RKI Instruments Digester Gas Monitor User Manual
Digester Gas Monitor
Operator’s Manual
Part Number: 71-0266RK
Revision: 0
Released: 10/9/14
www.rkiinstruments.com
WARNING
Read and understand this instruction manual before operating
detector . Improper use of the dete ctor could result in bodily harm
or death.
Periodic calibration and maintenance of the detector is essential
for proper operation and correct readings. Please calibrate and
maintain this detector regularly! Frequency of calibration
depends upon the type of use you have and the sensor types.
T ypical calibration frequencies for most applications a re between
3 and 6 months, but can be required more often or less often
based on your usage.
Digester Gas Monitor Operator’s Manual
Product Warranty
RKI Instruments, Inc. warrants gas alarm equipment sold by us to be free from defects in
materials, workmanship, and performance for a period of one year from date of shipment
from RKI Instruments, Inc. Any parts found defective within that period will be repaired or
replaced, at our option, free of charge. This warranty does not apply to those items, which
by their nature, are subject to deterioration or consumption in normal service, and which
must be cleaned, repaired, or replaced on a routine basis. Examples of such items are as
follows:
a) Absorbent cartridges d) Batteries
b) Pump diaphragms and valves e) Filter elements
c) Fuses
Warranty is voided by abuse including mechanical damage, alteration, rough handling, or
repair procedures not in accordance with the operator’s manual. This warranty indicates
the full extent of our liability , and we are not responsible for removal or replacement costs,
local repair costs, transportation costs, or contingent expenses incurred without our prior
approval.
THIS WARRANTY IS EXPRESSLY IN LIEU OF ANY AND ALL OTHER
WARRANTIES AND REPRESENTATIONS, EXPRESSED OR IMPLIED, AND
ALL OTHER OBLIGATIONS OR LIABILITIES ON THE PART OF RKI
INSTRUMENTS, INC., INCLUDING BUT NOT LIMITED TO, THE WARRANTY
OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. IN NO
EVENT SHALL RKI INSTRUMENTS, INC. BE LIABLE FOR INDIRECT,
INCIDENTAL, OR CONSEQUENTIAL LOSS OR DAMAGE OF ANY KIND
CONNECTED WITH THE USE OF ITS PRODUCTS OR FAILURE OF ITS
PRODUCTS TO FUNCTION OR OPERATE PROPERLY.
This warranty covers instruments and parts sold to users by authorized distributors,
dealers, and representatives as appointed by RKI Instruments, Inc.
We do not assume indemnification for any accident or damage caused by the operation of
this gas monitor, and our warranty is limited to the replacement of parts or our complete
goods.
Digester Gas Monitor Operator’s Manual
Table of Contents
Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
About the Digester Gas Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Chapter 2: Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
External Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Reset Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Buzzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Inlet and Exhaust Fittings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Internal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Display PCB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Main PCB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Termination Jumper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Ground Stud. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Power Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Power Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
AC & DC Circuit Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Regulator and Gauge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Flow Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Flow Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Flowmeters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Hydrophobic Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Water Trap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Dryer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Solenoid Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Check Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Factory Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Optional Horn/Strobe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Chapter 3: Installation and Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Mounting the Digester Gas Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Wiring the Digester Gas Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Connecting the AC Power Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Connecting the DC Power Source. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
RS-485 Modbus Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Connecting External Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Digester Gas Monitor Operator’s Manual Table of Contents
Connecting Recorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Making Fitting Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Compression Fitting Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Hose Barb Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Starting Up the Digester Gas Monitor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Adjusting the Flow Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Chapter 4: Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Detection Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4 - 20 mA Signal Output Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Viewing and Resetting Min/Max Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Battery Charging (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Alarm Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Alarm 1 Condition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1
Alarm 2 Condition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2
Alarm 3 Condition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3
Fail Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Flow Fail Condition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4
Low DC Power Condition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Chapter 5: Global Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Viewing and Changing Global Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Chapter 6: Configuration Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Viewing and Changing Channel Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Chapter 7: Input Setup Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Selecting the Detector Head Input Type and Gas Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Chapter 8: Calibration Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Calibration Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Entering Calibration Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Calibration Timeout Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Performing a Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Performing a Fresh Air Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Performing a Gas Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Viewing Maximum Spans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Chapter 9: RS-485 Modbus Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Wiring the Digester Gas Monitor in a Modbus System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Table of Contents Digester Gas Monitor Operator’s Manual
Recommended Modbus Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Termination Jumper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Using the Digester Gas Monitor in a 4-wire Modbus System . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Modbus Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Supported Modbus Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Chapter 10: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Sensor Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Replacing the Methane Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Replacing the Oxygen Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Replacing the H
Replacing the CO
Replacing the Air Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Replacing the Hydrophobic Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Replacing the Oil Mist Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Replacing the Water Trap Filter Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Replacing the AC Fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
S Sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
2
Sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
2
Digester Gas Monitor Operator’s Manual Table of Contents
Chapter 1: Introduction
Overview
This chapter briefly describes the Digester Gas Monitor. This chapter also describes the
Digester Gas Monitor Operator’s Manual (this document). Table 1 at the end of this
chapter lists the specifications for the Digester Gas Monitor.
About the Digester Gas Monitor
The Digester Gas Monitor is a fixed-mounted, four channel gas monitor that detects
methane, oxygen, carbon dioxide, and hydrogen sulfide. All four sensors may not be
installed in all versions of the Digester Gas Monitor. Gas readings and other messages are
indicated on an LCD display. All user adjustable parameters may be accessed using the
control switches on the display PCB.
The Digester Gas Monitor is designed to monitor digester conditions in a corrosive
environment with high humidity and high levels of H
in sample.
S. It requires compressed air to draw
2
The Digester Gas Monitor includes audible and visual alarms that warn you of hazardous
gas conditions. The alarm circuits include up to three levels of gas alarms. The fail circuit
alerts you to failures in the Digester Gas Monitor.
The Digester Gas Monitor has two modes of operation. They are Normal Operation during
which all samples are taken and Calibration Mode that enables you to calibrate the
Digester Gas Monitor’s active channels. It also has four selection menus that allow you to
configure various Digester Gas Monitor channel and instrument parameters: the Global
Menu, Configuration Menu, Input Setup Menu, and Modbus Menu.
About this Manual
The Digester Gas Monitor Operator’s Manual is organized as follows:
• Chapter 1 is an introduction to the Digester Gas Monitor.
• Chapter 2 describes the components of the Digester Gas Monitor.
• Chapter 3 describes the installation and start-up procedures of the Digester Gas
Monitor.
• Chapter 4 describes the operatio n of the Digester Gas Monitor.
• Chapter 5 describes the Global Menu which allows you to set instrument parameters.
• Chapter 6 describes the Configuratio n Menu whic h allo ws you to set channel
parameters.
• Chapter 7 describes the Input Setup Menu which allows you to set the input type for
each channel.
• Chapter 8 describes Calibration Mode which allows you to calibrate the Digester Gas
Monitor’s active channels.
• Chapter 9 describes the Digester Gas Monitor’s RS-485 Modbus output.
Digester Gas Monitor Operator’s Manual Overview • 1
• Chapter 10 describes the Digester Gas Monitor’s maintenance requirements and
procedures.
The Digester Gas Monitor Operator’s Manual uses the following conventions for notes,
cautions, and warnings:
NOTE: Describes additional or critical information.
CAUTION: Describes potential damage to equipment.
WARNING: Describes potential danger that can result in injury or death.
Caution: refer to accompanying documentation
!
~ Vac (AC voltage)
Vdc (DC voltage)
2 • About this Manual Digester Gas Monitor Operator’s Manual
Specifications
Table 1 lists specifications for the Digester Gas Monitor.
Table 1: Digester Gas Monitor Specifications
Description Specification
Detection
Methane
(CH
)
4
Oxygen (O
) Carbon
2
Dioxide (CO
Range
Alarm Points
0 - 100%
volume
Alarm 1:
100% volume
Alarm 2:
100% volume
Alarm 3:
100% volume
0 - 25%
volume
Alarm 1:
4% volume
(increasing)
Alarm 2:
25% volume
(increasing)
0 - 50%
volume
Alarm 1:
50% volume
Alarm 2:
50% volume
Alarm 3:
50% volume
Alarm 3:
25% volume
(increasing)
NOTE: There are different versions of the Digester Gas Monitor. Some versions may
not have all four gas sensors installed.
Input Power 100/115/220V ~ ±10%, 50/60Hz, 1.0/1.0/0.5A
or
24 V ± 10%, 2.5A VDC
Maximum
140 PSI
Compressed
Air Sample
Pressure
)
2
Hydrogen Sulfide (H
0 - 1000
ppm
Alarm 1:
1000 ppm
Alarm 2:
1000 ppm
Alarm 3:
1000 ppm
0 - 3000
ppm
Alarm 1:
3000 ppm
Alarm 2:
3000 ppm
Alarm 3:
3000 ppm
S)
2
0 - 5000
ppm
Alarm 1:
5000 ppm
Alarm 2:
5000 ppm
Alarm 3:
5000 ppm
Minimum
Regulator
Output PSI
No Sample Lines Connected: Regulator output set to 25 PSI
Maximum Recommended Sample Lines Connected: Regulator output set to
45 PSI
Required
Recommended
3.0 SCFH
Sample Flow
Rate
Compressed
63 liters maximum per detection cycle
Air Usage
Construction
Fiberglass/polyester with lexan window (NEMA 4X)
(housing)
Dimensions 24.0 in. H x 24.0 in. W x 10.0 in. D
(61.0 cm H x 61.0 cm W x 25.4 cm D)
Weight 45 lbs. (including horn/strobe)
Digester Gas Monitor Operator’s Manual Specifi cations • 3
Table 1: Digester Gas Monitor Specifications
Environmental
Conditions
• For indoor or outdoor locations (Type 4X)
• 0°C to 40°C (32°F to 104°F) max. ambient
• Maximum humidity of 95% relative
User Controls • Reset switch
• Control switches: ESCAPE, UP/YES, DOWN /NO, and ENTER
• Regulator output knob
•H
S Dilution Air and H2S Dilution Sample flowmeter valves
2
Relays
• Relay contacts rated for 10A @ 115/220V~ resistive or 10A @ 30V
resistive
• SPDT, Form C (common, normally open, and normally closed contacts)
Standard
Operator’s manual (this document)
Accessory
Optional
Horn/strobe
Accessory
WARNING: When using the Digester Gas Monitor, you must follow the instructions
and warnings in this manual to assure proper and safe operation of the
Digester Gas Monitor and to minimize the risk of personal injury. Be sure
to maintain and calibrate the Digester Gas Monitor as described in this
manual.
4 • Specifications Digester Gas Monitor Operator’s Manual
Chapter 2: Description
,
Overview
This chapter describes the Digester Gas Monitor’s external and internal components.
External Description
This section describes the housing and all external components of the Digester Gas
Monitor. For the purposes of this description, the housing door is considered the front of
the monitor.
BlowBackExhaust Calibration Gas Inlet
Dryer
Exhaust
Digester
Sample
Compressed
Air Inlet
Figure 1: External Component Location
Housing
The Digester Gas Monitor’s fiberglass housing is weather- and corrosion-resistant. It is
suitable for installation where general purpose equipment is in use. The housing door is
hinged on the left side and is secured by two latches on the right side. The LCD display,
status LEDs, and flowmeters are visible through the window in the housing door. Four
mounting feet are attached to the back of the housing (one at each corner). The mounting
feet allow you to install the housing to a vertical surface. These mounting feet are not
installed as shipped from the factory (see “Mounting the Digester Gas Monitor” on page 22
for instructions to install the mounting feet). Three conduit hubs on the bottom of the
housing are for external wiring connec ti ons .
FreshAir Inlet
Reset Switch
Push Button
Buzzer
Conduit Hub, 3/4"Aspirator/Sample, Exhaust
Reset Switch
The reset switch is on the bottom right of the housing in front of the buzzer. The reset
switch serves four functions:
• Resets the alarm circuits for “latched” alarms after an alarm 1, alarm 2, or alarm 3
condition passes.
You can set each channel for latched or self-resetting alarms in the Configuration
Menu. See “Viewing and Changing Channel Parameters” on page 51 for more
information.
Digester Gas Monitor Operator’s Manual Overview • 5
• Silences the buzzer during an alarm 1, alarm 2, or alarm 3 condition if the alarm
buzzer silence parameter in the Global Menu is set to CAN SILENCE BUZZER. See
“Viewing and Changing Global Parameters” on page 47 for more information on
setting the silence feature.
• Silences and resets the optional horn/strobe during an alarm 1, alarm 2, or alarm 3
condition if the strobe alarm setting parameters are set to Resettable STROBE in the
Configuration Menu. See “Viewing and Changing Channel Parameters” on page 51
for more information on setting the strobe alarm setting parameters.
• Silences the buzzer and optional horn/strobe if the fail silence parameter in the Global
Menu is set to CAN SILENCE FAIL. See “Chapter 5: Global Menu” on page 47 for
instructions to change this parameter.
• Displays and resets the minimum and maximum gas concentration values detected.
Buzzer
The buzzer is on the bottom right of the housing, behind the reset switch. The buzzer
sounds an audible alarm to warn you of gas alarms and instrument failures.
Inlet and Exhaust Fittings
There are a total of 7 fittings on the bottom of the Digester Gas Monitor housing.
Fresh Air Inlet
The fresh air inlet is a compression fitting and is located just to the left of the reset switch.
It accepts 1/4 inch OD rigid metal or rigid plastic tubing. The tubing connected to this inlet
needs to be routed to a fresh air environment.
Calibration Gas Inlet
The calibration gas inlet is a hose barb fitting and is located just to the left of the fresh air
inlet. It accepts 3/16 inch ID flexible tubing and is used to connect a calibration cylinder to
the Digester Gas Monitor during a calibration.
Blow Back Exhaust
The blow back exhaust fitting is a hose barb fitting and is located near the front left of the
Digester Gas Monitor’s bottom panel. This fitting allows debris removed during the blow
back procedure to be expelled. It accepts 3/16 inch ID flexible tubing.
Dryer Exhaust
The dryer exhaust fitting is a compression fitting and is located along the left side of the
Digester Gas Monitor’s bottom panel. It accepts 1/4 inch OD rigid metal or rigid plastic
tubing.
Digester Sample
The digester sample fitting is a compression fitting and is located below the dryer exhaust
fitting. A 1/4 inch OD tube must be connected to this fitting and routed to the area to be
sampled.
Compressed Air Inlet
The compressed air inlet fitting is a compression fitting and is located below and to the
right of the digester sample fitting and is used to connect an air compressor or a tank of
compressed air. It accepts 1/4 inch OD rigid metal or rigid plastic tubing.
6 • External Description Digester Gas Monitor Operator’s Manual
Compressed Air Filter/Water Trap
The compressed air filter/water trap is supplied with the Digester Gas Monitor to protect
the Digester from impurities in the compressed air line. The filter is not factory installed
and must be installed by the user. See “Making Fitting Connections” on page 28 for
installation instructions.
Aspirator/Sample Exhaust
The aspirator/sample exhaust fitting is a hose barb fitting and is located just to the left of
the conduit hubs. It accepts 1/4 inch ID flexible tubing.
Digester Gas Monitor Operator’s Manual External Descr iption • 7
Internal Description
This section describes the internal components of the Digester Gas Monitor. A flow
diagram is shown in Figure 2 and an internal component location is shown in Figure 3.
CH4
ChemTech
Flow Switch
0-5 SCFH
Flow Meter
3-Way S olenoid V al ve B
De-Energized:FreshAir
Particle
Filter
Fresh A i r In
Dryer Exhaust
2-Way S olenoid V al ve E
De-Energized: Normal Op.
Energized:Cal Gas
Wate r T rap
2-W ay Solenoi d Val ve D
De-Energized: Normal Op.
Energized: Blow Back
Energized:BlowBack
O2
De-Energized: Valve B
3-Way S ol enoid Val v e A
Dryer
Filter
Acropak
Dilution
0-2 SCFH
Flow Meter
7:1
H2S
Dilution
Sample
Flow Meter
0-0.5 SCFH
CO2
Energized:Sample
Restrictor
Restrictor
Valve
Check
Filter
Oil Mist
Blowback Exhaust
Aspirator Exhaust
Aspirator
Energized: Aspirator On
2-Way S olenoid V al ve C
De-Energized: Aspirator Off
Regulator
Cal
Gas
Fitting
Sample
Digester
Trap, Field
Filter/Water
Compressed Air
Air InFitting
Installed
Air Source Compressed
Compressed
Figure 2: Flow Diagram
8 • Internal Description Digester Gas Monitor Operator’s Manual
H
Mounting
Fo o t, 4X
Horn/Strobe
(Optional)
Main PCB
DisplayPCB
LCD
Housing
Hydrophobic
Filter
Water Trap
Dryer
Flow Me ter,
H2S Dilution
Sample,
.05 - .5 SCFH
Pressure
Gauge
Regulator
Mounting
Plate
Flow
Switch
Flow Me te r,
Flo w to
Sensors,
0. 6 - 5 S CF
Solenoid
Valve,
3 way
Filter,
Particle
Check V alv e
Flow Bl ock withSensors
Oil Mist Filter
Sol enoid V al ve, 2 W ay, 3X
Compressed Air Filter/WaterT rap
instal led. Locationto be determi ned at i nstall at ion.
Aspirator, Air-Vac
*F ilter i s user
Fl o w Met er,
H2S Dilution Air,
0. 2 - 2.0 SCFH
Figure 3: Digester Gas Monitor Component Location
Digester Gas Monitor Operator’s Manual Internal Description • 9
Display PCB
s
The display PCB (printed circuit board) is mounted to the power supply mounting plate
which is in turn mounted to the main PCB. The power supply mounting plate and main
PCB are described below. The display PCB includes the LCD display, the LCD contrast
adjust pot, the status LEDs, and the control switches. It is connected to the main PCB by
the display cable which is a 20 conductor ribbon cable assembly. The display cable
connects to a rectangular connector on the top edge of the display PCB and to the same
type of connector labelled “FRONT PANEL” on the top edge of the main PCB.
Status LEDs
Connector
LCD DisplayDisplay Cable
Control
Switche
LCD Contrast
Adjust Pot
Status LEDs
Figure 4: Display PCB Component Location
LCD Display
The four line display indicates gas readings and shows messages, settings, and other
data when you are operating the various selection menus and operating modes.
LCD Contrast Adjust Pot
The LCD contrast adjust pot is located to the left of the LCD. If the LCD contrast is too
dark or too light to read easily, use a small phillips screwdriver to adjust it until you can
easily read the LCD.
Status LEDs
The Digester Gas Monitor includes seven status LEDs that indicate the current status of
the monitor: the RX & TX LEDs, the pilot LED, the fail LED, the alarm 1 LED, the alarm 2
LED, and the alarm 3 LED (see Figure 4).
• RX & TX LEDs
These LED’s indicate data is being received (RX) and transmitted (TX) when the
Digester Gas Monitor’s Modbus output is operating.
•Pilot LED
The PILOT LED is on when the Digester Gas Monitor is receiving incoming power,
10 • Internal Description Digester Gas Monitor Operator’s Manual
either AC or DC power.
• Fail LED
The fail LED turns on when the Digester Gas Monitor is experiencing a fail condition,
including a flow fail. See “Fail Condition” on page 44 and “Flow Fail Condition” on
page 44 for a description of these conditions.
•Alarm 1 LED
The alarm 1 LED is on when the Digester Gas Monitor is experiencing an alarm 1
condition.
•Alarm 2 LED
The alarm 2 LED is on when the Digester Gas Monitor is experiencing an alarm 2
condition.
•Alarm 3 LED
The alarm 3 LED is on when the Digester Gas Monitor is experiencing an alarm 3
condition.
Control Switches
The Digester Gas Monitor includes four push button control switches that allow you to
enter the selection menus and Calibration Mode, navigate through the menus and
Calibration Mode, update instrument and channel parameter settings, and save changes
to the settings. The control switches, listed in Table 2, are to the right of the LCD display
(see Figure 4).
Table 2: Digester Gas Monitor Control Switch Functions
Button Function
ESCAPE • Moves backward through the menu and mode screens
• Aborts operations
• Cancels changes you make in the menus
• Enters the Configuration Menu (press with ENTER button)
• Enters the Global Menu (press with the UP/YES button)
UP (YES) • Initiates an operation or proceeds to the next screen when a yes/
no question is asked on a screen
• Changes the displayed setting
• Enters the Global Menu (press with ESCAPE) button
• Enters the Calibration Mode (press with ENTER button)
DOWN (NO) • Cancels an operation or sequence when a yes/no question is
asked on a screen
• Changes the displayed setting
• Enters the Modbus Menu (press with ENTER button)
ENTER • Saves changes you make in the menu and mode screens
• Accepts the displayed parameter setting
• Enters the Configuration Menu (press with ESCAPE button)
• Enters Calibration Mode (press with UP/YES button)
• Enters the Modbus Menu (press with DOWN/NO button)
• Initiates a manual detection cycle
Digester Gas Monitor Operator’s Manual Internal Descr iption • 11
Main PCB
m
p
This section describes the components of the main PCB.
Strobe Te rminal Stri p
TerminationJumper
Main PCB
Control PCB
AC In
Termi nal Stri
Detector/
Transmi tter
Termi nal
Strips
Common/
Channel Alar
Term i nal Strip
Control ler
Term i nal Strip
Channel A larm Terminal Strip
Figure 5: Main PCB Component Location
Terminal Strips
The Digester Gas Monitor includes 9 terminal strips for wiring connections. See “Wiring
the Digester Gas Monitor” on page 23 for detailed wiring procedures.
• Strobe Terminal Strip
The strobe terminal strip is a 2-point terminal strip located in the upper left corner of
the main PCB. When the optional horn/strobe is ordered with a Digester Gas Monitor,
the strobe terminal strip is used to wire the horn/strobe.
CAUTION: The strobe terminals are intended for use with the RKI supplied optional
horn/strobe. Consult RKI Instruments, Inc. before attempting to use these
terminals for any other alarm device.
GroundStud
• Detector/Transmitter Terminal Strips
Four detector/transmitter terminal strips are located along the bottom left side of the
12 • Internal Description Digester Gas Monitor Operator’s Manual
main PCB (see Figure 5 on page 12). These four 11-point terminal strips facilitate
wiring connections to the detectors. They also provide terminals to connect a
recording device to a 4 to 20 mA output for each channel. The top terminal strip is for
channel 1 connections and each subsequent strip is used for the next channel with the
bottom terminal strip being for channel 4 connections. The Digester Gas Monitor
detectors are factory wired to the terminal strips.
• Channel Alarm Terminal Strip
A channel alarm terminal strip is located to the right of the channel 4
detector/transmitter terminal strip (see Figure 5 on page 12). This 24-point terminal
strip facilitates wiring external alarm devices (horn, light, etc.) to relay contacts that
are field configurable for alarm levels and operation and are controlled by individual
channels. The contacts are labelled NO (normally open), NC (normally closed),
and C (common). See “Viewing and Changing Global Parameters” on page 47 and
“Viewing and Changing Channel Parameters” on page 51 for instructions to configure
the operation of these contacts.
• Common/Channel Alarm Terminal Strip
The common/channel alarm terminal strip is located in approximately the middle of the
main PCB above the channel alarm terminal strip. The terminals for relays A, B, C,
and D are factory wired and are not available for customer use. Only the fail relay
terminals are available for customer use. The contacts are labelled NO (normally
open), NC (normally closed), and C (common).
• Controller Terminal Strip
The 9-point controller terminal strip is along the lower right side of the main PCB (see
Figure 5 on page 12). The controller terminal strip facilitates various internal and
external wiring connections. Table 3 lists the function of each terminal.
T able 3: Terminal Assignments for the Controller Terminal Strip
Terminal Connects to:
DP SW
Flow switch (factory wired)
DP SW
EXT DC/24V BATT +
EXT DC/24V BATT -
+ connection from 24 VDC power source
- connection from 24 VDC power source
1
(or 24 V backup battery)
1
(or 24 V backup battery)
RS-485 A
RS-485 B Allow connection of the Digester Gas Monitor to a Modbus network
RS-485 C
Alarm Reset
Alarm Reset
Reset Switch Terminals (factory wired)
Alarm Buzzer + Buzzer + connection (factory wired)
1
1
Alarm Buzzer - Buzzer - connection (factory wired)
1
If 24 VDC is used as primary power source do not make wiring connections to the AC terminal strip.
Digester Gas Monitor Operator’s Manual Internal Descr iption • 13
•AC Terminal Strip
The 3-point AC terminal strip is located above the controller terminal strip (see
Figure 5 on page 12). The AC terminal strip facilitates wiring connections to the AC
power source.
Relays
The Digester Gas Monitor includes eight channel relays and one common fail relay. It also
includes four common/channel relays which are factory set for operational use of the
Digester Gas Monitor. All the relays have single-pole double-throw (SPDT) contacts, also
known as form C contacts, and are rated for 10 amps at 1 15 VAC (resistive). The contacts
are available at the channel alarm terminal strip and are labelled NO (normally open), NC
(normally closed), and C (common).
Not Available for Customer Use
Power Switch
Fail
Relay
Relay
A
Relay
B
Relay
C
Relay
D
AC Fuses
CH 1
Relay
1
CH 1
Relay
2
CH 2
Relay
1
CH 2
Relay
2
CH 3
Relay
1
CH 3
Relay
2
Relay
CH 4
1
CH 4
Relay
2
Channel
Relays
Figure 6: Digester Gas Monitor Relay Allocation
Channel Relays & Fail Relay
The eight channel relays are above the channel alarm terminal strip (see Figure 5 on
page 12 and Figure 6 on page 14). These relays are dedicated to specific channels.
Figure 6 illustrates the allocation of the channel relays.
The fail relay is located above the channel relays. The fail relay is a common relay.
Common/Channel Relays
The four common/channel relays, relays A, B, C, and D, are above the common/channel
alarm terminal strip (see Figure 5 on page 12 and Figure 6 on page 14). These relays are
used in the operation of the Digester Gas Monitor and are not available for customer use.
Termination Jumper
A two pin header with a termination jumper installed is located near the top edge of the
main PCB to the right of the display cable connector. It is labelled “RS-485 Line
Terminator” on the PCB silkscreen. The jumper has no function unless the Digester Gas
Monitor is wired into a Modbus installation. See “Chapter 9: RS-485 Modbus Output” on
14 • Internal Description Digester Gas Monitor Operator’s Manual
page 68 for instructions to use the Digester Gas Monitor in a Modbus system.
Ground Stud
The threaded ground stud is used for making connections to earth ground. It is located in
the lower right corner of the main PCB and is connected through the main PCB to the G
(ground) terminal on the AC terminal strip. It is also connected to each conduit hub with a
wire. A kep nut on the stud may be removed for installation of one or more user supplied
lugs to make wiring connections to earth ground. This stud is typically used to connect the
shield drain wire of shielded cable to earth ground at the Digester Gas Monitor.
Power Switch
The power switch is between the common/channel relays and the fuses (see Figure 5 on
page 12 and Figure 6 on page 14). The power switch turns the incoming AC power source
on and off at the Digester Gas Monitor. When the switch is up, the power is on.
Power Supply
The power supply is mounted to the power supply mounting plate which is located behind
the display PCB. The power supply mounting plate is mounted to the main PCB with four
standoffs. The power supply receives AC power from the external power source and
converts it to a DC voltage that is usable by the Digester Gas Monitor circuitry. A
polycarbonate cover prevents accidental contact with the AC terminals on the power
supply.
AC & DC Circuit Protection
Two AC fuses are used in the Digester Gas Monitor. The two fuses are located on the right
side of main PCB, between the power switch and the AC in terminal strip (see Figure 6 on
page 14). They cut off the incoming AC power in the event of a short circuit or other
electrical fault which causes a high current draw in the Digester Gas Monitor. They are
housed in vertical fuse holders and are held in each holder by a quarter turn cover. They
are fast blow fuses rated at 6 A, 250 V.
A polyswitch is used to protect the DC power input. It is located on the right side of the
main PCB above the AC fuses and is labelled on the PCB silkscreen as PS9. In the event
of a short circuit or other electrical fault which causes a high current draw in the Digester
Gas Monitor, the polyswitch will interrupt the DC power if the unit is powered from DC.
When the fault situation is corrected, the polyswitch resets and the unit will continue to
operate. The polyswitch is not user serviceable.
Regulator and Gauge
The regulator and gauge are located in the lower left corner of the Digester Gas Monitor
housing. The regulator’s maximum allowable inlet pressure is 300 PSI. A gauge above the
regulator indicates the output pressure (between 5 and 50 PSI). The output pressure, and
system flow, can be adjusted using the knob on the front of the regulator. The system flow
rises or falls as the output pressure is increased or decreased.
Flow Switch
The flow switch is located in the upper right corner of the Digester Gas Monitor housing.
The flow switch monitors the flow to the sensors and actuates if the flow rate goes below
1.6 SCFH.
Flow Block
The flow block is located in the center of the Digester Gas Monitor and is designed to
accept the gas sensors and route sample to each sensor. The methane, oxygen, and CO
Digester Gas Monitor Operator’s Manual Internal Descr iption • 15
2
sensors are retained in the flow block by brackets. The H2S sensor is retained by the Oring compression force of the O-rings it is inserted past. When viewed from the front of the
Digester Gas Monitor, the methane sensor is in the front right corner, the H
the front left corner, the oxygen sensor is in the back right corner, and the CO
S sensor i s in
2
sensor is in
2
the back left corner.
Sensors
Infrared Methane (CH4) Sensor
The IR CH
sensor is an infrared type plug-in detector. The IR CH4 sensor is installed in
4
the front right corner of the flow block when viewing the flow block from the front of the
Digester Gas Monitor. A small preamp circuit board with a 4-wire cable mates to the IR
CH
sensor and retains it in the flow block. The cable is wired to the main PCB. The
4
preamp circuit board allows you to replace the sensor without disconnecting the wiring.
Oxygen (O
) Sensor
2
The oxygen sensor is installed in the right back corner of the flow block when viewing the
flow block from the front of the Digester Gas Monitor. The oxygen cell is protected within
the sensor assembly. Through a series of chemical and electronic reactions, the oxygen
cell produces a millivolt output that is proportional to the detection range of the Digester
Gas Monitor. The leads extending from the sensor terminate in a connector that leads to
the main PCB. The connector allows the sensor to be replaced without disconnecting the
wiring.
Carbon Dioxide (CO
The CO
sensor is an infrared type plug-in detector. The CO2 sensor is installed in the
2
) Sensor
2
back left corner of the flow block when viewing the flow block from the front of the Digester
Gas Monitor. A small preamp circuit board with a 4-wire cable mates to the CO
sensor
2
and retains it in the flow block. The cable is wired to the main PCB. The preamp circuit
board allows you to replace the sensor without disconnecting the wiring.
Hydrogen Sulfide (H
The hydrogen sulfide sensor is a plug-in sensor that plugs into the back of the H
S) Sensor
2
S
2
preamp. The hydrogen sulfide sensor is installed in the front left corner of the flow block
when viewing the flow block from the front of the Digester Gas Monitor. The sensor and
preamp are retained in the flow block by two screws.
Through a series of chemical and electronic reactions, the H
S sensor produces a millivolt
2
output that is proportional to the detection range of the Digester Gas Monitor. The wires
extending from the amplifier are connected to the main PCB.
Flowmeters
Three flowmeters are part of the Digester Gas Monitor’s flow system.
Flow to Sensors Flowmeter
The Flow to Sensors flowmeter is located along the right side of the Digester Gas
Monitor’s flow system and indicates the flow rate being applied to the sensors. This flow
should always be 3.0 SCFH.
H
S Dilution Sample Flowmeter
2
The H
Monitor’s flow system and indicates the sample flow rate to the H
16 • Internal Description Digester Gas Monitor Operator’s Manual
S Dilution Sample flowmeter is located in the middle left of the Digester Gas
2
S sensor. The
2
appropriate flow rate depends on the full scale range of the H2S sensor. See “Adjusting
the Flow Rates” on page 33 for more information.
S Dilution Air Flowmeter
H
2
The H2S Dilution Air flowmeter is located in the middle right of the Digester Gas Monitor’s
flow system and indicates the fresh air flow rate to the H
rate depends on the full scale range of the H
page 33 for more information.
S sensor. See “Adjusting the Flow Rates” on
2
S sensor. The appropriate flow
2
Hydrophobic Filter
The hydrophobic filter is located in the upper left corner of the Digester Gas Monitor
housing and prevents water from entering the flow system through the sample inlet that
may have gotten past the water trap.
Water Trap
The water trap is located in the upper left corner of the Digester Gas Monitor housing. It is
slightly below and to the right of the hydrophobic filter. The water trap prevents water from
entering the flow system through the sample inlet. During the blowback procedure, the
water trap is emptied of its contents.
Dryer
The dryer is located in the center of the Digester Gas Monitor and removes any excess
humidity in the sample before the sample enters the flow chamber.
Solenoid Valves
There are five solenoid valves located throughout the Digester Gas Monitor’s flow system.
They control the direction of the flow. They are controlled by the Digester Gas Monitor’s
software and are actuated at various stages of the sampling process.
Check Valves
A check valve in the blowback exhaust line prevents fresh air from entering the sample
line through the blowback exhaust line.
Digester Gas Monitor Operator’s Manual Internal Descr iption • 17
Factory Wiring
The figure below shows the factory wiring. Standard channel assignment is shown. If your
Digester Gas Monitor has less than four sensors, your detector wiring will be slightly
different.
Black
Red
POWER SUPPLY
-V(DC-)
-V(DC-)
+ V (DC+)
+ V (DC+)
(G round )
N(Neutral)
L(Hot)
Wires Twisted
Green
White
Black
Wires Twisted
Detector/Transm itter
Terminal S trips
O2 Sensor
White
Green
Black
Orange
H2S
Sensor
Com mon/C hannel A la rm
Term inal S trip
FA IL
NONC C
RELAY-A
NONC C
RELAY-B
NONC C
RELAY-C
NONC C
RELAY-D
NONC C
White
Red
+S- WG RWGB + -
AMP
4-20m A
LELOXY
OU TPU T
CO2 S ensor
Green
Black
CH
1
CH
2
CH
3
CH
4
CH 4 Sensor
Terminal S trip
Black
Green
White
Red
Controller
ALARM
RESET
EXT DC
24V BATT
ALARM
BU ZZER
Red
Black
Conduit Hubs
Flow
Switch
Reset
Switch
Buzzer
Factory S oldered to
Back of Board
Wire
Nut
Diodes are
A
B
C E
D
shownfor
reference. They
are not u ser
3-W ay
Solenoid
3-W ay
Solenoid
2-W ay
Solenoid
2-W ay
Solenoid
2-W ay
Solenoid
accessible.
Figure 7: Factory Wiring
18 • Factory Wiring Digester Gas Monitor Operator’s Manual
Optional Horn/Strobe
This section describes the optional horn/strobe available for the Digester Gas Monitor. It
can be ordered with the Digester Gas Monitor or it can be ordered at a later date and be
field installed. The horn/strobe is wired to the Strobe Terminal Strip as shown in Figure 8
and Figure 9 below.
NOTE: If the Digester Gas Monitor is not ordered with a horn/strobe, the hole that is
intended for use with the horn/strobe will be plugged and the receptacle will not
be installed.
Strobe Terminal Strip
Strobe Receptacle
Figure 8: Strobe Terminal Strip Location
The Digester Gas Monitor can be ordered with a horn/strobe. This optional horn/strobe
allows the user to have both a strobe and a horn connected to the “Strobe” terminals of the
Digester Gas Monitor. Strobe operation can be programmed in the Global Menu (see
“Chapter 5: Global Menu” on page 47) and in Configuration Mode (see “Chapter 6:
Digester Gas Monitor Operator’s Manual Optional Horn/Strobe • 19
Configuration Menu” on page 51).
NOTE: See “Chapter 3: Installation and Start Up” on page 22 for complete Digester Gas
Monitor installation instructions.
CAUTION: Do not adjust the strobe brightness or the horn volume at the horn/strobe, as
this may overload the Digester Gas Monitor strobe control circuit.
Even if the horn/strobe is ordered at the same time as the Digester Gas Monitor, the horn/
strobe does not come factory installed to the Digester Gas Monitor. To install the horn/
strobe:
1. A 3/4 inch NPT nipple is provided for strobe installation. It is not installed on the horn/
strobe and is in its own bag in the shipping box. Guide the cable coming out of the
horn/strobe through the nipple.
2. Install the nipple onto the horn/strobe using an appropriate thread sealing method
such as Teflon tape.
3. If the horn/strobe has been ordered with the Digester Gas Monitor, a conduit hub will
be installed on the top of the housing and will be plugged with a conduit plug. The plug
is included to prevent any debris from falling into the Digester Gas Monitor during
shipment and installation. Remove the conduit plug from the strobe conduit hub.
Continue to step 5.
4. If the horn/strobe has been ordered for a Digester Gas Monitor that is already
installed, a plug is installed in a hole in the top of the housing. Remove this plug and
install the conduit hub that came with the horn/strobe.
A receptacle with 4 inch wires is included with the horn/strobe. Connect the red wire to
the “+” terminal and connect the black wire to the “-” terminal of the Strobe Terminal
Strip as shown in Figure 9.
5. Guide the cable coming from the horn/strobe through the conduit hub at the top right
of the Digester Gas Monitor housing.
NOTE: If there is a plug in the conduit hub, remove it before attempting to install the
horn/strobe.
6. Screw the horn/strobe into the conduit hub at the top right of the Digester Gas Monitor
housing using an appropriate thread sealing method such as Teflon tape. Make sure
the horn/strobe faces forward when installed.
20 • Optional Horn/Strobe Digester Gas Monitor Operator’s Manual
7. Connect the plug coming from the horn/strobe to the receptacle coming from the
S
strobe terminal strip.
6.81
5.97
4.83
6.17
trobe Terminal
Strip
Receptacle
Black
Red
-+
Plug
3/4" NPT Nipple
C onduit Hub
Digester
Housing
Note: Dimensions
Shown in Inches
Figure 9: Horn/Strobe Wiring/Outline and Mounting Dimensions
Digester Gas Monitor Operator’s Manual Optional Horn/Strobe • 21
Chapter 3: Installation and Start Up
Overview
This chapter describes procedures to mount the Digester Gas Monitor, make wiring
connections to the monitor, and start up the monitor.
WARNING: Perform all installation and start-up procedures in a known fresh air
environment, an environment free of combustible and toxic gasses and of nor mal
oxygen content. The Digester Gas Monitor is not in operatio n as a gas
monitoring device until the start up procedure is complete.
Mounting the Digester Gas Monitor
Perform the following procedure to install the Digester Gas Monitor at the mounting site.
1. Select the mounting site. When you select the mounting site, consider the following
factors:
• Is an AC or DC power source available?
• Is a vertical surface available to mount the Digester Gas Monitor?
• Is there enough room to open the housing door and make wiring and tubing
connections through the conduit hubs and fittings at the bottom of the housing?
• Are the display screen and status lights visible?
2. Close and latch the housing door.
3. The mounting feet for the Digester Gas Monitor are shipped in a separate bag that is
taped to the outside of the housing. Install the mounting feet to each corner on the
back of the housing so that the shortest section of the mounting foot is flush with the
back of the housing and the longest section of the mounting foot is offset away from
the housing. See the figure below.
Long
Housing
Section
Short
Section
Figure 10: Mounting Feet Installation
22 • Overview Digester Gas Monitor Operator’s Manual
4. Prepare the selected mounting site as required to mount the Digester Gas Monitor. It
should be mounted at eye level (4 1/2 to 5 feet from the floor). Refer to Figure 11 for
the outline and mounting dimensions.
5. Position the monitor on the vertical mounting surface. Use a level to ensure that the
Digester Gas Monitor housing is level in all planes. The flowmeters will not operate
properly if the Digester Gas Monitor is not mounted as shown below and level in all
planes.
6. Insert 1/2 in. screws through the slots in the mounting feet at each corner of the
housing to secure the housing to the mounting surface.
Horn/Strobe (Optional)
Ø.56,4X
25.59
23.75
25.59
Figure 11: Digester Gas Monitor Outline and Mounting Dimensions
Wiring the Digester Gas Monitor
This section describes procedures to connect the AC power source, DC power source,
Modbus wiring (refer to “Wiring the Digester Gas Monitor in a Modbus System” on
page 68), external alarms, and recording devices. See Figure 12 on page 24 for a general
diagram of all external wiring to the Digester Gas Monitor.
34.72
26.89
27.85
12.35
NOTE: User-Installed Compressed Air Filter/
Water T r ap N ot Shown in This View
WARNING: Make all connections to the Digester Gas Monitor before you plug in o r tur n on
the AC or DC power source. Before you make any wiring adjustments, always
verify that all power sources are not live.
Digester Gas Monitor Operator’s Manual Wiring the Digester Gas Monitor • 2 3
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