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

GDS-58DXP Operation & Maintenance Manual, Revision 1.00
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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

GDS-58DXP Operation & Maintenance Manual, Revision 1.0
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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