GDS Corp GDS-58DXP User manual

GDS Corp.
1245 Butler Road League City, TX 77573
409-927-2980 409-927-4180 (Fax) www.gdscorp.com
Operation and Maintenance
Manual
GDS-58DXP Dual Channel Sample Draw Monitor

GDS-58DXP Operation & Maintenance Manual, Revision 1.0
Page 2
CAUTION: FOR SAFETY REASONS THIS EQUIPMENT MUST BE OPERATED AND
SERVICED BY QUALIFIED PERSONNEL ONLY. READ AND UNDERSTAND
INSTRUCTION MANUAL COMPLETELY BEFORE OPERATING OR SERVICING.
ATTENTION: POUR DES RAISONS DE SÉCURITÉ, CET ÉQUIPEMENT DOIT
ÊTRE UTILISÉ, ENTRETENU ET RÉPARÉ UNIQUEMENT PAR UN PERSONNEL
QUALIFIÉ. ÉTUDIER LE MANUE D’INSTRUCTIONS EN ENTIER AVANT
D’UTILISER, D’ENTRETENIR OU DE RÉPARER L’ÉQUIPEMENT.
REVISION HISTORY
Revision 1.0 3/15/2022 Initial release
Copyright © 2021 GDS Corp. All Rights Reserved
P/N 1200-1105-01

GDS-58DXP Operation & Maintenance Manual, Revision 1.00
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CONTENTS
1SAFETY INFORMATION _______________________________________________ 5
2PRODUCT OVERVIEW ________________________________________________ 6
3HARDWARE _______________________________________________________ 11
4INSTALLATION _____________________________________________________ 12
5CALIBRATION ______________________________________________________ 17
6SETUP AND OPERATION _____________________________________________ 20
7MAINTENANCE_____________________________________________________ 25
8TROUBLESHOOTING GUIDELINES ______________________________________ 26
9SPECIFICATIONS ____________________________________________________ 27
10 MODBUS REGISTERS ______________________________________________ 30
11 SPARE PARTS ____________________________________________________ 31
12 DRAWINGS AND DIMENSIONS ______________________________________ 33
13 SAMPLE DRAW DUCT ASSEMBLY 20-0141 _____________________________ 37

GDS-58DXP Operation & Maintenance Manual, Revision 1.0
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TABLE OF FIGURES
FIGURE 2-1: GDS-58DXP SAMPLE DRAW MONITOR....................................................................................... 6
FIGURE 2-2: GDS-58DXP FLOW DIAGRAM...................................................................................................... 7
FIGURE 2-3: GDS-58DXP AMBIENT AIR SAMPLING ........................................................................................ 8
FIGURE 2-4: FILTER OPTION #1....................................................................................................................... 9
FIGURE 2-5: FILTER OPTION #2....................................................................................................................... 9
FIGURE 2-6: FILTER OPTION #3..................................................................................................................... 10
FIGURE 2-7: GDS-58DXP AIR DUCT SAMPLING............................................................................................. 10
FIGURE 3-1: GDS-58DXP WITH SINGLE TOXIC SENSOR................................................................................. 11
FIGURE 3-2: GDS-58DXP WITH SINGLE GDS-IR SENSOR ............................................................................... 11
FIGURE 4-1: POWER AND ANALOG SIGNAL WIRING PATH .......................................................................... 13
FIGURE 4-2: GDS-58DXP POWER AND SIGNAL WIRING ............................................................................... 14
FIGURE 4-3: ANALOG / RELAY MODBUS CONNECTIONS.............................................................................. 14
FIGURE 4-4: RELAY & MODBUS WIRING PATH............................................................................................. 15
FIGURE 4-5: GDS-58DXP WITH OPTIONAL MODBUS WIRING JUNCTION BOX (MBJB)................................. 16
FIGURE 6-1: GDS-58DXP GAS DETECTOR DISPLAY........................................................................................ 20
FIGURE 9-1: TOXIC SENSOR CHARACTERISTICS & RECOMMENDED WARM-UP TIME ................................. 28
FIGURE 9-2: GDS-IR SENSOR CHARACTERISTICS & RECOMMENDED WARM-UP TIME ................................ 29
FIGURE 11-1: GDS-58DXP ASSEMBLY WITH TOXIC SENSOR (SPARE PARTS) ................................................ 31
FIGURE 11-2: GDS-58DXP ASSEMBLY WITH GDS-IR SENSOR (SPARE PARTS)............................................... 32
FIGURE 12-1: GDS-58DXP DIMENSIONS (SINGLE TOXIC SENSOR)................................................................ 33
FIGURE 12-2: GDS-58DXP DIMENSIONS (GDS-IR SENSOR)........................................................................... 34
FIGURE 12-3: GDS-58DXP DIMENSIONS (STAINLESS STEEL PLATE, 1 SENSOR) ............................................ 35
FIGURE 12-4: GDS-58DXP ENCLOSURE DIMENSIONS (NON-METALLIC)....................................................... 36
FIGURE 13-1: SAMPLE DRAW DUCT ASSEMBLY ........................................................................................... 37
FIGURE 13-2: SAMPLE DRAW DUCT ASSEMBLY HOLE MOUNTING PATTERN .............................................. 37

GDS-58DXP Operation & Maintenance Manual, Revision 1.00
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1SAFETY INFORMATION
Important –Read Before Installation
Users should have a detailed understanding of GDS-58DXP operating and maintenance instructions. Use
the GDS-58DXP only as specified in this manual or detection of gases and the resulting protection
provided may be impaired. Read the following WARNINGS prior to use.
WARNINGS
▪The GDS-58DXP sample draw system must be installed, operated, and maintained in accordance with
information contained herein. Installation in any hazardous area must comply with all applicable
restrictions, requirements, and guidelines for said hazardous areas. It is the end user customer’s final
decision to ensure that the GDS-58DXP is suitable for the intended use.
▪The GDS-58DXP is designed and constructed to measure the level of certain gases in ambient air.
Accuracy in atmospheres containing steam or inert gases cannot be guaranteed.
▪Do not paint transmitter or sensor assembly.
▪Do not operate the GDS-58DXP if its enclosure is damaged or cracked or has missing components.
Make sure the cover, internal PCB’s and field wiring are securely in place before applying power.
▪Do not expose the GDS-58DXP to electrical shock or continuous severe mechanical shock. Protect the
GDS-58DXP from dripping liquids and high-power sprays.
▪Calibrate with known target gas at start-up and check on a regular schedule, at least every 90 days.
More frequent inspections are encouraged to spot problems such as dirt, oil, paint, grease or other
foreign materials in the sample tubing or in the sensor head.
▪Periodically test for correct operation of the system’s alarm events by exposing the sample extraction
point to a calibration gas concentration above the High Alarm set point.
▪If a purge unit is installed, read and follow all instructions regarding proper operation of the purge
system before applying power to the GDS-58DXP.
WARRANTY
GDS Corp. UPS products carry a 2-year limited repair or replacement warranty on electronics and
workmanship and one year warranty on sensors. GDS Corp. reserves the right to void warranty claims
based on evidence of misuse, abuse, or misapplication. Warranty period starts on date of shipment.
IF YOU HAVE QUESTIONS
GDS Corp
1245 Butler Road, League City, Texas 77573
409-927-2980 (Office), 409-927-4180 (Fax)
[email protected]
www.gdscorp.com

GDS-58DXP Operation & Maintenance Manual, Revision 1.0
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2PRODUCT OVERVIEW
The GDS-58DXP is designed to provide reliable gas detection in locations where the environment is not
suitable for the installation of traditional ambient sensors. The GDS-58DXP combines a highly reliable
brushless DC sample pump, low flow detection switch, visual flow meter and GASMAX DSX gas detector
into a single unit that provides 4-20mA analog output, programmable relays including system FAULT and a
MODBUS slave interface. The integrated Run/Cal switch and GASMAX DSX user-prompted calibration
procedure make normal maintenance quick and easy.
The GDS-58DXP consists of a gas detector coupled with an integrated pump / flow switch and wiring
junction box. The Run / Cal valve selects between the sample input and local calibration gas input. The
Visual Flow Indicator shows GREEN if flow is OK, and RED if flow is blocked or the pump fails. The Wiring
Junction Box provides an easy and convenient way for the user to attach power and signal wiring.
Figure 2-1: GDS-58DXP Sample Draw Monitor
Sample gas enters the unit through the Run/Cal valve where it is drawn into the explosion proof enclosure
Gas Detector
Wiring Junction Box
Visual Flow
Meter
Visual Flow
Indicator
Run / Cal Valve

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by the pump after passing through the first of two flame arrestors. Output from the pump is directed
through the low flow switch and exits the explosion proof enclosure through the second flame arrestor
where it travels to the flow meter and sensor flow cell and then exits the flow cell at ambient atmospheric
pressure. In the event of a pump failure or if flow is blocked for some reason, the 4-20mA output of the
GDS-58DXP will drop to zero.
Figure 2-2: GDS-58DXP Flow Diagram
GDS-58DXP SENSOR TECHNOLOGY
For toxic gases the GDS-58DXP supports a range of electrochemical (“echem”) sensors for toxic gases and
oxygen levels. These sensors use chemical reactions to sense the presence of gases such as hydrogen
sulfide, sulfur dioxide and many others. Each sensor contains an amount of chemical electrolyte that
reacts with the target gas to create free electrons that are amplified and measured. Once the electrolyte
is depleted, sensor output will diminish, and the sensor must be replaced.
IMPORTANT: TOXIC SENSORS ARE SUBJECT TO ACCELERATED DETERIORATION IF POWER IS NOT APPLIED
WITHIN 3 MONTHS OF SHIPMENT FROM GDS CORP.
For combustible gases the GDS-58DXP uses a GDS-IR infrared sensor. These sensors can be calibrated for
many different combustible gases.
Pump
Flow Switch
Cal Gas Inlet
Sample Inlet
Flow Meter
Sample Outlet
Sensor
Flow Cell
Power In
Signal Out
Run / Cal

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Infrared sensors use the fact that hydrogen-carbon bonds found in all hydrocarbon gases absorb infrared
light at certain frequencies. When the target gas passes between a source of infrared light and a suitable
detector, a reduction in detector output indicates the presence of gas. Infrared sensors cannot be
poisoned or damaged by chemicals in the target gas and typically have a very long and stable operational
life. GDS-IR sensors carry a 5-year warranty on the electronics and a 12-year warranty on the IR source.
IMPORTANT: INFRARED COMBUSTIBLE GAS SENSORS CANNOT DETECT COMBUSTIBLE HYDROGEN GAS
SAMPLING APPLICATIONS
When sampling from a static area, mount the GDS-58DXP as close as possible to the extraction point. Try
to keep the unit above the sampling point so that any moisture that condenses inside the tubing flows
back to the source.
Figure 2-3: GDS-58DXP Ambient Air Sampling
For stainless steel tubing runs (typically ¼” OD) GDS Corp recommends the installation of #1200-0387
end-of-line dust filter at the pickup point if the area contains significant amounts of dust or particulates
(See Fig. 2-3).
For tubing runs that can use flexible tubing, GDS Corp recommends the #20-0198 filter kit that includes a
non-metallic end-of-line filter / silencer with replaceable filter element and 50 feet of Tygon tubing.
If water may be present at the sample inlet point, GDS Corp recommends the #20-0186 Float Probe Kit
with 50’ of Tygon tubing or the #20-0187 Float Probe Kit with 100’ of Tygon Tubing. The float probe
ensures that the pickup point remains above the liquid level under most circumstances. The sample pump
used on the GDS-58DXP is capable of lifting liquid water to a height of 15 ft / 5m, and if the end of the
sample line is placed in liquid water, the pump will draw water through the inlet filter, flame arrestors,
sample pump, flow switch and flow meter and sensor flow cell, resulting in damage to the components.
1200-0387
¼” End of line filter
Customer-supplied
tubing & fittings

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In addition to end-of-line filters & probes, the GDS-58DXP offers three choices for inlet filters that are
directly integrated into the unit. These filters are mounted on the left side, in-between the flame arrestor
and Run/Cal valve.
Filter option #1 (“FIL” = 1) includes a coalescing / dust filter with integrated drain valve. This filter is best
for use in areas that do not have corrosive or acidic gases. The filter element is designed to remove
particles that are larger than 5 microns.
Figure 2-4: Filter Option #1
Filter option #2 (“FIL” = 2) includes a stainless steel coalescing filter with stainless steel drain valve. This
filter is recommended if there are any corrosive or acidic gases present that are not compatible with
materials such as plastics or mild steel. The filter element used in this filter is designed to remove particles
that are larger than 0.1 microns.
Figure 2-5: Filter Option #2
Side View
Front View
Filter:
P/N 1200-0398
Replacement element:
P/N 1200-0399
Side View
Front View
Filter:
P/N 2000-0147
Replacement Element:
P/N 2000-0137

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Filter option #3 (“FIL” = 3) includes a Pyrex clear coalescing filter with stainless steel drain valve. This filter
is recommended if there are any corrosive or acidic gases present and if the sample air or gas may contain
high levels of moisture.
Figure 2-6: Filter Option #3
IMPORTANT: WHEN DRAINING AN INLET FILTER, BLOCK THE SAMPLE FLOW BY REMOVING POWER FROM
THE UNIT OR SETTING THE RUN/CAL VALVE TO A POSITION BETWEEN RUN AND CAL.
Sampling inside air conditioning ducts presents several problems for ambient sensors. Rapid air flow can
damage the sensor, access for calibration or maintenance is difficult, and non-linear gas distribution can
result in errors. Using a GDS-58DXP with a #20-0141 Duct Sample Kit simplifies installation, maintenance
and calibration and samples a larger cross-section of the duct stream.
Figure 2-7: GDS-58DXP Air Duct Sampling
20-0141-03
Duct Sample Kit
Customer-
supplied
tubing
Side View
Front View
Filter:
P/N 2000-0136
Replacement Element:
P/N 2000-0137

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3HARDWARE
The GDS-58DXP consists of two NEMA 7 explosion-proof enclosures that contain the sample pump and
flow switch (left side) and GASMAX DSX gas monitor, sensor, and flow cell (right side). Gas enters the left
side enclosure via explosion proof flame arrestors, passes through the flow meter and into the sensor.
Figure 3-1: GDS-58DXP with Single Toxic Sensor
Figure 3-2: GDS-58DXP with Single GDS-IR Sensor
Sample Inlet
Signal or Power
Flowmeter
Visual Flow Indicator
GASMAX DSX
Sample Inlet
Signal or Power
Flowmeter
Visual Flow Indicator
GASMAX DSX

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4INSTALLATION
SELECTING A LOCATION
As compared to a fixed-point gas detector, the GDS-58DXP sample draw system provides a good deal of
flexibility when choosing a mounting location. Consider the following when considering where to install
the GDS-58DXP:
•Locate the GDS-58DXP where it will be easy to service and calibrate.
•Minimize the length of sample tubing.
•Mount the GDS-58DXP at or above the sample point, if possible, to minimize condensation
•Keep the sample pickup from becoming submerged in liquid. The sample pump is capable of drawing
water to a height of 15 feet. If liquid enters the flame arrestor or sample pump, damage will occur.
•If it is necessary to tie the sample outlet back to the sample source, make sure there are no
obstructions or restrictions. Any increase in pressure inside the sensor flow cell will result in reading
errors.
MOUNTING THE GDS-58DXP
The GDS-58DXP standard configuration is a dual aluminum explosion-proof enclosure and is available
standalone, on a 21” x 21” painted steel plate or in a 24” x 24” non-metallic or stainless-steel enclosure.
The GDS-58DXP must be mounted vertically for the flow switch and flow meter to operate properly.
INLET TUBING
Specifications for the inlet tubing depend on the target gas. Long runs of
sample tubing will cause a significant delay between the appearance of
gas and the resulting warning. Small diameter stainless steel (1/4” OD) is
ideal for most gases. Flexible tubing or tubing manufactured from Teflon
or PTFE may also be used.
Smaller diameter tubing results in faster response because of the smaller total volume of gas that must be
drawn from the sample point. Tests have shown that it takes approximately 3.5 minutes for a sample to
be drawn through 500 feet of 1/4” OD flexible tubing; this gives a delay rate of roughly 0.4 seconds per
foot of tubing. Larger diameter tubing with higher internal volume will result in a longer delay, while
smaller tubing may be subject to blockage from condensed water droplets or dirt particles.
NOTE: THE SAMPLE PUMP IS CAPABLE OF PULLING UP TO 7.0 PSI VACUUM, ENOUGH TO LIFT WATER
OVER 15 FEET. CARE SHOULD BE TAKEN NOT TO SUBMERGE THE SAMPLE EXTRACTION POINT IN LIQUID
Inlet Delay Calculation
For ¼” OD tubing, allow 5
seconds delay for every 10
feet of sample line

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AS THE PUMP WILL QUICKLY FILL THE FLAME ARRESTORS, FLOW SWITCH, FLOW METER AND SAMPLE
FLOW CELL WITH LIQUID.
SAMPLE EXHAUST
Changes in ambient pressure will affect the output from most sensors and allowing the sample to exhaust
directly to the atmosphere will minimize these affects. Long runs of tubing connected to the sample outlet
may increase the backpressure inside the sensor flow cell and cause higher than normal readings.
Returning a sample to a process stream may be desirable and will work if the process stream is only
slightly above ambient (< 5” of water column) and has a relatively constant pressure.
IMPORTANT: DO NOT RESTRICT THE SAMPLE EXHAUST OUTLET.
DC POWER & SIGNAL CONNECTIONS
To access signal and power connections, remove the cover on the wiring junction box mounted on the
right side of the GDS-58DXP. Power, ground (common) and signal outputs are shown in figure 5-4 below.
Connect power to TB1 pin 1 and ground to TB1 pin 6. Additional+24V (TB1 pin 2) and Common (TB1 pin 5)
connections are available for local strobes or horns. The “DC ON” LED is
connected across the DC input wiring and can be used to confirm the
existence of properly polarized DC power.
NOTE: Connector “TB1” is removable and allows power to the GDS-
58DXP to be temporarily removed for troubleshooting or maintenance
without physically disconnecting any field wiring.
Figure 4-1: Power and Analog Signal Wiring Path
Recommended Wire Gauge
< 100 ft #18 GA
100 to 500 ft #16 GA
500 to 1000 ft #14 GA
DC Power and 4-20mA
Analog Output Wiring

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Figure 4-2: GDS-58DXP Power and Signal Wiring
RELAY / MODBUS CONNECTIONS
Wiring terminals for the Serial MODBUS interface and four alarm relays is located on the back of the
GASMAX DSX display board. To access the wiring, remove the cover of the right-side enclosure,
disconnect the display, and flip it around to access the wiring terminals. Wiring as needed can be run
through the wiring junction box on the far-right side.
Figure 4-3: Analog / Relay MODBUS Connections
TB3 Relay Wiring:
1Lo Alarm NO
2Lo Alarm Common
3Lo Alarm NC
4Mid Alarm NO
5Mid Alarm Common
6Mid Alarm NC
7Hi Alarm NO
8Hi Alarm Common
9Hi Alarm NC
10 Fault Alarm NO
11 Fault Alarm Common
12 Fault Alarm NC
TB4 Analog / MODBUS
1 +24VDC
2 4-20mA Output 1
3DC COMMON
4RS485 DATA B
5RS485 DATA A
6ISOLATED COMMON
74-20mA Output 2
TB2 –1: +24VDC
TB2 –2: +24VDC
TB2 –3: 4-20mA Ch1 Out
TB2 –4: 4-20mA Ch2 Out
TB2 –5: Common
TB2 –6: Common
TB1 SENSOR #1
1 WHITE (DATA)
2 BLUE (4-20)
3 RED (+24)
4 BLACK (COMMON)
TB1 SENSOR #1
1 WHITE (DATA)
2 BLUE (4-20)
3 RED (+24)
4 BLACK (COMMON)

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Relays 1, 2 and 3 correspond to Low Alarm, Mid Alarm and High Alarm. Relay 4 is a Fault Alarm. Alarms
can be programmed to trigger above or below a certain value, work as normal or ‘failsafe’ and can be
made to latch if desired.
WARNING: CONTACTS ARE RATED FOR RESISTIVE LOADS ONLY! INDUCTIVE LOADS, SUCH AS COILS,
MOTORS OR SOLENOID VALVES MAY CAUSE ARCING AND INTERFERE WITH SENSOR DATA.
Figure 4-4: Relay & MODBUS Wiring Path
SERIAL MODBUS CONNECTIONS
The GDS-58DXP provides a single isolated MODBUS RTU slave interface that allow remote controllers or
PLCs to monitor many aspects of operation, including real-time data, range and alarm setpoints and alarm
and fault status bits. The GDS-58DXP operates at 9600 baud using an isolated RS-485 differential signal.
Access to the MODBUS RS-485 interface is provided on the back of the GASMAX DSX main display board.
MODBUS system architecture requires that the devices in any MODBUS loop be connected in a daisy-
chain layout. This minimizes signal reflections and improves signal noise margin. A MODBUS Termination
Jumper installs a load resistor across the MODBUS signal lines and should only be set to “A” (ON) at the
last device in the string.
Cable selection for MODBUS systems is important for both signal integrity and power distribution.
MODBUS / RS-485 transmissions use low-voltage differential signaling to achieve reasonable data rates
over very long distances, up to 4000 feet without a repeater. For MODBUS data signals, GDS Corp
recommends 20GA to 24GA shielded cable. Daisy-chain power distribution may require larger gauge wire
since it is critical that the supply voltage for the GDS-58DXP at the far end of the string not fall below
22VDC during power-up.
Relay Contacts
MODBUS Serial Port

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OPTIONAL MODBUS WIRING JUNCTION BOX [MJBJ]
If the GDS-58DXP is to be used in a MODBUS daisy chain configuration, GDS Corp recommends the
addition of the MODBUS Wiring Junction Box (see Fig. 4-3). This option minimizes the need to access
wiring inside the GDS-58DXP, provides individual wire landing points for incoming and outgoing MODBUS
and power wiring and shields, and makes it easy to temporarily disconnect the GDS-58DXP power or
MODBUS connections without affecting any other MODBUS device.
Figure 4-5: GDS-58DXP with Optional Modbus Wiring Junction Box (MBJB)
EXPLOSION PROOF INSTALLATION
The GDS-58DXP is designed for use in Class 1 Division 1 hazardous areas. Installation in these areas
should follow best industry standard practices and all appropriate electrical codes. Generally, these codes
require rigid metal conduit, poured seals and other installation elements necessary to ensure safety. For
maximum protection against RF interference or electrical surge, the GDS-58DXP enclosure and
interconnecting conduit must be properly grounded.
The GDS-58DXP can be equipped with a stainless-steel enclosure and Z-purge system for additional safety
in hazardous areas. See installation drawings for more details, or contact GDS Corp.
INTRINSICALLY SAFE INSTALLATION
The GDS-58DXP is not certified for use as an Intrinsically Safe device.

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5CALIBRATION
Calibration is critically important to ensure correct operation of the GDS-58DXP. The built-in CAL MODE
function is designed to make calibration quick, easy and error free; a successful ZERO and SPAN
calibration requires only four keystrokes.
Follow these GDS-58DXP calibration guidelines:
•CALIBRATION ACCURACY IS ONLY AS GOOD AS THE CALIBRATION GAS ACCURACY. GDS CORP
CALIBRATION GASES ARE TRACEABLE TO NIST (NATIONAL INSTITUTE OF STANDARDS AND
TECHNOLOGY) STANDARDS.
•NEVER USE CALIBRATION GAS THAT HAS PASSED ITS EXPIRATION DATE.
•CHECK THE SPAN GAS VALUE SETTING AND MAKE SURE IT MATCHES THE CALIBRATION GAS.
•BE SURE TO USE A CYLINDER OF ZERO AIR, A MIXTURE OF 21% OXYGEN AND 79% NITROGEN, AS
A ZERO REFERENCE UNLESS YOU ARE CERTAIN THAT NO TARGET GAS EXISTS IN THE AREA.
AMBIENT AIR WITH MINUTE AMOUNTS OF TARGET GAS MAY RESULT IN AN ‘ELEVATED ZERO’
CONDITION THAT MAY CAUSE A FAULT TO OCCUR ONCE THE AMBIENT GAS IS NO LONGER
PRESENT.
•ALWAYS CALIBRATE A NEW SENSOR BEFORE DEPENDING ON THE GDS-58DXP FOR PERSONNEL
OR EQUIPMENT SAFETY
•CALIBRATE ON A REGULAR SCHEDULE. GDS CORP RECOMMENDS A FULL CALIBRATION EVERY 3
MONTHS, WITH PERIODIC ‘BUMP TESTS’ ON A MORE FREQUENT BASIS TO ENSURE THAT THE
SENSOR HAS NOT BEEN AFFECTED BY TEMPERATURE EXTREMES OR THE PRESENCE OF
INCOMPATIBLE GASES.
•BE SURE TO RETURN THE RUN / CAL VALVE BACK TO THE RUN POSITION ONCE CALIBRATION IS
COMPLETE. IF THE VALVE IS NOT SET PROPERLY, THE GDS-58DXP WILL NOT PULL GAS FROM
THE REMOTE LOCATION AND THERE WILL BE NO INDICATION TO THE USER.

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Page 18
CALIBRATION PROCEDURE
Before beginning calibration, make sure you have the following items: A cylinder of calibration gas, fixed
flow regulator and a length of flexible tubing. A cylinder of ‘zero air’ may be necessary if the absence of
target gas cannot be confirmed in the sample area.
Attach a cylinder of Zero Air to the Run/Cal valve
and set the Run/Cal valve to the CAL position.
Press the ENTER key to access the MAIN MENU
Select the CALIBRATION option and press the
ENTER key
Calibration Menu. Select Sensor 1 or Sensor 2
using the UP or DOWN buttons. DOWN selects
Sensor #1 and UP selects Sensor #2
Select ZERO and press ENTER.
With the ZERO AIR flowing, wait for the present
gas value to stabilize. Press ENTER to continue.
EJECT MEMORY CARD
ABORT WARMUP
INFO
MAIN MENU
CALIBRATION
ALARM
RELAY
NETWORK
SELECT SENSOR ONE/TWO
ZERO
SPAN
CAL VAL 50
SELECT SENSOR ONE/TWO
ZERO
SPAN
CAL VAL 50
ZERO CAL <present gas value>
SENSOR ONE/TWO
PREV -ENT–START
ZERO AIR

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Wait for the ZERO CAL COMPLETE screen to
appear. The system will return to the Calibration
Menu.
Remove the cylinder or ZERO AIR and attach a
cylinder of SPAN GAS to the Run/Cal valve.
If the CAL (SPAN) VAL setting is correct, proceed
to SPAN calibration. If not, enter the CAL VAL
menu and adjust the CAL (SPAN) VAL to match the
calibration gas value.
Select the SPAN option and press ENTER.
With the SPAN GAS flowing, wait for the present
gas value to stabilize. Press ENTER to continue.
Wait for the SPAN CAL COMPLETE screen to
appear. The system will return to the Calibration
Menu.
Disconnect the cylinder of SPAN GAS
Reset the Run / Cal valve to RUN
Calibration is now complete.
ZERO CAL
1. COMPLETE
DONE, STOPPING
SELECT SENSOR ONE/TWO
ZERO
SPAN
CAL VAL 50
SELECT SENSOR ONE/TWO
ZERO
SPAN
CAL VAL 50
SPAN CAL <present gas value>
SENSOR ONE/TWO
PREV -ENT–START
SPAN CAL
1. COMPLETE
DONE, STOPPING
SPAN GAS

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6SETUP AND OPERATION
UNDERSTANDING THE USER INTERFACE
Once installed, apply power to the GDS-58DXP and verify that the LCD display is active. There are three
magnetic switches on the face of the GDS-58DXP, arranged to the left, right and below the display. The
left-side switch is “DOWN” and has an arrow pointing down. The right-side switch is “UP”and has an
arrow pointing up. The switch below the display is “ENTER”. These three switches are used to access the
MAIN MENU to perform calibration, configuration, and troubleshooting.
Figure 6-1: GDS-58DXP Gas Detector Display
OPERATIONAL DISPLAY
During normal operation, the gas detector display shows the current gas value, sensor ID number, sensor
range and engineering units and target gas. The bottom line will scroll through the memory card status,
date, time and sensor warning code if one exists (WARN XXX).
Channel One showing a reading of 14% LEL
methane. Date is 8/15/2019.
Channel Two showing a reading of 20.8% oxygen
and a time value of 15 minutes and 33 seconds past
12 noon.
14
ID 001
0-100 %LEL
METHANE
08/15/2019
S1
ID 001
0-25 %
OXYGEN
12:15:33
S2 20.8
UP:
Move cursor up
DOWN:
Move cursor
down
ENTER:
Enter MAIN MENU
Select Item