I was going to call this Instructable emergency tubing connections with string. But I now use this method often, even when not an emergency situation. It works when you need to connect any small flexible hose to copper tubing or metal pipe, and do not have hose clamps or barbed fittings.
Step 1: Materials
Assuming that you already have a rubber or vinyl hose, and a metal tube you need to connect it to, you will need:
String. Best is fine nylon cord, but it just needs to be strong. Several feet (a meter or so) long.
Tools: A knife or scissors.
Step 2: Optional step - If using copper tube, flare the end just a bit.
Copper is soft, you can flare the end out slightly with needle nose pliers, a nail set, or a center punch.
Step 3: Make the first wrap
Wrap the string around twice, make a simple knot , and pull it tight.
Step 4: Make second wrap
Making sure the first wrap stays tight, take another wrap and a half with the two ends and tie a knot (it will be at the bottom this time) and again pull tight. It helps to grasp the ends with a tool to get a good grip.
Step 5: Third wrap
Now take another wrap and a half, pull tight, and make a final double knot. This knot will be on top.
Step 6: This won't come apart
Each successive wrap increases compression considerably. If you later cut the string loose, you will see the the deep imprint of the string and it will be obvious how tight the connection was.