Many jewelers think that by having a check valve on their torches
they are protected from a torch flashback but this is not true.
Check valves are only designed to prevent high-pressure oxygen
from flowing into the natural gas pipe.
When a torch flashback happens there is a 5,000 degree flame inside
the hose and pipe and it will melt right through a check valve.
This allows the flame to reach all the way to the gas meter,
which explodes.
A flashback arrestor will extinguish this flame, as well as prevent
oxygen from getting into the gas pipe, and protect the gas meter.
This why the new Fire Code specifically requires a “combination
flashback arrestor check valve”, a device which performs both functions.
Click here to learn more about what NYC Jewelers must do to comply with the new New York City Fire Code and Fire Department Rules
- Click here to find out what the new Fire Code and Fire Department Rules require NYC jewelers to do
- Click here to find out why a check valve without a flashback arrestor does not comply with the new Fire Code
- Click here to find out what a torch flashback is, how it happens and why it is so dangerous
- Click here to learn the difference between “torch-
mount” and “regulator- mount” flashback arrestor check valves, and how to put them on your torches - Click here to learn what to do if you install a flashback arrestor check valve and then can’t light the torch
- Click here to read the official notices about the new Fire Code and Rule 2609-
01 sent to NYC jewelers the Fire Dept. - Click here to e-
mail a question to G- TEC
New regulations in New York City require jewelers to do 2 things -
- Install combination flashback arrestor check valves on torches connected to piped
natural gas, and
- Torches connected to piped natural gas must have a pressure supply of at least 5 psi
and not more than 15 psi
This is what the Fire Code says:
(To read the Fire Code go to http://www.nyc.gov/html/fdny/html/home2.shtml then at the menu on the left
click on Fire Code. The section excerpted below begins on page 337.)
SECTION FC 2609: Piping Manifolds And Hose Systems For Fuel Gases And Oxygen
2609.1 General - The use of piping manifolds, protective equipment and hose systems
in oxygen-fuel gas systems, including natural gas supplied from a utility for use
in
an oxygen-fuel gas system, shall be designed in accordance with Section FC 2609,
Chapter 30 and NFPA 51.
2609.8 Piped Natural Gas Precautions - When piped natural gas is used with oxygen
in any hot work operation a listed protective device that serves as a combination
flashback arrestor and backflow check valve shall be provided at an approved location
on both the natural gas and oxygen supply lines to ensure safe operation of all devices,
equipment and systems, including the utility gas meter. Where the pressure of the
piped natural gas supply is insufficient to ensure such safe operation, approved
equipment shall be provided between the gas meter and the fuel consuming appliance
that increases pressure to the level required for such safe operation. Not withstanding
and section of this code to the contrary, such flashback arrestors and check valves,
and pressure increasing equipment, shall be installed as components of both new and
existing installations.
Fire Department Rules, which accompany the Fire Code go on to say:
(To read the entire document go to http://www.nyc.gov/html/fdny/html/home2.shtml then at the menu on the left click on “FDNY Rules”. The section excerpted below begins on page 329.)
Section 2609-
(a)Scope. This section sets forth standards, requirements and procedures for the design, installation, operation and maintenance of devices and installations utilizing piped natural gas and oxygen, including torches used in the manufacture of jewelry. This section shall apply to both new and existing devices and installations.
(e) Design and Installation Requirements
(3) Pressure booster. When the natural gas supply pressure is less than five (5) psig a pressure booster shall be provided to increase pressure to at least five (5) psig, but not more than 15 psig.
(4) Flashback arrester and check valve. A UL listed combination flashback arrestor and backflow check valve shall be installed:
(A)On the oxygen supply line, between the final oxygen supply pressure regulator and each fuel consuming device
(B)On the natural gas supply line, between the final natural gas supply pressure regulator and the fuel consuming devices.
(f) Operational Requirements
(1) Natural gas supply pressure. Natural gas pressure supplied to a device shall not exceed 15 psig, and the oxygen supply pressure to a device shall not exceed the natural gas supply pressure.
Questions? -
Check valves only prevent
oxygen from flowing into the natural gas pipeline
Flashback arrestor check valves
extinguish the 5,000 degree
flame from a flashback and
stop oxygen from flowing into the
natural gas pipe.
Torch flashbacks happen when the tip of a jeweler’s torch is blocked. Because oxygen pressure is so much higher than natural gas pressure (natural gas
pressure is ¼ psi and some jewelers set oxygen pressure as high as 70 psi),
when the tip is blocked oxygen will flow into the city gas pipe.
If a spark gets into the tip as it is blocked you have all the elements for fire, fuel, heat and oxygen, inside the torch. A 5,000 degree flame burns through the hose and the pipe all the way to the gas meter, which explodes.
What does a gas meter explosion look like?
Working with a NYC gas utility and independent testing laboratory, several models of gas meters were subjected to torch flashbacks. Click on the YouTube link below to see what happens when a torch flashback reaches the gas meter.
When a torch flashback reaches
the gas meter it can explode violently
and pieces of the casing will fly
across the room, injuring anyone
working nearby
Flashback arrestor check valves come in pairs; the piece with the red stripe goes on the natural gas pipe and the piece with the green stripe goes on the oxygen pipe.
There are two kinds of flashback arrestor check valves, “torch-mount” and “regulator-mount”
and the difference is the direction the gas flows through them.
“Torch-mount” flashback arrestor check valves are designed to connect right onto
the handle of a large casting or melting torch, as in the photo. If your torch has
fittings that allow the flashback arrestor check valve to be screwed right on, then
“torch-mount” flashback arrestor check valves are the right choice.
“Regulator-mount” flashback arrestor check valves
will be the right choice for most bench jewelry
torches used in soldering and brazing.
In spite of being called “regulator-mount” these flashback
arrestor check valves actually connect to the black pipe under
the work bench, then the red and green hoses screw onto the
flashback arrestor check valves.
This allows the jeweler to use the torch with maximum flexibility
for fine, detailed work and keep the flashback arrestor check
valves out of the way.
Torch-
Regulator-
On September 1, 2008 the Fire Department sent notices to NYC jewelers to tell them about the new Fire Code.
Click here to see a copy of that notice.
If you have a question about the new NYC Fire Code click here to send an e-mail
to G-TEC Natural Gas Systems.
On March 16, 2009 the Fire Department sent a notice to NYC jewelers to explain Rule
2609-
Click here to see a copy of that notice.
Click here to download a copy of the complete text of Rule 2609-
If you have questions about the new Fire Code or Rule 2609-
718-
Some jewelers will find that after the flashback arrestor check valve is
installed their torches will not light at all, or the flame will be very weak.
This happens because utility natural gas pressure in New York City is very low and
the flashback arrestor check valve actually blocks gas flow.
If this happens the Fire Code says:
Where the pressure of the piped natural gas
supply is insufficient to ensure such safe
operation, approved equipment shall be
Provided between the gas meter and the fuel
consuming appliance that increases pressure
to the level required for such safe operation.
G-TEC Natural Gas Torch Boosters are Approved by the Fire Department and will elevate
utility natural gas pressure enough so that the flashback arrestor check valve protects
the gas meter and the jeweler has a hot, robust flame at the torch. Click on the
document at the right to read Certificate of Approval # 5120 for TB-
Torch Boosters. Other Torch Booster models require a Site-
Click here for information about larger Torch Booster systems.
