NONINSULATED TERMINAL AND SPLICE INSULATION
When noninsulated terminals and splices are used, some form of insulation must be used to cover the bare conductor. The two most common forms of insulator used for terminals and splices are transparent tubing (commonly called spaghetti) and heat-shrinkable tubing. If spaghetti is used, it must be tied with lacing twine, as illustrated in figure 2-13. Heat-shrinkable tubing is shrunk to the desirable size by applying dry heat. It is also a good way to insulate terminals and splices, as illustrated in figure 2-14. This tubing shrinks to approximately one-half its original diameter when heated with an electrical hot-air gun (figure 2-15). Here are the steps for using the hot-air gun:
Figure 2-13. - Spaghetti tied with lacing twine.
Figure 2-14. - Shrunken sleeve.
Figure 2-15. - Typical hot-air gun.
Hold the heat source 4 to 5 inches away from the wire. Apply a heat of 275°F to 300°F for about 30 seconds. Rotate the wire while applying the heat so that the heat is evenly distributed.
Do not apply heat higher than 300°F as this may damage the wire. Do not continue to apply heat after the tubing has shrunk onto the wire. Further application of heat will not cause additional shrinkage of the tubing.
COMPRESSED AIR/NITROGEN HEATING TOOL
The compressed air/nitrogen heating tool (figure 2-16) is a new tool in the fleet and was designed as a portable source of heat. This tool is safe for use around fueled aircraft because an open heating element is not required. The compressed air/nitrogen heating tool can be used on heat-shrinkable tubing.
Figure 2-16. - Compressed air/nitrogen heating tool.
Table 2-1. - Compressed Air/Nitrogen Heating Tool Power Requirements
Refer to the operator's manual for safe operating procedures for the compressed air/nitrogen heating tool. A brief summary of these procedures follows:
Push down and fully turn the air regulator knob counterclockwise. This is to ensure that the air regulator is off. Remove the dust cap from the air inlet nipple. The inlet nipple is what we connect the air or nitrogen source line to.
If nitrogen is used, make sure that you are in a well-ventilateed area. Using nitrogen is a poorly ventilated area. Using nitrogen is a poorly ventilated area can result in suffocation.
As noted in table 2-1, the compressed air/nitrogen source CANNOT be greater than 200 psig.
Set the power switch to the ON position. The power lamp and heated-air-on lamp will both illuminate. (If the lights do not come on, check the switch on the gun handle. The switch must be positioned toward the front of the handle.) There is a 1-minute warm-up time. During this warm-up period, ensure that the indicated air pressure increases to 10 to 15 psig on the air-pressure gauge. You can now adjust the temperature control knob to the desired temperature setting. You can turn the air/nitrogen pressure off and on to the gun without powering down the module by using the switch mounted on the gun handle.
After you complete your task with the compressed air/nitrogen heating tool, use the following shutdown procedures:
Noninsulated Copper Terminals
The procedure for crimping a copper terminal (noninsulated) to a copper wire is as follows:
Q.11 What is a major advantage of the crimped terminal over the soldered terminal?