Lampwork Etc.
 
AKDesign

LE Live Chat

Enter Live Chat

No users in chat


Frantz Art Glass & Supply

Beads of Courage


 
  #1  
Old 2006-07-03, 4:05am
categ50 categ50 is offline
Senior Member
 
Join Date: Feb 11, 2006
Posts: 125
Default Filling bulk tank

I have been having a problem with my HH for a few months. After a new bulk tank re-fill, I noticed a soot problem on all of my transparent beads. Then one day I noticed oil coming out of the vent holes of the torch!!! I turned everything off, took apart the torch and cleaned it and hung the hose up to drain. Put it all back together, and same problem. So I took the tank back to my local AGL Welding Supply and explained the problem to them. "What oil?", they wanted to know and looked at me like I was from Mars. So, they played with the tank and looked at the tank and after 45 minutes said there was nothing wrong with the tank! But they gave me a new tank . I brought it home, and the same problem. Then on WC I saw a post from 3 years ago about cleaning a HH. Someone said they hadn't cleaned their's ever, and Melinda said that she must have a good supplier that doesn't over-fill the tank.
My question; What is the correct pressure of the tank for lampwork, and what is over filling the tank. I would like to be armed with this info for when I take the tank back to AGL Tank Filling Guys and not feel like I am hitting a .
Cate
Reply With Quote
  #2  
Old 2006-07-03, 7:44am
kbinkster's Avatar
kbinkster kbinkster is offline
PyronamixK
 
Join Date: Jun 24, 2005
Location: Spatula City
Posts: 4,196
Default

If you have a new tank, it should have an Overfill Protection Device (OPD) installed. This prevents overfilling, as the name implies.

Take the torch with the oily stuff on it and the line over to them and see what they say.

Also, tipping the tank on its side has been known to cause problems. Did they try that when they were looking at it?

Last edited by kbinkster; 2006-07-03 at 7:46am.
Reply With Quote
  #3  
Old 2006-07-03, 8:28am
bhhco's Avatar
bhhco bhhco is offline
What, Me Worry?
 
Join Date: Jul 09, 2005
Location: Texas
Posts: 343
Default

Quote:
Originally Posted by categ50
My question; What is the correct pressure of the tank for lampwork, and what is over filling the tank. I would like to be armed with this info for when I take the tank back to AGL Tank Filling Guys and not feel like I am hitting a .
Cate

Edit: The following assumes you are using a bulk propylene (or similar mapp-like gas) tank. If not, skip it. Sorry.

Well, it's a short question, but it will be along answer. And there will hopefully be others to answer too.

First, the correct pressure is "tank pressure". That's about all that is ever specified when the question comes up. Not trying to be evasive, but the tank pressure is whatever it needs to be to force a gas to be a liquid. And as the temperature changes, that pressure changes. (Which is why a frosty 1# mapp canister has to be warmed up to get the pressure back up, to get the flow through a HH).

At 60 degrees, the tank pressure could/would be about 97 psig. But at 110 degress (in the sun) the tank pressure could/would be over 220 psig. When they filled the tank, they probably did it by weight, at the temperature of the day/time. "Usually", on a "normal day", the bulk tank pressure is "about" 170 psig. That's why you will get odd looks in you try to pin down the pressure... it's in constant motion, between pretty wide swings, keeping the gas in a liquid state. I have even measured pressure at retail studios that was over 270 psig (the pressure relief valve on the tank will pop open at about 320-380 pisg - I forget the limit for propylene tanks). IMHO, some of the "my HH flame doesn't look like your HH flame" situations is because the pressure of each person's system, depending on the current temperature, could be different by up to 180 psig - and that will make a big difference in lighting and running the flame. For reference, two-gas torch nominally operates at only 5 to 10 psig and they are regulated to stay at a that set pressure +/- 1 to 2 psig, with a pressure regulator. Hotheads operate at tank pressure, without a regulator, so the pressure swing could be quite dramatic.

Liquid in your line. Yes. There is a theoretical reason and practical reason this could/would occur.

Theoretically, as the liquid becomes a high pressure gas and leaves the tank and travels through the hose, it will encounter a temperature change along the way, Usually, during the summer, it goes from a hot outside to a cooler inside. We are now back to the temperature thing... some of the gas could convert back into a liquid, sort of like condensation. Some, not all, but enough to be really annoying. Theoretically.

Practically, when the gas shop fills the tank, they are dealing with a large bulk tank normally used for welding. Since it is exempt from the federal overfill prevention device (OPD) regulation, and since no welder ever wants to be shorted on his gas fill, there is a tendency to overfill... from a lampworkers standpoint, but not from the filler or welders standpoint. All welders will put a regulator on it (which also has a internal filter) and will reduce the pressure/flow from the tank, so the "slight" over fill is no problem... for welders. Filling anything other than a BBQ grill tank (which you cannot use for propylene), is a little hit or miss anyway when it's done by weight versus volume, unless you very carefully calcuate the temperature effect. Couple the "overfill", with transport and set-up, without keeping the tank perfectly upright (I've seen them laying on thier side in a cars backseat), and the liquid then migrates into the valve - or so I been told, but I don't know that for certain. If it's so, then the first thing usually out of the tank could be liquid, if the tank valve is not burped before the hose is attached.

And there is a hypothetical answer too. Propane is not all propane. Propane (like two-gas torch users use, and you use on a BBQ grill) is a blend of liquid fuels, propane and butane, and has three grades (but no one ever reall specifies grade unless they are willing to pay a premium price), and "todays blend" could be 90%/10% - Propane/Butane. Propylene is a mix of several different gases (not just two, like "propane"). So the blend could be quite different, tanker truck to tanker truck. Hypothetically, something is "separating out" in the line, and maybe it's the "special additive of the day".

Hope this helps a little. This is not meant in anyway to be a knock against the Hothead. It's just a part of the art.



note: edited for assumption and typos (but probably not all).
__________________
"Education is what remains after we have forgotten what we learned" ~ I forget who said that.

Last edited by bhhco; 2006-07-03 at 8:38am.
Reply With Quote
  #4  
Old 2006-07-03, 9:15am
Dale M.'s Avatar
Dale M. Dale M. is offline
Gentleman of Leisure
 
Join Date: Jun 10, 2005
Location: A Little Bit West of Yosemite Valley
Posts: 5,200
Default

Bhhco and Kbinkster pretty much nailed it.... There is not much to add here. The problem is probably NOT the company or personnel who is filling the tank, its all inherent in the "systems".... Some added thoughts, disconnect the hose for torch and tank each time you finish torching and hang it to drain if not every time at least once a week if you torch multiple times a week... Use the valve on torch!... Its not just off/on... It regulates the flame!. I have found that when you light torch you turn up flame till its big and bushy and can grow no more, you have maxed out torch capabilities. NOW turn the valve back down till center cone of flame takes on sharper pencil point cone shape and flame over all takes on a few shades darker blue, this is a more neutral flame (less fuel rich) it will be hotter and **cleaner** that with HH valve just open all the way...

As for filling a typical tank... Check safety collar on tank and find out "tare weight" of tank is. Should be something like 18 pounds ( typical 5 gallon tank - BBQ size). Propane weighs in at about 4.25 pounds per gallon, and a tank with OPD valve will only accept 4.7 gallons. So doing the math... you have about 19.9 pounds of fuel and a 18 pound tank, total weigh for FULL tank should be 37.9 pounds... This is only way to check if tank is under/over full when you pick it up... This is also way to check how empty a tank is... Closer to its tare weigh the emptier its getting....

Also ethyl mercaptan is what is uses to put an odor into propane, it is also the oily culprit that is accused of collecting inside hose and causing the oily globs.... But stop to consider that it is something like 1.5 pound of ethyl mercaptan in something like 10,000 pounds of propane... Its a very minute amount of possible oily gunk per gallon....

The oily gunk in hose is probably just "oils" in propane that are dropping out of suspension and lining hose insides as propane flows thorough it. Remember propane is a refined petroleum based fuel and even a small of impurities can be included in its production. Lots has been said about oil in bottom of tank, but consider this. The propane comes off the TOP of tank in a vapor. There is no "dip tube" or any part of valve that reaches bottom of tank so you could have ounces of oils on bottom of tank and unless it evaporates and become a vapor, there is no way the can get sucked into hose....

A couple of interesting reads...

http://everything2.com/index.pl?node=Propane
http://www.artglassanswers.com/forum/viewtopic.php?t=7
http://www.eia.doe.gov/pub/oil_gas/p...e/propbro.html
http://www.eere.energy.gov/afdc/altfuel/propane.html

Dale
__________________
You can lead a person to knowledge, but you can't make them think.

To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.
Vendor-Artist-Studio-Teacher Registry

To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.
San Francisco - A Few Toys Short of a Happy Meal
Reply With Quote
  #5  
Old 2006-07-04, 8:59am
smutboy420 smutboy420 is offline
Senior Member
 
Join Date: Sep 11, 2005
Location: albany ny area
Posts: 428
Default

I think that the ethyl mercaptan being any oily substance Can build up in a tank after many many refills. It does have a tendancy to come out of soultion with the propain when temps are low.
esp if under 35 degres C. But if its warmer then that it can boil off and become a gas. With in theroy could explain it getting in to the lines and torch.
Why it tends to happen with a hot head torch I havn't come up with a why yet. But so far I'm thinking it has to do with the way a hot head uses no regulater and only useing an orfice to reduce the pressure. Makes for a nice room temp gas distilation/condesing set up.
Reply With Quote
  #6  
Old 2006-07-04, 11:09am
Dale M.'s Avatar
Dale M. Dale M. is offline
Gentleman of Leisure
 
Join Date: Jun 10, 2005
Location: A Little Bit West of Yosemite Valley
Posts: 5,200
Default

After doing some more research, I find the Ethyl Mercaptan can be in a gaseous state or liquid state. Also it is HIGHLY FLAMMABLE!!!...... So... I have serious doubts the oily gunk we fine in HH hoses and HH themselves is the Ethyl Mercaptan!...

As I stated before, it believe the oils or gunk are merely petroleum by products that have dropped out of suspension and condensed in hose....

Dale
__________________
You can lead a person to knowledge, but you can't make them think.

To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.
Vendor-Artist-Studio-Teacher Registry

To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.
San Francisco - A Few Toys Short of a Happy Meal
Reply With Quote
  #7  
Old 2006-07-05, 7:29am
smutboy420 smutboy420 is offline
Senior Member
 
Join Date: Sep 11, 2005
Location: albany ny area
Posts: 428
Default

I'm also woundering about pump oil at the filling station as a culprit.
I noticed the other day at the place we get our propain from that there where some oil nipples on the pump on the filling station rig. I noticed it was also beat up and leaky. So then I started thinking about oiled head air compressers and how there allways is some oil mist that blows past the piston rings and gets in to the air supply.

I have no ideal if its could be that or not. but it was one of them things that made me go, hum????????
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump




All times are GMT -7. The time now is 12:36pm.


Powered by vBulletin® Version 3.7.5
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Your IP: 44.200.179.138