Rob, I want my posts to be both understandable and consistent on what I’ve said earlier re: Arrestors & Check Valves so I’ll repeat some things here plus add a few extra details & info.
#1 : A Check Valve is Not considered an 'Arrestor.'
#2: Typical Arrestors sold today contain ‘Both’ a Flashback stop function + a Check Valve. I’ll bet that’s the type of Arrestor you have. Because Flashback prevention is not always appropriate but a Check Valve may be, such as with an oxygen Concentrator, ‘stand alone’ Check Valves are used.
Not to put too fine a point on things but details can matter. I try to be fairly complete in what I write intending to follow-up when necessary. My intention anyway.
Arrestor & Check Valve subject matter is fairly easy to understand when fully explained. Only talking about parts of a Torch (protective) system, especially to those unfamiliar with these products, their terminology & how products work can be confusing at best. ‘Full understanding’ often (usually) requires revisiting subjects several times, explaining something in a different way, using new examples or adding more detail to make things clearer.
#3. When I speak about Arrestors I mean products that contain Both a Flashback stop prevention function + a Check Valve.
Small size Torches are beneficial for jewelry makers. Adding an Arrestor to a Torch handle makes the Torch heavier, possibly unbalanced and is unnecessary with common jewelry making Torches. Most jewelry Torches could not have an Arrestor added to the Torch handle anyway. because there are no threaded, gas line connectors on the handle to screw on an Arrestor. The Meco is an exception that does have threaded connectors on the handle although one or two attached Arrestors to it’s small, handle would be odd, to say the least for typical soldering work being done. A casting operation using a Large, commercial (welding type) Torch running high gas pressures is a case where a Set of Arrestors added to the Torch handle may be beneficial.
#4. For most jewelry makers using small, hand Torches attaching an Arrestor to a Regulators output is the correct way to go.
#5. Your comment re: “zero pressure situation” and Check Valves… I’ll explain differently. Zero pressure is possible but unusual. **You are correct re: the purpose of a Flashback stop & Check Valve function. Exactly how the Flashback is stopped is fairly simple but for another discussion if of interest. Again, Check Valves prevent the reverse flow of a gas (or a liquid) in a system from mixing with another gas or liquid.
If you’ve seen diagrams that indicate the reverse, as you said, or something else they are incorrect …or possibly not explaining something clearly.
Example of a situation more likely than ‘zero pressure:’ The fuel gas source (I’ll use a propane Disposable for example) runs very low on propane. Propane output pressure becomes very low… lets say around 3 PSI. Oxygen coming into the Torch at lets say 5-6 PSI. The Torch Tip has become clogged from spattered solder, other debits, etc. Oxygen coming into the Torch might overpower the low pressure propane entering the Torch. Without a Check Valve in the propane line (any fuel gas) or an Arrestor that contains a Check Valve nothing would prevent oxygen from flowing into the propane Disposable! A major safety issue. Same thing if using a refillable propane Tank or any other fuel gas container.
Any fuel gas getting into an oxygen Concentrator without the protection of a Check Valve on the Concentrator output is a different problem. Any fuel gas will contaminate the Nitrogen filter(s) in the Concentrator and stop it from producing oxygen. A real pain to clean the Nitrogen filter(s) or at worst $ to replace the nitrogen filter(s).
#6. The Flashback stop function of an Arrestor ‘Does’ create a small, pressure drop as gas passes through. The Check Valve inside an Arrestor, or a separate (stand alone) Check Valve, ‘does Not’ drop pressure.
Extra info: Check Valves have a ‘Cracking’ (opening) minimum pressure / PSI depending on the specific Valve product.
The Check Valve Paige Tools suggest using on an oxygen Concentrator opens at about 1.5 PSI, way below the oxygen PSI coming out of Concentrators. Oxygen will easily pass through the Check Valve with No pressure drop.
Because of very low Residential delivery pressure of Natural Gas (NG) in the US, about ¼ PSI, a Check Valve will not open & NG would not get to the Torch. A gas pressure Booster would be required to increase NG pressure.
Trying to run a Torch on Residential delivery PSI NG… that’s too low to open a ‘stand alone’ Check Valve is a Safety Gamble! It’s possible oxygen coming into the Torch from any oxy source (Concentrator, Disposable oxy Cylinder or Refillable oxy Tank) to get into the home natural gas system, because of the same potential Torch blockage issue explained above …a NG + oxygen scenario you Do Not want. Using a NG Booster pressure of the NG is increased to about 25 PSI. Then, a traditional Regulator can be attached to the Boosted NG output. (Remember, a standard Arrestor has both a Flashback stop function + Check Valve). The booster option for NG is expensive but because it allows the use of a traditional Regulator gives good safety protection.
Please Call us with questions. (206) 527-1515