Det-Tronics SW9200x User Manual

Instructions 95-8409-01

SlickWatch™ Oil Slick Detection System
SW9200A

Detector Electronics Corporation
6901 West 110th Street •Minneapolis, Minnesota 55438 USA
Tel: [phone] or 800.765.3473 •Fax: [phone]

11/94 95-8409-01

Section 1

General Information

The installation, operation and maintenance instructions
contained in this manual are for use by qualified person­nel only. All personnel assigned to this equipment
should read the instructions provided before initiating
any procedures. The manual should be maintained on
file so that it is available to installation, operation and
maintenance personnel. To avoid injury to personnel or
damage to the equipment, do not perform any proce­dures other than those described in this manual unless
instructed by the factory or qualified by training.

GENERAL DESCRIPTION

The SlickWatch oil slick detector is a remote electro-opti­cal instrument designed to detect oil films floating on
water surfaces. Oil detection is based on changes in
infrared reflectance that occur when an oil film is present
on the water.

These changes are detected by measuring the water
surface reflectance at two points in the infrared spectral
region near 3 microns. In this region, sharp changes in
reflectance due to absorption bands are observed.
Water surface reflectance dips from approximately 2% at
2 microns to a valley of 0.75% at 2.7 microns and then
rises sharply to a peak of 4.7% at 3.07 microns before
returning to approximately 2% at 4 microns.

The reflectance spectrum of oil films differs from that of
water surfaces in an unambiguous manner when viewed
in the 3 micron region. Oil films do not exhibit the deep
valley and adjacent sharp peak at approximately 2.7 and

3.1 microns. When a ratio is computed using
reflectance readings at the peak and valley points, water
surfaces exhibit a low reflectance ratio while oil films
show a much higher reading.

The SlickWatch system consists of a transmitter and a
receiver which are mounted above the water surface to
be monitored. The transmitter projects a light beam to
the water surface and the reflected infrared light is ana­lyzed by the receiver. An alarm relay is activated when
an oil film is detected.

FEATURES

• Non-contact design – instrument never comes in con­tact with contaminants being monitored.

• Reliable, continuous monitoring day and night.

• Low maintenance.

• Modular design for easy service.

• Internal Fault alarm.

• Rugged, explosion-proof construction.

• CSA certified.

SPECIFICATIONS

HOUSING SIZE—

Transmitter and receiver dimensions are: 12-l/4 inches
(W) x 11-1/2 inches (H) x 9-1/2 inches (D).

WEIGHT—

Transmitter: 34 lbs. (15.4 kg).
Receiver: 39 lbs. (17.7 kg).

©Detector Electronics Corporation 1994 11/94 95-8409-01

INSTRUCTIONS

SlickWatch™

Oil Slick Detection System

SW9200

DET -TR O NICS

®

SENSITIVITY—

Minimum film thickness detected is approximately 0.1
micrometer average thickness.

MOUNTING—

3/8-16 bolts (4 per housing) to user-supplied mounting
plate. The mounting plate interfaces between the instru­ment housings and the user-supplied mounting frame­work.

OPERATING VOLTAGE—

105 to 125 VAC, 50/60 Hz.

POWER CONSUMPTION—

Transmitter: 250 watts.
Receiver: 60 watts.

OPERATING TEMPERATURE—

In ambient air with instrument shaded from direct sun­light: –4°F to +110°F (–20°C to +43°C) at 60 Hz opera­tion; –4°F to +100°F (–20°C to +38°C) at 50 Hz opera­tion.

OPERATING HEIGHT—

5 to 30 feet above the water surface, depending on
wave angle. (See graph in APPENDIX).

AREA MONITORED—

A circle with a diameter approximately 0.05 times the
height of the instrument above the water. Typically 28
square inches at a 10-foot operating height.

RESPONSE TIME—

Approximately 63% of final reading within 20 seconds
after a step change in water surface condition.

OIL ALARM—

SPST relay, rated at 7 amps continuous, 120 VAC or 28
VDC. Also rated at 1/3 HP at 120 VAC. Contacts are
closed under normal clean water conditions and open
when oil film is present.

INSTRUMENT STATUS ALARM—

SPST relay, rated at 7 amps continuous, 120 VAC or 28
VDC. Also rated at 1/3 HP at 120 VAC. Contacts are
closed under normal conditions and open when the
beam is interrupted or a malfunction occurs.

ANALOG OUTPUT—

A 0 to 10 VDC analog output is available from the instru­ment. Under 2.0 VDC corresponds to clean water while
over 2.0 VDC corresponds to an oil film on the water sur­face.

OPERATION IN HAZARDOUS ENVIRONMENTS—

Canadian Standards Association certified for operation
in Class I, Div. 1 Groups C & D, and CSA enclosures 3 &

4. Temperature code T2A for 250 watt transmitters.

FUNCTIONAL DESCRIPTION

A functional description of the operation of the SW9200
is detailed in the following paragraphs. See Figure 1.

2

Figure 1—Functional Block Diagram

SIGNAL

PROCESSING

ELECTRONICS

RATIOMETER

OPTIONAL

4 TO 20 MA

CONVERTER

THRESHOLD

DETECTOR

THRESHOLD

DETECTOR

STATUS

ALARM
RELAY

ALARM
RELAY

OPTIONAL

ANALOG
OUTPUT

ANALOG
OUTPUT

INFRARED

PHOTO

DETECTOR

LAMP

RECEIVER

OPTICS

DENOM.

NUM.

RATIO

REFERENCE

FILTER

FILTER
WHEEL

TRANSMITTER

OPTICS

ADJUST

MOTOR

ACTIVE
FILTER

A1605

TRANSMITTER

The transmitter projects a beam of light onto the water
surface to be monitored. A tungsten halogen lamp is
mounted at the focal point of an aluminum parabolic
reflector in the transmitter housing.

RECEIVER

The receiver contains the optical and mechanical com­ponents and electrical circuits that receive the light emit­ted by the transmitter and process the signal to obtain
an oil film/no oil film output.

Receiver Lens

Light enters the receiver through the infrared transmitting
lens located within the lensholder. The lens focuses the
incoming light onto the face of the infrared photodetec­tor.

Filterwheel Motor

This motor is a small 115 VAC shaded pole ball-bearing
motor. The filterwheel is attached to the motor shaft.

Filterwheel

The filterwheel is located between the receiver lens and
the photodetector. It contains the DENOMINATOR
(active) and NUMERATOR (reference) optical interfer­ence filters. Rotating at a rapid rate, the filterwheel
chops the incoming light beam and alternately passes
infrared light at the two distinct wavelengths to the pho­todetector.

Sync Pickoff

The sync pickoff is a small, “U”-shaped optical switch
mounted on the Rear Panel printed circuit board and
straddling the filterwheel. It employs a light source and
a silicon photodetector at opposite ends of the “U” to
sense when each filter is in front of the infrared photode­tector. Light emitted by the sync pickoff passes through
slots in the outer edge of the filterwheel and generates
the synchronization signal.

Photodetector

The infrared photodetector is mounted at the focal point
of the receiver lens. The photodetector converts the
intensity of the incoming infrared light to a proportional
electrical signal. It alternately senses the light intensity
at both wavelengths during each revolution of the filter­wheel. The photodetector is thermo-electrically cooled
to increase the sensitivity to infrared light.

Amplifiers

The signal at the photodetector is amplified by the
preamplifier circuitry. The gain of the preamplifier can
be adjusted with an internal potentiometer to optimize
the signal strength for long or short operating distances.

The amplified signal is fed to the AGC amplifier, which
maintains the signal within the proper operating range.

Signal Processing Electronics

The signal from the AGC amplifier is separated into two
outputs: active (DENOMINATOR) and reference
(NUMERATOR).

Ratiometer

The ratiometer circuit generates an analog output by cal­culating the ratio of the NUMERATOR (reference) signal
to the DENOMINATOR (active) signal.

Optional Film Thickness Discriminator

This option converts the 0 to 10 VDC voltage into a posi­tive voltage (approximately +1.0 VDC) for “thin” oil films
(average thickness of less than 10 micrometers) and a
negative voltage (approximately -15.0 VDC) for “thick” oil
films (average thickness greater than 10 micrometers).
With this option the oil alarm relay is energized when a
“thick” film is present and inhibited when a “thin” film is
present.

Optional Selectable Criteria Alarm

With this option the oil alarm relay activates only if either
of the following conditions are met:

1. The time of uninterrupted oil observation exceeds a

preset duration between 1 second and 999 sec­onds.

2. The percentage of accumulated time during which oil

is observed exceeds a preset percentage between
10% and 90% measured over a 1000 second interval.

Optional 4-20 mA Converter

This option converts the 0 to 10 VDC voltage into a 4 to
20 mA current when a load resistor is connected
between the RATIO output and the signal ground. The
loop resistance cannot exceed 500 ohms.

Threshold Detector: Oil Alarm Relay

This threshold detector activates when the voltage of the
RATIO increases above a preset value. Activation of this
threshold detector causes the oil alarm relay to energize
indicating that oil is present on the water surface within
the instrument’s field of view. The threshold level at
which the oil alarm relay is energized can be adjusted
and tested on the front panel.

3 95-8409

Threshold Detector: Instrument Status Alarm Relay

This threshold detector activates when the NUMERATOR
voltage level approaches zero. Activation of this thresh­old detector causes the instrument status alarm relay to
de-energize. Because the relay is energized in normal
operation and is de-energized when the beam is
blocked or when an instrument malfunction occurs, the
alarm is fail-safe.

Receiver Power

The incoming power (115 VAC) is used to operate the fil­terwheel motor, the oil alarm relay, the obstruction/instru­ment status alarm relay and the low voltage power sup­plies. The instrument’s signal circuits are powered by a
±15 VDC supply. The circuit that controls the photode­tector’s thermo-electric cooler is powered by a +5 VDC
supply.

Fuses

The incoming power line is fused internally to protect the
instrument from damage. These fuses are accessible on
the front panel.

Section 2

Operation

SAFETY INFORMATION

EXPLOSION-PROOF INTEGRITY

WARNING

The SW9200 housings or associated junction
boxes must never be opened when circuits are
alive and hazardous vapor conditions may exist. In
procedures where the cover, window assembly or
junction box is to be opened when circuits are alive,
first ensure that no hazardous vapor conditions
exist.

CAUTION

If power is to be disconnected for an extended peri­od, e.g., over one week, the instrument should be
removed to a protected environment.

Special precautions must be taken with the SW9200 to
ensure the integrity of the explosion-proof housings.
When the instrument is in operation, the window assem­blies must be securely tightened. The cover bolts must
be torqued to 20 foot pounds.

It is recommended that the window retaining ring tight­ness be verified after shipment and just prior to initial
setup. The window assembly retaining ring must be
tightened to hold the window securely against the win­dow cover. The retaining ring must be tightened until

0.003-inch feeler stock will not penetrate more than 1/8th
of an inch between the window and the window cover.
This should be checked on both the transmitter and the
receiver around the entire circumference of the window
on both the inside and the outside.

Scratches may affect the strength of the instrument win­dows, so care must be taken to avoid scratching them
during installation, operation, and servicing. Similarly,
the mating surfaces of the cover and the housing flange
should not be scratched and these surfaces should be
protected during servicing.

The light beam projected by the SW9200 transmitter
could cause combustible materials within its path to
ignite, or raise the temperature of an object within its
path above the self-ignition temperature of some gases.
Check the temperature code for the transmitter wattage
used (see instrument nameplate) and do not install the
instrument at any location where this dangerous condi­tion could occur. Do not allow any object to intercept
the transmitter beam path to the water surface.

PERSONNEL SAFETY

The American Conference of Governmental Industrial
Hygienists (ACGIH) has roughly established Threshold
Limit Values (TLVs) or maximum allowable exposures to
bright light sources during an eight-hour workday.
According to ACGIH, “these values are to be used as
guides to the control of exposure to light and should not
be regarded as the fine line between safe and danger­ous levels”.

WARNING

It is possible to exceed the ACGIH limit values by
viewing the oil slick detector’s light source directly
from the center of the light beam at distances less
than approximately ten feet from the source. DO
NOT stare directly into the light source at close
range.

As with the sun, which greatly exceeds the Threshold
Limit Values established by the ACGIH, the eye’s self­protection mechanism (blinking) activates and automati­cally prevents overexposure.

FRONT PANEL CONTROLS

Front panel controls are described in the following para­graphs and are illustrated in Figure 2. Access to the front
panel controls is gained by removing the receiver win­dow assembly.

ZERO

The ZERO adjustment potentiometer is used to factory
set the analog output (RATIO) for oil-free water.

4

95-84095

MODE

The MODE selector switch permits adjustment of the
instrument’s response time and testing of the alarm
relays.

Align

A shorter response time (approximately 2 seconds) is
used only during the alignment and testing process.

Operate

A longer response time (approximately 20 seconds) is
used during normal operation to compensate for short
term signal variations and to prevent the oil alarm from
activating on short oil slicks.

Test

Test mode activates the oil alarm circuits.

OIL ALARM

Adjust

The OIL ALARM adjustment potentiometer is used to set
the threshold at which the RATIO voltage energizes the
oil alarm relay. The OIL ALARM is adjustable from 10%
full scale to 100% full scale. This adjustment is disabled
when the Film Thickness Discriminator optional p.c.
board is used. When the Selectable Criteria Alarm
optional p.c. board is installed, this control sets the
threshold at which the selectable criteria alarm circuit is
activated.

Figure 2—Front Panel Controls

ZERO

OUTPUT

OPERATE

ALIGN

TEST

O

V

mA

LO

MID

HI

CALIBRATION
ADJUSTMENT

SET-

POINT

RATIO DENOM NUM

MODE

SENSITIVITY

VAPOR ALARM

OUTPUT

SIG GND OUT OPT

OUTPUT
SELECT

A1395

SPARE

FUSE

1 A

FUSE 1 A

ADJUST

Setpoint

The OIL ALARM Set Point test jack is used to access the
oil alarm threshold setting. This test jack is not used with
the Film Thickness Discriminator option.

OUTPUT

The OUTPUT test jacks permit access to the NUMERA­TOR, DENOMINATOR AND RATIO outputs:

RATIO (brown)

RATIO (processed ratio of the two reflected IR beams):
0 to 10 V.

DENOM (red)

DENOMINATOR (intensity of one of two reflected IR
beams): 0 to 1 V.

NUM (blue)

NUMERATOR (intensity of the second of two reflected IR
beams): 0 to 1 V.

SIG. GND. (green)

The SIG. GND. test jacks permits access to signal
ground.

OUT. OPT.

The OUT. OPT. test jack permits access to the optional
RATIO output and is used only if an Options p.c. board
(e.g. Film Thickness Discriminator) is installed.

FUSE

Two power line fuses have been located on the front
panel for accessibility. For standard 115 V power, only
the hot line is fused. The other fuse is a spare.

OUTPUT SELECT

This switch is used to select the type of RATIO output
that is available at the junction box:

O – Optional output mode

This position is available for optional processing data
output (e.g. Film Thickness Discriminator) if the optional
board is installed.

V – Voltage output mode

This position brings the RATIO output in 0-10 VDC to ter­minal 1 of the junction box.

mA – Milliamp output mode

This position brings the RATIO output in 4-10 ma to ter­minal 1 of the junction box, if this option was installed.

INSTALLATION

INSPECTION

Since the instrument may be subjected to shock or
vibration during shipping, an inspection of the connec­tions and filterwheel is recommended.

Prior to the initial setup of the instrument, open the hous­ing (see Access to Internal Components procedure) and
check that the printed circuit board(s) are securely held
in the connector(s). If a board has become dislodged,
return it to the proper connector. The Synchronous
Demodulator Board is on the left of the filterwheel and
the Options Board is on the right (Figure 3).

Observe the location of the keys and do not attempt to
insert the printed circuit board(s) backwards. Be certain
that the board is firmly seated in the connector and that
both the top and bottom are held by the card guides.
Check that the ribbon connectors on the AGC/TE Cooler
Board and on the Rear Panel Board are fully engaged
and that the latches are locked. Rotate the filterwheel to
check that it spins freely. Check that the two receiver
connectors are securely engaged.

SITE REQUIREMENTS

The SW9200 is normally mounted from five to 30 feet
above the water surface to be monitored. It views a
small area of the water surface directly below the instru­ment. The maximum operating height is determined by
the turbulence of the water surface below the instrument.
A graph in the APPENDIX shows the maximum operating
height as a function of water turbulence, where turbu­lence is characterized by the maximum angle of the
waves.

The instrument’s viewing path down to the water must be
unobstructed. It should be placed where oil spilled on
the water is likely to be carried past the receiver’s field of
view by spreading, prevailing winds, currents, waves or
deflecting booms. An ideal site is just at a dam spillway,
where turbulence is relatively low and constant. External
hazards to the instrument, such as boat docking activity
and possible vandalism, must be taken into account
when choosing a location for instrument mounting. The
instrument’s field of view should be as far as possible (at
least 12 inches) from obstructions in the water such as
pilings, walls, ladders, etc., as such obstructions tend to
repel an oil film by breaking up the film’s surface tension.

If the instrument is installed in a high temperature, high
humidity, or corrosive atmosphere, instrument air or dry
nitrogen purge is recommended.

Do not install the instrument so that the receiver directly
faces an intense heat source.

6

CAUTION

If power is to be disconnected for an extended peri­od (e.g. over one week), the instrument should be
removed to a protected environment.

MOUNTING

The SW9200 transmitter and receiver are bolted side by
side to a user-supplied mounting platform. See Figure 4
for hole locations on the mounting plate. The transmitter
and receiver housings are attached to mounting plate as
shown in Figure 5. A suggested mounting framework is
illustrated in Figure 6.

The mounting framework must be securely stabilized to
assure retention of alignment over time and temperature
fluctuations. The framework should also be isolated
against external vibration.

A hinged mounting platform is recommended for ease of
service and adjustment. This type of platform has both a
“service” and an “operate” position, which facilitates
access to the controls without altering alignment.

INITIAL SETUP

When the inspection procedures and special precau­tions detailed above have been carefully observed, the
initial setup of the SW9200 is accomplished by following
Steps 1 through 11 below:

CAUTION

Do not remove protective window covers until Step

7.
Do not mount instrument until power is available.

In order to minimize the possibility of condensation
forming inside the instrument, once mounted the
instrument should not be left without power for
extended periods of time.

1. Attach the transmitter and the receiver to the user-

supplied mounting plate with the 3/8-16 x 1-1/2”
stainless steel bolts, nuts and washers provided with
the instrument.

2. Connect external wiring as shown in Figure 7.

CAUTION

Power wire with AC voltage closest to ground
potential should be connected to terminal “N”.
Power wire with AC voltage furthest from ground
potential should be connected to terminal “L”.

Strip the insulation back 1/4 inch. Insert the stripped
wire into the terminal under the appropriate number.
Tighten the screw above the number by turning it
clockwise using a screwdriver with a 1/8” blade. All
terminals in the junction box are numbered. Low
voltage signal lines (RATIO, NUMERATOR and SIG­NAL GROUND) and high voltage power lines from
the junction box should be in separate cables, if
possible. If the signal and power lines are not in

7 95-8409

DC POWER SUPPLIES

OPTICAL FILTER

THERMOELECTRICALLY
COOLED PHOTODETECTOR

FILTERWHEEL MOTOR

STATUS RELAY

REAR PANEL PC BOARD

CONNECTOR/RELAY PC BOARD

OPTIONS PC BOARD

SIGNAL CONNECTOR

POWER CONNECTOR

IR LENS

IR WINDOW

FILTERWHEEL

REAR PANEL PC BOARD

PREAMP GAIN CONTROL

AGC/TE COOLER PC BOARD

PREAMPLIFIER
PC BOARD

SYNC PICKOFF

A1396

DUAL RATIO PC BOARD

Figure 3—Location of Receiver Boards and Assemblies

separate cables, the high voltage power wires (115
VAC line and Power Ground) must be shielded from
the signal lines for safety reasons. Any conduit
installed must be of a flexible, explosion-proof type
which will allow 180 degree rotation of the mounting
plate and instrument and allow adjustment of the
housings for optimum alignment.

WARNING

If both conduit entrances to the junction box are
not used, the unused entrance must be fitted
with an explosion-proof pipe plug with at least
five full threads engaged.

RATIO, NUMERATOR and SIGNAL GROUND wiring
from the junction box should be connected to exter­nal readout devices of at least 5,000 ohms
impedance. If the 4-20 mA output is installed, the
loop resistance must be less than 500 ohms.

3. Connect OIL ALARM relay and STATUS ALARM
relay signal terminals (4,5,6 and 7) to external read­out devices (e.g. indicator lamps, alarm buzzers,
motors, computer interface, etc.). The Oil Alarm
relay contacts open when a film of oil is present on
the water surface. The Status Alarm relay contacts
open when an obstruction or instrument failure is
detected.

4. Connect transmitter and receiver to the power
source. DO NOT apply power.

5. In preparation for optical alignment, remove the
receiver window assembly by rotating it counter­clockwise. Avoid touching the window with bare
hands. Move the window assembly to a safe place,
being careful not to scratch the window.

6. Set the MODE selector switch on the front panel to
the ALIGN position and replace the window assem­bly.

7. Remove protective window covers from both the
transmitter and the receiver. Do not discard.

8. Be sure that the cover bolts are tight. Check tight­ness of junction boxes and window assemblies.

9. Rotate both transmitter and receiver mounts 180
degrees so that the instrument is viewing the water
surface.

10. As power is first applied to the instrument, the trans­mitter lamp should light and a faint rotation noise
may be heard within the receiver housing.

11. Allow at least one hour warmup time with the instru­ment operating continuously before proceeding to
alignment.

NOTE
The instrument is designed for continuous opera­tion. Excessive application and disconnection of
power to the transmitter will shorten the life of the
lamp.

8

4

(101.6)

4 1/2

(114.3)

4

(101.6)

4 1/2

(114.3)

2

(50.8)

2

(50.8)

10 3/4

(273.05)

10

(254)

7/16 DIAMETER

(11.11)

NOTE:

1. ALL OBSTRUCTIONS ON MOUNTING PLATFORM
MUST LI E OUTSIDE OF THE DOTTED LINE

2. OVERALL PLATE DIMENSIONS MUST BE DETERMINED
BASED ON MOUNTING FRAMEWORK DESIGN

A1456

Figure 4—Mounting Platform Hole Pattern

25

(635)

11 1/4

(285.8)

MOUNTING
PLATFORM

A1457

NOTE: USE 3/8 INCH HARDWARE

Figure 5—Mounting Platform

PADLOCK

HINGE

4 FEET

EASY ACCESS TO ALL

COMPONENTS FOR

SERVICING

EASY ACCESS
FOR ALIGNMENT
ADJUSTMENTS

A1606

Figure 6—Typical Mounting Framework (User-Supplied)

OPTICAL ALIGNMENT

Accurate alignment is generally not critical when the
water surface is turbulent, but it is quite critical when the
water surface is calm. For this reason, alignment should
be accomplished when the water surface is calm to
allow for the worst-case situation. If the water surface to
be monitored is affected by tides or storm flood varia­tions, these steps should be followed at mid-tide or the
usual water level.

While alignment is time-consuming, it can be reassuring
to note that it should not be necessary to repeat this pro­cedure for the duration of the instrument’s use at a par­ticular site. Once the correct alignment has been
achieved, the housings will be locked in position and
removal of the cover or window assemblies for servicing
should not affect the alignment of the instrument.

1. Use shims to “toe in” the transmitter and receiver so
that both appear to be aimed at approximately the
same point on the water surface directly below the
instrument, as shown in Figure 8.

2. Using the test jacks on the front panel, connect a
digital voltmeter (with a resolution of at least 1 milli­volt DC) between the NUMERATOR output (blue)
and SIGNAL GROUND (green).

NOTE
All voltage readings must be taken using a DC volt­meter with a 10 Megohm input impedance. Use of
other devices will give inaccurate readings.

3. Change the transmitter angle slightly and note the
change in the voltage observed in Step 3. If the
voltage decreases, change the angle in the opposite
direction to increase the NUMERATOR voltage.

9 95-8409

HEIGHT ABOVE WATER

SEPARATING DISTANCE

θθ

A1455

Figure 8—Alignment of Transmitter and Receiver

Assuming Assuming

14.5 Inches 368.3 Millimeters

Height Diameter Separation Angle Separation Angle Shim Thickness

Above Water Monitored From Vertical From Vertical Under Box

(Feet) (Meters) (Inches) (Millmeters) (Degrees) (Degrees) (Inches) (Millimeters)

5 1.52 3.00 76.20 6.89 21.63 0.544 13.811
10 3.05 6.00 152.40 3.46 11.21 0.272 6.906
15 4.57 9.00 228.60 2.31 7.53 0.181 4.604
20 6.10 12.00 304.80 1.73 5.66 0.136 3.453
25 7.62 15.00 381.00 1.38 4.53 0.109 2.762
30 9.14 18.00 457.20 1.15 3.78 0.091 2.302

Figure 7—System Interwiring Diagram

4. When the maximum possible voltage has been
obtained and recorded with the transmitter, adjust
the receiver angle until a maximum NUMERATOR
signal strength is obtained. Record the voltage.

5. Repeat Steps 3 and 4 to maximize the NUMERATOR
output.

6. Once optimum alignment has been obtained, care­fully tighten the mounting nuts with a wrench, being
careful to maintain the proper angle of alignment
obtained in the previous steps.

7. Return the MODE selector switch on the front panel
to the OPERATE position.

OPERATION/PERFORMANCE CHECK

SIGNAL STRENGTH

The NUMERATOR voltage should be measured to deter­mine if the signal strength reflected from the water sur­face and received by the instrument is within the proper
range. This voltage will decrease as the water surface
becomes more turbulent and will increase as the water
surface calms. The NUMERATOR voltage should be
observed under the worst-case surface turbulence con­ditions as well as with the calmest water surface possi­ble.

1. Observe and record the NUMERATOR voltage
under the worst-case water surface turbulence con­ditions.

2. If the voltage drops below +0.25 VDC, increase the
preamplifier gain as described in Step 3.

3. To adjust the preamplifier gain, follow the Access to
Internal Components procedure (see MAINTE­NANCE section) and locate the Preamplifier p.c.
board within the heat sink fins. The Preamplifier
Gain Adjustment potentiometer is located on the
Preamplifier p.c. board and can be reached by
inserting a screwdriver between the fins from the
bottom of the heat sink (as viewed when the cover is
open but attached to the housing by its hinges).
Turn the Preamplifier Gain Adjustment potentiometer
clockwise to increase the preamplifier gain.

4. Observe and record the NUMERATOR voltage with
very calm water surface conditions.

5. If the voltage exceeds +0.75 VDC, decrease the
preamplifier gain by turning the Preamplifier Gain
Adjustment potentiometer counterclockwise.

OUTPUT ZERO

The Output Zero (RATIO) is factory set for oil-free water.
The Output Zero (RATIO) should be checked periodical­ly and the ZERO potentiometer should be adjusted when
necessary.

1. With the instrument viewing oil-free water and both
transmitter and receiver windows in place, record
the RATIO voltage at the junction box (TERMINAL

1). If the RATIO voltage is not 1.0 ±0.5 VDC, the
ZERO potentiometer should be adjusted as
described in the following steps.

2. Remove the receiver window and locate the ZERO
potentiometer on the front panel.

3. If the RATIO voltage recorded in Step 1 was higher
than 1.0 ±0.5 VDC, rotate the ZERO potentiometer
counterclockwise until the RATIO output is within the
desired range.

4. If the RATIO voltage recorded in Step 1 was lower
than 1.0 ±0.5 VDC, rotate the ZERO potentiometer
clockwise until the RATIO output is within the
desired range.

OIL RESPONSE CONFIDENCE TEST

To verify that the instrument is responding to the pres­ence of an oil film on the water surface:

1. With power applied to the instrument, connect a dig­ital voltmeter between the RATIO output (brown) and
SIG. GND. (green) on the front panel, or on the
appropriate terminals in the junction box.

2. With the instrument viewing clean water, introduce a
small amount of test oil - either in a test pan or on
the actual water surface being monitored.

3. The RATIO should increase above +2.0 VDC. If the
RATIO output does not increase, consult
Troubleshooting Table.

STATUS ALARM CONFIDENCE TEST

To verify that the instrument status alarm is working
properly:

1. With power applied to the instrument, block the
beam with an opaque object.

2. The Status Alarm should activate within 120 sec­onds. If Status Alarm does not activate, contact the
factory for assistance.

10

INSTRUMENT OUTPUT

The 0-10 VDC RATIO output is available on all SW9200
instruments at the RATIO (brown) test jack on the front
panel, and at terminal 1 of the receiver junction box
when the OUTPUT SELECT switch is set to position V
(volts). When viewing an oil film using the standard 0-10
VDC output, the RATIO output will vary according to the
type and severity of the oil spill. The output does not
increase linearly with film thickness. Generally, a thin
film of oil will give a RATIO output between +1.5 and +10
VDC, with wide fluctuations due to irregularities in the
film. Thicker oil films (greater than 10 um average thick­ness) tend to produce a steady RATIO output between
+3.0 and +7.0 VDC.

An optional Film Thickness Discriminator can be ordered
with the instrument. Located on the Options p.c. board,
this option converts the standard 0 to 10 VDC RATIO
output to a “high” -”low” output. With the Film Thickness
Discriminator option, the OUTPUT SELECT switch on the
front panel must be set on the O position (options).
When a “thin” film (less than 10 micrometers) is
observed, the RATIO output will be a positive voltage
(approximately +1.0 VDC). When a “thick” film (greater
than 10 micrometers) is observed, the RATIO output will
be a negative voltage (approximately -15.0 VDC).

The Selectable Criteria Alarm option, located on the
Options p.c. board, delays the activation of the oil alarm
relay until either of two selectable conditions are met.

NOTE
If either the Film Thickness Discriminator or
Selectable Criteria Alarm Option has been pur­chased with the SW9200, additional information will
be found in the APPENDIX.

An optional 4-20 mA output can be ordered with the
instrument or can be field installed at any time after pur­chase. The 4-20 mA output option, located on the
Options p.c. board, converts the standard RATIO output
from 0 to 10 VDC to 4-20 mA. If installed, the 4-20 mA
output will be available at terminal 1 of the receiver junc­tion box when the OUTPUT SELECT switch on the front
panel is set to the mA position. The 4-20 mA current can
be tested by removing the RATIO wire in the junction
box and connecting a current meter between the RATIO
wire and terminal 1. The 4-20 mA output will drive a
user-supplied load of 0 to 500 ohms. The 4-20 mA out­put is surge protected by transient protection devices.

NOTE
The Film Thickness Discriminator, the Selectable
Criteria Alarm and the 4-20 mA Output options can­not be used in combination in the SW9200.

The RATIO output in this manual is indicated in 0-10
VDC. For instruments using the 4-20 mA output, the
standard 0-10 VDC output can be read at the RATIO test
jack (brown) on the front panel or at the receiver junction
box when the OUTPUT SELECT switch is set to the V
position. In addition, a voltage to current transfer curve
is provided in the APPENDIX.

Outputs should be monitored as required by the particu­lar application. When the instrument views clean water,
the RATIO voltage will be between 0.5 and +1.5 VDC.
The voltage levels at the outputs of the NUMERATOR
and DENOMINATOR will vary according to the water
surface condition.

If the above mentioned indications do not occur, or in
the event of a prolonged instrument status alarm, consult
the Troubleshooting Table.

OIL ALARM THRESHOLD ADJUST­MENT

Based on the specific application of the instrument,
select the RATIO voltage threshold at which the Oil
Alarm will activate. The Oil Alarm is factory set at +2.0
VDC. To test the SW9200’s sensitivity to oil films, allow it
to view clean water and then add a small quantity of oil
to the water, either in a test pan or on the water surface
being monitored. Appropriate containment and cleanup
procedures must be carefully followed to avoid violation
of Federal, state or local regulations. If the oil alarm acti­vates at a smaller quantity of oil than required by the
instrument’s application, instrument sensitivity may be
slightly decreased (or increased) by the following proce­dure:

1. Attach a digital voltmeter between the OIL ALARM
SETPOINT jack (grey) and SIG. GND. (green) on the
front panel.

2. Adjust the OIL ALARM ADJUST potentiometer on
the front panel so that the Oil Alarm set point voltage
is slightly lower than the desired RATIO output.

NOTE
The oil alarm threshold adjustment is disabled
when the Film Thickness Discriminator optional p.c.
board is used.

The oil alarm threshold adjustment provides the
definition of “oil observation” for the Selectable
Criteria Alarm Option. See the APPENDIX for infor­mation on the alarm criteria settings for this option,
if installed.

11 95-8409

INFRARED PHOTODETECTOR
TEMPERATURE ADJUSTMENT

The infrared photodetector is thermo-electrically (TE)
cooled to increase its sensitivity to infrared light and to
maintain a constant sensitivity over a wide range of
ambient air temperatures. Two temperature settings are
available on the AGC/TE Cooler p.c. board. The JP-1
setting (two left pins) maintains the detector temperature
at approximately -20oC and the JP-2 setting (two right
pins) maintains a temperature of approximately 0oC.
The coolest temperature setting (JP-1) should be used
under normal ambient conditions and for normal and
long operating heights. The JP-2 setting should be used
for short operating heights and in extremely hot environ­ments where the cooler may not be able to maintain a
constant -20oC temperature.

Section 3

Maintenance

GENERAL PRECAUTIONS

As with all precision electro-optical equipment, care
must be taken to avoid sharp blows to the instrument.
Do not drop it or allow heavy objects to strike it. Do not
touch the windows, lenses, lamps, filters, or other optical
surfaces with bare hands. Customary precautions for the
use of explosion-proof instruments in hazardous environ­ments should be observed. In procedures where either
cover, window assembly, or junction box are to be
opened when circuits are alive, first ensure that no haz­ardous vapor conditions exist.

WARNING

Live line voltage is exposed at several points within
the SW9200. This is potentially dangerous, and
contact by maintenance personnel must be avoid­ed.

ACCESS TO INTERNAL COMPONENTS

All internal components of the transmitter and receiver
are mounted to the cover (see Figure 3). Access to
these components is obtained either by swinging open
the cover on its hinges, or by removing the cover and
associated components from the housing.

1. Disconnect all power to the instrument. Rotate the
mounting plate 180 degrees so that the instrument
faces up.

2. Remove the 20 bolts which hold the cover to the
housing.

3. Swing open the cover to permit access to the con­nector(s). DO NOT OPEN the receiver cover more
than three inches, to prevent undue stress on the
connector(s).

4. Disconnect the connector plug(s) from the recepta­cle(s). The transmitter has one connector and the
receiver has two connectors. The instrument can be
inspected or serviced on-site while the cover is
opened and attached by its hinges. If service is to
be performed off-site, the cover and attached com­ponents may be removed from the housing as
described in Step 5.

5. With the cover swung open, lift the cover up to dis­engage the hinges. Care must be taken to avoid
scratching the flanges or damaging the internal
components.

Each time the instrument housing is opened for mainte­nance, the desiccant pack should be checked. When
the desiccant is expanded only slightly, no change is
necessary. If it is expanded to twice or more its original
size, the desiccant should be replaced. Extra desiccant
packets are available from Detector Electronics (see
Recommended Spare Parts List). DO NOT replace the
desiccant until all other maintenance procedures have
been completed. Remove the old desiccant by cutting
the strings that attach it to the power supply wiring.
Remove the plastic bag on the replacement packet and
tie it to the power supply wiring. Be sure that the desic­cant packet is securely attached to the power supply
wiring so that it cannot come loose inside the housing.
Close the cover immediately after replacing the desic­cant.

To reattach the cover to the instrument housing:

1. Holding the cover completely open, slide the cover
hinge pins onto the housing hinges. Do not tighten
the hinge screws.

2. If necessary, replace the desiccant pack.

3. Reconnect the plug(s) and receptacle(s) in the
housing and close the cover. Guide the cable to
insure that it is not pinched.

4. Rotate the mounting plate 180 degrees so that the
instrument is in position for operation.

12

SCHEDULED MAINTENANCE

NOTE
To avoid dropping assemblies, tools, etc., into the
water, it is recommended that all maintenance pro­cedures be accomplished with the mount and
instrument rotated up to face the technician.

It is recommended that the following maintenance pro­cedures be performed periodically as described:

Maintenance Procedure Scheduled Interval

12 mo. 24 mo.

Clean exterior optical components X
Clean interior optical components X
Replace filterwheel motor X
Replace 250W lamp* X*
Replace desiccant X

*

Interval is dependent on line voltage (see Replacement

of Transmitter Lamp procedure).

CLEANING OF OPTICAL COMPONENTS

Exterior (12 month interval) - Due to the gradual accumu­lation of dust, chemical deposits, or other foreign matter,
the exterior optical surfaces must be cleaned at least
every twelve months. In some applications, cleaning of
the windows may be required more frequently. The
need for cleaning can usually be detected by a gradual
decrease in the NUMERATOR and DENOMINATOR out­puts and/or by visual inspection of the optical surfaces.

1. Disconnect all power to the instrument.

NOTE
If possible, direct a flow of clean, oil-free com­pressed air onto the optical surfaces before and
after cleaning.

2. Clean the outer surfaces of the transmitter and
receiver windows with clean cotton swabs and alco­hol. Finish with clean optical tissue. DO NOT
TOUCH the windows or other optical surfaces with
bare hands.

3. Reconnect the instrument and reapply power.

Interior (24 month interval) - Interior optical components
(inside surface of window, lens, filters and sync pickoff)
should be cleaned every two years. Although it is possi­ble to perform all these procedures on-site, a lab envi­ronment is preferable as it is cleaner and easier to work
in. (See ACCESS TO INTERNAL COMPONENTS.)

Window

Interior windows are reached by removal of the transmit­ter and receiver window assemblies. Clean as
described in exterior optical cleaning procedure above.

Lens, Sync Pickoff and Optical Filters

1. Remove motor and filterwheel by following
Replacement of Filterwheel Motor procedure.

2. The lens is located in the center of the receiver
baseplate. Using clean cotton swabs and alcohol,
clean both sides of the lens. Finish with clean opti­cal tissue.

3. The sync pickoff is located at the center of the Rear
Panel p.c. board on the inside of the motorbox. The
optical surfaces are located on the inside of the “U”
shaped device. Using clean cotton swabs and alco­hol, clean both optical surfaces of the sync pickoff.
Remove any excess alcohol and completely dry the
surfaces with clean, dry cotton swabs.

4. The optical filters are located in the filterwheel,
which is attached to the motor shaft. Clean both
sides of each filter using clean cotton swabs and
alcohol. Finish with clean optical tissue.

REPLACEMENT OF FILTERWHEEL MOTOR (12 month
interval)

It is recommended that this procedure be performed in a
lab environment. (See ACCESS TO INTERNAL COMPO­NENTS). Cleaning of interior optical components should
be done after the filterwheel motor is removed. Power
should be disconnected for this procedure.

1. The receiver cover and internal components should
be placed so that the open side of the motorbox
faces the technician and so that the power supplies
are to the left. The assembly should be securely
propped during this procedure to avoid damage to
the internal components.

2. Remove the Sync Demod and Options p.c. boards
and disconnect the motor connectors. Note the
routing of the wires.

3. While holding the motor still, remove the four 6-32
screws that attach the motor and standoffs to the
front panel.

13 95-8409

4. Avoiding contact with the sync pickoff on the Rear
Panel p.c. board, carefully slide the motor and
attached filterwheel out of the motorbox. Viewing
ports have been provided on each side of the motor­box to permit visual inspection of the position of the
filterwheel relative to the sync pickoff.

5. Remove the nut that holds the hub to the filterwheel
and detach the filterwheel from the hub. DO NOT
TOUCH the optical filters with bare hands.

6. Remove the nut from the replacement motor hub
and slide the filterwheel onto the replacement motor
shaft. Make sure that the side of the filterwheel with
the filter retaining rings/fan blades is facing toward
the body of the motor. Replace the nut, using low
strength thread locking compound on the threads of
the hub. Make sure the compound is thoroughly
dried before rotating the filterwheel.

7. Replace the motor/filterwheel assembly ensuring
that the filterwheel edge is straddled by the sync
pickoff. Check that the filterwheel does not come
into contact with the sync pickoff during rotation.
Route the wires so that they are not in front of the
lens.

8. Replace the four screws that hold the motor to the
front panel. Reconnect the motor connectors.

REPLACEMENT OF TRANSMITTER LAMP (Variable
Interval)
Replacement of the 250 watt lamp is dependent on the
line voltage at the installation:

LINE VOLTAGE EXPECTED 250 W LAMP LIFE

*

130 VAC 2,000 hours
123 VAC 4,000 hours
117 VAC 8,000 hours
111 VAC 16,000 hours

*

Repeated application and disconnection of power to
the instrument or excessive shock/vibration can signifi­cantly reduce the expected lamp life.

WARNING

Do not inspect the transmitter while the lamp is
operating. To avoid possible eye damage, discon­nect instrument power before checking.

To replace the transmitter lamp, use the following proce­dure:

1. Disconnect all power to the instrument.

2. As an additional precaution, disconnect power wires
at the junction box.

3. Remove the window assembly from the transmitter
housing by rotating it counterclockwise.

4. Move the window assembly to a safe place, being
careful not to scratch the window.

5. Remove the old lamp by rotating it counterclockwise
in the socket. DO NOT TOUCH the transmitter
reflector with bare hands.

NOTE
DO NOT TOUCH the lamp envelope with bare fin­gers. Use lamp wrapper provided with new lamp,
clean white gloves, or clean optical tissue when
inserting a new lamp. Also, be careful to avoid
touching the inner surface of the reflector.

6. Install the new lamp by rotating it clockwise until it is
firmly seated in the socket. Replacement lamps are
available from the factory. (See Recommended
Spare Parts List.)

7. Be sure that the lamp is centered in the reflector and
does not touch the edge of the reflector opening. If
the lamp is touching the reflector, gently apply side­ways pressure to bend the lamp/socket assembly
until it is no longer touching the reflector opening
and is centered. Use clean gloves, tissue, etc., and
do not touch the reflector surface or lamp envelope
with bare hands, since acid from the fingertips will
etch the lamp envelope and materially reduce the
life of the lamp.

8. Replace the window assembly and tighten down
securely until at least five full threads are engaged.

9. Check tightness of cover bolts and window assem­blies on both housings.

10. Reconnect power wires in the junction box.

11. Close and recheck tightness of junction box cover.

12. Reapply power.

13. Repeat Optical Alignment procedure.

14

TROUBLESHOOTING

For assistance in rectifying set-up problems and simple
malfunctions, consult the Troubleshooting Table.

If malfunctions cannot be corrected by carefully follow­ing the procedures described in this manual, contact the
factory for assistance. In many cases, sufficient informa­tion to correct the malfunction can be provided over the
telephone. If it is necessary to contact the factory by
telephone, it is helpful to have the operation and mainte­nance manual accessible and to obtain the following
readings for the service technician:

Instrument S/N_______________________________
Optionspurchased____________________________
RATIO _______________ VDC
DENOMINATOR _______________ VDC
NUMERATOR _______________ VDC
Oil Alarm Set Point ____________ VDC
Operating Height _____________ FT

General Description of Water Surface (Calm,
Turbulent, Oily, Flow Rate, etc.):
__________________________________________________
____________

Both field and factory service are available from Detector
Electronics. If it becomes necessary to return an instru­ment to the factory, extreme care must be taken in pack­ing the instrument for shipment. The monitor should be
enclosed in a plastic bag, surrounded with at least two
inches of foam or shipping pellets on all sides and
shipped in a heavy duty carton. Lack of sufficient cush­ioning can cause extensive damage to internal compo­nents. It is not usually necessary to return the transmitter
and, if carefully packed, just the receiver cover and
attached components can be shipped without the hous­ing.

15 95-8409

TROUBLESHOOTING TABLE

SYMPTOM: Transmitter lamp does not light.

POSSIBLE CAUSE: No power to transmitter.
CHECK: Voltage into transmitter. Should be nameplate voltage rating (±10%).
REMEDIAL ACTION: If wrong voltage, check external fusing or defective power wiring to transmitter.

POSSIBLE CAUSE: Defective lamp.
CHECK: Voltage into transmitter before concluding that the lamp is defective.
REMEDIAL ACTION: See Replacement of Transmitter Lamp procedure.

SYMPTOM: Transmitter lamp consistently burns out before 6 months.

POSSIBLE CAUSE: Constant high line voltage.
CHECK: Voltage into transmitter. Should be nameplate voltage rating (±10%).
REMEDIAL ACTION: Reduce power line voltage.

POSSIBLE CAUSE: Excessive vibration or shock at transmitter.
CHECK: Environment at transmitter.
REMEDIAL ACTION: Alter mechanical environment at transmitter with vibration isolators, etc.

POSSIBLE CAUSE: Repeated application and removal of power to the transmitter.
CHECK: History since installation.
REMEDIAL ACTION: Maintain power to the instrument at all times.

SYMPTOM: Transmitter lamp lights, but no output voltage on NUMERATOR relative to SIGNAL

GROUND.

POSSIBLE CAUSE: No power to receiver.
CHECK: Voltage into receiver. Should be nameplate voltage rating (±10%).
REMEDIAL ACTION: If wrong voltage, check external fusing or defective power wiring to receiver.

POSSIBLE CAUSE: Fuse blown in receiver.
CHECK: Listen for faint sound of filterwheel motor in receiver.
REMEDIAL ACTION: If filterwheel is not turning, replace fuse.

POSSIBLE CAUSE: Filterwheel motor failure.
CHECK: Is filterwheel rotating?
REMEDIAL ACTION: If filterwheel does not rotate after replacing fuse, see Replacement of Filterwheel Motor pro-

cedure.

POSSIBLE CAUSE: Transmitter and receiver not properly aligned.
CHECK: NUMERATOR voltage when a flashlight or 60W light bulb is held in front of receiver window.

Voltage should increase from zero.

REMEDIAL ACTION: Repeat Alignment procedure.

SYMPTOM: NUMERATOR voltage relative to SIGNAL GROUND exceeds 0.75 VDC or drops below

0.25 VDC after proper alignment.

POSSIBLE CAUSE: Improper Preamplifier Gain setting.
REMEDIAL ACTION: See Step 3 and Step 5 of Signal Strength Operation/Performance Check.

16

SYMPTOM: RATIO voltage is negative or 4-20 mA output is below 4 mA.

POSSIBLE CAUSE: The ZERO adjustment potentiometer located on the front panel is not set properly.
CHECK: Setting of ZERO adjustment potentiometer on front panel.
REMEDIAL ACTION: Adjust ZERO potentiometer until RATIO is 1.0 ±0.5 VDC (See Output Zero OPERATION/

PERFORMANCE CHECK procedure).

POSSIBLE CAUSE: Instrument malfunction.
CHECK: NUMERATOR and DENOMINATOR voltage when a bare flashlight bulb or bare 60 watt light

bulb is held in front of the receiver window.

REMEDIAL ACTION: Replace printed circuit boards one at a time and repeat CHECK. Contact factory if fault

cannot be located.

SYMPTOM: RATIO voltage is steady and does not appear to be responding to oil within field-of-

view.

POSSIBLE CAUSE: Malfunction of signal processing circuitry.
CHECK: RATIO voltage when a small amount of oil is introduced within the instrument’s field of view.

The RATIO voltage should increase above +2.0 VDC.

REMEDIAL ACTION: Substitute spare boards and assemblies until defective part is located and RATIO responds

properly to oil. Defective part can be returned to factory for analysis and repair.

SYMPTOM: Oil Alarm does not activate when oil is present in instrument’s field-of-view, or Oil

Alarm activates too frequently.

POSSIBLE CAUSE: Improper Oil Alarm threshold setting.
CHECK: Voltage at OIL ALARM SETPOINT test jack (grey) relative to SIGNAL GROUND (green).
REMEDIAL ACTION: Adjust setpoint if required. See Oil Alarm Threshold Adjustment procedure.

POSSIBLE CAUSE: Malfunction of Oil Alarm circuitry.
CHECK: RATIO voltage relative to voltage on OIL ALARM SETPOINT jack. If RATIO voltage exceeds

alarm setpoint, and alarm does not activate, a malfunction of alarm circuitry exists.

REMEDIAL ACTION: Replace Rear Panel p.c. board and/or Oil Alarm relay on Connector/Relay p.c. board.

SYMPTOM: Signal strength of NUMERATOR and DENOMINATOR decreases when water becomes

calm.

POSSIBLE CAUSE: Transmitter and receiver not properly aligned.
REMEDIAL ACTION: Repeat Alignment procedure.

SYMPTOM: RATIO output is negative or very positive and does not respond to oil on the water.

POSSIBLE CAUSE: Transmitter and receiver not properly aligned.
CHECK: NUMERATOR voltage.
REMEDIAL ACTION: If NUMERATOR voltage is less than +0.25 VDC, repeat Alignment procedure.

17 95-8409

CORRECTIVE MAINTENANCE

GENERAL INFORMATION

The SW9200 electronics, located in the receiver, are comprised of six printed circuit boards and electrical wiring and
components located on the Receiver Baseplate and the Motorbox. Two of the printed circuit boards are permanently
mounted and the other four are easily removed and replaced as indicated below:

P.C. BOARD PERMANENT OR REMOVABLE

Preamplifier permanent

AGC/TE Cooler removable

Synchronous Demodulator removable

Rear Panel removable

Options removable

Connector/Relay permanent

The receiver functions described in Section 1 and Figure 1 of this manual are located on a printed circuit board or
assembly as shown below:

RECEIVER FUNCTION LOCATION

Infrared Photodetector Detector/Preamp Assembly

Sync Circuitry Rear Panel and Sync Demod p.c. boards

Amplifier Preamp and Sync Demod p.c. boards

Signal Processing Electronics AGC/TE Cooler and Sync Demod p.c. boards

Ratiometer Rear Panel p.c. board

Threshold Detector Rear Panel p.c. board

Obstruction/Status Alarm Relay Connector/Relay p.c. board

Adjustable Threshold Detector Rear Panel p.c. board

OIL Alarm Set Rear Panel p.c. board (accessed from front panel)

Oil Alarm Relay Connector/Relay p.c. board

4-20 mA Converter Options p.c. board

Assemblies and printed circuit boards are available as spare parts. To facilitate troubleshooting and corrective main­tenance of the SW9200, users are advised to stock the items listed in the Recommended Spare Parts List.

P.C. BOARD AND ASSEMBLY REPLACEMENT

(See Figure 3 for locations)

Synchronous Demodulator and Options P.C. Boards

The Sync Demod board is located to the left and the Options board is located to the right of the filterwheel motor
inside the motorbox. Remove either board by pulling it out of its connector on the Rear Panel p.c. board and sliding it
through the card guides out of the motorbox. To replace the Sync Demod or Options board, make sure that the notch
on the board matches the key in the connector and slide the board along the card guides into the motorbox. Make
sure that the board is seated firmly in the connector.

18

Rear Panel P.C. Board

The Rear Panel p.c. board is attached to the side of the
motorbox next to the Connector/Relay p.c. board. The
Sync Demod and Options board must be removed
before the Rear Panel board can be removed.

To remove:

1. On the Connector/Relay p.c. board, remove the

STATUS ALARM and OIL ALARM relays from their
sockets.

2. Release the ribbon connector that connects the

Rear Panel board to the Connector/Relay board.

3. Remove the six screws that hold the Rear Panel

board to the motorbox tabs.

4. Pull the top of the Rear Panel board away from the

motorbox to release the two connectors at the top of
the board.

5. Being careful not to touch the sync pickoff with the

filterwheel, remove the board.

To replace:

1. Being careful not to touch the sync pickoff with the

filterwheel, slide the board into place.

2. Firmly press the connectors at the top of the board

into the mating connectors on the motorbox.

3. Attach and lock the ribbon connector to the

Connector/Relay p.c. board.

4. Replace the six screws that hold the Rear Panel

board to the motorbox tabs.

5. Examine the wire lug (connected to the green wire)

that is screwed to the Rear Panel board. Be sure
the lug does not short against any traces on the p.c.
board. It may be necessary to space the lug away
from the board with a small lockwasher.

6. Replace the STATUS ALARM and OIL ALARM relays

in their sockets on the Connector/Relay p.c. board.

Because the sync pickoff can easily be dislodged during
this procedure, check the sync pickoff connection after
replacement of the Rear Panel p.c. board.

AGC/TE Cooler P.C. Board

The AGC/TE Cooler board is mounted in the Detector/
Preamp assembly within the fins of the heat sink.

To remove:

1. Release the ribbon connector that connects the

AGC/TE Cooler board to the Preamplifier board,
which is permanently attached to the bottom of the
heat sink.

2. Holding the ribbon connector to the side, pull the
AGC/TE Cooler board so that the connector to the
motorbox disengages. Slide the board out of the
heat sink fins.

To replace:

1. Position the board so that the two parts of the con­nector to the motorbox are lined up.

2. Holding the ribbon connector to the side, slide the
board into the fins of the heat sink as far as it will go,
so that the connector to the motorbox engages.

3. Attach and lock the ribbon connector from the
Preamplifier board.

Detector/Preamp Assembly

The Detector/Preamp assembly is comprised of the
infrared photodetector mounted inside a baffle, an opti­cal filter, the heat sink and the permanently mounted
Preamplifier p.c. board. The Detector/Preamp assembly
is located on the top of the motorbox, beside the power
supplies.

NOTE
Exposure to direct light (particularly fluorescent light
or sunlight) can cause permanent damage to the
infrared photodetector. Care should be taken to
avoid exposing the photodetector to light when the
Detector/Preamp assembly is removed from the
instrument.

To remove:

1. Remove the four 6-32 screws that hold the assembly
to the motorbox.

2. Lift the assembly up until the baffle clears the motor­box.

To replace:

1. Position the assembly over the motorbox so that the
connector and hole for the baffle are aligned.

2. Slide the assembly into place.

3. Replace the four 6-32 screws that hold the assembly
to the motorbox.

Sync Pickoff

The sync pickoff is mounted in a socket that is located in
the center of the Rear Panel p.c. board. The sync pick­off is removed by pulling it from the socket. To replace
the sync pickoff, install with the red dot up (toward the
motorbox connectors).

19 95-8409

DEVICE REPAIR AND RETURN

Prior to returning devices or components, contact the
nearest local Detector Electronics office so that an RMI
(Return Material Identification) number can be assigned.
A written statement describing the malfunction must
accompany the returned device or component to expe­dite finding the cause of the failure, thereby reducing the
time and cost of the repair to the customer.

Pack the unit or component properly. Use sufficient
packing material in addition to an anti-static bag or alu­minum-backed cardboard as protection from electrostat­ic discharge.

Return all equipment transportation prepaid to the
Minneapolis location.

Office Locations
Detector Electronics Corporation

6901 West 110th Street
Minneapolis, Minnesota 55438 USA
Telephone [phone] or (800) 765-FIRE
Telex 6879043 DETEL UW
Cable DETRONICS
Facsimile [phone]

Detector Electronics Corporation
3000 Wilcrest
Suite 145
Houston, Texas 77042 USA
Telephone [phone]

Detector Electronics Corporation
466 Conchester Highway
Aston, Pennsylvania 19014 USA
Telephone [phone]
Facsimile [phone]

Detector Electronics (UK) Limited
Riverside Park, Poyle Road
Colnbrook
Slough, Berkshire
SL3 OHB
ENGLAND
Telephone [phone]
Telex 848124 GRAVIN G
Facsimile 0753 684540

Detronics Scandinavia AB
Box 81
S-260 83 Vejbystrand
SWEDEN
Telephone [phone]
Facsimile 431-52236

Detector Electronics Europe S.r.l.
Milano I-20143
Via Carlo D’Adda, 5
ITALY
Telephone [phone]
Facsimile 39 2 89407638

Detronics AB
Rochussenstraat 49A
3015 Ec Rotterdam
HOLLAND
Telephone [phone]
Facsimile 010-436-0296

Det-Tronics Deutschland
Walter Kidde GmbH
Postfach 1457
Harkortstrasse 3
D-4030 Ratingen 1
GERMANY
Telephone [phone]
Direct 49 2102 405152
Facsimile 49 2102 405109
Telex 8589029

Detectomatic S.A.
AV17 Con Calle 72, No. 71-92
Apartado 10055
Maracaibo, Venezuela
Telephone [phone]
Facsimile 58-61-529144
Telex 61331

Detector Electronics Corporation
C/O Walter Kidde Aerospace
The ADELPHI
No. 1 Coleman Street #05-02
SINGAPORE, 0167
Telephone [phone]
Facsimile (65) 334-1607

20

ORDERING INFORMATION

RECOMMENDED SPARE PARTS

Description Part Number

Transmitter lamp (250 watt) 102709-001
Filterwheel motor - 115 VAC 006624-001
1 Amp Fuse 107407-002
Alarm Relay, 115 VAC 102590-001
Alarm Relay, 230 VAC 102589-001
Desiccant Pack 102669-001
2 Inch Diameter Lens 005616-001
Test Power Cable 005791-001

Sync Demod p.c. board 005795-001
AGC/TE Cooler p.c. board 005797-001
Detector/Preamp assembly 005798-001

Rear Panel - standard or 4 to 20 mA 005794-004
Rear Panel - Film Thickness 005794-005
Rear Panel - Selectable Criteria 005794-006

Film Thickness Discriminator 005828-001
Selectable Criteria Alarm 005829-001
Single 4 to 20 mA Output 005793-001

For assistance in ordering a system to meet the needs of
a specific application, please contact:

Detector Electronics Corporation
6901 West 110th Street
Minneapolis, Minnesota 55438 USA
Telephone [phone] or (800) 765-FIRE
Telex 6879043 DETEL UW
Cable Detronics
Facsimile [phone]

APPENDIX

This APPENDIX contains:
Film Thickness Discriminator Option

Selectable Criteria Alarm Option
Maximum Operating Height Graph
Voltage to Current Transfer Curve

Receiver Interconnections....................C2322-R130XC

FILM THICKNESS DISCRIMINATOR
OPTION

GENERAL DESCRIPTION

The oil slick detector bounces a beam of light off an
oil/water surface below and analyzes the reflected opti­cal signal. The optical signal reflected from a thin oil film
(average thickness of less than 10 micrometers) pro­duces a RATIO output between +1.0 and 10.0 VDC with
wide fluctuations due to irregularities in the film. The sig­nal reflected from a thick oil film (average thickness
greater than 10 micrometers) produces a steady RATIO
output between +4.0 and +7.0 VDC. The optional Film
Thickness Discriminator printed circuit board processes
the differences between the reflected signals and pro­vides information on whether a thin or thick oil film has
been detected.

FUNCTIONAL DESCRIPTION

In the first stage of processing, the RATIO signal into the
Film Thickness Discriminator is simultaneously com­pared with a “window” and differentiated (the rate of
change is measured).

“Window” Condition

The RATIO signal is compared with a “window”, where
the upper limit is set by the potentiometer labeled “upper
window” and the lower limit is set by the potentiometer
labeled “lower window” on the printed circuit board.
When the RATIO output is within the “window” limits, the
voltage at the green test point is positive. When the
RATIO output is either above or below the “window”, the
voltage at the green test point is negative. The “window”
voltages are adjustable and are usually factory set at
+4.0 VDC for the lower window and +7.0 VDC for the
upper window.

Rate of Change Condition

The RATIO signal is fed into a differentiator, which sens­es the rate of change of the signal. When the RATIO out­put is steady and unchanging, the yellow test point is
positive. When the RATIO output is either increasing or
decreasing, the yellow test point is negative.

21 95-8409

The final output stage of the Film Thickness
Discriminator compares the RATIO voltage conditions
from the first processing stages. If the RATIO voltage is
within the “window” and is steady (the conditions
required for a thick film), the blue test point voltage is
negative and the oil alarm is activated. If the RATIO volt­age is above or below the “window” or is not steady
(either condition indicating a thin film), the blue test point
voltage will be negative and the oil alarm will not be acti­vated.

SPECIFICATIONS

Specifications of the optional Film Thickness
Discriminator printed circuit board are tabulated below:

Power Consumption: less than 0.1 Watts
Alarm: Alarm relay is activated

and contacts open.

Alarm Response Time - ON: approximately 70 sec-

onds for an abrupt
change from clean water
to a continuous thick film
– longer if the thick film
has breaks in it.

Alarm Response Time - Off: approximately 5 seconds

for an abrupt change
from a continuous thick
film to clean water.

INSTALLATION

If the Film Thickness Discriminator board is ordered with
the instrument, the optional printed circuit board is
installed and ready for operation. If this option has been
ordered after the delivery of the instrument, one opera­tional amplifier (A211) on the inside of the Rear Panel
p.c. board must be removed prior to installation of the
Film Thickness Discriminator board. Removing A211
disables the normal oil alarm condition where the relay is
activated on either thin films or thick films. The Film
Thickness Discriminator board is then plugged into the
Options p.c. board connector (see Figure 3 and P.C.
Board and Assembly Replacement procedure in the
MAINTENANCE Section of this manual).

SELECTABLE CRITERIA ALARM
OPTION

GENERAL DESCRIPTION

An optional printed circuit board for the Oil Slick
Detector, the Selectable Criteria Alarm option adds con­siderable flexibility in selecting the criteria and condi­tions under which the oil alarm will activate. This option
delays activation of the oil alarm relay until either of the
following conditions is met:

1. The time of uninterrupted oil observation*exceeds a
preset duration between 1 and 999 seconds. The
duration of oil observation is set in one second
increments by direct reading thumbwheel switches
labeled OIL DURATION (SECS) on the printed cir­cuit board.

2. The percentage of accumulated time during which
oil observation*exceeds a preset percentage mea­sured over a 1000 second interval. The percentage
of accumulated time is set in increments of 10% by
a direct reading thumbwheel switch labeled %OIL
(X10) on the printed circuit board.

*Oil observation is defined by the oil alarm threshold set­ting.

NOTE
When either of the above conditions is met, the oil
alarm relay activates (contact open) for approxi­mately 60 seconds, then deactivates (contacts
close). If oil film is constantly present in the detec­tor’s field of view, the oil alarm will close twice
(once for each criteria) for approximately 60 sec­onds every 1000 seconds.

For example, if the OIL DURATION switches are set for
20 seconds, the oil alarm relay will activate after the
instrument observes any continuous slick that exceeds
20 seconds in duration. However, if a large spill occurs
where the resulting slick observed by the instrument has
small 1 second breaks of clean water every 15 seconds
(due to turbulence, wind action, etc), the oil alarm relay
will not activate because no continuous period of oil
observation exceeds 20 seconds in duration. The inter­nal timer is reset every time clean water is observed.
The alarm will not activate even though the water surface
is covered with oil 94% of the 1000 second measure­ment cycle (15 out of every 16 seconds).

Following the same example, if the %OIL switch is set at
10%, the oil alarm relay will activate after the total accu­mulated time of oil observation exceeds 10% of the 1000
second measurement cycle or 100 seconds. The oil
alarm relay will activate 106 seconds after the oil slick

22

described began. The six extra seconds are the result
of six 1 second intervals of clean water that were
observed during the first 100 seconds of the measure­ment cycle.

INSTRUMENT OUTPUT

If the OUTPUT SELECT switch on the front panel is set
on position V, the RATIO output at terminal 1 of the junc­tion box will be the standard 0 - 10 VDC. If the O posi­tion is used, the RATIO output at the junction box will be
0 VDC when the OIL Alarm relay contacts are closed
and approximately -14 VDC when the Oil Alarm relay
contacts are open.

INSTRUMENT SENSITIVITY

The instrument can be decreased in sensitivity to nui­sance oil in the water or to residual sheens by increasing
either the OIL DURATION thumbwheel setting or the
%OIL thumbwheel setting, or both. Likewise, the instru­ment can be increased in sensitivity to small spills by
decreasing either the OIL DURATION thumbwheel set­ting or the %OIL thumbwheel setting, or both. The opti­mum settings for the alarm conditions depend on the
user’s requirements and the condition of the water sur­face at the installation site. The settings are best deter­mined by trial and error until the nuisance alarm rate due
to residual or background oil is reduced to an accept­able level.

The factory settings for the Selectable Criteria Alarm
board are 60 seconds and 50%. These settings can be
changed without removing the receiver assembly from
the housing. Open the receiver cover and locate the
Selectable Criteria Alarm board to the right of the filter­wheel motor. The yellow thumbwheel switch at the top of
the board is %OIL (X10). The other three white thumb­wheel switches are OIL DURATION (SECS). The top
switch is units, the second switch is tens and the bottom
switch is hundreds.

OIL ALARM RELAY CLOSURE

The Oil Alarm relay contacts are closed when clean
water is observed. When oil film is observed by the
instrument, the Oil Alarm relay contacts will open after a
delay of N seconds (N is the setting of the OIL DURA­TION switches). The Oil Alarm relay contacts will remain
open for approximately 60 seconds and then will close,
even if oil is still present. If oil continues to be observed,
the Oil Alarm relay contacts will close again for approxi­mately 60 seconds each 1000 seconds until the oil spill
is removed.

23 95-8409

WAVE ANGLE (DEGREES)

θ

100

10

1

OPERATING HEIGHT (FEET)

A1608

1 10 100

Relationship of Wave Angle to Operating Height

Printed in USA
Detector Electronics Corporation

6901 West 110th Street •Minneapolis, Minnesota 55438 USA
Tel: [phone] or 800.765.3473 •Fax: [phone]