[SOUND] Before looking closer at torch handles, we need to explain a few terms
and understand some of the hazards associated with oxy-fuel equipment.
The terms are reverse flow, flashback,
backfire, and sustained backfire.
Reverse flow is when either the oxygen enters the fuel gas side of the system,
or the fuel gas enters the oxygen side of the system.
This occurs when there's a restriction of one of the gases or
an imbalance of pressure.
This can be caused by a clogged or blocked tip, or
allowing one of your cylinders to run out of gas.
If a reverse flow condition exists, a flashback can occur.
Flashback is the retun of a flame through the torch into the hose and
even into the regulator.
It could potentially reach the cylinder.
This condition could cause an explosion anywhere within the system.
Flashback arrestors are designed to prevent the flame from traveling
beyond the point of the arrester.
Flashback arrestors contain a sintered filter which prevents
a flame from passing through the filter element.
Backfire is the return of a flame back into the torch,
which produces a popping sound.
The flame will either extinguish or reignite at the tip.
This is normally the result of accidentally bumping the tip against
the workpiece, operating the tip too close to the workpiece, or
allowing the tip to become overheated.
The last event is a sustained backfire.
This is when a backfire occurs and continues burning in the torch.
This condition may be accompanied by a popping sound followed by
a continuous whistling or hissing sound.
Some of the causes for this are improperly maintained equipment, overheating of
the equipment, or improper pressure settings for the equipment being used.
[SOUND] >> This is a typical Victor handle.
On most of our popular handles,
you'll notice there'll be a built-in flash arrester and a built-in check valve.
One of the misconceptions in our industry is a check valve will stop a fire,
that's not true.
What a check valve is designed to do is to stop the gas from getting on the wrong
side of the torch.
A flash arrester is designed to stop a fire.
A flash arrester will stop the fire from advancing further up the system.
>> And if your torch doesn't have a check valve or flashback arrestor it,
we strongly recommend that you install them before operating.
>> And if you do, you may have heard it there, you put them at the torch or
the regulator or both places.
And if you decide to put them at the regulator and at the torch,
make sure you check with the manufacturer's data sheet to make sure
it will not restrict flow to your torch.
[SOUND] >> To reiterate what Tim said,
the best rule is to have safety devices as close to operation as possible.
This means incorporating check valves and flashback arrestors into the torch.
[SOUND] >> This is a typical Victor handle.
It's designed to deliver the gas in a safe manner to the mixer.
One of the big misconceptions in our industry is that the mixer is in
the handle, and that's not true.
Each individual component has its own mixer.
Today, we're gonna talk about heating and cutting,
the most popular uses of the torch.
>> And this is a heating attachment.
A heating attachment can be used for heat treating, priming,
descaling, straightening, many other options.
Before you use this heating attachment,
you need to be sure to check the cone end of your attachment has two O-rings.
And on those O-rings, you have to make sure they're neither missing nor damaged.
That could lead to a leak that might lead to an accident.
So be sure to repair them or replace them before using.
>> And here's the typical cutting attachment.
Do the same inspection on the cone end, as Ken just advised.
In addition, we also wanna make sure that we check the seating end for the tip, no
dents or scratches in here, because this will eventually be a metal-to-metal seal.
Before attaching the cutting attachment to the torch,
we wanna inspect the exceeding area of the torch handle and also the thread assembly.
Then you wanna attach them, hand-tighten only.
At this point, if we use a wrench on it, you're gonna damage the O-rings.
So we're gonna hand-tighten this on there, all right?
After you get that on, one of the things we wanna do,
we're now gonna take and open this preheat valve all the way on the handle.
If we don't open it all the way, you'll get a restriction in your cutting oxygen.
This will now be your preheat adjustment for your oxygen.
Now, we'll take a look at the tip.
You wanna make sure you can inspect the tip on the end, make sure preheat holes
are free of debris, and the cutting hole itself is free of debris.
You also wanna check the seating end.
This is going to be a metal-to-metal seal, so
we gotta make sure there's no scratches or dents in the system.
Now, unlike the cutting attachment to the handle,
we'll now tighten this on with a wrench, and
you need to tighten it securely because of the metal-to-metal seal.
We'll then take a look at the cutting lever itself,
make sure it moves freely, there's no resistance, and we're ready to go.
[SOUND] >> Your torch inspection checklist should
include the following, inspect valves, fittings, and seating areas for damage.
Ensure both O-rings are intact and in place.
Ensure the torch is free from oil and grease.
Make sure the tips are free from slag or obstruction.
[SOUND] >> Manufacturers such as Victor provide
tip charts, and they help you to determine the proper flow settings.
Note that alternate fuels use different tips,
and they require different pressure settings.
>> The thickness of your plate would determine what tip you use, and
in turn, the tip will determine what pressures I need.
Take, for example, this is a number one acetylene cutting tip, and
I'll set my pressures at 25 PSA on the oxygen and about 5 on the fuel gas.
If I would change thickness and, say, go to an inch plate, I'd also have to change
the tip to a number two and my pressures would be different at the regulator.
So I'd refer to the tip charts that Ken had mentioned earlier.
[SOUND] >> If you don't have tip charts,
ask your equipment supplier to help with recommended settings.
Also remember the one-seventh rule for using acetylene.
Make sure you have adequate capacity from the acetylene cylinder to support
the acetylene consumption of the tip you're using.
After connecting the attachments and tips,
you need to check the entire system for leaks.
The steps to perform a leak test are as follows.
First, ensure that the adjusting mechanism is completely backed out.
Open the gas slowly until the high pressure gauge reading stabilizes,
then shut off the cylinder valve.
Monitor the gauge for any pressure drop,
which would indicate a leak of the high pressure side of the system.
If no leak is evident, open the cylinder valve and
adjust the oxygen regulator to deliver 20 PSI.
Repeat the process with the fuel gas valve and regulator, but
be sure to adjust the fuel gas regulator to deliver only 10 PSI.
Close both the oxygen and fuel cylinder valves.
Turn the adjusting screw or knob counter clockwise one-half turn.
Observe the gages on both regulators for a few minutes.
If the gauge readings do not change, then the system is leak tight.
Open the cylinder valves again.
Any movement of the needles indicates a possible leak.
If you observe a leak, stop.
Do not use leaking equipment.
Check all the connections.
If you can't find the leak,
have the equipment inspected by a qualified technician.
Just like we purged a cylinder valve and hoses earlier, we need to purge the torch.
In this case, it's to eliminate the possibility of gases mixing prematurely,
which could lead to a flashback or worse.
>> To purge the torch, the first thing you wanna do is
open the oxygen valve on the torch handle all the way.
And with a cutting attachment, also open the preheat oxygen valve and
depress the cutting lever for three to five seconds.
We'll shut that off and we'll repeat the process for the fuel side.
We're gonna open the fuel side for three to five seconds and then shut it off.
>> And Ken, this is a good time to recheck your regulators to make sure you maintain
the same pressure.
[SOUND]