Application Note
Issue Date September 8, 2008
Pilot Burners/Thermocouples
Application
Good Practice
Rules
This document is intended to aid the appliance engineer or authorized
service contractor in making a standing pilot application. Pilot burners are
manufactured with a variety of tips and mounting configurations.
Representative types of mounting with standard pilots are illustrated in
Figure 1. Dimensions shown are approximate and may vary, provided the
requirements of good ignition are met. See Good Practice Rules.
The following are good practice rules for governing the location of the
pilot:
• Locate the pilot so that it can be reached easily for lighting.
• Locate the pilot in a position that has a fixed relation to the main
burner (see Figure 1).
Mounting Position Examples for Pilot Burners
Pilot I g ni tion Port 3 / 8 " Above
and 1/4" A way (Or C l o s er )
from Center of Nearest Main
Burner Port
pilot
Figure 1: Pilot Location
• Locate the pilot burner in a position that will receive incoming air and
not products of combustion from the main burner. The pilot should
be located where it will not be affected by an excessive draft of
incoming air.
• Locate the pilot burner in such a position that it does not receive the
full force of igniting or extinguishing puffs from the main burner.
• Locate the pilot burner in a position that will allow ready removal for
cleaning.
© 2008 BASO Gas Products 1
Part No. BASO-AN-PB/THERMOCOUPLES, Rev.- www.baso.com
After
Installation
When the pilot burner has been installed, carefully make the following
observations and tests:
1. Ensure the main burner flames do not impinge on any part of the pilot
burner.
2. Ensure the pilot burner will ignite the main burner under all pilot
burner conditions that maintain the safety shutoff device (BASO®) in
the On position. (See the Safety Turn Down Test section.)
3. Ensure the pilot burner will not be smothered out or snuffed out:
• when the main burner is ignited from a cold start.
• when the main burner is ignited with the appliance at the
maximum temperature conditions of operation.
• with normal variation in air adjustments of the main burner.
• with rapid Off and On operation of the main burner with the
combustion chamber cold.
• with rapid Off and On operation of the main burner with the
combustion chamber hot.
• with continued operation of the main burner.
Thermocouple
Output Test
Instructions for
Testing BASO
Pilot Burners with
K15, K16, K19, 80,
85, 87, and 88
Thermocouples
4. To ensure proper operation, the pilot flame must produce a
satisfactory millivoltage as described in the Thermocouple Output
Test section.
Note: When a pilot is to be applied to an appliance already in the field,
obtain the appliance manufacturer’s recommendations for the
correct pilot specification and location dimensions for the
particular model appliance.
When the pilot is applied properly, the thermocouple will produce an open
circuit millivoltage as shown in Table 1. Normal operating voltages, as
shown, must be obtained to give trouble-free performance. Perform the
following tests with the Y99AB Test Kit.
Attach the proper junction terminal of the millivoltmeter to the
thermocouple lead and measure the open circuit voltage. Allow at least
five minutes for each meter reading. For specifications, see Table 1.
2 Pilot Burners/Thermocouples Technical Bulletin
Table 1: Thermocouple Output Table
Thermocouple Lead
Series
Number
Code Number Turn Down
(mV)
Open Circuit
Range (mV)
Minimum
Fixed Load
Voltage (mV)
K14
K15
K16
K19
80 4 20 - 28 8
88D, 88F, 88J, 88E,
4 20 - 28 8
88H
87D, 87F, 87K, J87D,
4 25 - 35 8
K16K, L87D, N87D,
K16S, JC87F, L87F
K19 4 25 - 35 8
Safety
Turn Down Test
!
WARNING: Fire or Explosion Hazard. Avoid accumulation
of unburned gas and resulting personal injury or
property damage by making sure the main burner
lights under all pilot burner flame conditions that
maintain the BASO in the On position. Follow the
procedure below to assure the location of the pilot
with respect to the main burner is acceptable.
Turn Down Test
with the Use of
the Y99AB Test
Kit
To perform the turn down test with the Y99AB Test Kit (purchasable
from your BASO Gas Products authorized wholesaler):
1. Disconnect the thermocouple from the BASO safety shutoff device
and connect it to the test kit (see Figure 2). Hold the BASO in the
open position during this test using battery power from the test kit.
Power
Manual
Main
Valve
Manual
Pilot
Button
Power Unit
Pilot Burner
Gas Line
Source
BASO
Reset
Button
Thermostat
44549-7
Actuator
500
7
0
0
0
0
3
20
3
0
0
0
1
MILLIVOLTS
D.C.
PENN-BASO CONTROLS
9
4
0
0
1
0
Thermocouple
Lead
0
0
5
0
0-1000 0-50
MILLIVOLTS
44549-8
MILLIAMPS
0-500
ADJUST
MILLIAMPS
MILLIVOLTS
Red
Black
y99ab
Figure 2: Using the Y99AB for the Turn Down Test
Pilot Burners/Thermocouples Technical Bulletin 3
2. Reduce the flame on the pilot through the use of the “B” valve to the
point where the open circuit millivoltage reading is not more than
4 millivolts.
3. Cycle the main burner On and Off at least three times. The main
burner must ignite each time within four seconds.
If you cannot secure ignition of the main burner when the millivoltage
reading is 4 millivolts, the pilot has been located improperly with respect
to the main burner. Relocate the pilot; repeat Steps 2 and 3.
Turn Down Test
without
Instruments
If you do not have the Y99AB Test Kit, perform the turn down test using
the following steps:
1. Reduce the flame on the pilot, through the use of the “B” valve to a
point where the pilot flame does not impinge on the thermocouple
(see Figure 3).
This flame must ignite main
burner as long as . . .
. . . This flame keeps
BASO On.
Inlet Fitting
Marking
Figure 3: Turn Down Test without Instruments
2. Cycle the main burner On and Off at least three times. The main
burner must ignite each time within four seconds.
3. Then wait at least three minutes for the BASO to drop out. (Main
burner flame will go out.)
4. If the BASO does not drop out, reduce the pilot flame further and
repeat Steps 2 and 3.
4 Pilot Burners/Thermocouples Technical Bulletin
burnflam
5. If you cannot secure ignition of the main burner when the pilot flame
has been reduced to the point at which the BASO drops out, the pilot
has been located too far from the main burner and must be moved
closer. Repeat Steps 2, 3, and 4.
Observe the pilot flame under the various test conditions and ensure it
appears stable at all times. Use a millivolt meter to determine the stability
of the pilot flame. During the observation, or test of pilot performance,
position the doors of the appliance in their normal operating position.
Good pilot operation can be affected by many draft conditions, appliance
design, and recirculation of combustion products.
1007 South 12th Street
PO Box 170
Watertown, WI 53094 www.baso.com
1-877-227-6427 (1-877-BASOGAS) Printed in U.S.A.
Pilot Burners/Thermocouples Technical Bulletin 5
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