| 摘要 |
<p>A device to indicate the build-up of blockage in a filter unit or initiate an automatic cleaning or replacement operation comprises a flexible diaphragm (1) supporting a circuit contact (6) held against a complementary contact by a spring (9) until a build-up of back-pressure on the diaphragm from within the unit, in response to a developing blockage is sufficient to overcome the spring and open the circuit, thus initiating a parallel alarm or other response circuit.</p> |
