Safety Controls and Burner Management Systems

(BMS) on Direct-Fired Multiple Burner Heaters

Introduction
Safety controls on direct-fired heaters have New legislation has been introduced to
1. Introduction
continuously evolved over the recent past, and standardise the requirements. In most
the evolution has accelerated over the last five provinces of Canada the code is CSA
2. Background years. This has been due to the introduction of B149.3, which is an adaptation of NFPA,
government legislation which actively enforces however this is currently legislated as a
~ Mandatory the application of existing codes. minimum requirement.
Purging Most operating companies within North
Heater designs and quality standards have
America are implementing BMS in new and
followed the practice of API 560. For most
existing heaters in accordance with required
~ Permissives operating companies this is now mandatory and
guidelines; however there are some
& Interlocks used as a minimum standard with individual
installations that still rely only on manual
companies adding their own requirements. With
operator intervention or the plant
Safety Controls or Burner Management
~ Safety Shut- Emergency Shutdown (ESD) as the safety
Systems, this evolution has not occurred.
off Valves control. The most common reason
provided by these companies is that they
Although some detailed and prescriptive
have operated with the manual system and
~ Pilots & guidelines have been around for many years, the
absence of flame monitoring equipment for
Ignition rate and degree of adoption varies significantly
years without incident; why should an
within the industry. Most operating companies
Systems have their own standard, which may still vary
investment be made in a BMS now?
from facility to facility. In addition to this, for The general consensus is becoming to
~ Dedicated each installation, it is not unusual for adjacent standardise the requirements of a safe and
Flame heaters built two years apart to have a different operable BMS for each heater, to ensure a
Monitoring BMS design, simply because different safe light off and normal operation while
engineering contractors built them. With reducing the amount of nuisance trips. But
Systems increasing government legislation and we all must bear in mind that the safety of
regulations as well as mounting lawsuits for personnel and environment is of the utmost
~ Alarms & accidents in which applicable codes and importance; as such a proactive approach
Shutdowns guidelines have not been adhered to, it is must be taken.
important to review the BMS requirements for
both existing and new heater installations.
~ Combustion
Draft /
Pressure
Alarms &
Controls

~ Dedicated
Logic Solver
 Safety Controls and Burner Management Systems Page 2 of 12
(BMS) on Direct-Fired Multiple Burner Heaters

Background
In the past, most heaters have operated on temperature control from the outlet
temperature to a control valve in the main gas line, with a single shut-off valve upstream
on the Control valve. This shut-off valve was either automatic with the plant ESD or
operated manually with an Operator action, with each company having various additions
to this basic concept.

The following is a list of new requirements that are common to various heater and BMS
codes.

1) Mandatory Purging.
2) Permissive Interlocks
3) Double Block and Bleed systems
4) Pilots and Ignition Systems
5) Dedicated Flame Monitoring Systems
6) High / Low Pressure, Temperatures and Flow.
7) Combustion Air and Draft Pressure Alarms and Controls
8) Dedicated Logic Solver

Each of these requirements have been developed due to incidents that have occurred
because of the lack of them.

Mandatory Purging
The most important function of the heater control system is to A time to achieve the four volume changes may be
prevent the possibility of an accumulation of combustible gas calculated from the required flow rate. In the event the
followed by accidental or improper ignition sequence resulting in purge does not continue for the prescribed time or required
an explosion. Correct pre-ignition purging of the heater is crucial purge, permissives are no longer met and a re-purge is
to the safe operation of the heater. required. Only when a successful purge is completed can
any ignition source be introduced.
The normal practise for the purging of a natural draft heater has
been to allow a period of time for a heater to naturally purge. CSA B194.3-05 Section 9.2 Pre-purge
Typically this would have been 20-30 minutes on a cold light off, 9.2.1: When either an intermittent or interrupted
and would have been at the discretion of the operator. The pilot or a direct transformer spark ignitor is used to
alternative is to purge with steam, if available. Caution must be light the main burner and the combustion air supply
taken when doing so to prevent possible steam condensation from is by mechanical means, the appliance control
affecting the operation of the ignition and flame monitoring system shall provide a proven purge period prior to
instrumentation. the ignition cycle. This purge period shall provide
at least four air changes of the combustion zone
The timed purge is to be proven. The codes imply that there has to and flue passages at an airflow not less than 60% of
be a means to prove there has been four volumes changes or air in that required at maximum input.
the heater prior to light-off. It is not possible to measure the air
flowrate during a natural purge. Therefore the options available to NFPA 86 Section 5-4.1 Pre-ignition (Pre-purge, Purging
provide a proven purge are: Cycle)
a) Purge Blower or Fan 5-4.1.2: A timed pre-ignition purge shall be
b) Steam purge from radiant section provided. At least 4 standard cubic feet (scf) of
c) Induced Draft Purge (via Steam eductor in the Stack) fresh air or inert gas per cubic foot (4 m3/m3) of
heating chamber volume shall be introduced during
Furthermore, depending on the jurisdiction there may also be a the purge cycle.
minimum purge flow rate that must be adhered to.
 Page 3 of 12 Safety Controls and Burner Management Systems Page 3 of 12
(BMS) on Direct-Fired Multiple Burner Heaters

Permissives & Interlocks

These can be numerous and may include all of Typical interlocks would include
the items on the BMS. The interlocks are high/low fuel and pilot gas pressure,
usually designated on the P&ID with the high/low stack temperature, loss of
symbol I. These are used in the flame, high/low firebox pressure and
configuration of the operating procedure and loss of combustion air. In addition to
logic so as to ensure the safe sequential these general trips each heater must be
operation of the heater particularly in start-up examined individually to determine if
and during operation. The permissives are an additional trips may be required due to
integral part of the start-up and light-off the heater design or configuration.
procedure. The main importance of the These non-standard trips are designed
interlocks is to detect the need for partial or to protect the heater and personnel
total shut down of the heater. from tube and structural damage that
may occur from improper operation for
a long duration. PLC Panel
Shut-off Valves
The safety shut-off valves are the key component in the BMS The CSA code even goes one step further and requires a
to prevent the accumulation of an explosive mixture in the double block and bleed arrangement on each main and pilot
heater. Standard practice is to provide automated safety shut- burner. Although the code does not provide the same
off valves installed in a double block and bleed configuration exception afforded by NFPA a variance application can be
on the main and pilot headers. An additional safety shut-off made to the authority having jurisdiction to implement a
valve should be located on each individual burner for multiple similar valve train. The addition of more valves does not
burner systems. These shut-off valves must also be certified for necessarily equate to a safer heater from a reliability
use safety shut-off valves. In accordance with CSA standpoint.
requirements these valves need to be certified to CSA 6.5
certified and per NFPA requirements these valves need to be CSA B194.3-05 Section 5.3 Safety Shut-off Valves
FM-7400 listed.
5.3.1: Safety shut-off valves shall not be bypassed
During normal operation the bleed is automatically closed on
light-off request and likewise opens automatically on shut 5.3.4: An appliance that has a maximum rated input in excess
down. The vent valve is to be proven closed prior to opening of 10,000,000 Btu/h (3000 kW), up to and including
of the shut-off valve; on shutdown the upstream shut-off valve 50,000,000 Btu/h (15 000 kW), with single burner or multiple
is to be confirmed closed before the vent valve opens to burner flame safeguard controls shall be equipped with not
prevent fuel from being unnecessarily vented. The valves must less than two automatic safety shut-off valves piped in series
also be in their de-energized state and proven prior to heater and wired in parallel that are certified in accordance with
purge and start-up. ANSI Z21.21/CSA 6.5 and marked C/I.

The configuration discussed above works well for a single 5.3.5: An appliance that has a maximum rated input in excess
burner system but this cannot be applied to multiple burner of 10,000,000 Btu/h (3000 kW), up to an including
systems; unless they are all to operate in tandem. In order to 100,000,000 Btu/h (30 000 kW), with multiple burners that
keep the heater running in the event of a single burner failure have multiple burner flame safeguard controls shall be
the fuel gas must be isolated from the failed burner. Strict equipped with not less than two automatic safety shut-off
adherence to the codes and guidelines would require two valves per burner, certified in accordance with ANSI
separate safety shut-off valves piped in series for each burner. Z21.21/CSA 6.5 and marked C/I, one of which shall be in the
An exception is provided in NFPA that would allow for the common valve train and may be of the fast opening type.
shutdown of a single burner, provided that all burners fire into The downstream valve shall be provided with a mandatory
a common combustion chamber and certain conditions are manual-reset function to open.
met.
 Safety Controls and Burner Management Systems Page 4 of 12
(BMS) on Direct-Fired Multiple Burner Heaters

Shut-off Valves (Continued)

5.3.9; An appliance that has a maximum rated input in excess 5-7.1.2: Each safety shut-off valve required in 5-7.2.1
of 10,000,000 Btu/h (3000 kW), up to and including and 5-7.3.1 shall automatically shut off the fuel to the
50,000,000 (15 000 kW), and a burner manifold pressure in burner system after interruption of the holding
excess of 0.5 psig (3.5 kPa) shall medium (such as electric current or fluid pressure) by
(a) have main burner shut-off valves supervised by an any one of the interlocking safety devices, combustion
approved valve proving system that prevents main burner safeguards, or operating controls.
automatic safety shut-off valves from opening when a leak is
detected; or NFPA 86 Section 5-7.2 Fuel Gas Safety Shut-off
(b) be equipped with and automatic vent valve that is Valves
(i) normally open and energized to close;
(ii) sized in accordance with Table 2;
(iii) installed in a vent line that is connected into the 5-7.2.1: Each main and pilot fuel gas burner system shall
burner valve train immediately downstream of the first be separately equipped with two safety shutoff valves
automatic safety shut-off valve in the main burner valve piped in series.
train; and
(iv) wired in parallel with the first automatic shut-off valve. 5-7.2.2: Where the main or fuel pilot gas burner system
There shall be no other valve or valves installed in the vent capacity exceeds 400,000 Btu/hr (117 kW), at least one of
line the safety valves required by 5-7.2.1 shall be proved
NFPA 86 Section 5-7 Safety Shut-off Valves (Fuel Gas or closed and interlocked with the pre-ignition purge
Oil) interval.
5-7.1.1: Safety shut-off valves shall be utilized as a key safety
control to protect against explosions and fires.

Certified Safety Shutoff Valve

 Safety Controls and Burner Management Systems Page 5 of 12
(BMS) on Direct-Fired Multiple Burner Heaters

Pilots and Ignition Systems

Unfortunately the majority of heaters pilot be used. The dedicated pilot is to
still in use within the industry rely on ensure that there is always a continuous Exception; Repeating the pre-ignition
a manual ignition system. This source of ignition for the main burner. purge shall not be required where the
means the heater is manually lit by Hence the pilots are continuously in conditions of (a), (b) or (c) are satisfied.
the operator inserting an oily rag or operation and need to be from a secure (a) The heating chamber
an ignition torch to the base of the fuel source such as natural gas. temperature exceeds 1400F
burner. With todays technology and Continuous pilots provide a safe stand- (760C )
easy accessibility to the electronic by mode of operation in case the main (b) For any fuel-fired system, all of
ignition system it is no longer burners are to be turned off and negate the following conditions are satisfied:
necessary to manually light the the need to re-purge the heater after a (1) each burner and pilot is
heaters and potentially place the main burner shutdown. The heat supervised by a combustion
operator in harms way. release from the pilots is minimal and safeguard in accordance with Section
will not cause any damage even if there 5-9; (2) each burner system is
The electric ignition system consists is no process flow through the coils. equipped with safety shutoff valves in
of an ignition rod provided with the accordance with Section 5-7; and (3)
burner and a high voltage ignition CSA B194.3-05 Section 8.2 electric at least one burner remains operating
transformer. When all interlocks are Ignition Systems in the combustion chamber of the
cleared and permissives are in place 8.2.1: Electric ignition systems of other burner to be reignited.
the ignitor lights the pilot burner than the direct transformer type shall (c) All of the following conditions are
which then in turn lights the main not be used to ignite pilot or main satisfied (does not apply to fuel oil
burner. An electronic ignition burner gas except with the approval of systems): (1) each burner and pilot is
system, controlled by the BMS, the authority having jurisdiction. supervised by a combustion
eliminates the need for the operator safeguard in accordance with Section
to provide an ignition source for the 8.2.2: Direct-transformer spark ignition 5-9; (2) each burner system is
burners; which is considered to be shall not be used to ignite pilot gas equipped with a gas safety shutoff
the most dangerous part of the start- unless the pilot is proved. valve in accordance with Section 5-7
up procedure. As the BMS controls and (3) it can be demonstrated that
the combustible concentration in the
the ignition of the burners the heater NFPA 86 Section 5-4.1 Pre-ignition
heating chamber cannot exceed 25
purge cannot be so easily bypassed. (Pre-purge, Purging Cycle)
percent of the LEL.
5-4.1.5: Prior to re-ignition of a burner
Typically each burner is provided after a burner shutdown or flame
with its own pilot and ignition system. failure, a pre-ignition purge shall be
We recommend that a continuous accomplished.
 Page 6 of 12 Safety Controls and Burner Management Systems
(BMS) on Direct-Fired Multiple Burner Heaters

Dedicated Flame Monitoring Systems

Each burner is equipped with its own flame monitoring devices, independent detectors are required to supervise the pilot
and the main flame. Exceptions may be made depending on the type of pilot and burner. In most installations two different
detection techniques are used, a flame (ionisation) rod to monitor the pilot flame and an UV (Ultraviolet) or IR (Infrared)
Scanner to see the main flame. Flame rods are typically used on the pilot flame as they are more cost effective, however
the same detectors should not be used on the main flames as these typically run at a higher temperature and the flame rod
would burn out in a short amount of time.

Some certified flame monitoring devices have an adjustable flame failure response time, typically from one to four seconds.
The Canadian code further requires that any flame monitor that can fail in the flame-proving mode be supplied with a
self-checking mechanism, which means the burner will remain on for longer than 24 hours. As the flame monitor is the most
critical instrument in detecting a loss of flame and initiates the isolation of the fuel gas it is recommended that a self-check
scanner be provided for all systems regardless of the firing cycle. Dependant on the size of the burner, it may only take
several seconds to accumulate an explosive mixture, which explains the need for such a device.

CSA B194.3-05 Section 9.4.4

9.4.4; 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.

CSA B194.3-05 Section 9.1.1 Combustion Safety Control System

9.1.1; A combustion safety control system shall
(c) De-energize the main burner fuel shutoff valve in the event of a flame failure
(ii) Within 4 s for an appliance that ha an input in excess of 400,000 Btu/h (120 kW)

NFPA 86 Section 5-9 Combustion Safeguards (Flame Supervision)

5-9.1: Each burner flame shall be supervised by a combustion safeguard having a maximum flame failure response
time of 4 seconds or less, that performs a safe-start check, and is interlocked into the combustion safety circuitry.

5-9.2: Each pilot and main burner flame shall be supervised independently.
 Safety Controls and Burner Management Systems (BMS) Page 7 of 12
on Direct-Fired Multiple Burner Heaters

Alarms and Shutdowns

Alarms and shutdowns provided by the heaters instrumentation provide added safety and permissives to allow the system to
transition from different stages of heater operation in a proper and safe manner. There is some instrumentation typical to all
systems and others that are dependent on the size, purpose, and configuration of the heater. The instrumentation is located on
the fuel gas trains and the heater itself. In the past, switches have been widely used for these applications for various reasons,
however it is strongly recommended that transmitters be used in lieu of switches. Switches may fail in an unsafe position without
providing any indication until the unit is required to operate. Transmitters report back dynamic information and have built-in
diagnostics, so they are able to provide indication of failures. Considering the losses involved if an incident was to occur, it is far
more cost efficient to use the more reliable transmitters.

The alarms required for the fuel gas are common for all systems. These are high / low main fuel gas pressure, and high / low
pilot gas pressure. These are required to keep the operating pressure of the burners within the design parameters provided by
the burner manufactures. Operation outside of these limits will cause flame instability among other problems. If a forced draft
fan or blower is required to provide combustion air to the blowers, a low combustion air flow alarm and low low flow trip is to be
provided.

Other measurements and alarms should be provided in order to protect the heater itself from improper operation. A high stack
temperature will warn of possible leakage in the convection section, resulting in an uncontrolled fire, whereas a low alarm will
protect from possible acid gas condensation. A high-high stack temperature will cause a shutdown of the main burners.

Heater draft measurement and alarm will help ensure that the heater operates within the design draft profile. Operations
outside this range may cause flame instability and improper/incomplete combustion.

Dependant on the process fluid, heated low process flow alarms may be required. If the process fluid is susceptible to either
coking or degradation at temperatures above design, it is recommended that a low flow alarm be provided and a main burner
shutdown on loss of flow. Low process flow will also result in high tubeskin temperatures as not enough heat is being removed
from the tubes.

CSA B194.3-05 Section 9.5 Gas Pressure Safety Limit Control

9.5.1: When the design outlet pressure of an appliance pressure regulator is in excess of 0.5 psig (3.5 kPa), a high-
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 exceeds the highest normal operating pressure by more than 25%. .

9.5.2: For appliances with inputs in excess of 400 000 Btu/h (120 kW), or with the design outlet pressure of the
appliance regulator being in excess of 0.5 psig (3.5 kPa), 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.

NFPA 86 Section 5-8 Fuel Pressure Switches (Gas or Oil)

5-8.1: A low pressure switch shall be provide and shall be interlocked into the combustion safety circuitry.

5-8.2: A high gas pressure switch shall be provide and shall be interlocked into the combustion safety circuitry. The
switch shall be located downstream of the final pressure-reducing regulator

5-8.3: Pressure switch settings shall be made in accordance with the operating limits of the burner system.
 Safety Controls and Burner Management Systems Page 8 of 12
(BMS) on Direct-Fired Multiple Burner Heaters

GENERAL BMS OVERVIEW

 Safety Controls and Burner Management Systems Page 9 of 12
(BMS) on Direct-Fired Multiple Burner Heaters

Combustion Draft / Pressure Alarms and Controls

Heater draft is the motive force that will ensure proper air and flue gas flow through the heater. The most critical draft
point is at the arch as it is the controlling variable in the design of the burner and heater itself. This measurement is a
critical indicator in the operation of a fired heater and alerts the operator to any tendency to go positive.

Although this is normally not a shut-down device, it is closely linked to opening the stack damper blade. The pressure
control loop consists of a pressure transmitter located at the heater arch and an actuator on the stack damper. A low
draft pressure (high firebox pressure) alarm should be added to this transmitter. The control loop is to be configured
such that the stack damper opens when there is a low heater draft. In the event that the heater draft is still too low but
the stack damper is 100% open the burner firing rate must be reduced.

Dedicated Logic Solver

Traditionally most BMSs have been implemented using a extensively used because of their high reliability and
discrete series of relays and switches as the logic solver. When their fault-diagnostic capabilities. In recent years, the
designed correctly these hardwired panels may prove to be very functionality and use of the two processors, PLCs and
reliable. Unfortunately the permissives and interlocks on such DCSs, have merged, and for the purpose of these
systems are easily bypassed. With the advent of the requirements, they are designated micro-processor
microprocessor, unitized flame safeguard controllers have been based systems.
introduced. These units provide the required logic to safely
start and stop the heater. The draw back of these units is that 9.7.2: Programmable controllers may be used for the
they are only designed to control single burner systems. monitoring, sequencing, and control of all aspects of
burner or process, or both
The area of biggest change in BMS systems as of late is the
ability to use a Programmable Logic Controller (PLC) as the 9.7.2.2: the microprocessor-based system shall b solely
primary safeguard and logic solver. Certain conditions must be dedicated to the BMS. Logic for functions other than
adhered to in order to validate their use, which vary between the BMS application shall not be part of the I/O
different codes. Common requirements are that a power or structure, memory, or software program. The
hardware failure will not prevent the system from reverting to a following shall apply:
safe condition and an external watch dog timer must be used to (a) The software program shall reside in some
monitor a dedicated output channel. Any failures will cause the form of non-volatile memory storage .
system to revert to a safe condition. As technology advances (b) A watchdog timer internal to the BMS
and the introduction of true safety rated systems progresses, processor shall monitor the program scan
these requirements and guidelines will inevitably change. time
(c) In the event of a power failure, the
CSA B194.3-05 Section 9.7 Programmable Controllers microprocessor-based hardware and software
9.7.1: When a microprocessor is used as a primary shall not prevent the system prom reverting to
safeguard device, the requirements of Clause 9.7.2 a fire-safe condition
shall apply. (d) The BMS shall be equipped with a master fuel
Note: Programmable logic controllers (PLCs) and trip relay .
distributed control systems (DCSs) form part of a (e) Redundant processors with automatic transfer
family of microprocessor-based burner schemes shall be permitted
management systems (BMSs) and diverse (f) the designer of the BMS and the software
sequence control applications. These devices shall provide the end user and the authority
execute their application programs in a rigidly having jurisdiction with the documentation
organized sequential manner. They are
 Safety Controls and Burner Management Systems
(BMS) on Direct-Fired Multiple Burner Heaters Page 10 of 12

Dedicated Logic Solver (continued)

NFPA 86 Section 5-3 Programmable Controllers for Safety Service 5-3.2.1; A programmable controller-based system
5-3.1.2: In the event of a power failure, the programmable specifically listed for combustion safety service
controller (hardware and software) shall not prevent the shall be permitted where applied in accordance
system from reverting to a safe default condition. A safe with the listing requirements and the
condition shall be maintained upon the restoration of manufacturers instructions.
power.
5-3.2.2: A programmable controller not listed for
5-3.1.3: The control system shall have a separate manual combustion safety service shall be permitted to
emergency switch, independent of the programmable monitor safety interlocks, or to provide burner
controller that initiates a safe shutdown. control functions, provided

5-3.1.4: Any changes to hardware or software shall be

documented, approved, and maintained in a file on the
site.

PLC Panel with Lights and Push Buttons

 Safety Controls and Burner Management Systems Page 11 of 12
(BMS) on Direct-Fired Multiple Burner Heaters

Operating philosophy

Burner Management
Systems
Power On Check Start
Permissives Purge

Continue Check
Permissives Complete
Burner Purge
Management
System
Hand
to DCS Ignite Pilot(s)

Prove
Confirm Pilots
Burner(s) Light
Burner(s)

The main function of the BMS is to allow and ensure the safe start-up, operation, and shutdown of the Fired Heater. Once the
logic is configured and the system properly commissioned the BMS will provide a safe and consistent operating sequence. The
human interface will guide the 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 typically wait for the
operator to request the heater to start, although all permissives are met and the the heater is ready to purge. Once the
heater start/purge is requested a pre-set timer will commence. Assuming the timing is not interrupted by an Interlock
activation, it will continue until complete. Once finished, it will notify the operator that Purge Complete has been
accomplished.
3) Ignite Pilots. Once the purge is completed, the operator will be notified that the system is ready to start the pilots. The
pilot header double block and bleed valves will energize. Instantaneously, the individual local pilot firing valves will open
and the ignition transformers will 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 pilot has its own dedicated flame detector, which in most cases is via a flame rod. Once proven, the
individual pilot valve will hold in and continue to burn, in the event a pilot is not lit.
5) Light Main Burners. Before the main burners are lit, the PLC will continue to check the permissives to ensure it is safe to
light the main burners. The two main permissives are that there is sufficient flow in the process coils and the 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 the minimum fire rate. A five second trial for ignition is provided from the time the individual isolation valve is
opened until the detection of the flame. If the flame is not detected, the individual main burner isolation valve is de-
energized.
6) Confirm Main Burner Status. Once this is achieved the system is ready to be ramped up to operating conditions. This is
usually performed manually until the process variable is close to the operating set point, then the temperature and gas
flow/pressure controllers can then be switched to auto mode.
 Safety Controls and Burner Management Systems Page 12 of 12
(BMS) on Direct-Fired Multiple Burner Heaters

Conclusion
There are a number of codes and guidelines pertaining to the safety control and burner management system for direct
fired heaters. The controlling code within Canada is CSA B149.3, but the most common guideline referred to around the
world is NFPA 86. Due to changing government legislation as well as safety and insurance concerns, there is an increase
in the necessity to upgrade or install the heater safety systems (BMS) to comply with published codes and guidelines.

These codes and guidelines are specific when in regards to the valve train and certain safety instrumentation. There is
little aid when incorporating the safety and operability aspects of the overall heater and BMS unit. Unlike boilers, there
are a variety of configurations and process fluids that a direct fired heater may be designed for. As such, there are many
safety interlock and operation permissives that must be reviewed on a case-by-case basis.

Adherence to the published codes and guidelines is a great start and will create a good foundation for the heaters safety
system. In order to design the system for maximum reliability and operability, each system should be reviewed
individually and the safety controls designed accordingly.

Fuel Gas Skid (BMS)

Roger Newnham, C.Eng Paul Chau, P. Eng

President Vice-President
Born Heaters Canada Ltd. Born Heaters Canada Ltd.