1. BURNER MANAGEMENT SYSTEM
Burner Management System: The control system dedicated to combustion safety and operator
assistance in the starting and stopping of fuel preparation and burning equipment and for preventing
misoperation of and damage to fuel preparation and burning system.
 AutomaticBurnerManagementSystem- Nonrecycling: A burner management system by which
a furnace is purged and a burner is started, ignited and stopped automatically but does not
recycle automatically.
 Automatic Burner Management System- Recycling: A burner management system by which a
furnace is purged and a burner is started, ignited and stopped automatically and recycles on
preset pressure range.
 Manual Burner management System: A burner management system by which a furnace is
purged and a burner is started, ignited and stopped manually.
 Manual, Supervised Burner Management System: A burner management system by which a
furnace ispurgedand a burneris started,ignitedandstoppedmanually.Interlocks are included
to ensure that the operation follows established, proper procedures.
The following is a list of new requirements that are common to various heater and BMS codes.
 Mandatory Purging
 Permissive Interlocks
 Double Block and Bleed System
 Pilots and Ignition Systems
 Dedicated Flame Monitoring Systems
 High / Low Pressure, Temperature and Flow
 Combustion Air and Draft Pressure Alarms and Controls
 Dedicated Logic Solver
Applicable / Governing
Codes
Specifications / Minimum Criteria / Requirements
API-556
“Instrumentation, Control
and Protectivesystemfor Gas
Fired Heaters”
 Prior to each fired heater startup, provision shall be made for the removal
of combustible gases which may have entered the heater during the
shutdown period.
 A timed pre-ignition purge cycle shall be repeated after every shutdown of
all fuel sources.
 Safety shutoff valves shall be fail safe and should remain closed until safe
conditions are present.
 For applications that use double block and bleed on main fuel gas, it is
recommended that the bleed valve is confirmed closed before the double
block valves open. The basis is to mitigate blowing fuel gas to atmosphere.
 When the purge cycle is complete (sequence permissive), manually
command the pilot gas shut off valves to open. This can be in the form of
manual rest or pushbutton. A pilot trial for ignition timer may or may not
be used for this step.

2. 1. Some application use a manual reset solenoid valve. For these
applications, solenoid construction with a lever that cannot be
defeated is recommended.
2. For application that uses a double block and bleed on pilot gas, it
is recommended that the bleed is confirmed closed before the
double block valves open. The basis isto mitigate blowing fuel gas
to atmosphere. Should the bleed valve open or fail to prove
closed during the start up sequence, a manual isolation valve
beneath the bleed valve may be considered to continue the light
off sequence.
3. A startup override of the low pilot gas pressure trip is actually
required to permit opening of the pilot gas block valves.
Otherwise, low pressure condition at startup below trip set point
would not allow the block valves to be sequenced open.
 Complete light off for pilots, and confirm pilots are lighted via visual or
electric flame monitoring.
 For multiple burners, it is typically recommended to light one burner at a
time. If a burner fails to light (typically within 10 to 15 seconds), that
burner should be isolated prior to troubleshooting. Allow that burner area
to purge itself prior to relight attempt. The basis is to ensure the unburned
fuel gas concentration in the firebox is not permitted to exceed 25% of the
LEL during light off, otherwise a re-purge is required.
NFPA -85 (National Fire
Protection Agency)
“Boiler and Combustion
systems Hazards Code”
 The burner management safety functions shall include, but shall not
limited to, purge interlocks and timing, mandatory safety shutdowns, trial
timing for ignition and flame monitoring
 Momentary Closing of Fuel Valves: Logic sequences or devices intended to
cause a safety shutdown, once initiated, shall cause a burner or a master
fuel trip,as applicable,and shall require operator action prior to resuming
operation of the affected burner(s).
 Flame Monitoring and Tripping System: The basic requirements of any
flame monitoring and tripping system shall be as follows
1. Combustion instability situation shall be brought to the attention
of the operator for remedial action.
2. An emergency shutdown of the involved equipment shall be
automatically initiated upon detection serious combustion
problems that will lead to the accumulation of unburned fuel.
NFPA -86 (National Fire
Protection Agency)
“Standards for Oven and
Furnaces”
 A timed pre-ignition purge shall be provided. At least 4 standard cubic feet
(scf) of fresh air or inert gas per cubic foot (4 m3/m3) of heating chamber
volume shall be introduced during the purge cycle.
 Safety Shut-off Valves shall be utilized as a key safety control to protect
against explosions and fires.
 Each safety shut-off valve required shall automatically shut off the fuel to
the burner system after interruption of the holding medium (such as
electric current or fluid pressure) by any one of the interlocking devices,
combustion safeguards, or operating controls.
 Each main and pilot fuel gas burner system shall be separately equipped
with two safety shutoff valves piped in series.( these shutoff valves needs
to be FM-7400 listed)
 Safety shutoff valves shall not be bypassed
 Where the main or fuel pilot gas burner system capacity exceeds 400000

3. Btu/hr (117kW), at least one of the safety valves required for individual
burner shall be proved closed and interlocked with pre-ignition purge
interval.
 Prior to re-ignition of a burner after a burner shutdown or flame failure, a
pre-ignition purge shall be accomplished.
Exception; Repeating the pre-ignition purge shall not be required where
the conditions of (a), (b) or (c) are satisfied:
a) The heating chamber temperature exceeds 1400°F (760°C).
b) For any fuel fired system, all of the following conditions are
satisfied:
1. Each burner and pilot is supervised by a combustion
safeguard
2. Each burner system is equipped with safety shutoff
valves
3. At least one burner remains operating in the combustion
chamber of the burner to be re-ignited
c) All of the followingconditions aresatisfied (does not apply to fuel
oil systems):
1. Each burner and pilot is supervised by a combustion
safeguard
2. Each burner system is equipped with a gas safety shutoff
valve
3. It can be demonstrated that the combustible
concentration in the heating chamber cannot exceed
25% of the LEL.
 A trial for ignition of a gas burner shall not exceed 15 seconds.
 Current to spark igniter must be discontinued at the end of the 15 second
trial for ignition period unless the flame is contained in an explosion proof
radiant tube.
 Each burner flameshall besupervised by a combustion safeguard having a
maximum flame failureresponsetime of 4 seconds or less, that performs a
safe-start check, and is interlocked into the combustion safety circuitry.
 Each pilot and main burner flame shall be supervised independently.
 A low pressure switch settings shall be provided and shall be interlocked
into the combustion safety circuitry.
 A high gas pressure switch shall be provided and shall be interlocked into
the combustion safety circuitry.The switch shall be located downstream of
the final pressure-reducing regulator.
 Pressure switch settings shall be made in accordance with the operating
limits of the burner system.
 In the event of a power failure, the programmable controller (hardware
and software) shall not prevent the system from reverting to a safe default
condition.A safe condition shall be maintained upon restoration of power.
 The control system shall have a separate emergency switch, independent
of the programmable controller that initiate a safe shutdown.
CSA-B149.3-05
“Code for the field approval
of fuel related components
on appliances and
equipment”
 When either an intermittent or interrupted pilot or a direct transformer
spark igniter is used to lightthe main burner and the combustion air supply
is by mechanical means, the appliance control system shall provide a
proven purge period prior to the ignition cycle. This purge period shall
provide at least 4 volume changes of the combustion zone and flue
passages at an airflow not less that 60% of that required at maximum

4. input.
 An appliance that has a maximum rated input in excess of 10000000
Btu/hr (3000kW), up to and including 50000000 Btu/hr (15000 kW), with
single burner or multiple burner flame safeguard controls shall be
equipped with not less than two automatic safety shut-off valves piped in
series and wired in parallel that are certified in accordance with ANSI
Z21.21/CSA 6.5 and C/I.
 An appliance that has a maximum rated input in excess of 10000000
Btu/hr (3000kW), up to and including 100000000 Btu/hr (30000 kW), with
single burner or multiple burner flame safeguard controls shall be
equipped with not less than two automatic safety shut-off valves piped in
series and wired in parallel that are certified in accordance with ANSI
Z21.21/CSA 6.5 and C/I, one of which shall be in the common valve train
and may be of the fast opening type. The downstream valve shall be
provided with a mandatory manual-reset function to open.
 An appliance that has a maximum rated input in excess of 10000000
Btu/hr (3000kW), up to and including 50000000 Btu/hr (15000 kW), and a
burner manifold pressure in excess of 0.5 psig (3.5kPa) shall
a) Have main burner shut off valves supervised by an approved valve
proving system that prevents main burner automatic safety shut
off valves from opening when a leak is detected; or
b) Be equipped with and automatic vent valve that is
1. Normally open and energized to close
2. Installed in a vent line that is connected into the burner
valve train immediately downstream of the first
automatic safety shut off valve in the main burner valve
train;
3. Wired in parallel with the first automatic shut off valve.
 Electric ignition system of other than the direct transformer type shall not
be used to ignite pilot or main burner gas except with the approval of the
authority having jurisdiction.
 Direct transformer park ignition shall not be used to ignite pilot gas unless
the pilot is proved.
 Flame detectors that can fail in a flame proving mode shall be of the self
checking type when the burner firing cycle can last longer than 24hr
without cycling.
 A combustion safety control system shall
1. De-energize the main burner fuel shut off valve in the event of a
flame failure
a) Within 4 seconds for an appliance that has an input in excess of
400000 Btu/he (120kW)
 When the design outlet pressure of an appliance pressure regulator is in
excess of 0.5 psig(3.5 kPa),a high pressuresafety limitcontrol device shall
be installed and shall initiate shut off of the supply gas if the pressure at
the point of connection exceeds the highest normal operating pressure by
more than 25%
 For appliance with inputs in excess of 400000 Btu/hr (120kW), or with the
design outlet pressure of the appliance regulator being in excess opf 0.5
psig (3.5kPa), a low pressure safety limit control device shall be installed
and shall initiate shut off of the supply gas if the pressure at the point of
connection drops below 50% of the lowest normal operating pressure.

5. The main functionof BMS isto allowandensure the safe start up, operation and shutdown of the Fired
Heater.Once the logicis configuredandthe systemproperlycommissioned the BMS will provide a safe
and consistentoperatingsequence.The humaninterface will guidethe operator so that the heater may
be safely operated, and if needed, be quickly and safely restarted.
The following sequence of operation is typical for most Fired Heaters.
1. Initially, the PLC will check that all the permissives and interlock are in place to allow start up.
2. Start purge. The PLC will check that the permissives are at their correct status. The system will
typicallywaitforthe operatorto requestthe heater to start, although all permissives are met and
the heater is ready to purge. Once the heater start/purge is requested to pre-set timer will
commence.Assumingthe timingisnotinterruptedbyan Interlock activation, it will continue until
complete.Once finished,itwillnotifythe operatorthat “Purge Complete”has been accomplished.
3. Ignite pilots.Once the purge iscompleted,the operatorwill be notified that the system is ready to
start the pilots.The pilotheaderdoubleblockandbleedvalveswill energize. Instantaneously, the
individuallocal pilotfiringvalveswill openandthe ignitiontransformerswill be energized.The pilot
valves and the ignition transformers will only be energized for a maximum of 10 seconds. If the
pilot flame is not detected within this time the individual pilot isolation valve will close.
4. Prove Pilots. Each pilots has its own dedicated flame detector, which in most cases is via a flame
rod. Once proven,the individual pilotvalvewill holdinandcontinue to burn, in the event a pilot is
not lit.
5. LightMain Burners.Before the mainburnersare lit,the PLC will continue to check the permissives
to ensure itissafe to lightmainburners.The twomainpermissivesare that there is sufficient flow
in the process coils and the pilot burners are proven. The system then proceeds to energize the
main header vent and shut off valves. The first burner will light at minimum firing rate. A five
secondtrial forignitionisprovidedfromthe time the individual isolation valve is opened until the
detectionof the flame.If the flame isnotdetected, the individualmainburnerisolation valve isde-
energized.
6. Confirm Main Burner status. Once this is achieved the system is ready to be ramped up to
operatingconditions.This is usually performed manually until the process variable is close to the
operatingsetpoint,thenthe temperatureandgasflow/pressure controllers can then be switched
to auto mode.