mega minor

fsankar · #1 2009-12-29, 7:35pm

What pressures do you operate the mega minor at? They say it is low pressure but I am using bottles can I go higher in pressure. What is the advantage of operating at a higher pressure. High means more than 10 psi on the O2 and I dont know hwt the propane should be
Franklin

De Anza Art Glass Club · #2 2009-12-30, 2:11am

I'll have access to the instruction sheet next week. If I am remembering correctly, the pressure for propane was given at 3 psig and for oxygen at 7 psig.

I don't believe there is an advantage to operating at higher pressure. This is an opinion only and I can't back it up with any documentation right now. Higher pressure means for the same size flame, the control valves are open less. If the control valves are needle globe valves, this shouldn't be an issue as far as controlling the flame goes. If the control valves are of a lesser quality, the higher pressure might help in controlling the flame because the valve is most effective at throttling only for a short range after being opened. However, operation when nearly closed creates greater wear on the disk and seat of the valve. This is more of a concern with liquids than with gases and probably is not a concern when operating a torch for hobby purposes.

Personally, I would operate at the lowest pressure that gives you the full range of flame size and oxidation that you would need. I would only increase pressure above the manufacturer's recommendation if you need a larger flame or a more oxidizing flame.

Another reason for increasing pressure is your flashback arrestor. There are many manufacturers of flashback arrestors and I believe one manufacturer recommends a minimum of 2 psig to get flow through the valve and other manufacturers that provide graphs for flow rate versus inlet pressure do not show a value for inlet pressures less than 5 psig. (Examples: one model of Smith Equipment brand requires a minimum of 2 psig for gas to flow, and their charts show this is true for propane but also show that oxygen will flow at less than 10 psig. One model of Victor flashback arrestors requires a minimum of 5 psig difference between inlet and outlet for gas to flow.)

The flashback arrestor will also give an indication of the maximum pressure you can use, but I'm confident that you will not approach those values. Some flashback arrestors state that the maximum pressure for propane is 50 psig and the maximum pressure for oxygen is 150 psig, but your flashback arrestor may have a value engraved on the body or provided on a label which is much less.

Dale M. · #3 2009-12-30, 9:36am

Operating at a higher pressure means you can run more fuel and oxygen through torch, this can move the flame front away for the face of torch thus the torch will run cooler. Also allows for a bigger flame. Also getting flame front further out from torch faces generally means less carbon build on torch face because combustion happens further out.......

Generally its recommended that fuel pressure be about 1/3 of oxygen pressure for soft glass work and for boro work about 1/2 oxygen pressure. How ever people who have experienced problems with fuel pressure regulator being unstable at very low pressures have had good luck bumping fuel pressure up higher than the accepted parameters ...

Ultimately its the torch needle valves that control the FLOW of the fuel to torch face. Bumping up pressures makes the valve adjustment more critical and possibly harder to manage...

Dale

fsankar · #4 2009-12-30, 2:17pm

Thanks for the replies. From your actual experience do you know if the increased pressure cause more O2 consumption. ie to get the same size flame as when it is on low pressure. I am trying to adjust the torch and not sure what is good or very good. The small cones are fuzy on the ends but if I reduce the flow I get a smaller flame and I think it cause more carbon build up. So if I increase the pressure at this point does it mean I am using more O2?
What is a soft flame. To me they all feel soft but I cant keep my finger in the flame too long ,

I only have 5 on each hand.
Franklin

ArtcoInc · #5 2009-12-30, 6:54pm

As a general rule, one runs the oxygen pressure at 2-3 times the gas pressure. Since the Minor (and Mega Minor) can be run with household pressure natural gas, and since most houses have low pressure (like 1/3 - 1/2 psi), you can run the Minor on oxygen pressure as low as around 1-2 psi.

As Dale mentioned, some regulators don't work too well in the very low pressure range. Kicking the oxygen pressure up to, say, 5-10 psi often makes the regulators happy, which makes the torches happy.

Increasing the pressure should *not* increase the oxygen consumption! The amount of oxygen going through the torch in controlled by the valves on the torch, not the pressure at the regulator. The pressure just controls how much 'push' the oxygen has to flow through the hoses and the torch. If you have long hoses, or a torch with a lot of internal 'resistance', you need to kick up the pressure a little to compensate. Now admittedly, with the oxygen at a higher pressure, it does make the valves a little more 'sensitive', and a little adjustment at the valves can make a big(ger) adjustment in the oxygen flow.

A 'hard' or 'soft' flame is not just about mixture (ie: reduction or oxidizing). It is about the total amount of gas and oxygen flowing through the torch, the velocity of the flame, and the length and shape of the flame.

A 'hard' flame is a sharp, focused, piercing flame, like when you open both the gas and oxygen a lot. It will typically be a longer flame. Oxidizing flames tend to be 'harder' flames.

A 'soft' flame is a feathery, whispy flame ... one when you open both the gas and oxygen a little. It will typically be a shorter flame. A 'soft' flame does have more of a tendency to carbon up, and/or cause the torch to heat up.

HTH

Malcolm

fsankar · #6 2009-12-31, 9:14am

Thanks Malcolm. My regulator seem to be suffering from the not so good at low pressures. I found that by increasing the pressure I get more noise from the O2 which is not a problem but since it is a pain in the you know where to refill these bottles I was concerned about wasting O2 unnecessarily. The flame is longer also. I have no way of measuring the gas flow and am trying to use the sound to determine if it flowing faster. Is there any way to sense whats happening with the flow? I think that by opening more (turning the dials on the torch) gas I use more gas. So why not try to open only what is needed? but.....Sorry just thinking aloud. Can you comment on what the small cones should be like. I am getting flared ends on the small cones but in a video on flameworking I saw nice crisp cones.
Franklin

Dale M. · #7 2009-12-31, 10:22am

They do make flow gauges that can be attached to regulator, but unless you learn to control the flame with the torch knobs (aural and visual), the flow gauge only tell you consumption rate, not if torch flame is correct.... IF you are really worried about filling tanks, you need to go with natural gas if available (or "delivery style" propane supply and have it piped in to studio) and oxygen concentrator(s)....

Dale

fsankar · #8 2009-12-31, 8:08pm

That is correct. Learning to control the torch with the knobs is not as easy as it looks in the videos. or is it? reading the replies here helps. Some more practice and adjusting should also help . Thanks.
Franklin

ArtcoInc · #9 2009-12-31, 8:37pm

Get yourself some glass that reacts to a reduction flame (and some that react to an oxidizing flame, if you can find some). Use these to practice setting your mixture.

Malcolm

fsankar · #10 2010-01-02, 4:45am

Good advice thanks.
Franklin

De Anza Art Glass Club · #11 2010-01-04, 3:21pm

I tried to scan the instruction sheet, but I can't get it in a format that will download in a readable image.

Copied from sheet, retaining all capitalization and wording, and only edited to remove redundancy:

MEGA MINOR BENCH BURNER

SURFACE MIX BURNER – TO BE USED WITH EITHER --
Propane & Oxygen OR Natural Gas & Oxygen

DO NOT USE WITH ACETYLENE GAS

Also Required: Approved hoses, clamps and pressure regulators for fuel & oxygen (Hoses MUST be secured to burner with clamps) B Style fittings on torch.

VERY IMPORTANT:
When attaching hose to burner: -- MUST use 2 wrenches 5/8 & 11/16 to tighten or loosen hose nuts to prevent twisting of torch valve assembly.
Above supplies can be obtained at local welding and/or fuel supplier.

Heat sink may loosen due to shipping and handling. It should be positioned at least 1/8" back from end of burner. Adjust if required.

Cleaning Tool (Included) – For use on COOL Burner head ONLY – Do NOT use tool into flame. Adjust length of wire to approx 1" – insert deep into gas tubes and approx 3/8" into oxygen holes.

To prevent overheating of heads and nozzle tubes:

1) Do not have small gas flame burning with little or Or No oxygen.
2) Low velocity small flames can cause a red glow At face of the burner. This will prematurely Oxidize burning away the nozzle tubes.

Always adjust control valves to avoid red glow at Burner head and red tinge in the flame. Increasing oxygen flow will reduce this.

Do not allow molten glass to touch the front burner face because glass deposits in & around the nozzle tubes and almost impossible to remove.

NORTEL burners run on LOW pressures
Propane: 1 – 5 PSI
Natural Gas: 1/4 to 2 PSI (6" water column or more)
Oxygen: 5 – 8 PSI

NOTE: Mounting holes are provided in the base to secure the burner to the work table.

NORTEL MACHINERY INC.
1050 Clinton Street Buffalo, NY 14206
Tel: 716-852-2685 FAX: 716-852-6374
In CANADA TEL: 416-438-3325
Fax: 416-438-7140

Emal: info@nortelmfg.com

fsankar · #12 2010-01-04, 6:17pm

Thanks. Pressures are really low. Any idea what will spoil if it operate at a higher pressure.

Franklin

Dale M. · #13 2010-01-04, 9:35pm

It will just make valves more sensitivity to adjustment and probably frustrate user more trying to get a proper flame....

Dale

fsankar · #14 2010-01-05, 6:04pm

You got it. That must be the problem. I am off to try and get the regulator to put out low pressures. At least I should be able to get 5 propane and 8 O2.
Thanks
Franklin

fsankar · #15 2010-01-08, 4:15pm

How do you get a pin point flame on a mega minor?
Franklin

ArtcoInc · #16 2010-01-08, 5:56pm

Quote:

Originally Posted by fsankar

How do you get a pin point flame on a mega minor?
Franklin

By changing your attitude

Seriously, neither the Minor nor the Mega Minor produce the 'pin point' flame that *some* other torches make (premix centerfires, GTT triple-mixes, etc).

But .... 99% of the time, you don't need one. Usually, it's a matter of learning to control the glass and the heat. Watch people like Lucio Bubacco, or any of the Japanese artists, produce fine, intricate work on large, soft flame torches.

When you start doing something like inside-out work, then it might be time to look at another torch. Until then ... learn to use what you have.

Malcolm

fsankar · #17 2010-01-23, 5:45pm

Its working ok now. Need lots of practice. you do get a smallish flame by opening up the O2 but knowing how to adjust the gas and O2 is an art by itself.
Franklin

olivia · #18 2015-06-25, 3:50pm

I just replaced my Minor with a mega minor ---and i am having a terrible time learning how to adjusting the flame---I have been using a minor for 9 years . with the mega minor i can't seem to strike or reduce glass and it seems to burn the frit . I almost want to send this torch back---I only use soft glass --can you help me? I use natural gas and oxycon on 5 .
Olivia