Claims
- 1. A method for controlling internal air pressure within a tubular thermoplastic film bubble which comprises initially inflating said bubble with air under pressure until a desired internal pressure is achieved, continuously sensing and monitoring said internal pressure by means of a pressure sensor device in communication with the interior of said bubble, said pressure sensor device continuously sending a signal to a pressure control device, and when said pressure falls below a preselected level actuating an air pressure input valve, said valve being in communication with said control device, a source of air under pressure and the interior of said bubble, whereby makeup air pressure is added to said bubble, and when said air pressure within said bubble is above a pre-selected level, said air pressure is immediately reduced through an exhaust valve in direct communication with said bubble, said exhaust valve being pressure-actuated; and said exhaust valve being responsive to small incremental pressure variations as well as sudden surges of high pressure.
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a continuation-in-part of U.S. application Ser. No. 501,118 filed Aug. 28, 1974, now abandoned.
US Referenced Citations (8)
Foreign Referenced Citations (2)
Number |
Date |
Country |
917,033 |
Aug 1954 |
DT |
1,087,720 |
Oct 1967 |
UK |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
501118 |
Aug 1974 |
|