Finally! You're ready to take the lamp underground! Cavers have relied on carbides as their primary light sources for generations. They produce a light unlike that of incandescent bulbs, but they are also known to be temperamental and high maintenance. There are many joys of using carbide lamps, but there are also some frustrations. It is for that reason that you will need to know a few things before taking your caplamp underground. This page will discuss some of the advantages of using carbide lamps, as well as logistic problems you will need to navigate.
Advantages of carbide lamps
There is no one best lamp for all caves. Nonetheless, carbide lamps have shown themselves to be highly versatile. One of the most prominent features of the carbide lamp is its soft diffuse of light. As has already been mentioned, the light of a carbide will extend into the cavers peripheral vision giving broader illumination than an incandescent bulb. Also, if calcium carbide can be bought locally, the cost of carbide caving (hour for hour) will be less than with an incandescent bulb. Furthermore, there is no battery-operated light that can compete with a carbide lamp's durability. Cavers have reported dropping their lamps down pits, clanging their way to the bottom only to promptly relight. (One caver has reported dropping his lamp 50 feet onto rocks with no ill effects.) Also, the lamp not only produces light, but heat. Some cavers have used a carbide's flame to heat small meals. You can also use the heat from the flame to hold back hypothermia in tight situations. You can easily make a heat tent simply by setting down the lamp and holding the bottom of your shirt open above it. Finally, a good carbide lamp, if properly maintained, can last for decades. It is no wonder that carbide lamps are still favorites among cavers.
Operating the lamp
First, you will need to know how to get the lamp operational. Fill the lamp bottom one half (1/2) to two-thirds (2/3) full of carbide. Do not overfill the lamp bottom, because the calcium carbide will expand as it gets wet. Next, get the acetylene started. This is easily done by spitting into the lamp bottom. Next, replace the lamp bottom to the lamp top. Turn the drip mechanism on, but slowly. Feel, listen to, or smell the gas coming from the tip. Once the flow is sufficient, cup your hand over the reflector, and use the palm of your hand to strike the striking mechanism. This will result in a pop as the acetylene ignites. Most cavers will find a flame of 1-1 1/2 (one to one and a half) inches will do nicely, and will help a full charge of carbide to last about four hours. (However, this depends on the size of the lamp bottom.) When turning off the lamp, make sure to blow out the flame rather than letting it run down. A small flame will let carbon build up on the inside of the tip, and it will have to be cleaned.
Moving through the cave
Many neophyte cavers have to make a few adjustments to the way that they cave when using carbide lamps. Many people will tilt their heads sideways in some low passages. This will (unsurprisingly) tilt the lamp sideways. Doing this prevents the drip from working properly. Doing this briefly will have little effect, but in a crawlway you may find your light growing dim. A carbide caver should keep his or her head upright, or remove the light from the helmet and hold it in his or her hand.
Be conscious of the person in front of you. You will not be shocked to know that the flame is hot. Though the "carbide assist" is a common joke about speeding a slow caver along, the caver in front of you will not see the humor in it.
If you are going on a vertical trip, it is likely that your first choice may not a carbide lamp. Though people have successfully gone vertically caving with carbide lamps for years, they have been extremely careful. When a rope is loaded, the flame of a carbide can quickly melt through it. This is a potentially deadly situation. In a day and age where good electric lights are readily available, there is no reason that you should take the extra risk of using an open flame on rope.
Next, you will need to carry carbide with you into the cave. In the old days of mining, workers would carry carbide in a flask with them on their shifts. These flasks were metal and had a reasonable seal in order to keep the carbide dry. In modern times, carbide flasks are considered more to be collectors' items than something that one would take underground. Most cavers choose to carry their carbide in one of several ways. First, and most often, a caver will carry a labeled baby bottle with a gasket. The gasket is vital! Baby bottles are not waterproof on their own. Should your carbide become wet, it will then be useless in your lamp in a best-case scenario. In a worst-case scenario, the acetylene will reach your lamp's flame and ignite! To make a gasket, you will need to purchase rubber nipples for the baby bottle. Cut the circular bottom off of the rubber nipple, and place that between the cap and the threaded top of the bottle. This should make your bottle waterproof. But, you should check it before taking it underground, just in case. Fill the bottle with water, replace the cap, invert the bottle, and then give it a bit of a squeeze. If the water doesn't leak, then it's safe for your carbide. If the bottle leaks, then try to readjust, invert, or resize the gasket. If you would like to carry a larger volume of carbide into the cave, you can use a Nalgene bottle. Even without a gasket, these are generally considered airtight if the lid is tight. The next method of carrying carbide into a cave is in spare bottoms. Many lamps were sold with spare bottoms and lids. When all of the carbide is expended, the bottoms can easily be exchanged. However, you must make sure to not put the lid on the used bottom too tight. Make sure that gas can continue to escape. Even functionally expended carbide produces some acetylene. Another method of transporting carbide is inside bicycle inner tubes. Cut a section of inner tube and tightly knot one end. Fill the tube with carbide and knot the other end. This allows you to have a collapsible container. This will take up less and less room in your pack as the trip goes on. The last method is to pack the carbide in film canisters. Film canisters are waterproof, and carry enough carbide to last a while. Many cavers say that one and a half canisters carry about one charge of carbide, but the volume of lamp bottoms vary, what constitutes a full charge also varies. Also, make sure that the lid on the film canister is taped on so you do not accidentally spill your carbide, get the carbide wet, and expose your pack and it's contents to a corrosive substance!
Caring for your spent carbide is also an important matter. After caving for a while, you will have used up enough carbide, that you will need to give your lamp another charge. You cannot dump the carbide inside the cave. Spent carbide is damaging to the cave environment. You will need a "dump bag" and a blunt stick (like a popsicle stick) to scoop out the lamp bottom. When clearing the bottom of your lamp of spent carbide do not blow into the lamp bottom! This can cause the dust to fly out of the bottom, and into your face and eyes. If spent carbide gets into your eyes, you must flush your eyes thoroughly and consult a doctor immediately. Also, if you feel the need to tap the lamp to free up the spent carbide, never tap or strike the threads. If you bend your threads, then the lamp bottom may be finished. Never use a knife or any acute object to scrape out a lamp bottom. If you puncture the brass, you will need to do a "field patch" in order to make it back out of the cave.
Many cavers believe that a dump bag should NOT be airtight. Though some cavers have opted to use Ziploc bags to store spent carbide, they generally have done a thorough job of getting as much use of their carbide as possible. Even spent carbide will continue to emit some gas. Therefore, that gas will need to escape. However, you do not want the spent carbide to escape either. Furthermore, spent carbide is caustic, so you will need to select a proper dump bag. Neophytes have discovered that a paper bag will not last long as a dump bag, and that cleaning up spent carbide is a hassle. Cavers have tried various methods of storing spent carbide. You can use the bottom corner of a military MRE (meal ready to eat) bag kept closed with a "chip clip." (The disadvantage to this is having to eat the MRE.) You may decide to use two bread bags, one rolled up inside the other. However, there are as many methods of storing spent carbide as there are cavers. It may be beneficial to ask members of your grotto what they use. Whichever method you use, it would probably be best if you carried your dump bag high in your pack. This is partly for the sake of convenience when you need a new charge of carbide, and partially because of the gas that is constantly being emitted.
If carbide lamps ran perfectly 100% of the time, you would only need your lamp, water, and carbide. However, these lamps have earned the reputation of being the most finicky and temperamental lights on the face of the earth. And they have earned the reputation well. For anything that can go wrong with your light you should bring that spare part with you. Many people have different versions of a "necessities" list. Some of the more modest include a dry felt, an extra tip, and a spare flint. Some of the more inclusive extend to even including felt clips, entire striker assemblies, wing nuts, gaskets, and multiple tips. A list somewhere in between is probably sufficient and safe, but it is a matter of preference. The reality of the situation is that felts may get wet, you may loose a tip, flints will get wet, and gaskets get worn and finally give out at the most inconvenient moments. (And when gaskets give out, they have a habit of leaking acetylene and producing a ball of flame.) Just remember to plan for what can go wrong.
Another bit of equipment that must come along with every carbide trip is a tip cleaner or reamer. Tips commonly become clogged with debris or impurities. Hence, tip cleaners were invented. A tip cleaner is a small cylinder with several small wires that can be extended from or retracted into the cylinder. Remove the tip, and push one wire into the tip. Hopefully, this will have dislodged the obstruction. Tip reamers are also sold. A reamer is a small tapered piece of metal that can likewise be used to dislodge debris. Repeated cleanings will cause the tip hole to become much larger. Thus, the tip will need to be replaced eventually. This is a fact of carbide life. However, a tip reamer will widen the tip's orifice much more quickly than a wire-type tip cleaner. This may be advantageous in a few rare occasions, but generally it limits the life span of the tip. A further disadvantage of the reamer is that they have been known to break inside the tip. This creates an obstruction that you are unlikely to remove in the cave.
Also, in order to conduct necessary repairs on the lamp, you must carry a pair of needle nose pliers. In order to unscrew hex nuts, to remove/replace hot tips, and to perform other necessary unpleasantries, some sort of tool is necessary.
Now, your total packing list should look something like this:
Miscellaneous words of advice
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