Oxygen Very High Flow Regulator Mounted 3 Function Flash Back Arrestor - Multiple Use.
Reduced Pressure Drop. G1/2 inlet and outlet connections. Other connection sizes are available up to G1" - Please enquire with Noz-Alls 01242 681052

This DEMAX5N very high flow five chamber flashback arrestor is physically large, generally this is not a problem as the FBA will be mounted to an equally large high flow regulator.
As with the DGN91 arrestor the increase in the surface area of the flame arresting element (s) presents a much reduced flow restriction along with the increase in potential flow rate.  The useful flow rate is that based on the flow once the pressure drop has been taken into account - See the flow graphs.

In addition to the greatly increased flow rate possible when compared to working with the DGN91 high flow FBA or in deed using "standard" DGN FBA the larger and higher flow flashback arrestors (FBA) presents less of a flow restriction which makes these larger FBA very useful when you need to operate at a higher flow rates or with higher working pressure, this is because the FBA presents less of a pressure drop to the system / nozzle which allows for correct and safer operation of the process. 

The larger higher flow flashback arrestors are also a must when operating with long hoses, the pressure drop is much greater, which is simply due to the length of hose.  Therefore it is good practice to fit larger higher flow FBA to minimise the pressure reduction.  Long hoses should always be as large a bore as possible, again to minimise the pressure drop, a smaller bore working "whip end" may be fitted.  Ensure the hose check valve does not reduce the flow / induce a pressure drop, HCV must be marked with the BSEN5175-2 (or BSEN730-2) standard.
This FBA is rated for use with oxygen with a working pressure up to 25 bar gauge.

• Overall Length - 111mm
• Body diameter - 64mm
• Body length - 66mm
• Inlet and outlet bore dia. 10mm
• Weight 1.27kg

FBA connections:- 
Special purpose high flow flashback arrestors stocked with G1/2 connections but are available with sizes from G3/8 to G1 connections if required.  (Flow capacity is the same).

• Captive inlet connection nut - 24mm AF
• Outlet male G1/2 thread - approx. 20.8mm over crests - nipple head cone sealing.
• Body outlet connection hexagon - 22mm AF

German manufactured DEMAX5N FBAs have 3 functions:-
"FA"  Flame Arrestor  - The first is the flame quenching element which is of course a sintered metal filter which absorbs the heat from a flashback (when the conditions are within the design parameters)
"NV" Non Return Valve - The second function is that these regulator mounted FBA incorporate a non-return valve to prevent the back feeding of gases, the primary cause of flashbacks.
"TV" The third and final element to this flashback arrestor is the thermal cut off valve which is activated by heat. This thermal trip is a final fail safe designed to cut the incoming gas supply off permanently.
The thermally activated cut off valve is not and will not be triggered by experiencing a flash back alone. An external fire or an internal fire would cause the valve to close, helping to prevent further damage, by shutting off the incoming gas.

These flashback arrestors may be used continually even when having suffered many flashbacks, these flashback arrestors do not require resetting.  

These FBA were formally tested by BAM now by IBExU

Causes of Flashback
Should you be unfortunate and experience a flashback then it is important to investigate why, this is so you may prevent any future problems from occurring.
The primary cause for the majority of flashbacks will be due to incorrect lighting up procedure and failure to purge the gases properly. 
Remember, long hoses require extra purge time.
The second most common cause is lighting up with too low a fuel gas flow combined with a leaking oxygen valve.
When you light your nozzle, and it goes "BANG" that is wrong and should not happen, ever, no matter what nozzle or gases are being used.

Therefore - check your gas equipment for - damage - for leaks et cetera before lighting up and then light up correctly.  If you need advice please give Noz-Alls a call on 01242 681052.