1. Wash jars, lids and bands in hot, soapy water and rinse thoroughly in hot water. Dry bands, set aside. Heat lids in a saucepan of hot water, but do not boil.
2. String and break beans into 1-inch pieces. Wash beans in a pan or sink through 3 changes of water. Lift beans up out of water.
3. Precook beans 5 minutes in boiling water to cover.
4. Pack beans tightly into 7 hot quart jars to within 1/2 inch of top. Add 1 teaspoon canning salt. Cover with boiling water in which beans have been precooked, leaving 1/2 inch space at top of jar. Wipe jar rims clean. Cover jars with hot lids and screw bands on the jars.
5. Pour 2 quarts of boiling water into 7-quart pressure canner, with canner basket in place.
6. Place 7 quart jars upright into hot canner.
7. Place cover on canner and lock securely.
8. Adjust burner to maximum heat. When steam flows freely from the vent pipe, reduce heat to maintain a moderate steam flow. Allow steam to flow for seven to ten minutes to eliminate all of the air from canner and jars.
9. Place pressure regulator on vent pipe. The automatic air vent will rise and seal the canner.
10. Use maximum heat to raise pressure to 10 lbs., then lower heat to maintain 10 lbs. pressure for 25 minutes. Raise or lower heat to prevent fluctuations in pressure. WATCH CLOSELY.
11. After 25 minutes, remove canner from burner. Allow pressure to return to zero at its own accord. When the automatic air vent has dropped, remove pressure regulator from vent pipe. Let canner cool for 1 to 2 minutes and carefully remove cover and jars.
Let jars cool 12 to 24 hours and then test for a seal by pressing the center of the lid. If the lid does not flex up and down, it is sealed. Remove bands. Wipe jars and lids with a clean damp cloth. Label and store jars in a cool, dry, dark place.