Bobcat Popping

[Quixeh]

Hi All,

We've recently purchased a Bobcat second hand, and its our first dual-fuel torch after using a hot head for a year or so.

We've noticed a small popping sound as we add the oxygen (3.5 L/m from a 5 L/m Oxycon), and we wanted to know if this is normal or if there is a leak in the torch or we've setup something incorrectly. It didn't happen the first time we brought the setup home, but it's been sat in the shed for a week while we waited for some better sodium flare glasses.

I've taken a video to demonstrate, although it does slightly exaggerate the noise!

https://youtu.be/0XY6LS2yChY

All equipment was originally from tuffnells, if there is something wrong is it likely they will be able to service/repair?

Thanks Everyone!

[flame n fuse]

I have a bobcat and haven't noticed that 'pop'. Looking at your flame, it seems quite small when you have turned the oxy down. It may have nothing to do with the problem, but what pressure is your propane set to? - I use about 3 bars. Also, have you checked for leaks where the pipes join the torch (using the bubbly stuff you can buy from B&Q) - just wondering when you turn the oxy off at the torch, maybe the gas is finding a small gap to escape elsewhere.

[tuffnell glass]

Hi,
    That's a weird one.

Is the torch "face" plate (that's the flat tip of the torch )still tight on the torch . Sometimes when the torch has been used very hot on borosilicate the plate starts to lift off the torch and you can see a gap between the torch and the plate, I wondered if this happened if it might be leaking from there.

I would also turn up the propane a bit too.
Best wishes,
Martin
Tuffnell Glass

[Dietmar]

This popping noise is normal when you (re)open the oxy valve on most torches. The increased supply of oxygen increases the combustibility of the gas mix and the flame burns faster. There might have been some traces of propane inside the oxy canals and this mix ignited when leaving the torch head. There is no reason to worry for this single popp.

A GTT torch loves oxygen! If the torch gets not enough oxygen it overheats at the front plate. If the torch is running on maximum usefull flame with plenty of oxygen the mantle (outside tube) is really cold untill the joint to the front plate.

Exept you want to turn your GTT torch into a rocket engine it works fine with a bbq regulator (50mbar). Every exess pressure will make it more difficult to adjust the right size and chemistry of the flame. There is just too less part of a turn on the knob between closed and too much. The torch in the video is running on (or under) the absolute minnimum of oxygen. It should be cleaned before every session to prevent the buildup of carbon residues in the orifies.