| A knife is an essential piece of safety equipment | | | | all the cylinders are filled to approximately the same |
| used primarily to cut guidelines, free entanglements, | | | | air pressure (but not less than 2000 psig prior to |
| and repair damaged lines. Since the knife is used to | | | | beginning a dive). |
| cut guidelines, a small sharp knife mounted on the | | | | By following the above recommendations, air planning |
| forearm where it is easy to reach is more valuable | | | | for the dive is considerably simplified. Diving cylinders |
| than a larger knife worn on the leg. If you already | | | | are usually fitted either with a K-valve,which has no |
| use a large knife then it should be worn where it will | | | | reserve, or a J-valve, which maintains a small reserve |
| not easily get tangled. Wearing the knife inside a | | | | air supply. However, the amount of air reserve |
| custom suit pocket designed to hold it is preferable. | | | | provided by a J-valve is inadequate for safe cavern |
| Alternative sites include the BC hose, tank waist | | | | diving. Instead you should rely on your pressure |
| strap, or shoulder. The outside of your leg is the | | | | gauge to make sure that you have sufficient air to |
| least desirable location for your knife. | | | | safely exit the cavern and to deal with any |
| Some divers prefer to carry two knives which are | | | | emergency that may develop. If you are equipped |
| mounted so that they can reach one with either | | | | with a J-valve, then the valve should be placed in the |
| hand in the event that the other is occupied. While | | | | activated position, not the reserve position. Some |
| most divers use either a single 71.2- or 80-cubic-foot | | | | care is necessary to insure that the Jvalve |
| tank, cavern divers have used most all types and | | | | mechanism is secured to avoid creating a potential |
| sizes of tanks successfully. For reasons which will | | | | line trap. Most cavern divers find that duct tape |
| become clear later, it is best that all dive team | | | | wrapped around the valve is adequate. |
| members use the same size scuba cylinder and that | | | | |