Scott Instruments 4688IR Series Manual instruction

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Rev: 4688IR (G)
Date: 10/30/03
CN: 3209
Part #087-0007G
IR
Series 4688IR/4679IRSeries 4688IR/4679IR
Series 4688IR/4679IRSeries 4688IR/4679IR
Series 4688IR/4679IR
Operation & Maintenance Manual
THREE KEY POINTS TO OPERATIONAL SAFETY
To assure both personnel and facility safety, it is extremely
important to observe all transmitter installation and operational
safety requirements. The three key points listed below may be
found in the contents of this manual.
#1 - Install the system correctly following all local, state, and
federal guidelines.
#2 - Perform regular operational tests on the transmitter. This
helps ensure the unit is functioning properly.
#3 - Maintain a zero adjustment log for each transmitter and
adhere to the schedule. Infrared combustible gas transmitters
require periodic zero adjustment in order to continue to operate
accurately. Failure to properly operate and maintain this
instrument could result in serious injury.
! SAFETY FIRST !
®
SERIES 4600-IR
ESC
IR
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1
Model 4688-IR / Model 4679-IR
Operation & Maintenance Manual
Manual #087-0007G, 10/2003
Transmitter Quick Start
1. Mount and wire the transmitter (See "Transmitter Installation").
2. Apply power to the transmitter. All segments and indicators on the
display will turn on for 2 seconds, then will turn off for 2 seconds. The
transmitter will subsequently enter a 30 second warm-up period
(countdown shown on the display).
3. Select the gas to be detected.
a. Touch the magnet to the up arrow key and observe
"USER" on the display.
b. Touch the magnet to the E key and observe
"A1.SP" is the first parameter to be displayed.
c. Repeatedly touch (or hold to scroll) the magnet to
the UP key until the display shows "SR.GN." Touch
the E key.
d. The display should read "1". Use the Up or Down arrow keys to
change the number to the appropriate gas as shown in the following
table below. See Appendix 3 for gas cross-sensitivity tables.
e. When the display has the correct gas, touch the magnet to the E
key and observe the display read "SEt". Then, touch the magnet to the
Z key 3 times until the display shows "RUN."
The instrument is now ready to operate! Consult the manual
for more information on the instrument's many features.
Parameter SR.GN = Gas Notes
Standard
Gas Set
1
2
3
4
5
6
10
Methane
Ethane
Propane
Butane
Pentane
Hexane
Propylene
Extended
Gas Set
9
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Ethylene
Acetone
IPA
MEK
Toluene
Methanol
Butadiene
Pure Methane
20% Hexane
Ethanol
Benzene
Xylene
Isobutanol
Rotosolv-1
Cyclohexane (0-60% LEL)
Only ONE
"extended" gas
can be selected
on tran s m itte rs
ordered with
th is o pti o n.
Other standard
gases are still
selectable.
Model
4679IR CO2
Gas
Detector
ONLY
64 Carbon Dioxide
Hydrocarbon
settings are
not available
AL1 AL2 FAULT
INHIBIT MAINT
AL1 AL2 FAULT
INHIBIT MAINT
ESC
IR
SERIES 4600-IR
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2
Model 4688-IR / 4679-IR
Operation & Maintenance Manual
Manual #087-0007G, 10/2003
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3
Model 4688-IR / Model 4679-IR
Operation & Maintenance Manual
Manual #087-0007G, 10/2003
Contents
Start-Up, General Information, & Installation _________ 5
Introduction _____________________________________________ 6
Principle of Operation _____________________________________ 6
Other Gas Sensitivities - Model 4688-IR ONLY __________________ 6
Lower Explosive Limit - Model 4688-IR ONLY ___________________ 7
Suitability For Use in Hazardous Locations _____________________ 7
Using a Flowcell _________________________________________ 7
General Instrument Overview Map _________________________ 8
Transmitter Installation _____________________________________ 9
Installation Considerations _________________________________ 9
Using the Rain Shields and Filters __________________________ 10
Wiring and Power _______________________________________ 12
Mounting the Transmitter __________________________________ 13
Powering The Transmitter _________________________________ 15
Installation Drawings _____________________________________ 16
Transmitter Operation ________________________________ 21
Basic Instrument Adjustments ______________________________ 22
Navigating the Instrument _________________________________ 22
RUN Mode _____________________________________________ 22
How to Adjust Transmitter Parameters _______________________ 22
Adjusting LCD Display Contrast ____________________________ 23
Acknowledging Latched Alarms ____________________________ 24
Inhibiting Output ________________________________________ 24
Zeroing the Transmitter ___________________________________ 24
Adjusting the Loop Output Parameters _______________________ 26
Setting Alarm and Sensor Parameters ___________________ 27
Relay N.O./N.C. Status ___________________________________ 27
Optional Alarm Relays ____________________________________ 28
Sensor Parameters______________________________________ 30
Report Generation______________________________________ 30
Setting Transmitter Security________________________________ 31
The LOCK Menu ________________________________________ 31
Toggling Parameter Security On/Off (LK.ON) __________________ 32
Changing the Password (LK.PW) ___________________________ 32
Auto-Lock Timer (LK.tM) __________________________________ 32
Instrument Parameter Change Example ___________________ 33
Serial Communications ________________________________ 35
Setting Up for Digital Communications ___________________ 36
Using MODBUS®Serial Communications _________________ 38
Configuring the Master Device and Tagging Data Elements _______ 38
Registers, Coils, and Addresses ____________________________ 39
Accessing Parameter Data - The ABCs of Reading and Writing ___ 40
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4
Model 4688-IR / 4679-IR
Operation & Maintenance Manual
Manual #087-0007G, 10/2003
Writing a Parameter to Memory ___________________________ 41
Instrument Navigation & Parameter Reference_______ 43
Parameter Navigation Map ________________________________ 44
The USER Menu _____________________________________________ 45
Alarm Relay Parameters __________________________________ 45
Sensor Parameters______________________________________ 46
The LOCK Menu ____________________________________________ 49
The COMM Menu ___________________________________________ 50
Loop Current Parameters _________________________________ 50
Report Generator Parameters _____________________________ 50
Serial Communication Parameters __________________________ 52
The FACT Menu ________________________________________ 54
Maintenance, Troubleshooting, & Product Support ____ 55
Maintenance ________________________________________________ 56
Routine Maintenance_____________________________________ 56
Periodic Maintenance ____________________________________ 57
Troubleshooting ____________________________________________ 62
General Difficulties ______________________________________ 62
Fault Codes ____________________________________________ 63
Resetting Factory Defaults _________________________________ 66
Contacting Scott Instruments _______________________________ 66
Technical Specifications _____________________________________ 67
Appendix 1 - MODBUS®Registers & Coil Addressing ______ 68
Addresses _____________________________________________ 68
MODBUS®Read-Only Register Descriptions __________________ 69
Appendix 2 - (FSR) Command Functions ___________________ 71
Appendix 3 - Instrument Cross-Sensitivity _________________ 74
Record Your Parameters!___________________________________ 76
Spare Parts & Accessories __________________________________ 77
Scott Instruments Warranty ________________________________ 78
Statement of Year 2000 Compliance ___________________________ 78
Index________________________________________________________ 79
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5
Model 4688-IR / Model 4679-IR
Operation & Maintenance Manual
Manual #087-0007G, 10/2003
Start-Up, General
Information, &
Installation
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6
Model 4688-IR / 4679-IR
Operation & Maintenance Manual
Manual #087-0007G, 10/2003
Introduction
The GasPlus-IR 24VDC powered INFRA-RED GAS TRANSMITTER uses
infrared absorption technology to monitor the level of combustible
hydrocarbon gases (Model 4688-IR) or CO2(Model 4679-IR) in the
surrounding atmosphere and transmits an analog (4-20 mA) or digital
(Modbus®) signal that is proportional to the measured concentration. The
output signal is linear for the specific gas being measured. Linearization
curves for numerous gases are built into the instrument and are user
selectable.
The instrument features 2 alarm relays capable of indicating high and high-
high alarm conditions, and a separate relay for indicating faults (relays are
optional). A local display reports concentration readings in units of either
%LEL or %V/V (user selectable), as well as system status. The operator
panel interface uses a Scott Instruments magnetic screwdriver for accessing
the system parameters and may be password protected. Non-intrusive user
setup and calibration permits operation and maintenance from within
classified areas.
Principle of Operation
Infrared radiation propagating from an incandescent emitter passes through a
volume of gas, then is reflected by a mirror onto 2 fixed detectors. One
detector is tuned to a wavelength that is absorbed by hydrocarbons or CO2,
while the other detector is tuned to a nearby wavelength that is not absorbed.
The ratio of the output voltages of the 2 detectors is used to compute the
concentration of gas. As gas concentration increases, the incremental output
produced by the detectors decreases. The instrument then uses a gas-
specific algorithm to linearize the signal. Since the amount of infrared
absorption differs with each gas, the instrument's cross-sensitivity will vary.
For example, an instrument setup to detect methane, which absorbs less
infrared radiation than most other hydrocarbons, will produce high readings
when exposed to most other combustible gases.
Other Gas Sensitivities - Model 4688-IR
ONLY
The Model 4688-IR is specifically tuned to detect certain hydrocarbon gases
and will not detect non-hydrocarbon combustibles such as NH3, H2, etc. Scott
Instruments' Model 4600 GasPlus Universal Toxic Gas Transmitter provides
an excellent solution for many of these gases. Hydrocarbons not listed as
available (see parameter SR.GN) may or may not be detectable by the
transmitter. Consult the factory for further information.
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7
Model 4688-IR / Model 4679-IR
Operation & Maintenance Manual
Manual #087-0007G, 10/2003
Lower Explosive Limit - Model 4688-IR ONLY
Combustible gas mixtures can be ignited only between certain concentration
limits. These limits are known as the Lower Explosive Limit (LEL) and the
Upper Explosive Limit (UEL). When these terms are used, it is assumed that
a normal atmospheric air background (20.9% O2) is present. For example,
the LEL for methane is a concentration of 5.00 %V/V (volume per volume) in
air.
Combustible gas sensors are designed to operate at concentrations under
the LEL, and typically the readings are calibrated in %LEL. For methane, 100
%LEL is defined as a concentration of 5.00% in air; 50% LEL is defined as a
concentration of 2.5%, and so on. If the reading is under 100% LEL, the gas
at the sensor cannot ignite. However, even very low readings indicate that
there may be a significant gas leak at some distance from the sensor.
Readings exceeding 100% LEL are possible.
Suitability For Use in Hazardous Locations
The Models 4688-IR and 4679-IR are designed to be acceptable for use in
Class 1, Zones 1 and 2, Groups B, C, and D hazardous (classified) locations
(these locations are approximately equivalent to Class 1, Division 1 and 2,
Groups B, C, and D, as defined in the pre-1996 NEC). The instrument
accomplishes this primarily through the use of the explosion-proof method of
protection (Ex d). The 1 exception is the heater which uses the intrinsically-
safe (Ex ib) method of protection.
Using a Flowcell
When using the GasPlus-IR with a flowcell, it is important to recognize that
output will vary with gas pressure. The Ideal Gas Law establishes a
relationship between pressure and the number of molecules. Where
P=pressure, V=volume, n=number of molecules, R=gas constant, and
T=temperature): P V = nRP V = nR
P V = nRP V = nR
P V = nRTT
TT
T
If temperature is held at a constant, the number of molecules in a given
volume of gas (gas density) will vary linearly with pressure. Since the amount
of infrared absorption increases with gas density, the higher the pressure in
the flowcell with respect to atmospheric, the higher the instrument's
concentration output will be (and vice-versa). Note that the flowcell pressure
can be either positive (i.e., gas is being pushed into the flowcell) or negative
(i.e., gas is being pulled through the flowcell).
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