Need a Recommendation for Flashback Arrestors

[JHCC]

I'm planning to add flashback arrestors to my oxypropane torch, and I'm having trouble figuring out the capacity requirements. Some manufacturers say something like "Rated capacity of 40 SCFH with a 5 PSIG pressure drop". Others won't give a capacity number, but give a chart showing the inlet pressure on the x axis, the scfh on the y axis, and a selection of curves labelled by the difference between inlet pressure and outlet pressure. According to my tips and pressures chart, my existing setup would range from 1 scfh (propane on my smallest brazing tip) to 80 scfh (cutting O2 on my biggest cutting tip). The latter number could theoretically go up to 380 scfh, although I doubt I'll be needing to cut 5" thick steel any time soon. 

So, would one of these 40 scfh arrestors work with my current setup, or should I go with the other type?

[JHCC]

Addendum: having found a good deal on eBay for a heavy duty set of Victor flashback arrestors (i.e., about a third of the retail price), I've gone ahead with those. However, they are the ones that have the flow/pressure graphs, so I'll still need to figure out how that that works. Any thoughts would be welcome.

[gewoon ik]

Make sure they are unused. 

We had an incident where one failed in a bang. Lucky the manifold started burning and the safety valves (don't know the names, the ones that closes if the pressuredrop is to big) shut it down. And also good is was on a manifold at the end of the system.

[JHCC]

Yes, these are new, still in factory packaging.

[Goods]

I thought flashback arresters weren’t required with propane, but very necessary with acetylene. Was I wrong?

 

[Frosty]

The hazard is high pressure oxygen forcing itself up the fuel hose if there's a blockage in the torch tip. So YES a flashback arrestor is necessary in any oxy fuel torch.

A fuel air torch can't flash back for two reasons: First, the only pressure in the system is on the fuel side. Second, fire requires oxygen to burn and there is no high pressure oxygen in a fuel air torch so any reverse flow in the fuel line is into an oxygen free environment and ignition can NOT take place. No flash back hazard.

I don't know about modern oxy fuel torches but the All States rig I own has flashback arrestors built into the torch itself. The ONLY backfire possible is in the tip itself and All State torches are famous for sounding like artillery when you thumb the fuel switch off. 

Frosty The Lucky.