PEMTECH PT395 Series User manual

Model PT395
Stand Alone Sensor
For Combustible Hydrocarbons
Revision 6
Operator’s
Manual
Pem-Tech, Inc.
Houston, Texas
U.S.A

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Table of Contents
Notice and limited Warranty 3
Service Policy 4
Specifications 6
Overview 7
Target gases and Detection Ranges 8
Transmitter Board assembly 9
Connection Board assembly 10
Wiring Diagram
DC Power and 4-20mA Signal Output 11
Low and High Alarms 12
Installation 13
Start Up 15
Normal Operation 16
Gas Reading Display 16
Signal Output 4-20mA 16
Alarm Conditions 17
Low & High Alarm, Fault 17
Resetting Alarms 18
Calibration 19
Sensor calibration 19
Recommended Calibration Gases 21
Calibration errors and remedies 22
Calibration Flow Chart 23
Description, General Information 24
Selective response to different Combustible Gases
Adjust alarm set points 26
Setting Low & High Alarm Levels 26
MAINTENANCE
Factors affecting sensor accuracy 28
Routine maintenance 28
Sensor Inspection 28
Sensor Sensitivity 28
Sensor Replacement 29
Spare Parts 30

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NOTICE
PEM-TECH INCORPORATED SHALL NOT BE LIABLE FOR TECHNICAL OR
EDITORIAL ERRORS OR OMISSIONS MADE HEREIN; NOR FOR INCIDENTAL
OR CONSEQUENTIAL DAMAGES RESULTING FROM THE FURNISHING,
PERFORMANCE, OR USE OF THIS MATERIAL.
LIMITED WARRANTY
PEM-TECH Incorporated warrants all equipment manufactured by it to be free from
defects in workmanship and material, provided that such equipment was properly
selected for the service intended, properly installed, and not misused. Equipment
received by Pem-Tech for warranty repair or replacement will be return-shipped at
the lowest transportation cost.
The warranty provided by Pem-Tech does not cover defects which result from acts
beyond the control of PEM-TECH including, but not limited to: damage by accident,
negligence, tampering, or failure to operate in accordance with the procedures
outlined in the Operations Manual. PEM-TECH’s liability under no circumstances
will exceed replacement of the unit claimed to be defective.
The warranties specified herein are in lieu of any and all other warranties, express or
implied. In no event, whether as a result of breach of warranty or alleged
negligence, shall PEM-TECH be liable for special or consequential damages,
including, but not limited to, loss of profits or revenue; loss of equipment or any
associated equipment; cost of capital; cost of substitute equipment, facilities or
services; down time costs; or claims of customers of the purchaser for such damages.
Please call factory for RMA (return merchandise authorization) number before sending any
equipment for repair or replacement.

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SERVICE POLICY
Pem-Tech has service facility at the factory. For all the repairs contact at our toll free
number 1-800-379-3894 or visit our website www.pem-tech.com
For all repairs call us for a Return Material Authorization number (RMA). Inform us
briefly the nature of the problem and obtain shipping address. Properly pack the
equipment before shipping. Also include your complete shipping address and
contact name and phone number.
For non-warranty repairs you must provide the limit to repair costs. State if a quote
for repair cost is required before you can authorize the repair cost. For this an
additional charge may be applicable.
NOTE:
1. For all the repairs under warranty, serial number must be legible on the items
being repaired.
2. Shipping point is FOB Houston.

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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.
CAUTION
If needed the sensor threads should be coated with silicone free grease. The
junction box cover threads should also be lubricated .
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.

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SPECIFICATIONS
SENSOR TYPE Catalytic Beads
WEIGHT 4 Lbs.
RANGE 0 –100 % LEL
TEMPERATURE RANGE: -40 F to 158 F ( -40 C to 70 C )
HUMIDITY: 0 to 95% RH, non-condensing
ACCURACY: 5 % of full scale
REPEATABILITY: 5 % of gas applied
RESPONSE TIME: With 100% LEL gas applied:
50% full scale in < 10 seconds
90% full scale in < 30 seconds
( CSA Performance Test )
CLASSIFICATION: CSA Class I, Div. 1 Groups B,C, & D
C22.2 No 152
CE0081 II 2 G Ex d IIC T6
Suitable for use in hazardous locations
POWER INPUT: 14 - 30 VDC ( 24VDC Nominal)
POWER CONSUMPTION: < 4 Watts
ANALOG OUTPUT 4-20mA DC linear.
Maximum of 300 Ohms loop resistance
DISPLAY 3 Digit LED display.
ALARM RELAYS Low, High, & Malfunction Relay contacts
Normally open or Normally closed,
Form “C” type. Relay rating: 1 amps @ 30VDC
VISUAL ALARM Alarm LED indicators
INDICATORS Amber for Low alarm,
Red for High alarm &
Red for Malfunction

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Overview
Model PT395 is a single point fixed sensor for the detection combustible
hydrocarbon vapors in ambient air. Detection range is 0 –100 % LEL (Lower
Explosive Limit). PT395 displays the gas concentration and transmits a linear 4-
20mA analog output signal that is proportional to the gas concentration displayed.
The unit is also equipped with 3 forms “C” type alarm relay contacts. Two (2) alarm
relays are fully programmable as Low and High alarms and 1 for sensor Fault or
Malfunction.
The sensor also features a non-intrusive calibration. Calibration is performed by
activating an internal magnetic switch. All calibration and alarm configuration data
is maintained in a non-volatile memory
Sensor transmitter board and connection board are enclosed in an explosion proof
junction box (rated Class I, Div 1 & 2). The unit consists of three assemblies, the
transmitter and display board, the connection board, and the stainless steel sensor
head assembly. Each of these assemblies can be purchased separately.
Figure 1. Model PT395 Sensor

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Transmitter Board
The transmitter board assembly consists of the signal conditioning circuit,
microprocessor, digital display and 4-20 mA output circuit. Three (3) LED provides
visual indication of currently active alarms. 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.
Figure 2. Model PT395 Transmitter and connection board assembly
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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 as C (common), NC (normally
closed) and NO (normally open). See Figure 3.
The 3 pin terminal at the bottom of the board is labeled SENSOR. Three (3) wires
from the sensor head assembly are connected to this terminal.
These wires are connected as follows:
R Red wire (Sensor Positive 2 VDC Supply)
B Black Wire (Sensor Ground)
G White Wire (Sensor signal out)
For proper operation these wires must be connected as noted above.

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Wiring Diagram: DC Power and 4-20mA signal output
Figure 3. Connection to DC Power Supply and PLC input module
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