NFPA 8502

  • Thread starter Mufeed Al-ghumgham
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Thread Starter

Mufeed Al-ghumgham

Dear List,

We have a local Fuel Gas pressure controller for NG Boiler application. We
are studying now to transfer it to DCS/control room. I want to know from
dear list participants, is it mandatory by NFPA 8502 standard to have this
controller in the Field and not in the DCS/control room. I want to add
also that this controller is used during start-up sequence for the boiler.


Mufeed AL-Ghumgham

Jinbin zhang

You can do it, but shall choose the fail-safe control system. Signals that initiate mandatory MFT shall be hardwired. It conforms to NFPA8502 to do so.

Arnold Dillon

We work a lot with NG Boiler applications and to the best of my
knowledge, there is no mandate regarding the location of the gas
pressure control. The NFPA requires a Burner Management System (BMS) to
monitor safety functions like High Gas Pressure, Low Gas Pressure, High
Steam Pressure, etc. to assure that a safety limit isn't violated with
the burner in service. If the BMS detects a safety related problem,
then it shuts down the burner via double block valves on the gas train.
If the BMS is a software based system, then that control normally MUST
be in a separate controller (processor) from any other control

Your gas pressure control should fall into the category of any other
control function and can be anywhere that you choose to locate it. The
pressure control logic will regulate the pressure to a satisfactory
value, but if the pressure exceeds a safety limit, then there should be
some High and Low pressure switches that provide BMS inputs to shut down
the burner regardless of what happens with your gas pressure control.

Having said all of this, we have had very good luck using either
self-contained regulators or local pressure controllers to regulate gas
pressure. Their response time is usually very good. Also, being
locally set, the operators don't tinker with the setpoints, get them out
of adjustment, and cause a lot of nuisance burner trips.

Hope this helps.

Arnold Dillon

Hall, Christopher W


NFPA 8502 does not make it mandatory to have your fuel gas pressure
controller local to the boiler. It is most common in the process industries
here in the UK to have all the controls driven by a DCS with a separate
independent system handling burner management and/or emergency shutdown.
There are in fact many ways to satisfy the requirements of NFPA 8502, some
are more convenient and easier to maintain than others. There are also a
number of companies that specialise in the design and implementation of
boiler controls. You might like to talk to some of them via their web
sites. Good luck.

Chris Hall - Control Engineer