3.7 When the measurements are complete, push “On/Off” button to turn off and
conserve battery power. Rewind the tape into the carriage reel assembly. Wipe the
tape as it is rewound by placing the spring-loaded wiper in the “On” position.
6.3.8 Lock the reel by rotating reel lock crank down, position. Follow the same
procedure as described in step 6.2.13.
7.0 CARE AND MAINTENANCE:
Proper care and maintenance should be practiced to maintain long, trouble free and accurate
service and to maximize battery life, as follows:
7.1 When not in use, make sure power is off as evidenced by display being extinguished.
7.2 Store sensor head assembly in the fully wound position and store in a dry location. Do
not allow the instrument to remain for long periods in direct sunlight, or store in
temperature above 125°F, or in temperature below freezing. Such temperatures may
damage the liquid crystal display.
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7.3 Wipe excess oil or water from tape, and sensor head. Each time the sensor is raised from
the tank, hold the spring-loaded tape wiper switch in the “On” position.
7.4 Never permit tape and sensor head to unwind freely (control speed of descent by usage of
a restraining force on crank).
7.5 BATTERY REPLACEMENT (See Approval Label for correct type):
The battery should be replaced whenever the “LO BAT” symbol appears at the upper left
corner of the display. If the sensor is used to obtain temperature reading when the battery
is low, large errors may result. Always replace battery in a gas free atmosphere. Remove
the six machine screws on the hub cover. Lift the cover with its attached P.C. Board. The
battery is retained within the reel turning drum by a spring clip battery holder. Remove
the battery from the battery cap connector. Replace the battery with a fresh battery of the
type listed on the approval label only. Take care to align the viton cover casket, and
machine screw fasteners when re-assembling to tape reel hub.
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SECTION VIII
8.0 CALIBRATION PROCEDURE:
8.1 ULLAGE:
The ullage circuits do not require calibration in the field with proper care and handling
the equipment should function indefinitely.
8.2 TEMPERATURE SENSOR CALIBRATION (Field Operation Only):
The temperature sensor and its associated electronic circuitry have been accurately
calibrated at the factory. Temperature calibration by MMC is recommended at twelve-
month intervals, with periodic checks being carried out as necessary between these
intervals.
Before attempting any calibration, make sure that the battery is at a proper voltage level
as evidenced by the fact that “LO BAT” does not appear at the upper left corner of the
display when the equipment is powered. Low battery voltage will produce errors in
temperature readings. If “LO BAT” appears on the display, check battery voltage and
replace. If necessary, calibration of the temperature sensor may be accomplished as
follows:
8.2.1 Use thermometers accurate to ±0.1° and preferably graduated in one-tenth degree
intervals. If mercury thermometers are employed, use two separate thermometers
to provide greater resolution. One to cover low temperatures and the other to
cover the high temperatures.
8.2.2 Remove six machine screws on the hub cover. Lift the cover and attached P.C.
Board from Hub exposing two potentiometers at back lower left of board. Lowest
potentiometer, marked (R13), is the “Zero” control and the potentiometer to the
left and above, marked (R18), is the “span control. (See drawing B-2401-31).
8.2.3 Turn display on by depressing power “On/Off” button momentarily. Place system
in temperature mode by depressing “Mode” switch. Display should now read
temperature at sensor tip.
8.2.4 Prepare two temperature baths, a cold bath of approximately one-gallon of water,
and a hot bath of approximately one gallon of water at a temperature of at least
60° higher than the cold bath.
8.2.5 Place the sensor in the cold bath with thermometer and stir the bath well to
equalize temperature. Keep sensor and thermometer together at approximately the
same point in the bath.
8.2.6 Record: Sensor Cold Reading as = pc (as read from digital display).
Record Reference: Thermometer Cold reading as = tc
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