Gather your supplies. This works best if you have everything at hand, ready to go.
Clean the mason jars by running them through the dishwasher or washing with hot, soapy water. Rinse and drain on a drying rack.
Wash the beans, then snap off the ends and break them into bite-size pieces (about 1-inch pieces). Set them aside.
Place the rings and lids in a small saucepan and cover with water. Set the stovetop to low heat and bring the water with the rings/lids to a light simmer or steaming. Allow this to steam/simmer for 10 minutes. Don't bring it to a full boil.
Set a large pot of water on the stove to boil over medium high heat. This will be to fill the mason jars so you can gauge how much you'll need based on how many green beans you have.
Cold pack the green beans, which means you simply pack the clean, warm mason jars with green beans. Leave about 1-inch headspace at the top of the jar. Fill all of the jars, whether pints or quarts, until the green beans are all in jars.
Sprinkle 1 teaspoon of canning salt over the beans in the quart jars. Use 1/2 teaspoon canning salt over the pint jars.
Once the jars are full of green beans, use the funnel to carefully pour the boiling hot water (be very careful!) over the green beans just until the beans are covered. (Remember that there should be 1-inch headspace at the top of the jar.) Use a butter knife to stick down into the jar to remove air bubbles if needed.
Use a clean towel or paper towel to dry the rim of the jars.Then take the hot lids/rings and place on of each on top, place the lid on the jar and tighten the ring around it.
Pressure cook the jars.
It's important to read and follow the instructions for the pressure canner that you have as each one might be slightly different. Place the canner rack in the canner and fill the canner with water up to the line indicated. There isn't much water needed. Ours is just a few inches.
Place the canner on the largest burner. Set the stovetop to medium-high heat. You want to process quart jars and pint jars separately since they take different amounts of time to process.
Place the jars (ours takes up to 7 quarts and 10 pints) in the canner. Place the lid on the pressure cooker and lock it into place. Leave the weighted gauge off for right now.
Let the water boil inside until you see steam starting to come out of the steam spout. Once this happens, place the weighted gauge on the steam spout. At this time, the canner will start to pressurize.
Allow the pressure to rise until the dial gets to 10 pounds of pressure. At that point, set the timer for 25 minutes for quarts and 20 minutes for pints. While the beans are processing, watch the pressure dial gauge closely. If it starts to rise above 10 pounds, lower the heat. If it starts to drop below 10 pounds, raise the heat. Keep it as close to 10 pounds as possible for the time interval needed.
Once the time is up, turn off the heat, and allow the pressure to come to zero. Don't touch the canner before that.
Once the gauge is reading zero, take off the weighted gauge and then loosen the lid to open the canner. Do this carefully and keep your face away from it because there may be steam trapped.
Use the jar lifters to lift each jar out of the canner. Be careful...they will be very hot!
Place them on a wire rack to cool completely. You may hear the jars "pop" which means they are sealing.
Allow the jars to cool completely, then check to make sure they are sealed.