Heathus OMD Manuale utente
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OMD™ USER’SOMD™ USER’S
OMD™ USER’SOMD™ USER’S
OMD™ USER’S
Manual
Heath Consultants Incorporated
Houston, TX
713/844-1300
Fax: 713/844-1309
1-800-HEATH-US
www.heathus.com Heath....Leadership, Innovation, Performance
Then, Now and Tomorrow
RevD
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TABLE OF CONTENTS
SPECIFICATIONS ............................................................................5
CHAPTER I
OVERVIEW ......................................................................................7
CHAPTER II
INSTALLATIONPROCEDURE ...................................................... 10
Crossbar Installation ......................................................................10
Additional Notes On Crossbar Installation..................................... 11
Power Box Installation ................................................................... 12
Cable Assemblies Installation ........................................................13
Display Installation .........................................................................14
Display Connectors ........................................................................15
Vehicle Grounding Strap ................................................................15
Protective Cage..............................................................................16
CHAPTER III
OPERATING PROCEDURE ...........................................................18
Start Up..........................................................................................18
Display Function.............................................................................20
HOLD ........................................................................................20
LIGHT........................................................................................21
SAMPLE....................................................................................22
PPM Range....................................................................................23
Alarm Set Point ..............................................................................25
Error Messages..............................................................................26
Shut Down......................................................................................27
CHAPTER IV
ALIGNMENT PROCEDURE...........................................................28
Lamp Alignment .............................................................................29
Receiver Alignment ........................................................................30
CHAPTER V
CALIBRATIONCHECK .................................................................31
Verifying Calibration With Internal Cell ..........................................31
Verifying Calibration With External Cell .........................................32
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CHAPTER VI
MAINTENANCEINFORMATION...................................................34
General .........................................................................................34
Recommended Spare Parts..........................................................34
Troubleshooting.............................................................................34
CHAPTER VII
SERVICEINFORMATION .............................................................37
Warranty and Warranty Repairs ....................................................37
Customer Assistance and Service Locations ................................38
Appendix A
SURVEY PROCEDURES - MOBILE OMD™ ................................40
Appendix B
DRAWINGS...................................................................................55
USINGADOBE ACROBAT READER ............................................60
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SYSTEM SPECIFICATIONS
OMDTM System Specifications
Configuration: Double - ended
Sensitivity: 1 PPM / meter CH4
Measurement Range: 1 to 200 PPM
Accuracy: ± 10% (1 to 100 PPM range)
± 20% (100 to 200 PPM range)
Above 200 PPM = Not relatively
accurate
Display Ranges: 10, 30 and 90 PPM
Self - test: During boot – up
Calibration/Test: Via operator, self - contained
Calibration: Via RS-232 through software
Base - Line Compensation: Via RS-232 through software
Display: Back-lit 2" x 6" graphics LCD,
adjustable contrast
Operator Interface: Sealed membrane switch overlay
Operator Alarms:
Signal: High pitch audible with
adjustable set point, pitch
increases with concentration.
Adjustable volume.
Error: Low pitch audible with
adjustable set point
Error alarms
provided for: Warm-up,LowLight,
CommunicationFailure&
Batterylow
SystemPower: 72 Watts @ 12 VDC
System Voltage: 12 - 16 VDC
NOTE: To avoid damage to the OMD™power box, the fuse
must be removed prior to charging or jumping the battery
in the survey vehicle!
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SYSTEM SPECIFICATIONS
SystemWeight:
External Sub - Systems: 17 pounds
Power Box 6 pounds
Internal Display 3 pounds
Cables 4 pounds
CrossbarAssemblyLength: 63.25, 32, 51.25in. ±2in.
MechanicalMounting: Strutbracketmount
Installation Time: 2 hours, typical
External Housing Rating: NEMA 3S and IP 54
Display Housing Rating: Spill proof
External Sub -
System Materials: Aluminum and plastic
Environmental PCB Control: Conformal PCB coating
Operating Temperature
Range: - 22°F to 122°F
Operating Humidity Range: 5 to 100 % RH, non-condensing
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Chapter I
OVERVIEW
The Optical Methane Detector (OMD™), is the first of the
“next generation” leak detection systems which address the
high cost presently associated with leak surveying. This new
technology combines sensitivity, selectivity and speed through
the combined use of optics and electronics. The OMD is
mounted on the front of a survey vehicle and detects the pres-
ence of methane in air. It provides for the detection of gas
leaks down to 1 part per million (PPM). It has no moving parts
that will prevent the instrument from operating. It requires no
support gases and is virtually maintenance free.
Based on the absorption of infrared (IR) radiation by methane,
the OMD consists of an IR light source directed at an IR
optical detector. These two are spaced approx. four feet apart
across the width of the vehicle. An optical filter in front of the
detector transmits primarily methane specific IR wavelengths
from the light source. In the absence of methane, these wave-
lengths are unaffected and produce a steady output signal from
the detector. When the vehicle passes through a plume of
natural gas, methane in the plume will absorb some of the IR
light reaching the detector. As a result there is a sudden de-
crease in IR light at the detector causing a decrease in detector
output. This change in detector output is transmitted to the
display panel located next to the vehicle’s driver and becomes
a signal, both audio and visual. Gas concentration is calculated
in the OMD by converting the methane to light ratio to PPM.
The data is displayed in both analog and digital form. The
analog display appears as a peak scrolling across the display
screen. The OMD will also detect other hydrocarbons such as
ethane and propane but with less than half the sensitivity.
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TheOMDoperatesreliablyunderavarietyof environmental
conditions including dry weather, snow, ice and temperatures
from-22° F to+122° F. Itssensitivity,calibration or response|is
notaffectedbysmall fluctuations in thelightbeamorbyreasonable
amountsofdust,or snow ontheoptics. Aninternalcalibrationtest
cellisincludedso the operatorcanverifyproperoperationfrom the
vehiclecabat any timebefore,duringor after aleaksurvey. An
InstallationMountingKitisavailableformountingtheOMDtothe
frontofavehicle. Allinterconnectingcablingisprovidedwith the
OMDincludingthecableto obtain powerto operatetheinstrument
fromthesurveyvehicle 12 voltbattery. AnRS232 port isincluded
wherebya personal computermaybe connected toacquire and
save the survey data with the appropriate software.
Depending on local meteorological conditions, a given amount
of gas escaping from the ground will produce a plume that
varies in size and uniformity of concentration levels. The
plume, of its very nature, defies quantification by fixed or
moving detectors. Regardless of these uncertainties, it is of
paramount importance to be able to detect gas when gas is
present. Concentration levels of the measured gas are of
interest, but are of secondary importance. Consequently, the
ability of a detector to detect the plume with accuracy and
precision is not as important as its ability to do so with good
sensitivity (or a low detection limit) and with a minimum of
false alarms.
There are two kinds of false alarms: false negatives and false
positives. False negatives occur when a leak is missed. The
detector is saying there is no gas present when, in fact, a leak
was present but undetected. False positives occur when the
detector says that a gas leak is present when it really is not.
Examplesoffalsepositives experienced includethedetectionof
OVERVIEW
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autoexhaust and swamporsewer gas. Due totheselectivity of the
OMD,falsepositivescausedbyauto exhaust are greately mini-
mized.
NEW
Experienced operators should use their discretion. Operators
should take into account that the wind must be favorable,
towards the path of the OMD light bar, to obtain the optimum
results. Increased speed from FID survey comes from the
instantaneous response of the OMD; however, there are a
variety of factors to consider such as, legal limits, terrain and
inclement weather for the OMD operation. Please refer to
the GPTC Guide for Transmission and Distribution Piping
Systems: 1998-2000 Guide Material Appendix G-192-11
Section 4 Leak Detection, 4.4 Leakage surveys and test
methods (a) Surface Gas Detection Survey. Part (3) Utiliza-
tion. The use of this survey method may be limited by ad-
verse conditions (such as excessive wind, excessive soil
moisture or frost or surface sealing by ice water). The survey
should be conducted at speeds slow enough to allow an
adequate sample to be continuously obtained by placement of
equipment intakes over the most logical venting locations,
giving consideration to the location of the facilities and any
adverse conditions which might exist.
OVERVIEW
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Chapter II
INSTALLATION PROCEDURE
It is virtually impossible to predict the exact installation proce-
dure for every different type of vehicle on the market. There
are some details that will have to be worked out on the spot
with your particular vehicle and here are a few ideas to con-
sider.
There are five parts to consider when installing the OMD: 1)
The crossbar assembly, 2) The power box, 3) The cable assem-
blies, 4) The display unit, and 5) Vehicle Grounding Strap.
Crossbar installation:
The OMD components are pre-aligned at the factory and
should not require re-alignment when the system is installed on
the vehicle. It is, however, important that the u-bolts be at-
tached in such a way that they do not bend the support rod.
The u-bolts should be tight enough to hold the OMD crossbar
securely in place, but not so tight as to distort the crossbar. If
that happens, re-alignment may be required. We recommend
using only two insulated u-bolts to mount the OMD crossbar to
minimize the possibility of distorting the crossbar. The follow-
ing procedure will generally work best.
For your convenience, we have put together an OMD mounting
kit, which includes strut channels, shelf brackets, u-bolts and
mounting hardware (Heath P/N 2510651).
Use two strut channels that are approx. 24” long each (Heath P/
N 2510652). These strut channels are mounted vertically to
the front bumper of your vehicle, parallel to each other and
approx. three feet apart. It is most fortunate if you have a front
bumper that is relatively flat vertically, in which case the strut
channels can be mounted directly to the bumper. If the bumper
Indice
