PEMTECH PT395 Series User manual

PT395 Series
Stand Alone Gas Detector
Toxic, Oxygen Deficiency, & Combustible (HC)
Revision 5
September 2015
Operat
or’s
Manual
Pem-Tech, Inc.
Houston, Texas
U.S.A
www.pem-tech.com
Gas Detection Technology

PT395 Series Detector
2
Table of Contents
Notice and limited Warranty 3
Specifications 4
Overview 5
Table 1. List of target gases 6
Transmitter Board assembly 7
Connection Board assembly 7
Accessories 8
Installation 10
Transmitter Wiring 11
Wiring Diagrams
DC Power and 4-20mA Signal Output 13
Low and High Alarms Connections 14
Start Up 15
Normal Operation 16
Gas Reading Display 16
Signal Output 4-20mA 16
Alarm Conditions 17
Alarm & Sensor Fault 17
Calibration 18
Sensor calibration Procedure 18
Calibrating Oxygen Depletion Sensor 21
Figure 7. Calibration Apparatus Setup 23
Response check / Bump Test 24
Calibration errors and remedies 25
Calibration Flow Chart 26
Adjust Alarm Levels 27
Setting Alarm Set Point 27
Alarm Conditions 29
Resetting Alarms 30
MAINTENANCE
Routine maintenance 31
Sensor Inspection, sensitivity and replacement 32
Spare Parts 34
Sub-assemblies and calibration accessories

PT395 Series Detector
3
IMPORTANT
Be sure to read and understand this instruction manual before installing,
operating or servicing the gas detection equipment.
WARNING
•Do not open the sensor enclosure with power applied unless it is verified that
no combustible gases or vapors are present. Calibration or maintenance
should not be performed if there is any indication of the presence of
combustible gas near the sensor.
•If anytime an intrusive sensor calibration procedure has to be performed then
de-classify the area before opening the sensor junction box.
•The sintered flame arrestor on the stainless steel sensor head is an integral
part of the complete sensor assembly. Do not operate the gas sensor with the
flame arrestor removed or damaged.
•The detector muse be earthed / grounded for the electrical safety. A safety
lug on the right side of the enclosure is provided for grounding.
CAUTION
•If needed the enclosure threads may be coated with silicone free grease.
Silicone based lubricants must never be used.
•Follow the wiring instruction for proper and safe operation under normal
conditions. Be sure that all wiring complies with NEC and all local ordinances.

PT395 Series Detector
4
SPECIFICATIONS
Sensor Type:
Continuous diffusion / adsorption
Combustibles (HC): Infrared & Catalytic Bead
Carbon Dioxide: Infrared
Toxic and Oxygen: Electrochemical
Typical Measuring Ranges
See Table 1 for target gases and range
Repeatability
±2 % Full scale
Electrical Classification
Explosion Proof
ATEX: II 2 G EX d IIC T6 (Tamb = -34°C to +100°C)
CSA: Class I, Div 1 & 2, Groups B,C& D
C22.2 No 30-M1985 &
C22.2 No 142-M1987
Ingress Protection
NEMA 4X, IP66
Approvals
CSA , ATEX/IECEx
Typical Response Time &
Operating Temperature Range
See Table 1 for details
Operating Humidity
15% to 90% RH, non-condensing
Storage Temperature
-40°F to +167°F (-40°C to +75°C)
Mechanical Specifications
Height: 7.4inches (188 mm)
Width: 6.2 inches (159 mm)
Depth 4.9 inches (125 mm)
Display
3 Digit LED Display
Status Indicators
3 Digit LED display for gas concentration,
calibration mode and fault status.
3 LED for Alarm Status / indicators
Input Power
14-28 VDC. 24 VDC nominal
Power Consumption
Toxic: 65 mA @ 24 VDC typical
Infrared: 60 mA @ 24 VDC typical
Catalytic Bead: 240 mA @ 24 VDC typical
Alarm Relays
3 each Fully programmable for Low & High alarm levels and
sensor Fault. Also programmable as Latching or Non-
Latching
Relay Ratings
SPDT Form “C” type Relay contacts
1 Amps @ 250 VAC or 30 VDC
Analog Output
Linear 4-20mA ; 0 -100% Full Scale (300 Ohms max. load)
2.0 mA - Calibration mode
< 1.0 mA - Sensor malfunction
Cable Requirement
3 wire shielded cable for Power and Analog output
Terminal connectors 12 AWG Max
Input / Output Protection
Transient over voltage suppressor,
Reverse polarity protection
EMI/RFI Immunity
Cable Entry Hub
¾” NPT Female
Adapter available for ½” NPT / M20

PT395 Series Detector
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Overview
1. Model PT395 Sensor is a single point fixed detector and transmitter for the
detection of toxic and flammable gases in ambient air. Detector is designed
and built suitable to be used in hazardous area. The detector is approved for
use in Class I Division 1 & 2 classified areas (North America) or Zone 1 and 2
(International).
2. The transmitter features a display and three programmable relays for
controlling external devices like alarms, sirens, switches and solenoid
valves. The transmitter provides an industry standard 3-wire, 4-20mA
(source) output for connection to a gas detection system or a PLC.
Table I lists the target gases and the detection ranges. The unit displays the gas concentration
and transmits a linear 4-20mA analog output signal proportional to the gas concentration
displayed. The unit is also equipped with a forms “C” type alarm relay contacts.
The detector also features a non-intrusive calibration. Calibration is performed by activating an
internal magnetic switch. Calibration is an easy automated procedure that does not require
any manual adjustment to the unit. All calibration and alarm configuration data is retained in a
non-volatile memory.
Digital Display
Field Cable Entry (x2)
¾” NPT
One Entry with Ex Plug
Stainless Steel (316)
Sensor Head Assembly
Transmitter assembly
Mounting Holes (X2)
Earth Ground Lug
Figure 1. PT395 Series Detector
Alarm LED Indicators

Toxic Gases
Target Gas
Max Range
Sensor
Type
Res.
Calib Gas
Range
(user
Selectable)
Default
Calib Gas
Used
Response
time (T90)
seconds
Recovery
Time (T10)
seconds
XXX
Operating Temperature
Default alarm Levels /
Set Points
Min
Max
Alarm 1
Alarm 2
Ammonia
(NH3)
50 ppm
Electrochemical
Sensors
0.1 ppm
5-35 ppm
25 ppm
< 60
~ 90
-4°C / 24°F 50°C / 122°F 5 ppm 10 ppm
Carbon Monoxide
(CO)
100 ppm
1 ppm
20-50 ppm
50 ppm
< 25
~45
-20°C / -4°F 55°C / 131°F 20 ppm 50 ppm
Carbon Monoxide
(CO)
300 ppm
5 ppm
50-150 ppm
50 ppm
< 25
~45
-20°C / -4°F 55°C / 131°F 100 ppm 150 ppm
Chlorine
(CL2)
10 ppm
0.1 ppm
2-10 ppm
5 ppm
< 60
~50
-20°C / -4°F 55°C / 131°F 2 ppm 5 ppm
Hydrogen
1,000 ppm
10 ppm
100-500 ppm
500 ppm
< 35
~120
-20°C / -4°F 55°C / 131°F 200 ppm 500 ppm
Hydrogen Sulfide
(H2S)
100 ppm
1 ppm
20-50 ppm
50 ppm
< 35
~45
-40°C / -40°F 65°C / 149°F
(intermittent) 10 ppm 15 ppm
Hydrogen Sulfide
(H2S)
500 ppm
1 ppm
50-150 ppm
50 ppm
< 35
~45
-40°C / -40°F 65°C / 149°F
(intermittent) 50 ppm 100 ppm
Mercaptan
100 ppm
1 ppm
20-50 ppm
50 ppm
< 35
~ 45
-20°C / -4°F 55°C / 131°F 10 ppm 15 ppm
Nitrogen Dioxide
50 ppm
1 ppm
10-50 ppm
10 ppm
< 50
~ 75
-20°C / -4°F 55°C / 131°F 10 ppm 15 ppm
Nitric Oxide
(NO)
100 ppm
1 ppm
20-50 ppm
25 ppm
< 45
~ 50
-20°C / -4°F 55°C / 131°F 20 ppm 50 ppm
Oxygen
(O2)
25 %V/V
0.1 %
Calibrated in fresh air.
Purged with Pure Nitrogen
< 15
from 20.9% to 0
~ 40
-20°C / -4°F 55°C / 131°F
19.5%V/V
(falling)
Sulfur Dioxide
(SO2)
100 ppm
1 ppm
20-50 ppm
25 ppm
< 35
10 ppm SO2
~45
-20°C / -4°F 55°C / 131°F 5 ppm 10 ppm
Carbon Dioxide
(CO2)
5 %
Infrared
Sensors
0.1 %
2 – 5 %
2.5 ppm
< 35
~ 45
-40°C / -40°F 75°C / 167°F 2 % 3.5 %
Carbon Dioxide
(CO2)
100%
1 %
10 – 100 %
50 ppm
< 35
~ 45
-40°C / -40°F 75°C / 167°F 20 % 50 %
Combustible Hydrocarbons
Target Gas
Max Range
Sensor Type
Res.
Calib Gas
Used
Response Time
(T90) seconds
Recovery Time
(T10) seconds
Accuracy
%
Operating Temperature
Default alarm Levels /
Set Points
Min
Max
Alarm 1
Alarm 2
Flammable
(Hydrocarbons)
100 % LEL
(5% Methane in
Air)
Catalytic
Bead 1 % 50 % LEL < 25 ~ 40 ±2 -40°C / -40°F 75°C / 167°F 20 % 40 %
Hydrocarbons
(Methane /
Propane)
100 % LEL Infrared 1 % 50 % LEL (methane or
propane) < 25 ~ 40 ±2 -40°C / -40°F 75°C / 167°F 20 % 40 %
Table 1. Reference Table for Target Gas Range and default parameters
Rev 2: 1/5/16

Transmitter Board
The transmitter board assembly consists of the signal conditioning circuit,
microprocessor, LED display and 4-20 mA output circuit. The transmitter board
assembly is connected to the connection board via ribbon cable and secured
onto the stand-off via two thumb screws. To remove the transmitter board
simply move the thumb screws counter-clockwise and slowly pull the transmitter
board away. Unplug the ribbon cable to completely remove the transmitter
board from sensor unit.
Note: Do not use force to tighten the thumb screws when installing the
transmitter board back on the connection / termination board.
Connection Board
The termination or connection board consists of relays and DC-DC power
converters for the transmitter board and the sensor. The power converters are
protected against reverse polarity.
A 3 pin terminal is provided for user interface to the monitoring device for power
input and 4-20ma output. Three (3) Pin terminal blocks are also used for alarm
connections. Each pin on alarm terminal block is labeled as C (common), NC
(normally closed) and NO (normally open). See Figure 3.
The 4 pin terminal at the bottom of the board is labeled SENSOR. Wires from the
sensor head assembly are connected to this terminal.
Each terminal contact is labeled as R(ed), G(reen), W(hite), B(lack). the toxic
sensors are 4 wires while Hydrocarbons LEL (Catalytic bead) and all infrared
sensors are 3 wires.
See figure 2 for drawing of Transmitter board and connection board assembly.

PT395 Series Detector
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Accessories
Range of accessories is available for the use of detector in various applications.
Rain / Dust guard: To protect the sensor head assembly against the
accumulation of dust / sand on the sintered disk of the head assembly. Also to
protect against water splashes.
Duct Mount Kit: This is an optional kit designed to monitor the gas vapors in
Heating, ventilation and air conditioning duct (HVAC).
Figure 2. PT395 Series Transmitter and connection board assembly




















PT395 Series Detector
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Flow Thru Adapter. A machined aluminum assembly with either 1/8” Hose barb
fittings or ¼” Compression fittings. This adapter is designed to use in application for
continuous flow of gas through the sensor head assembly.
Calibration Adapter with Tubing: Also a part of calibration accessories. Used
along with the flow regulator to flow the calibration gas to the sensor. Attached is 6
feet ¼” nylon tubing.
Magnetic Wand: A tool used to initiate the internal magnet sensitive switches for
alarm configuration and to initiate sensor calibration.
Pipe Mount Assembly: Includes hex bolts and stainless steel bracket to mount
the sensor to up to a 2” pipe.

PT395 Series Detector
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Installation
Refer to figure 3 for Detector explosion proof enclosure for mounting and conduit
connection.
The unit has 2 integral mounting holes. The unit can be mountd directly to a surfce
or to a horizontal or vertical pipe structure. An optional pipe mount bracket can be
used to mount the unit to a pipe up to 2” in diameter or cross section. Two (2)
Cable entries are provided on each side of the enclosure. Either side can be used for
the cable entry. The other side must be plugged with the one supplied with the
unit. An approved plug for hazardous location must always be used.
5.50"
7.4"
4.9"
(125mm) (139.7mm)
(188mm)
Ø 0.3" (7.6 mm)
2 Places
3
4" NPT Female
Both Sides
Cable Entry
Figure
3. Overall Dimensions

PT395 Series Detector
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Transmitter Wiring
Follow steps below for installation.
3. Remove the enclosure cover and un-plug the transmitter board by simply moving
the thumb screws in counter-clockwise direction until they have loosened up.
Slowly pull the transmitter board and detach the ribbon cable. Do not completely
un-screw or remove the thumb screws from the transmitter board.
4. Using a 3 conductor cable connect the termination board with the monitor or
controller as shown in figure 4. A shielded instrumentation cable must be used to
connect the detector to the controller for power and signal output. Refer to the
cable size chart at the end of this section for proper cable.
5. For Audio / Visual alarm connection or Alarm Relay Dry Contact, refer to figure 5
for wiring diagram. Be sure that the power rating of the alarm device does exceed
the Ampere rating of the alarm relay contacts. See relay ratings in the
specification section of the manual.
6.
7. Reconnect the transmitter board with the connection board with the 10 pin ribbon
cable. Mount the transmitter board on two 2 stand-offs using thumb screws on
the board. Note: Do not apply excessive force to tighten the screws.
8.
9. Place the cover back on the enclosure.
Caution: Cable Shield wire should be grounded at the controller or PLC
side not inside the detector enclosure.

PT395 Series Detector
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10. Note: Minimum voltage required for proper operation is 16VDC. If necessary
verify the input voltage by using Digital Multi Meter (DMM) at +V and –V terminals
on the connection board.
Reference Wire size Table
Assuming +24VDC or power input from the source, 8 volts of maximum voltage drop at the
detector power terminals, following would be power consumption of the detector
Cable Size
Cable resistance
Ω/km (Ω/1000Ft)
Max Cable Length*
Meters / (feet)
0.5 mm2(20AWG) 34 (10.4)
425
(1400)
0.82 mm2(18AWG) 21.4 (6.5)
670
(2200)
1.3 mm2(16AWG) 13.4 (4.08)
1030
(3400)
2.0 mm2(14AWG) 8.45(2.57)
1490
(4900)
Data above is for a stranded copper type cable
* The max cable length is estimated based on 24 Volts DC power to the detector and
maximum load of 100 Ωon the controller or signal receiver.
Max resistance per core : R = V/I 8volts / detector consumption (A)
Max Loop resistance for toxic & infrared 67.8 Ω
Catalytic Bead: 29.8 Ω
Sensor Head
Types
Nominal Power
At VDC
With 8 Volts of drop,
V= 16 volts
I = P/V
Combustible
(Catalytic Bead) 4.3 watt 268 mA
All Toxics & Infrareds ~1.9 watt 118 mA
The wire size data below is for reference only. Refer to the manufacturer
specification of the cable that is being used to ensure the maximum cable length
and proper operation of the unit.

PT395 Series Detector
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Figure 4. Wiring Diagram for Power and 4-20 mA signal connection




































PT395 Series Detector
14
Figure 5. Wiring diagram for Alarm Relay Connection






















 


PT395 Series Detector
15
Start Up
1. After installation apply power to the unit. Allow the sensor to warm up for at least
15 minutes. For Ammonia sensors allow at least 2 hours for warm up time. Upon
power up the unit will display 00 on the LED display. If the LED display does not
indicate 00 then check to see if the ribbon cable connector is properly inserted. If
necessary unplug the ribbon cable and plug it back again. The connector is keyed
and can be inserted only one way.
2. During the warm up time the sensor may display reading other than 00. However,
the 4-20mA analog output will remain at 4mA (0 reading) and the alarm relay is
inhibited. The reading will slowly goes down to zero. After warm up time the
sensor will return to its normal operation. Refer to section “Adjust Alarm Set
Points” to modify alarm parameters. Change the alarm levels if different set-point
is desired.
3. The sensors are calibrated at the factory before they are shipped. However, it is a
good practice to check the accuracy by simply applying the calibration gas after
the warm up time and check to see if the concentration displayed matches with
concentration of the test gas within tolerance. If calibration is required then follow
the steps in the Calibration procedure. If the unit is powered up for the first time
then allow at least 15 to 20 minutes before attempting calibration or bump test.

PT395 Series Detector
16
Operation
Normal Operation
The sensor is considered in normal operation after startup procedure is complete
and is not indicating any alarm or sensor fail (FAULT) condition.
Gas Reading Display
The sensor displays the gas concentration in % volume or ppm (parts per million)
by volume.
Signal Output 4-20mA
The 4-20mA signal output is directly proportional to the detection range of the
sensor. The output signal generated is proportional to the gas concentration
displayed on the transmitter LCD.
Use the formula below to compute the mA output for any given gas concentration
or vice versa.
Formula to convert gas reading to mA:
( 16 x gas_reading ) + 4 = Analog output (mA)
Detection Range
Formula to convert mA to gas reading:
( mA Output - 4 ) x Detection Range = gas_reading
16
(Note: Detection Range is the full scale range of the sensor)

PT395 Series Detector
17
% / ppm
Volume
mA Output
0
4.0
10
5.6
20
7.2
25
8.0
50
12.0
75
16.0
100
20.0
The above table is for the detector with Full scale range of 100 ppm / % (volume)
Alarm Conditions
Alarm (High gas reading)
When the gas concentration reaches the predefined alarm set point then the alarm
condition exists. The sensor will flash “ALr” for few moments and then display
the gas reading. Also the alarm relay is energized.
For oxygen the alarm is activated on the falling edge. For example if the alarm level is
set at 18 %, the relay will be energized if the oxygen level is at or falls below 18%
Fault (Sensor Fail)
PT395 is in Fault (Malfunction) condition when the sensor assembly malfunctions. In
Fault condition the 4-20mA output generated would be less than 1.0 mA. The
sensor displays “FLt” when sensor in Fault.

PT395 Series Detector
18
Calibration
Refer to Table at the end of this section for the recommended calibration gas for
the target sensor. Also see section on Spare Parts for part numbers for other
calibration accessories.
Following items are needed for the sensor calibration:
•Calibration adapter with tubing
•Magnet tool to activate the switch on the transmitter board assembly.
•Calibration gas bottle with flow regulator. The flow of the calibration gas should
be approximately 0.5 to 1.5 LPM (liters per minute)
See Figure 7 for setup
The sensor can be auto calibrated without removing the enclosure cover and
declassifying the zone. A magnet tool is used to activate the internal switch to
initiate the calibration. Once the calibration is initiated the alarm relays will be
inhibited and the 4-20mA analog signal will be held at approximately 2mA to avoid
any false alarm.
Figure 6. Magnetic switch position to activate calibration Mode switch
Magnetic Wand
Low
High
Fault

PT395 Series Detector
19
Follow the steps below to calibrate the sensor.
4. Remove the rain / splash guard if attached.
5. Make sure the detector and ambient air is clear of any target gas vapors.If the air
is contaminated then apply the purging (zero) air to the sensor in order to remove
the toxic vapors from the sensor head assembly. ( If zero air is applied then do not
remove air until after step 5)
6. Place the magnetic tool against the cover at 8 o’clock position to activate the
magnetic switch as shown in figure 7.
7. Place and hold the magnet until display indicates the “CAL” . Move the magnet
away from the cover.
8. While the CAL message is being displayed the sensor is making its initial
adjustments. It may take 5 to 10 seconds. (Note: Do not apply calibration gas yet)
9. Once the initial adjustments have been made, remove the zero air if applied. The
unit will display / flash the default Calibration Gas concentration or the
concentration of the calibration gas used last time. Make sure the Calibration Gas
value displayed on the LCD matches the gas concentration of the cylinder being
used for calibration. Else simply place and hold the magnet to the cover at 8
o’clock position to change the default Calibration gas concentration. Hold the
magnet at its place on the enclosure cover until the display reads the desired cal-
gas value. Refer to Table 2 below for the range of calibration gas concentration
used. The recommended calibration gas concentration is typically 50% of the full
scale range of the detector. For example, for 100 ppm H2S Detector, a 50 ppm H2S
Calibration Gas is used. The selected calibration gas value will be stored in a non-
volatile memory and remains unchanged until modified.
*** Note: For Oxygen deficiency pure nitrogen is applied as calibration gas and
thus value is not adjustable. Similarly for LEL detectors the Calibration Gas is
fixed at 50% LEL.

PT395 Series Detector
20
10. The microprocessor waits 60 seconds for the user to apply the calibration gas
while flashing the display approximately twice every second. Attach the calibration
adapter to the sensor head assembly and turn the gas on. When the flow of the
gas is detected by the sensor the display flashing rate will slow down to once every
second. If no gas is detected within 60 seconds the sensor aborts calibration and
will display Calibration Error code for few seconds before returning to normal
operation.
11. Apply the calibration gas for about 2 minutes.
12. After 2 minutes the sensor will display Adj for 5 to 15 seconds while making
adjustments and recording the calibration data into memory. When completed the
display will starts flashing rapidly. At this time remove the calibration gas and
allow the sensor to clear. Do not remove the calibration gas while the sensor is
adjusting. Remove the gas only when the adjustment is completed and the
display is rapidly flashing with calibration gas value.
13. While the gas from the sensor head assembly is being cleared the 4-20mA analog
output will be held at 2.0mA and alarm relay will not be activated until the sensor
has cleared. Once cleared the unit will return to its normal operation. The 2mA
level on the analog output line is an indication to any connected gas monitor that
the sensor is in calibration mode thus avoiding any false alarm.
Also refer to “Sensor calibration Flow Chart” for quick calibration review and
“Calibration Error and remedies”
If the ambient air is contaminated you may have to apply the zero air to clear
all the residual gas from the sensor head assembly. The sensor must clear
down to zero after the calibration gas in order to return to normal operation
for successful and accurate calibration.