Removing a Visible Pump Glass Cylinder by Tim Rohr

If you ask a room full of Petronuts ,for the best method to remove a cylinder in one piece, the answers will be as diverse as asking the cooks at a barbecue contest for the best way to cook a beef brisket. In spite of the fact that these are two totally different issues, there is one common thread that both sides are in universal agreement on. "Go slow."

Haste makes Waste... Its a slow process... Patience is the best approach...
First I carefully... Do not rush... Let it sit for awhile...
Slow and cautious... Patience works!... Slow and steady wins the day ...
Lots of patience... It may take a few days... Slow way is always the best...
Take your time... Go real slow... Slowly release pressure...

The quotes above were all taken from member threads about their experience in removing cylinders. I imagine by now you have the general idea. Take your time! Replacement cylinders are costly.

In spite of the best precautions many members have still broken their cylinders as evidenced by the following quotes.

* You are not guaranteed success after you get it off.
* You MAY hear a disheartening sound that you will never forget
* Many of the readers here have heard that sound...like a metallic "tink"!
* DOZENS of guys have had a perfectly good cylinder crack down there AFTER removing the glass
* I saw a guy do this once only to hear a loud pop about 5 minutes after the last rod was cut.
* When I tapped the chisel, the glass ring EXPLODED!
* It shot out across the room as if it were a spring under high tension.
* The sound of that glass breaking is one that you will never forget
* I heard a "crack" turned around and the glass was broke

The best advice is to not remove the cylinder if at all possible. To remove or not to remove depends on several factors:
1. What is the value and scarcity of the cylinder?
2. Can the cylinder be accessed for cleaning without removal?
3. Can the gallon indicators be removed for cleaning and restoration?
4. What quality of restoration is required?
5. Is their sufficient room between the cylinder and the edge to safely remove the litharge?
6. Do you have a lot of patience for working slowly in a small space?
7. Does the cylinder already have an inherent weakness such as a small crack or BB hole?
8. Will the pump be exposed to the elements or possible vandalism necessitating the replacement of the original glass cylinder with an acrylic cylinder?

SAFETY NOTE:
1. Cylinder have been known to aggressively shatter without warning, so wearing safety goggles is a must.
2. Wear a good respiratory mask : Litharge is the cement used to seal the cylinder to the top and bottom plate. It contains lead oxide. Lead oxide can be fatal if swallowed or inhaled. It causes irritation to skin, eyes, and respiratory tract. It affects gum tissue, central nervous system, kidneys, blood, and reproductive system. It is also a known carcinogen. I didn't wear a respiratory mask the first time I removed a cylinder and experienced breathing difficulty halfway through the process.

I'm going to divide this procedure into three parts:
PART 1: Removal of the cylinder rods
PART 2: Removal of the litharge
PART 3: Removal of the cylinder

PART 1: REMOVAL OF THE CYLINDER RODS

1. The whole procedure should be done while the cylinder is in a vertical position. This will keep the tension on the glass the same as it has been for the last 50 years. Secondly lets talk about temperature. Glass doesn't pass heat very well** (low heat transitivity) so the difference between temperature of the outer glass and the temperature of the inner glass can be very high. Since glass is brittle, when the rapid expansion of the outer glass is not matched by expansion of the inner glass, the layers of glass shear and "POW" goes the cylinder. Early glass is more brittle than modern glass and cold weather and old glass don't mix! Try to perform this procedure during warm weather during which time there is expected to be minimal fluctuation in temperature.

2. The first step is to remove the pressure on the cylinder by loosening the tension on the cylinder rods. Personally I have always started by using a wire wheel attachment in a die grinder to clear the exposed threads at the bottom of the cylinder rod of old paint and rust. This will provide a clean thread path for the nut to come off. Follow this by soaking the threads with the penetrating oil of your choice. For a severely rusted nut, it is best to leave the penetrating oil on for at least 24 hours. One member has reported success using an eye dropper and giving each nut a drop or 2 of Muriatic Acid. It might take a few days to dissolve the rust. This gives the penetrating oil enough time to penetrate the rust. This method is is particularly useful if the cylinder rods thread into the bottom plate.

3. I always try to tighten the nut first, just enough to move it a little. This will fracture the rust and has worked well for me in the past. If there is clean thread behind the nut it will allow the nut to move thus fracturing the rust on the exposed side and allowing the penetrating fluid to do it's work. DO NOT force the nut tighter if it refuses to move.

4. Once all nuts have been broken loose and the penetrating oil has been allowed time to soak in, it's time to take the next step. Loosen the nut " turn and then re-tighten and equal amount. Doing this several times helps to crush the rust between the threads. When finished I re-tighten the nut a little and apply more penetrating oil and proceed to the next cylinder rod. (If rusted badly you may be lucky to get it to turn just 1/8 of a turn. It will tell you how much it is willing to give, don't ask for more.) You get the picture.

5. Repeat this on all cylinder rods, following a star pattern by loosening the nuts directly across from each other, in sequence. This is the same procedure as tightening lug nuts on the rim of a car tire. This takes the pressure off the cylinder a little at a time and keeps the pressure uniform around the cylinder. If you start taking the nuts all the way off in one shot in an uneven manner the glass may crack or explode. Personally I've never broken a cylinder by loosening it too fast but plenty of people have, so why take a chance! It may take a few days to get the cylinder out, but that is far better than laying out $800 ton replace a beautiful blue Fry Cylinder. When finished reapply the penetrating oil and repeat in 24 hours. Repeating this process in 24 hours lessens binding and breakage. You will know when the backing off is no longer needed. Turn each nut about " to " turn each day.

6. Let's assume that you are not in the "Cylinder Gods" favor and the nuts refuse to loosen. Heat may be your only choice. I always protect the cylinder with a protective piece of insulation at the point heating will take place. I also place a wet rag on top of the bottom cylinder plate at the point where heating is taking place. Directing the acetylene torch at the nut, I'll heat it just long enough for the nut to start glowing red and then follow the same directions as above but without penetrating fluid. The key is to heat the nut as quickly as possible without heating the rod. If too much heat is applied for too long , both rod and nut will expand equally and all advantage will be lost. It is also easy to feel movement that is mistaken for the nut loosening when in fact you are twisting the rod and it will snap off. It goes without saying that a lot of caution must be used when doing this.

7. If none of the above procedure worked, I would use a 3" wheel on a die grinder to remove one facet of the nut. This helps to loosen the nut and allows for more penetration of acid and penetrating oil. I would then proceed as stated above.

8. Your last choice and most undesirable is to saw through the cylinder rods. It subjects the cylinder to uneven and sudden release of tension. That being said, some members have done it successfully!

PART 2: Removal of the Litharge

Cylinder are cemented to the bottom and lower cylinder plate with a mixture known as Litharge. Litharge is a mixture of Lead(II) oxide(PbO) and glycerin. It sets to a hard, waterproof, acid-proof cement that has been used to join the flat glass sides and bottoms of aquaria, sealing pipe joints, and was also once used to seal glass panels in window frames. It is a component of lead paints. Old timers would use Litharge to glue a loose valve seat back onto a block. That gives you an idea how hardy this mixture is. It was also used at one time to hold the lead plates in place in a battery. This gives you an idea of it's resistance to acid. In spite of it's hardiness members have reported using a variety of fluids to help break the bonds of Litharge: Muriatic acid*, break fluid, paint thinner, laquer thinner, WD-40, oven cleaner, Acetone, Methyl Ethyl Ketone or MEK and penetrating oils, such as Kroil.
*Never use Muriatic Acid on Galvanized castings, aluminum or pot metal (die-cast zinc). It is safe to use on cast iron. When using Muriatic acid, be sure to wear rubber gloves and eye protection. Also have a mixture of Household Baking Soda [Arm & Hammer] mixed with water for neutralizing the acid followed by a clean water rinse.

Removing Litharge takes time, tenacity and the delicate tool control of a brain surgeon. You have to pick at the stuff with the thoroughness of a tooth-cleaning dental hygienist. You may need a variety of tools such as:
* A razor-blade utility knife
* A small flat-blade screwdriver
* A scratch awl
* A short piece of hack saw blade curved to match the cylinder diameter,
* A variety of dental picks
* Any anything else that will help you to accomplish the task.

Which tools will work for you, will depend upon the gap between the cylinder glass and the lip on the iron base. The smaller the gap the more difficult the job.

I took several pieces of Litharge, placed it in a baby food jar, and let them soak for several days in paint thinner. I found the Litharge to be just as hard and difficult to break as it was prior to soaking. You may want to try the same thing using some of the other solvents mentioned and decide which works best for you. I believe that the condition of the Litharge has a bearing on whether the solvent helps the process. If the Litharge is crumbly and loose the solvent gets greater penetration and surface coverage. If the Litharge is solid the benefits are less noticeable.

If the Litharge is solid, scarify it using any of aforementioned tools, before applying the solvent. I used a small finger drill to make a lot of holes all the way around cylinder. If there is insufficient gap between the cylinder glass and the rim, a finger drill will not work. I then poured brake fluid on the Litharge (Brake Fluid is the most frequently mentioned solvent), let it sit for a few days, reapply solvent as needed, if it has dried up or soaked in. When I was comfortable that nothing more was to be gained by adding more solvent the picking began. When picking got tough I applied more brake fluid, waited 24 hours and repeated the process. I try to avoid contact between the tool and the glass as much as possible.

One member said, "I have always used brake fluid....has never failed"

Another member said "I've always had good luck with Muriatic acid. It doesn't evaporate like lacquer thinner does. Even though the compound is supposed to be resistant to acid......it never seems to work out that way. I guess that it's due to the age and time apparently breaks down it's toughness?"

Another member said, "Every time I walked by the pump, I sprayed some WD-40 onto the Litharge." Then every now-and-then I'd take a small screwdriver and scrape out whatever portion of the cement had loosened up. Then more WD-40.

DO NOT use a carbide grinder, it is to difficult to control in the limited work space and a broken cylinder is almost assured.

PART 3: Removal of the Cylinder

Never, never check the cylinder to see if it is loose, keep picking until the cylinder tells you it is loose. If all the Litharge has been removed, the cylinder should be loose, if not give it some very gentle taps near the bottom, with the meat of your palm and it should come loose.

When you finally get the cylinder out (remember, the top of the cylinders is still attached to the top plate), turn the cylinder upside down in a cradle that will hold it steady, while you proceed to pick the Litharge out of the upper plate groove. DO NOT lay the cylinder on it's side to work on it. Whatever you do, DO NOT pry with anything!!! If you have not removed all tension and pressure on the glass before you try to remove it, disaster will strike! Its a slow process but not that bad when you consider the cost of a new cylinder!

Tips:
Tokheim glass cylinders are the toughest to get out...and the most apt. to break.

Don't try to remove the rings used on some pumps like Guarantee Measure. The minimal benefits do not justify the rick of breaking the cylinder.

Good luck.

Copyright 2013
Tim Rohr


Edited by Oldgas (Mon Mar 11 2013 07:47 PM)