MMC D-2401-2 Operating instructions

MMC INTERNATIONAL CORP.
OPERATING AND MAINTENANCE
INSTRUCTIONS
INTRINSICALLY SAFE
TRIPLE FUNCTION GAUGING TAPE
FOR RESTRICTED APPLICATIONS
LIQUID MEASURE OF ULLAGE, OIL/WATER
AND TEMPERATURE
MODEL D-2401-2
TECHNICAL APPROVED BY:
FACTORY MUTUAL AND BASEEFA FOR
CLASS I, DIVISION I, GROUPS C & D
AND
LLOYD'S REGISTER AND 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
AUG 2006DRAWING FILE NO. A-2401-60

TABLE OF CONTENTS
PAGE
NUMBER
NOTICES
i
I. GENERAL
1.0 SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 LINEAR ACCURACY SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 SPECIAL FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
II. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
III. THEORY OF OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
IV. REQUIRED CONDITIONS AND RECOMMENDATIONS FOR SAFE USAGE
4.1 REQUIRED CONDITIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2 RECOMMENDED SAFE USAGE CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
V. OPERATION
5.1 FAMILIARIZATION WITH OPERATING CONTROLS AND FEATURES
LOCATED ON THE TAPE REEL HUB COVER PANEL . . . . . . . . . . . . . . . . . . . . 8
5.2 ULLAGE/INTERFACE MEASUREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.3 TEMPERATURE MEASUREMENT PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . 10
VI. CARE AND MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
VII. CALIBRATION PROCEDURE
7.1 ULLAGE AND INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.2 TEMPERATURE SENSOR CALIBRATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
VIII. GAUGING TAPE REPLACEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
IX. HUB COVER AND P. C. BOARD REPLACEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
X. FAULT FINDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
XI. APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
XII. LIST OF DRAWINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

NOTICE TO ALL EQUIPMENT USERS
If your gauging device has been equipped with an all Stainless Steel Triple Function Sensor (Material Type 316SS).
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 a 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.
The all stainless steel Triple Function sensor is IMO Resolution MEPC.5 (XIII) approved, and therefore also meets
the International requirements of a petroleum carrier, or a dual classed chemical / petroleum carrier.
We hope that this sensor performs satisfactorily for all your applications and we would appreciate any return
comments you may have concerning its response to various products.
Best Regards,
MMC International Corp.
i

SECTION I
I. GENERAL
1.0 SPECIFICATIONS:
Display Readable Temperature Range . . . . . . . . . . . . . . . . . . . . °F = -40°to 199.9°*
*Reading Limit Due to 3-1/2 Digit LCD Display on °F Range. °C = -40°to 150.0°
Guaranteed Temperature Calibration Range . . . . . . . . . . . . . . . . 32°F to 190°F
(and 0°C to 88°C)
Accuracy Over Calibration Range . . . . . . . . . . . . . . . . . . . . . . . . ±0.5°F (±0.2°C)
Accuracy Linear Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . ±1/8” (±3.0MM), Plus ±0.01%
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 (supplied) . . . . . . . 9 Volt Eveready #522 or
Duracell MN1604
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
Ambient Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to 80°C
Storage Temperature Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -67°F to 185°F
-55°C to 85°C
Available Tape Length - Single Face Scale . . . . . . . . . . . . . . . . . . . 50 FT or 15 Meters
75 FT or 25 Meters
100 FT or 30 Meters
100 FT (10ths & 100ths)
120 FT (37 Meters)
Hazardous Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Certified Intrinsically Safe
BASEEFA and Factory Mutual
Gas Groups C&D
Page 1

1.1 LINEAR ACCURACY SPECIFICATION:
MMC PORTABLE ELECTRONIC GAUGING TAPE
STANDARD PRODUCTION
LINEAR MEASUREMENT ACCURACY
Applicable Equipment: MMC Models D-2401-2 (Trimode),
D-2401-2UI (Ullage/Interface,
D-2401-2UT (Ullage/Temperature)
Tape Lengths: 50 FT., 75 FT., 100 FT, 120 FT and
15 Meter, 25 Meter, 30 Meter 37 Meter
Basic Gauging Tape Style: Steel, 0.375 wide x 0.006 thick,
yellow or white faced, black and red
graduation markings. Manufactured in
accordance with Federal Specification
GGG-T-106F.
System Linear Accuracy at 68°F: English Reading, ±1/8" of reading
plus ± 0.01% of total tape length.
Metric Reading, ±3MM 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 extra cost. Certification cost to standards of accuracy
more precise than the stated system accuracy will be quoted upon request.
Page 2

1.2 SPECIAL FEATURES:
Conductive Tape Surface to Drain Off any Static Charge
Grounding Cable with Heavy Alligator Clamp
Watertight Electronics Construction with Sealed Switches
All Stainless Steel Fasteners
Nylon Coated Aluminum Reel Housing for Light Weight Portability
Low Battery Display Indicator
High Daylight Visibility with Liquid Crystal Display
Push-button Night Light
Rapid Multiple Temperature Measurements
IMO approved for oil/water interface Detection
Full stow “ Pop-up” button spring loaded Tape Wiper housing Gas Seal
Page 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 repeat-
ability 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 ±0.2°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 and fluid
which is electrically conductive, such as water.
2.4 The system is certified as intrinsically safe for electrical equipment in hazardous
atmospheres by Factory Mutual, BASEEFA /SIRA, CSA, and SAA.
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 Mili-amperes in either the ullage, interface or the temperature mode), insuring 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.
Page 4

SECTION III
3.0. THEORY OF OPERATION
3.1 Drawing D-2562-1FRL illustrates the main components of the Ullage, Temperature 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, 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 a 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 suitability 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 with-
in 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, though the electronic component network,
with the turning drum, input to an A to D converter is caused to vary linearly with temperature.
Span control (R18) is adjusted to provide a fixed reference voltage, 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.
Page 5

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 re-calibration is recommended at yearly intervals. Please note that units
returned
Temperature Calibration during standard or extended warranty periods are not covered by
warranty statement.
Page 6

SECTION IV
4.0 REQUIRED CONDITION AND RECOMMENDATION 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 also 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 guidance 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 CONDITION
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:
4.2.1 The grounding of the unit, and adhering to the specific company safety
standards or directives, is the sole responsibility of the operator.
4.2.2 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.
4.2.3 Clean oil distillates are in general, known to be accumulators of static
electricity due to their low conductivity (I.E., less than 100 Pica Semians/Meter)
and therefore may require relaxation periods of longer than 30 minutes before
gauging is attempted.
4.2.4 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.
4.2.5 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 the completion of the working
operation.
Page 7

SECTION V
5.0 OPERATION
5.1 FAMILIARIZATION WITH OPERATING CONTROLS AND FEATURES LOCATED
ON THE TAPE REEL HUB COVER PANEL:
5.1.1 Turn on power by momentarily depressing the “Off/On” 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.
5.1.2 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 battery (below 7.0 Volts) are unreliable.
5.1.3 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 “Off/On” 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 in the Ullage/Interface mode, will read 00.0
instead of 1XX.XX.
5.1.4 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
on the display indicative of the temperature of the sensor tip.
Once again depress the “Mode” switch and note 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 “Off/On” 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.
5.1.5 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.
5.2 ULLAGE/INTERFACE MEASUREMENTS:
5.2.1 If power is off, depress power “Off/On” push-button switch. The system
comes on in Ullage/Interface mode (display reads 1XX.X).
5.2.2 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
Page 8

5.2.3 Make sure “LO BAT” Does not show at left upper corner of display
5.2.4 After grounding the assembly, insert the barrel of the gauging
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 restraining 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.
5.2.5 Lower the sensor head slowly until a tone steady 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 fluid is water or other conductive fluid, the audible
tone heard, will be a “beeping” tone.
5.2.6 Define measurement by raising the sensor head until the sound
just ceases. Lower until sound is just heard again, to refine ullage level.
5.2.7 Place gauging tape against ullage referenced point and read ullage on tape
Note this reading as the surface liquid ullage level.
5.2.8 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.
5.2.9 Raise the sensor very slowly until the tone once again becomes continuous.
Repeat if necessary to refine water entry point (Interface level).
5.2.10 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.
5.2.11 When the measurement is completed, place the spring loaded wiper knob in
the “On” position while rewinding the tape until sensor is stored with
in 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”
5.2.12 Lock the reel by rotation the crank/reel lock thumbscrew down position (parallel
to hub).
Depress power “Off/On” switch to conserve battery power.
5.2.13 Close the vapor valve, disconnect the valve securing cap, remove the
gauging unit, disconnect the grounding cable. Replace the vapor valve cap.
Page 9

5.3 TEMPERATURE MEASUREMENT PROCEDURE
5.3.1 If power is off, turn unit on by depressing “Off/On” push-button switch.
Unit comes on in Ullage/Interface mode. Depress “Mode” push-button switch to
select temperature.
5.3.2 If unit was on and in Ullage/Interface mode, simply press the “Mode”
push-button to select temperature.
5.3.3 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.
5.3.4 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.
5.3.5 When the desired temperature ullage level is reached, allow the sensor to
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 insure accurate readings. The
viscous nature and low thermal conductivity properties of these petroleum products,
makes the joggling procedure a necessity to insure accurate temperature in a
minimum amount of time.
5.3.6 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.
5.3.7 When the measurements are complete, push “Off/On” 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.
5.3.8 Lock the reel by rotation reel lock crank down, position. Follow the
same final procedure as described in step 5.2.13 above.
Page 10

SECTION VI
6.0 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:
6.1 When not in use, make sure power is off as evidenced by display being extinguished.
6.2 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.
6.3 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.
6.4 Never permit tape and sensor head to unwind freely (control speed of descent by
usage of a restraining force on crank).
6.5 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 readings 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 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 gasket, cover, and machine screw
fasteners when re-assembling to tape reel hub.
Page 11

SECTION VII
7.0 CALIBRATION PROCEDURE
7.1
ULLAGE:
The ullage circuits do not require calibration in the field with proper care and
handling the equipment should function indefinitely.
7.2
TEMPERATURE SENSOR CALIBRATION
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:
7.2.1 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
cover low temperatures and the other to cover the high temperatures.
7.2.2 Remove the 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).
7.2.3 Turn display on by depressing power "Off/On" button momentarily. Place
system in temperature mode by depressing “Mode” switch. Display should
now read temperature at sensor tip.
7.2.4 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
at least 60° higher than the cold bath.
7.2.5 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.
7.2.6 Record: Sensor Cold Reading as = pc (as read from digital display)
Record Reference: Thermometer Cold reading as = tc
7.2.7 Repeat the above procedure in a hot bath.
7.2.8 Record: Sensor Hot Reading as = ph (as read from digital display)
Record Reference: Thermometer Hot Reading as = th
Page 12

7.2.9 Calculate Zero Correction = tc (ph - pc) - pc
th - tc
7.2.10 Place sensor in cold bath. Stir and wait until sensor reading on display
stabilizes. Note reading and then adjust “Zero” control potentiometer
marked (R13) so that the zero correction calculated in step 8.2.9. above is
added to or subtracted from the sensor reading. If the answer in step 8.2.9
above is positive, add the correction, if negative, subtract.
7.2.11 Now place thermometer in the cold bath with the sensor and stir. Now
adjust the “span” potentiometer until the two reading are equal (the
displayed reading, and the reading of reference thermometer).
7.2.12 Check readings in hot bath. Slight touch-up of “Span” control may be
required. Normally not more than a ±0.1 degrees correction is necessary if
the calculated measure “Cold” temperature procedure has been performed
correctly.
The above method allows the operator to perform the calibration in one
step. If desired, and particularly if the error is minor, an adjustment of
zero may be performed in the cold bath to equal the thermometer reading.
Then the span may be adjusted in the hot bath. However, this procedure
requires repetition until both cold and hot bath readings are correct without
further adjustment in either cold or hot baths.
Page 13

SECTION VIII
8.0 GAUGING TAPE REPLACEMENT (With or without new sensor attached)
The gauging tape used for the Trimode restricted gauging system is similar but not inter
-changeable with the gauging tapes used for closed gauging systems.
The tapes used are bright white faced steel core type, which have been encapsulated with a
tefzel jacket. (Tefzel is a registered trade name of the Dupont Corporation). The tapes is terminated
at the display electronics hub PCB module connection points, by soldered leads within tape reel internal
core. The sensor is connected to the tape be means of a quick connect plug to the tape socket plug.
As with all tefzel coated MMC gauging tapes, the outer surfaces are factory treated to render
the surfaces of the tapes anti-static properties.
The patented process to achieve the desirable anti-static condition, is not defeated by tape
wiping or cleaning with standard petroleum based solvents.
Gauging tape replacement is not difficult, but requires careful attention to the travel path of
tapes as it exits from the tape reel assembly, passes over the interior guide rollers, cursor pin assembly,
anti-chafing rollers and on through the wiper housing .
8.1 To replace a tape, remove the machine screws from the hub cover and lay it to the side.
8.2 Remove battery from the battery holder, unplug battery cap and storage barrel by loosening
cap nuts on wiper housing.
8.3 Remove round vapor seal assembly on top of the tape wiper by backing off the Allen set screws
which hold it in place and place tape wiper knob in “Off” position.
8.4 Completely unreel tape and sensor head. Note that the end of the metallic tape inside the hub
is grounded by a machine screw and washer. The tefzel tape cover at this point has been
trimmed away to permit good ground contact. Also note that the tape’s outer conductors are
spliced to two to the wires that originated at the circuit board. (Note the color of these wires
so that when reassembling, the correct wire will be connected to the top and bottom tape
conductors).
8.5 Detach the tape at the hub by removing the grounding machine screw and unsolder the splice
connections. Pull the tape through the slot in the side of the hub and out through the tape
wiper.
8.6 Attach a new tape to the hub by reversing the above procedure making sure that the tape
numerals face in the same direction as the previous tape numeral faced. Make sure that the
splices are well insulated (use shrink tubing) and that the grounding machine screw and
washer are fastened tightly to provide a good metallic ground between center ground tape
conductor and hub.
8.7 Replace battery, battery cap and hub cover. Connect old sensor to tape, if not supplied with
Replacement. Rewind tape on reel.
8.8 Replace tape vapor seal assembly and sensor storage barrel.
8.9 Perform a temperature calibration in accordance with Section VII.
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SECTION IX
9.0 HUB COVER AND P.C. BOARD REPLACEMENT
To replace the turning drum hub cover and P. C. Board, follow the steps outlined below:
9.1 Remove the six machine screws from the hub cover, and extract cover, gasket and P.C. Board.
9.2 Unplug battery cap.
9.3 Unsolder wires that go to small horn (Note that these wire originate from same strip that
connects battery cap).
9.4 Now carefully examine three conductor strips that originate at upper right hand corner of P.C.
board. These wires may not be the same color code as the replacements hub P.C. Board and it
is important that they be connected to the correct points. Note that one wire (ground) has a
terminal lug attached and therefore replaces the previous wire with terminal lug.
9.5 Now make a note of the wires that go to top and bottom splices of outer tape conductors. One
of these wires goes to a point on P.C. Board Labeled "+V". The other to a point on P.C.
Board labeled "SIG". Note which goes to top and which goes to bottom conductor. For
example: "SIG" to top connector and "+V" to bottom connector.
9.6 Unsolder spliced conductors and remove the nut ground connecting the gauging tape to the
driving drum. This now completes disassembly and the old hub assembly can be put aside.
9.7 Position new hub cover and P.C. Board and solder to horn and insulate the two free wires
originating from the battery cap strip line. The polarity of these two wires is not important.
9.8 Reconnect ground wire with terminal lug to driving drum ground post and replace and tighten
nut.
9.9 Re-solder and insulate “+V” and "SIG" wire to outer tape conductors taking careful notice
of where they originated. (see Step 10.5 above)
9.10 Replace battery and connect battery cap.
9.11 Re-assemble hub cover and attached P. C. Board with six machine screws being careful to
line up neoprene gasket.
9.12 Perform temperature calibration in accordance with Section VII.
.
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SECTION X
10.0 FAULT FINDING (SEE DRAWING B-2401-31)
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 "OFF/ON" switch is depressed.
PROCEDURE &
EXPLANATION: If unit does not turn on at all, check battery voltage using a voltmeter. If
battery voltage is lower than four (4) volts because units has been
accidentally stored for a lengthy period with power on the voltage is too
low to illuminate display. Replace battery. (See Section VII Paragraph
7.5). If battery is okay, check power “ON/OFF” switch using an OHM
meter. Switch should normal show an open circuit. When depressed OHM
meter reading should be less than 2 Ohms. If switch is okay integrated
circuit chip is probably at fault. Return to factory or service center for
repair.
PROBLEM NO. 2: Unit stays on all the time, even though "OFF/ON" push-button is depressed.
PROCEDURE &
EXPLANATION: This symptom is usually indicative of a faulty power “OFF/ON” push-button
switch. Check the switch with an Ohmmeter as explained in Problem
No.1 above.
PROBLEM NO. 3: Unit turns on and off, however, when "Mode" switch is depressed system
does not switch to temperature it stays in Ullage/Interface mode always.
PROCEDURE &
EXPLANATION: Use OHM meter to make sure "Mode" switch is normally open and when
depressed is closed. If switch is faulty replace. If switch check out okay,
problem is probably an integrated circuit chip. Return to factory for repair.
PROBLEM NO. 4: Temperature readings are erroneous
PROCEDURE &
EXPLANATION: A.) When display is on does "Lo Bat" appear at upper left corner? If
so, replace battery with a new battery.
B.) If “Lo Bat” does not appear and display contrast in temperature
mode is not good and in particular the decimal point is very faint
or not visible, check battery voltage using voltmeter. If voltage
has fallen below 5.0 “Lo Bat” may not appear. Usually, under
these conditions the temperature readings will show extreme
errors.
C.) If battery checks okay, it is possible that the temperature sensor
in the sensing head may have been damaged by dropping unit or
unit may be out of calibration, due to severe exposure or abuse.
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