Dwyer GSTA, GSTC Manual - GSTA

Bulletin AQ-GSTA

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®

Series GSTA Carbon Monoxide/Nitrogen Dioxide Gas Transmitters

Specications - Installation and Operating Instructions

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The Series GSTA Carbon Monoxide/Nitrogen Dioxide Transmitters monitor the gas
concentration in underground parking garages and loading docks. Carbon monoxide
is commonly used to measure the exhaust of gasoline engines, while nitrogen dioxide
is used for diesel engines. Field selectable current and voltage outputs allow the
transmitter to be used with almost any building management controller. For carbon
monoxide units, the user can adjust the output range to be 0 to 50 PPM up to 0 to 599
PPM. Nitrogen dioxide units come with a standard 0 to 10 PPM range. The output can
be inverted to read 20-4 mA or 10 (5) to 0 VDC using internal dip switches.

To maximize the accuracy of the Series GSTA, the sensor can be eld-calibrated using

the A-449 remote LCD display. When the sensor reaches the end of its life, the display
will indicate that the sensor needs to be replaced.

WARNING

accordance with the job wiring diagram and in accordance with national and local
electrical codes. Use copper conductors only.

CAUTION

CAUTION

CAUTION

designed for AC voltage operation.

NOTICE

replacements will not be covered under warranty, but they can be revived by allowing
them to stabilize in an environment above 40% RH for 10 days. Once revived, they
need to be recalibrated before use.

INSTALLATION

NOTICE

• The transmitter should be mounted at normal breathing height, approximately 5 to 6

ft above the oor.

• The unit may be mounted in the horizontal or vertical position. It should be mounted
in an area that is shielded from direct contact with the elements or direct sunlight.

• Mount in an area that will prevent the sensor from having any direct contact with
water.

• The unit should be placed in an area that will give an average of the air quality. Do
not place the unit so it will receive direct engine exhaust. Prolonged exposure to
direct engine exhaust may damage the sensor.

Disconnect power supply before installation to prevent electrical
shock and equipment damage. Make sure all connections are in

Use electrostatic discharge precautions (e.g., use of wrist straps)
during installation and wiring to prevent equipment damage.

Avoid locations where severe shock or vibration, excessive
moisture or corrosive fumes are present.

Do not exceed ratings of this device, permanent damage not
covered by warranty may result. The 4-20 mA models are not

The electrochemical sensors should be stored in an environment
with a minimum humidity level of 20% RH. If the sensor dries out,

These are general guidelines. Local laws or ordinances will take
precedence.

SPECIFICATIONS

Sensor: Field replaceable electrochemical, 2 years typical lifespan.
Range: CO: Switch selectable 200 or 500 PPM; NO

Output Drift: <5% per year in air.

Coverage Area: 5000 to 7500 sq ft typical.

Accuracy: CO: ±2% FS., NO
Resolution: CO: 1 PPM; NO
Temperature Range: -4 to 122°F (-20 to 50°C).
Storage Temperature: For best sensor life, 32 to 68°F (0 to 20°C).
Humidity Limits: 15 to 90% RH constant; 0 to 99% RH intermittent.

Response Time: <45 s to 90% CO, <25 to 90% NO

Span and Zero Adjustment: Via onboard push-buttons or using optional A-449
display.

Housing: UV resistant glass lled polycarbonate.
Output Signals: Switch selectable 4-20 mA (loop powered), 0-5 V @ 5 mA, or 0-10

V @ 5 mA; Switch selectable 0-5 V/1-5 V and 0-10 V/2-10 V; Switch selectable
normal or reverse output
Power Requirements: Current output: 10-35 VDC; Voltage output: 15-35 VDC or
15-29 VAC.

Electrical Connection: Removable terminal block, knockouts for conduit tting.
Calibration: Via onboard push-buttons (LCD model only) or using optional A-449

display. Span gas concentration is eld selectable.

Enclosure Rating: IP64.

Weight: 1 lb (.45 kg).

Compliance: CE.

MOUNTING

1. Remove the cover plugs from the face of the unit and the top cover.

2. Disconnect the display cable from the USB connector on the main circuit board (if
present).

3. Remove the desired conduit tting knock out and install conduit tting (not

provided).

4. Position the transmitter where it is to be mounted and mark the mounting holes in
each corner of the housing.

5. Drill or punch out marked locations.

6. Place the transmitter box over mounting holes on wall and align. Install wall mount
screws (not provided) in mounting holes.

7. Proceed with wiring according to Figures 1 and 2.

8. Set DIP SWITCH and IOUT/VOUT SWITCH as desired. Refer to Figure 3.

9. Reconnect the LCD cable to the USB port on the main circuit board (if present).

10. Replace cover and cover plugs on the face of the unit.

2: ±3% FS, at the time of calibration.

2: 0.1 PPM.

2: 10 PPM.

2.

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.

Phone: [phone]

Fax: [phone]

www.dwyer-inst.com

e-mail: [e-mail]

DUCT MOUNTING

RECEIVER

V OUT WIRING

RECEIVER

I OUT WIRING

CURRENT/VOLTAGE

H

MENU SWITCHES

SENSOR

Duct mounting kit includes an air ow pitot tube, air lter with barbed connections, two

short pieces of tubing and one long piece of tubing.

1. Mount the pitot tube into the duct observing the ow direction marked on the pitot

tube.

2. Attach the two short pieces of tubing to the barbed connections on each side of the

air lter.

3. Attach the remaining side of one of the short pieces of tubing to the barbed
connection on the transmitter.

4. Attach the remaining side of the other short piece of tubing to the high port on the
pitot tube.

5. Attach the long piece of tubing to the open barbed connection on the transmitter.

6. Attach the other end of the long tubing to the low port on the pitot tube.

SWITCH LOCATIONS

SELECT SWITCH

DIP SWITC

Figure 3

Setting the Current/Voltage Select Switch

To access the current/voltage select switch, remove the cover of the unit. The current/
voltage select switch is located on the circuit board as shown in Figure 3. Set the

switch to ˝IOUT˝ for current, ˝VOUT˝ for voltage.

DIP SWITCH Settings

To access the DIP SWITCH, remove the cover of the unit. The DIP SWITCH is located
on the circuit board as shown in Figure 3.

ALL DIP SWITCHES ARE FACTORY SET TO “ON”.

WIRING

Use maximum 18 AWG wire for wiring terminals. Refer to Figure 1 or Figure 2 for
wiring information. The terminal block is removable for ease of installation.

Wiring for 4-20 mA Output

4-20 mA output units may be powered by 10-35 VDC.

2

1

3

4

POWER
SUPPLY

+

+

Figure 1

Wiring for 0-5 or 0-10 V output

The 0-5 or 0-10 V units may be powered by 15-35 VDC or 15-29 VAC. Note polarity
when using DC power. The maximum load is 5 mA

(1 K Ω for 0-5 V or 2 K Ω for 0-10 V).

POWER
SUPPLY

-

+

-

-

2

1

3

4

5 V / 10 V Output Select (Applies only to Voltage Output)

DIP SWITCH #1 OFF: Output = 0-5 V
DIP SWITCH #1 ON: Output = 0-10 V

Zero Suppression (Applies only to Voltage Output)

DIP SWITCH #2 OFF: Output range = 1-5 V or 2-10 V, depending on output range
DIP SWITCH #2 ON: Output range = 0-5 V or 0-10 V, depending on output range

Output Normal or Invert

DIP SWITCH # 3 OFF: Output is inverted
DIP SWITCH # 3 ON: Output is normal

Menu Function (CO Model only)

DIP SWITCH #4 OFF: User ADJ (Output Range)
DIP SWITCH #4 ON: Sensor calibration/range = 200 PPM

-

Figure 2

+

"ADJ".

T

If the unit only requires zero calibration
place the unit in an area that contains
fresh air (no CO or NO2 gas).

In order to calibrate the span, hook up
a model
unit as shown in Figure 4. If CO model,
set menu function switch to 200 ppm.

In the home position, the display reads
actual gas concentration.

Place the unit in an area that contains
fresh air (no CO or NO2 gas).
minutes to stabilize.

ZERO CALIBRATION

USER ADJ as required.

To

calibration gas

VIEWING THE RANGE

NOTE: Requires auxilary display
A-449. Hook up as shown in Figure

4. Upon power up the unit will
momentarily display the range.

SPAN
DIGIT

The range of the unit is factory set
to 200 ppm CO. Also, the range is
user adjustable to any value from
50 to 599 ppm CO. If dip switch is
set to User ADJ, the factory setting
is 100 ppm CO.

SETTING THE USER RANGE

NOTE: Requires auxilary display
A-449. Hook up as shown in Figure

4. Set output range switch to
"USER ADJ".

or

The range can be
displayed at any time by
pressing the span key
for 5 seconds when
in the home position.

A-507

calibration

adapter

SPAN
DIGIT

ZERO

VALUE

SPAN
DIGIT

Press the digit key to
scroll through the digits.
The digits will blink as
they are selected.

Adjust the value of
the digit using the
value key.

When the desired
range has been selected,
press and hold the span
key until the lower
display reads "ADJ".
Then the display will
sequence to the home
position.

Figure 4

ZERO

VALUE

Press and hold the zero
key for 5 seconds.

SPAN AND ZERO CALIBRATION

A-449 auxilary display to the

SPAN

ZERO

Simultaneously
press span and
zero buttons for
5 seconds. The
lower display
reads “-0-”. The
upper display
reads “CAL”.

A-449

display

To adjust the display to set the
desired span gas calibration value:

SPAN

DIGIT

ZERO
VALUE

Hook the unit up to the span
calibration gas using calibration
adapter A-507 as shown in Figure 4.
Span gas flow is to be between

0.5 to 1.0 slpm (1 to 2 scfh). Allow
gas to flow for at least 3 minutes.

SPAN
DIGIT

Display reads “CAL OK” for 5
seconds, then returns to home
position.

Press the digit key to
scroll through the digits.
The digits will blink as
they are selected.

Adjust the value of the
digit using the value key.

Press and hold the span
key for 5 seconds.

Simultaneously

SPAN

ZERO

DIGIT VALUE

press span
and zero
buttons for 5
seconds until
the upper
display reads

ZERO
VALUE

Allow 3

Press the zero key for 5
seconds, the unit will
sequence to span
calibration and display
the user set span
calibration gas value.
Factory setting is 200 ppm
for CO,10.0 ppm for NO2.

If the sensor output is no longer
sufficient for calibration, then the
display reads “BAD SEN”. The
sensor must be replaced.

NOTE: In calibration mode, if no key
is pressed, then the unit will time out
and return to home position after 10
minutes.

When calibration is complete,
set menu function to 200 ppm or

Sensor Replacement

A replacement sensor is available from Dwyer Instruments.
For CO, order part number: A-505

2, order part number: A-506

For NO

WARNING

Replacing the Sensor

1. Remove the cover plugs from the face of the unit and top cover. Locate the
sensor, see Figure 3 – the sensor is mounted on three pin sockets. The circuit
board is labeled either “CO SENSOR” or “NO2 SENSOR” underneath the
sensor.

2. Remove and discard the sensor.

3. Remove the shorting wire spring located on the bottom of the new sensor.

4. Install the new sensor into the three pin sockets.

5. The unit must be re-calibrated whenever a new sensor is installed.

6. Allow 30 minutes for the unit to come to temperature equilibrium prior to
calibration. The unit has internal temperature compensation, and the sensor
must be at the same temperature as the unit to calibrate properly.

TROUBLESHOOTING

Sensors contain acid. Do not attempt to open sensors. Sensors
should be disposed of according to local laws.

Loop Resistance: The maximum allowable loop resistance depends on the power
supply voltage. Maximum loop voltage drop must not reduce the transmitter voltage
below the 10 VDC minimum. Maximum loop resistance can be calculated with the
following equation. Vps is the power supply voltage.

-10.0

ps

Rmax =

Some receivers, particularly loop powered indicators, may maintain a xed loop

voltage to power the device. This voltage drop must also be subtracted from the power
supply voltage when calculating the voltage margin for the transmitter. The following

equation takes this into account. Vrec is the receiver xed voltage.

Rmax =

0-10 V Output Models: Verify appropriate supply voltage. The 0-10 V output models
require a DC supply of 15-35 V or an AC supply of 15-29 V for proper operation
maximum. Maximum output load is 5 mA.

V
20 mA

-10.0-V

Vps

20 mA

rec

1. Verify that the unit is mounted in the correct position.

2. 4-20 mA Models: Verify appropriate supply voltage. The transmitter requires
a minimum of 10 and a maximum of 35 VDC at its connection for proper
operation. Choose a power supply with a voltage and current rating that meets
this requirement under all operating conditions. If the power supply is
unregulated, make sure voltage remains within these limits under all power line
conditions. Ripple on the supply should not exceed 100 mV.

MAINTENANCE

Upon nal installation of the Series GSTA Transmitter and the companion receiver,

no routine maintenance is required with the exception of calibration. As with all
electrochemical type gas sensors, routine calibration is required. It is recommended
that units be re-calibrated at 6 month intervals, to maintain the published accuracy,
or as required by local ordinances or other requirements. The units will maintain 5%
accuracy if they are re-calibrated at 12 month intervals.

Except for sensor replacement and calibration, the Series GSTA is not eld serviceable
and should be returned if repair is needed (eld repair should not be attempted

and may void warranty). Be sure to include a brief description of the problem plus
any relevant application notes. Contact customer service to receive a return goods
authorization number before shipping.

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.

Printed in U.S.A. 3/22 FR# 443847-00 Rev. 10©Copyright 2022 Dwyer Instruments, Inc.

Phone: [phone]

Fax: [phone]

www.dwyer-inst.com

e-mail: [e-mail]