35-3000RK-LEL
Combustible Gas Sample-Draw Detector
Operator’s Manual
Part Number: 71-0104RK
vision: P1
Re
Released: 9/18/04
RKI Instruments Inc.
33248 Central Ave.
Union City, CA 94587
PH: 800-754-5165 Fax: 510-441-5650
www.rkiinstruments.com
Product W arranty
RKI Instruments, Inc., warrants gas alarm equipment sold by us to be free from defects in
materials, workmanship, and performance for a period of one year from date of shipment
from RKI Instruments, Inc. Any parts found defective within that period will be repaired
or replaced, at our option, free of charge. This warranty does not apply to those items
which by their nature are subject to deterioration or consumption in normal service, and
which must be cleaned, repaired, or replaced on a routine basis. Examples of such items
are:
a) Absorbent cartridges d) Batteries
b) Pump diaphragms and valves e) Filter elements
c) Fuses
Warranty is voided by abuse including mechanical damage, alteration, rough handling, or
repair procedures not in accordance with the operator’s manual. This warranty indicates
the full extent of our liability, and we are not responsible for removal or replacement costs,
local repair costs, transportation costs, or contingent expenses incurred without our prior
approval.
THIS WARRANTY IS EXPRESSLY IN LIEU OF ANY AND ALL OTHER
WARRANTIES AND REPRESENTATIONS, EXPRESSED OR IMPLIED,
AND ALL OTHER OBLIGATIONS OR LIABILITIES ON THE PART OF
RKI INSTRUMENTS, INC., INCLUDING BUT NOT LIMITED TO, THE
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE. IN NO EVENT SHALL RKI INSTRUMENTS,
INC., BE LIABLE FOR INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
LOSS OR DAMAGE OF ANY KIND CONNECTED WITH THE USE OF
ITS PRODUCTS OR FAILURE OF ITS PRODUCTS TO FUNCTION OR
OPERATE PROPERLY.
This warranty covers instruments and parts sold to users by authorized distributors,
dealers, and representatives as appointed by RKI Instruments, Inc.
We do not assume indemnification for any accident or damage caused by the operation of
this gas monitor, and our warranty is limited to the replacement of parts or our complete
goods.
2 • 35-3000RK-LEL Combustible Gas Sample-Draw Detector
Table of Contents
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Flow System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Detection System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Mounting the Combustible Gas Sample-Draw Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Connecting the Sample Lines to the Sample-Draw Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Wiring the Combustible Gas Sample-Draw Detector to a Controller. . . . . . . . . . . . . . . . . . . . . . . . . 10
Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Introducing Incoming Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Setting the Fresh Air Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Replacing Components of the Combustible Gas Sample-Draw Detector . . . . . . . . . . . . . . . . . . . . . 16
Adjusting the Low Flow Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Assembling the Calibration Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Setting the Fresh Air Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Setting the Zero Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
35-3000RK-LEL Combustilbe Gas Sample-Draw Detector • 3
Overview
This operator’s manual describes the combustible gas sample-draw detector . This manual
also describes how to install, start up, maintain, and calibrate the sample-draw detector
when using it with a gas monitoring controller. A parts list at the end of this manual lists
replacement parts and accessories for the sample-draw detector.
Specifications
Table 1 lists specifications for the combustible gas sample-draw detector. See the controller
Operator’s Manual for information specific to the controller.
Target Gas Combustible gas, methane calibration standard
Input Power 24 VDC Nominal (23 VDC - 28 VDC)
Table 1: Specifications
Construction (housing) Fiberglass/polyester (NEMA 4X)
Dimensions 8.5 in. H x 6.5 in. W x 4.25 in. D
Weight 4.5 lbs.
Sampling Method Sample-draw
Sample Flow 1.5 SCFH (nominal)
Detection Range
Response Time 90% in 30 seconds
Linearity ±5% of detection range
Repeatability ±2% of detection range
0 to 100% LEL
1
4 • 35-3000RK-LEL Combustible Gas Sample-Draw Detector
Description
This section describes the components of the combustible gas sample-draw detector. The
sample-draw detector consists of the housing, flow system, and detection system.
Flow Adjust
Potentiometer
Pump/Pressure Switch
Terminal Block
Fail LED
Pilot LED
Flowmeter
Bypass valve
Hydrophobic
Filter
Mounting
Foot, 4X
Low FlowPotentiometer
Detector
Terminal Strip
Exhaust
Fitting
Inlet
Fitting
Relay
Interconnect
Terminal Strip
Oxygen Detector
(Not Used in This
Version)
CombustibleGas
Detector
3/4" Conduit Hub, 2X
Figure 1: Combustible Gas Detector Sample-draw Component Location
Housing
The sample-draw detector’s fiberglass housing is weather- and corrosion-resistant. It is
suitable for installation where general purpose equipment is in use.
The housing door is hinged on the left side and is secured by two latches on the right side.
The flowmeter and status lights are visible through a window in the housing door.
Four mounting feet are attached to the back of the housing (one at each corner). Use the
mounting feet to install the housing to a vertical surface. Use the two conduit hubs on the
bottom of the housing to make wiring connections to a gas monitoring controller.
An aluminum subpanel is mounted to the interior of the housing. The sample-draw
detector’s internal components are mounted to the subpanel.
35-3000RK-LEL Combustilbe Gas Sample-Draw Detector • 5
Flow System
The sample-draw detector’s flow system consists of the INLET fitting, hydrophobic filter,
pump, flowmeter, bypass valve, status lights, pressure switch, and EXHAUST fitting (see
Figure 1). Figure 2 illustrates how the gas sample moves through the flow system.
Exhaust
Bypass
Valve
Flowmeter
Inlet Filter Pump Sensor
Pressure Switch
To
Figure 2: Combustible Gas Sample-draw Detector Flow Diagram
INLET fitting
The INLET fitting on the right side of the housing allows the gas sample to enter the
sample-draw detector. The INLET fitting accepts 1/4 in. rigid tubing. See the Installation
section on page 9 to connect tubing to the INLET fitting.
Hydrophobic Filter
The hydrophobic filter is below the main circuit board. The filter pr events particulates and
water in the incoming gas sample from damaging the flow and detection systems. Replace
the filter when it appears dirty, discolored, or clogged.
Pump
The pump is behind the main circuit board near the top of the sample-draw detector.
The pump pulls the gas sample into the sample-draw detector. The pump operates on
24 VAC, which is generated from the 24 VDC supplied by the controller.
Flowmeter
The flowmeter is attached to the main circuit board near the top left corner (see Figure 1.)
You can see it through the window in the door. A ball in the flowmeter column indicates
the flow rate of the sample-draw detector. The flowmeter measures the flow in the range
0.2 to 2.0 SCFH (Standard Cubic Feet per Hour). The optimum flow rate is 1.5 SCFH.
Bypass valve
The bypass valve is to the left of the flowmeter. The bypass valve adjusts the flow rate to
the detector. Use a flat-blade screwdriver to adjust the bypass valve.
NOTE: The bypass valve allows fine adjustments of the flow rate. For a wider range of
adjustment, use the flow adjust potentiometer (see Figure 1.)
6 • 35-3000RK-LEL Combustible Gas Sample-Draw Detector
Status lights
Two status lights are above the flowmeter. They are also visible through the window in
the housing door.
Pilot light
The green Pilot light is on when the sample-draw detector is receiving power from the
controller.
Fail light
The red Fail light is on when the sample flow rate is below the low flow level.
NOTE: The factory set low flow level is 0.6 SCFH (±0.2). See “Adjusting the Low Flow
Setting” on page 17 to adjust this setting.
Pressure switch
The pressure switch is mounted to the opposite side of the main circuit board. The
pressure switch monitors the flow rate of the incoming gas sample.
If the flow rate falls below the preset low flow level, the pressure switch causes the fail
relay to interrupt the signal from the detector. The interrupted detector signal causes a fail
condition at the controller. The low flow level is factory-set at 0.6 SCFH (±0.2 SCFH).
EXHAUST fitting
The EXHAUST fitting on the right side of the housing allows the gas sample to exit the
sample-draw detector. The EXHAUST fitting accepts 1/4 in. rigid tubing. See the
Installation section on page 9 to connect tubing to the EXHAUST fitting.
Detection System
The detection system consists of the combustible gas sensor and the main circuit board.
Combustible Gas sensor
The combustible gas sensor is installed in a cavity block. The cavity block is mounted to
the aluminum subpanel near the bottom of the sample-draw detector. The combustible
gas sensor includes the sensing elements, flame arrestor, connector, and sensor leads.
NOTE: The cavity block includes a cavity for an oxygen sensor. This version of the
sample-draw detector does not include the oxygen sensor.
Sensing elements
Two sensing elements are protected within the sensor assembly. Through a series of
thermal and electronic reactions, these elements produce an electrical output that is
proportional to the detection range of the sample-draw detector.
Flame arrestor
The porous flame arrestor allows the gas sample to enter the sensor assembly and contact
the sensing elements. The flame arrestor also contains any sparks that may occur within
the sensor.
Connector
The top of the sensor includes five pins that plug into the socket connector . This connector
allows you to replace the sensor without disconnecting the wiring. The sensor leads are
soldered to the connector.
35-3000RK-LEL Combustilbe Gas Sample-Draw Detector • 7
Sensor leads
Four color-coded leads extend from the connector. The leads allow you to connect the
combustible gas sensor to the main circuit board.
Main Circuit Board
The main circuit board includes the interconnect terminal strip, detector terminal strip,
pump terminal strip, and relay (see Figure 1).
NOTE: The flowmeter and status lights are mounted to the main circuit board but are
considered part of the flow system.
Interconnect terminal strip
The interconnect terminal strip is the nine-point terminal strip near the bottom edge of the
main circuit board. Use the interconnect terminal strip to connect the sample-draw
detector to a controller
Detector terminal strip
The detector terminal strip is the nine-point terminal strip near the right edge of the circuit
board. Use the detector terminal strip to connect the combustible gas sensor to the main
circuit board.
NOTE: The combustible gas sensor is factory-wired to the circuit board. See the
“Installation” section on page 9 for all wiring procedures related to the sampledraw detector.
Pump terminal strip
The pump terminal strip is the four-point terminal strip near the top edge of the circuit
board. Use the pump terminal strip to connect the pump and pressure switch to the main
circuit board.
NOTE: The pump and pressure switch are factory-wired to the circuit board. See the
“Installation” on page 9 for all wiring procedures related to the sample-draw
detector.
Relay
The relay is to the left of the detector terminal strip. The relay is single-pole, double-throw
(SPDT) and is rated for 2 amps at 25 VDC (resistive). If the pressure switch senses a low
flow condition, the relay interrupts the signal from the sensor. The interrupted sensor
signal causes a fail condition at the controller
8 • 35-3000RK-LEL Combustible Gas Sample-Draw Detector
Installation
This section describes procedures to mount the sample-draw detector in the monitoring
environment and wire the sample-draw detector to a controller.
Mounting the Sample-Draw Combustible Gas Detector
1. Select the mounting site. Consider the following when you select the mounting site.
• Is there enough room to open the housing door and make wiring connections at
the bottom of the housing and tubing connections at the right of the housing?
Make sure there is sufficient room to perform start-up, maintenance, and
calibration procedures.
•Are the flowmeter and status lights visible?
7.3 in.
6.5 in.
4.0 in.
8.5
in.
8.9
in.
9.3
in.
Note: The housing is 4.25 in. deep.
Figure 3: Mounting the Combustible Gas Sample-Draw Detector
4. Close and latch the housing door.
3/4 in. conduit hub
(total of 2 hubs)
35-3000RK-LEL Combustilbe Gas Sample-Draw Detector • 9
NOTE: The sample-draw detector is shipped with the mounting feet “tucked under” the
housing to protect the mounting feet during shipment.
5. Slightly loosen the screw that secures the mounting foot to the housing, then rotate
the mounting foot 180 degrees (see Figure 3).
6. Tighten the screw that secures the mounting foot to the housing.
7. Repeat steps 3 and 4 for the remaining three mounting feet.
8. Position the sample-draw housing on a vertical surface at eye level (4 1/2 to 5 feet
from the floor).
9. Insert 1/4 inch or 5/16 inch screws through the slots in the mounting feet to secure
the housing to the mounting surface.
Connecting the Sample Lines to the Sample-Draw Detector
1. Attach 1/4 in. metal or rigid plastic sample tubing to the INLET fitting. Brass tubing is
recommended for most applications. If tubing corrosion caused by the air being
sampled is a concern, stainless steel tubing or rigid polypropylene tubing may be
used.
CAUTION: If you use flexible sample tubing (polyurethane for example), use an appropriate
metal insert to seal the connection between the tubing and the INLET fitting. See the
Parts List at the end of this manual, for an example of an appropriate metal insert.
2. Place the opposite end of the tubing at the sampling area.
CAUTION: Avoid loops or slumps in the incoming sample line. To reduce response time, keep the
incoming sample line as short as possible.
3. Attach rigid sample tubing to the EXHAUST fitting.
4. Route the opposite end of the tubing to an open area where the sample can safely
disperse.
Wiring the Sample-Draw Combustible Gas Detector to a Controller
WARNING: Always verify that the controller is off and that power to the controller is
off before you make wiring connections.
1. Turn off the controller
2. Turn off power to the controller.
3. Unlatch and open the housing door of the sample-draw detector.
4. Guide a six-conductor, shielded cable or six wires in conduit through one of the
conduit hubs at the bottom of the sample-draw housing.
5. Connect the cable to the sample-draw detector’s interconnect terminal strip as shown
in Figure 4.
6. Close and latch the housing door of the sample-draw detector.
10 • 35-3000RK-LEL Combustible Gas Sample-Draw Detector
CAUTION: If using shielded cable, leave the cable shield’s drain wir e insulated and disconnected
7. Route the cable or wires in conduit leading from the sample-draw detector through
CAUTION: Do not route controller power wiring and detector wiring through the same hub.
8. Connect the wires to the applicable detector terminal strip and power terminals at the
Pump.,
Internally Wired
at the sample-draw detector. You will connect the opposite end of the drain wire at
the controller.
one of the conduit hubs at the controller.
The power cable may disrupt the transmission of the sensor signal to the controller.
controller as shown in Figure 4.
LEL Sample-DrawDetector Housing
Pressure Switch,
Internally Wired
PUMP
PSW
Sample-Draw Detector
Main Circuit Board
ControllerLEL
Sensor Terminals
Controller Terminals
Figure 4: Wiring the Sample-Draw Detector to a Controller
HNGND GND
115VAC
ACTerminal
StripNot Used
On This
Version
Red
White
Green
Black
-(DC -)
+24VDC
35-3000RK-LEL Combustilbe Gas Sample-Draw Detector • 11
WHT GRN BLK
RD
Black
Green
White
_
4/2024V
+
P- AMPAMPLEL/ O2
Red
Combustible
Gas Sensor,
Internally Wired
Start Up
5. Connect the cable shield to an available chassis ground at the controller. The
grounding screw on one of the controller’s grounded conduit hubs is an example of a
chassis ground.
This section describes procedures to start up the sample-draw detector and place the
sample-draw detector into normal operation.
Introducing Incoming Power
1. Complete the installation procedures described earlier in this manual.
2. Verify that the wiring is correct and secure. Refer to the controller operator’s manual
for connections at the controller.
3. Turn on or plug in the power to the controller, then turn on the controller.
4. Verify that the sample-draw detector’s PILOT light is on.
5. Verify that the controller is on and operating properly. Refer to the controller
operator’s manual.
6. Verify that the flowmeter indicates a flow rate of approximately 1.5 SCFH. If
necessary, use the bypass valve or flow adjust potentiometer to adjust the flow rate.
NOTE: The following step tests for leaks in the sample line. This test will cause a low
flow condition at the sample-draw detector and a fail condition at the controller.
Be sure to put the controller into its calibration program or disable external
alarms before performing this test.
7. Verify that the incoming sample line is not leaking. To test the sample line, plug the
open end of the sample line with your thumb. If the flowmeter ball drops to the
bottom of the flowmeter, the incoming sample line is not leaking.
8. Remove your thumb from the sample line, verify that the flowmeter returns to a
normal flow rate.
9. Enable alarms or place the controller in normal operation.
CAUTION: Allow the sample-draw detector to warm up for 15 minutes before you continue with
the next section, “Setting the Zero Reading.”
Setting the Zero Reading
CAUTION: If you suspect the presence of combustible gas in the monitoring environment, use
the calibration kit and the zero air calibration cylinder to introduce “fresh air” to the
sensor and verify an accurate zero setting. See “Calibration” on page 18 for
instructions on using a zero air calibration cylinder for setting the zero reading.
1. Verify that the sample-draw detector is sampling a fresh air environment
(environment known to be free of combustible gas).
2. Verify a reading of 0 %LEL on the controller display screen for the applicable channel.
If the display reading is 0 % LEL, start up is complete. The sample-draw detector is in
normal operation. If the display reading is not 0 % LEL, continue with step 3.
12 • 35-3000RK-LEL Combustible Gas Sample-Draw Detector
3. Perform a zero operation at the controller. See the controller operator’s manual for
Maintenance
This section describes maintenance procedures. It includes preventive maintenance
procedures. This section also includes procedures to troubleshoot the sample-draw
detector, replace components of the sample-draw detector, and adjust the low flow
setting.
Preventive Maintenance
This section describes a preventive maintenance schedule to ensure the optimum
performance of the sample-draw detector. It includes daily, monthly, and quarterly
procedures.
Monthly Visual Checks
1. Verify that the pilot light is on.
2. Verify that the flowmeter indicates a flow rate of approximately 1.5 SCFH.
3. Verify a display reading of 0 %LEL at the controller. Investigate significant changes in
Monthly Response Test
instructions to perform a zero operation.
If necessary use the bypass valve or flow adjust potentiometer to adjust the flow rate
to 1.5 SCFH.
the display reading.
This procedure describes a test to verify that the sample-draw detector responds pr operly
to the target gas.
NOTE: To reduce the response time of this test, use a short incoming sample line. If the
sample-draw detector’s sample line is long, connect a shorter line for this test.
Make sure you reconnect the sample line after you complete this procedure.
NOTE: Performing a response test on the sample-draw detector may cause alarms. Be
sure to put the controller into its calibration program or disable external alarms
before performing this test
Preparing for the response test
NOTE: This procedure describes the RKI calibration kit that includes a dispensing valve
and a gas collection bag. A calibration kit that uses a demand flow regulator is
also available.
1. Verify that the display reading a the controller is 0 % LEL.
If the display reading is not 0 % LEL, set the zero reading as described in
“Calibration” on page 18, then continue this procedure.
1. Follow the instructions in the controller’s operator’s manual for entering calibration
mode.
2. Connect the calibration kit sample tubing to the fitting on the gas collection bag and
run the tubing through the tubing clamp provided with the calibration kit.
35-3000RK-LEL Combustilbe Gas Sample-Draw Detector • 13
3. Disconnect the incoming sample line from the sample-draw detector’s inlet fitting,
then connect the sample tubing from the gas collection bag to the inlet fitting.
Allow the sample-draw pump to draw out any residual gas in the gas collection bag.
4. Close the tubing clamp.
NOTE: This step will cause a low flow alarm.
5. Disconnect the calibration kit sample tubing from the inlet fitting.
NOTE: If you can verify a fresh air environment, it is not necessary to use a zero air
calibrating sample to set the zero reading at the controller. If you can verify a
fresh air environment, go to the next section, Setting the Zero Reading.
6. Screw the dispensing valve onto the test gas cylinder.
7. Connect the tubing from the gas collection bag to the dispensing valve, then open the
clamp.
8. Open the dispensing valve. The gas collection bag begins to fill.
9. Close the dispensing valve when the gas collection bag appears full.
10. Close the tubing clamp, then disconnect the sample tubing from the dispensing valve.
11. Remove the dispensing valve from the test gas cylinder.
Performing the response test
1. Connect the calibration tubing from the gas collection bag to the INLET fitting.
The sample-draw detector’s pump automatically begins pulling the test sample from
the gas collection bag when you connect the tubing to the INLET fitting.
2. After approximately one minute, verify that the reading at the controller stabilizes
within ± 10% of the concentration of the test sample. If the reading is not within ± 10%
of the test sample, calibrate the sample-draw detector as described in “Calibration” on
page 18.
3. Remove the calibration tubing from the INLET fitting, then reconnect the sample
tubing to the INLET fitting.
Quarterly Calibration
RKI Instruments recommends calibrating the combustible gas sample-draw detector
quarterly. Some applications may require a more or less frequent calibration schedule
depending on environmental conditions, frequency of gas exposure, and other factors.
Calibrate the sample-draw detector as described in “Calibration” on page 18.
Troubleshooting
The troubleshooting guide describes symptoms, probable causes, and recommended
action for problems you may encounter with the sample-draw detector.
NOTE: This troubleshooting guide describes sample-draw detector problems only. See
the controller Operator’s Manual if the controller exhibits any problems.
14 • 35-3000RK-LEL Combustible Gas Sample-Draw Detector
Fail condition
Symptoms
• The sample-draw detector’s Fail light is on.
• The monitoring device is operating properly but indicates a reading well below zero.
Probable causes
• The sample-draw detector’s flow rate is too low because of an obstructed sample line,
failed pump, etc.
• The sample-draw detector is malfunctioning.
• The sensor wiring is disconnected or misconnected.
Recommended action
1. At the sample-draw detector, set the correct flow rate with the bypass valve or flow
adjust potentiometer.
2. If you cannot set the correct flow rate, check the sample lines for obstructions or kinks.
3. Verify that the sensor wiring is correct and secure. “Wiring the Sample-Draw
Combustible Gas Detector to a Controller” on page 10 describes sensor wiring
connections.
4. Calibrate the sample-draw detector as described in “Calibration” on page 18.
5. If the fail condition continues, replace the sensor as described later in this section.
6. If the fail condition continues, contact RKI Instruments, Inc., for further instruction.
Slow or no response/difficult or unable to calibrate
Symptoms
• The sensor responds slowly or does not respond during the monthly response test.
• Unable to accurately set the zero or response reading during the calibration
procedure.
• The sensor requires frequent calibration.
Probable causes
• The calibration cylinder is low, out-dated, or defective.
• If a demand flow regulator calibration kit is used, the demand flow regulator is not
functioning properly.
• The sample-draw detector’s flow rate is too low because of an obstructed sample line,
failed pump, etc.
• The sample-draw detector is malfunctioning.
Recommended action
1. Verify that the calibration cylinder contains an adequate supply of a fresh test sample.
2. If a demand flow regulator calibration kit is used, use a different demand flow
regulator to determine if the original one if functioning properly.
3. If necessary, set the correct flow rate with the bypass valve or flow adjust
potentiometer.
4. If you cannot set the correct flow rate, check the sample line for obstructions or kinks.
5. If the calibration/response difficulties continue, replace the sensor as described later
in this section.
35-3000RK-LEL Combustilbe Gas Sample-Draw Detector • 15
6. If the calibration/response difficulties continue, contact RKI Instruments, Inc., for
further instruction.
Replacing Components of the Combustible Gas
Sample-draw Detector
This section includes procedures to replace the sensor, hydrophobic filter, and ferrules.
Replacing the combustible gas sensor
1. Turn off the controller
2. Turn off power to the controller.
3. Open the housing door of the sample-draw detector.
4. Unscrew and remove the two screws that secure the sensor retraining plate, then lift
the plate, connector, and sensor out of the housing.
5. Unplug the connector from the sensor.
6. Verify that you are using the correct replacement sensor (NC-6240 is printed on the
sensor), then plug the sensor into the connector.
7. Place the sensor in the combustible gas sensor cavity, then position the retaining plate
on the two standoffs.
8. Secure the retaining plate to the standoffs with the two screws you removed in step 4.
9. Close and latch the housing door.
10. Turn on power to the controller.
11.Turn on the controller.
CAUTION: Allow the replacement sensor to warm up for 15 minutes before you continue.
12. Calibrate the replacement sensor as described in “Calibration” on page 18.
Replacing the filter
1. Open the housing door of the sample-draw detector.
2. Disconnect the filter from the rubber elbows on each end of the filter, then remove the
filter from the sample-draw detector.
3. Install the new filter.
4. Verify that the flow rate is approximately 1.5 SCFH, then close the housing door.
Replacing the ferrules
The INLET and EXHAUST fittings each includes two ferrules that seal the inlet or exhaust
tubing to the fitting. Replace the ferrules if the seal is bad or if you replace the sample
tubing. Always replace the ferrules as a pair.
1. Unscrew the nut that holds the tubing to the fitting from the fitting.
2. Slide the nut away from the end of the tubing.
3. Cut off the end of the sample tube with the old ferrules off about one inch from the
end
4. Slide the nut off the sample tubing.
5. Position the nut so the threaded end is facing you, then insert the bottom (smaller)
ferrule into the nut. Insert the ferrule so the flat side is facing down.
16 • 35-3000RK-LEL Combustible Gas Sample-Draw Detector
NOTE: Make sure the bottom ferrule is laying flat in the nut.
6. Insert the cone-shaped front ferrule on top of the bottom ferrule. Insert the ferrule so
the smaller end of the cone is facing up.
7. Screw the nut onto the fitting by hand just until it stops turning.
8. Insert the sample tubing into the fitting until it bottoms out.
9. Firmly tighten the nut so the ferrules crimp onto the sample tubing and make a seal.
Adjusting the Low Flow Setting
NOTE: Adjusting the low flow setting will cause a low flow alarm at the sample-draw
detector and a fail alarm at the controller. Be sure to put the controller into its
calibration program or disable external alarms before performing this test
The factory-set low flow setting is 0.6 SCFH (±0.2). To adjust the low flow setting:
1. Use the flow adjust potentiometer (VR1) to set the flow to 0.6 SCFH.
If the sample-draw detector goes into low flow alarm before you can adjust the flow
down to 0.6 SCFH, adjust the low flow potentiometer 1/4 turn clockwise, then
attempt to set the flow again. Repeat this step until you are able to adjust the flow to
0.6 SCFH.
NOTE: The low flow potentiometer is accessible through a circular cutout in the main
circuit board. The cutout is labeled PS1.
2. Slowly turn the low flow potentiometer counterclockwise just until the sample-draw
detector goes into low flow alarm.
3. Increase the flow using VR1 until the unit is out of low flow alarm.
4. Decrease the flow very slowly and verify that the low flow alarm is 0.6 SCFH (±0.2).
If the low flow alarm is set too low, turn the low flow potentiometer slightly
clockwise. Repeat steps 3 and 4 if necessary.
5. Use the flow adjust potentiometer (VR1) to set the flow to 1.5 SCFH.
6. Make sure the sample-draw detector’s Fail light is off.
35-3000RK-LEL Combustilbe Gas Sample-Draw Detector • 17
Calibration
This section describes how to calibrate the combustible gas sample-draw detector. It
includes procedures to assemble the calibration kit, set the zero reading, set the response
reading, and return to normal operation.
The standard calibration gas for the sample-draw detector is methane. The sample-draw
detector may be calibrated to other combustible gases such as hexane or hydrogen. Use
the correct calibration gas for your installation.
NOTE: Calibrating the sample-draw detector may cause alarms. Be sure to put the
controller into its calibration program or disable external alarms before
continuing.
NOTE: This procedure describes calibration using a dispensing valve and a gas
collection bag. A demand-flow regulator calibration kit is also available for
calibrating the sample-draw detector without using a sample bag.
Preparing for Calibration
1. Follow the instructions in the controller’s operator’s manual for entering calibration
mode.
2. Connect the calibration kit sample tubing to the fitting on the gas collection bag and
run the tubing through the tubing clamp provided with the calibration kit.
3. Disconnect the incoming sample line from the sample-draw detector’s inlet fitting,
then connect the sample tubing from the gas collection bag to the inlet fitting.
Allow the sample-draw pump to draw out any residual gas in the gas collection bag.
4. Close the tubing clamp.
NOTE: This step will cause a low flow alarm.
5. Disconnect the calibration kit sample tubing from the inlet fitting.
NOTE: If you can verify a fresh air environment, it is not necessary to use a zero air
calibrating sample to set the zero reading at the controller. If you can verify a
fresh air environment, go to the next section, Setting the Zero Reading.
6. Screw the dispensing valve onto the zero air calibration cylinder.
7. Connect the tubing from the gas collection bag to the dispensing valve, then open the
clamp.
8. Open the dispensing valve. The gas collection bag begins to fill.
9. Close the dispensing valve when the gas collection bag appears full.
10. Close the tubing clamp, then disconnect the sample tubing from the dispensing valve.
11. Remove the dispensing valve from the zero air calibration cylinder.
18 • 35-3000RK-LEL Combustible Gas Sample-Draw Detector
Setting the Zero Reading
1. Open the tubing clamp, then connect the sample tubing from the gas collection bag to
the sample-draw detector’s inlet line. This step is not necessary if you verified a
fresh air environment earlier in this procedure.
2. Allow the sample-draw detector to draw sample for one minute.
3. Follow the directions in the controller’s operator’s manual for setting the zero
reading. If you used a zero air calibration cylinder to set the zero reading, proceed to
step 4. If you verified a fresh air environment, proceed to the next section, Setting the
Response Reading.
4. Allow the sample-draw detector to draw out any residual gas in the gas collection
bag.
5. Close the tubing clamp, then disconnect the gas bag sample tubing from the inlet
fitting.
NOTE: This step will cause a low flow alarm.
6. Unscrew the dispensing valve from the zero air calibration cylinder.
Setting the Span
1. Screw the dispensing valve onto the combustible gas calibration cylinder.
2. Connect the tubing from the gas collection bag to the dispensing valve, then open the
clamp.
3. Open the dispensing valve. The gas collection bag begins to fill.
4. Close the dispensing valve when the gas collection bag appears full.
5. Close the tubing clamp, then disconnect the sample tubing from the dispensing valve.
6. Remove the dispensing valve from the combustible gas calibration cylinder.
7. Open the tubing clamp, then connect the sample tubing from the gas collection bag to
the sample-draw detector’s inlet line.
8. Allow the sample-draw detector to draw sample for one minute.
9. Follow the directions in the controller’s operator’s manual for setting the span.
10. Allow the sample-draw detector to draw out any residual gas in the gas collection
bag.
NOTE: This step may cause a low flow alarm.
11. Disconnect the gas bag sample tubing from the inlet fitting.
12. Unscrew the dispensing valve from the combustible gas calibration cylinder.
Returning to Normal Operation
1. Wait approximately one minute to allow the combustible gas reading to decrease
below the alarm level.
2. Follow the instructions in the controller’s operator’s manual to exit the calibration
mode.
35-3000RK-LEL Combustilbe Gas Sample-Draw Detector • 19
Parts List
Table 2 lists replacement parts and accessories for the sample-draw combustible gas
detector.
Table 2: Parts List
Part Number Description
06-1248RK Sample tubing, 3/16 x 5/16, specify length, (for calibration kit)
17-2593RK Brass insert for flexible 1/4 OD x .17 ID tubing (for INLET and
EXHAUST fittings)
17-2683RK Front ferrule (for INLET and EXHAUST fittings)
17-2688RK Back ferrule (for INLET and EXHAUST fittings)
30-0610RK Pump
33-0165RK Hydrophobic filter
61-0145RK Combustible gas sensor, plug-in type, LEL range
71-0104RK Operator’s Manual, 35-3000RK-LEL sample-draw Detector
81-0002RK-01 Calibration cylinder, 50% LEL hydrogen in air 34 liter)
81-0002RK-03 Calibration cylinder, 50% LEL hydrogen in air, 103 liter
81-0007RK-01 Calibration cylinder, 50% LEL hexane in air, 34 liter
81-0012RK-01 Calibration cylinder, 50% LEL methanein air, 34 liter
81-0012RK-03 Calibration cylinder, 50% LEL methane in air 103 liter)
81-0076RK-01 Zero air calibration cylinder (34 liter)
81-0076RK-03 Zero air calibration cylinder (103 liter)
81-1001RK Dispensing valve (with knob)
81-1054RK Regulator (demand flow)
81-1126RK Gas collection bag (2 liter)
20 • 35-3000RK-LEL Combustible Gas Sample-Draw Detector
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