PURPOSE: To surely check the clogging condition of an air filter by measuring a change of differential pressure between front and rear of a pressurizing valve by a differential pressure instrument with contact point with time passage and checking it by a sequencer.
CONSTITUTION: At the time of pressurizing, air supplied from an air source 4 is introduced into a holding furnace 2 through the pressurizing value 7 and a pressurizing air filter 8, to rise the pressure. And the differential pressure between front and rear of the pressurizing valve 7 is measured by the differential pressure instrument 13 with contact point with time passage, to input to the sequencer 16. In this case, at the time of the setting value of a contact point indication 13a for pressurizing time or at excess time of this, what is within the quality control limit, is read by the sequencer 16 and an alarm lamp 18 and an alarm buzzer 19 are not worked, and then it is checked that the pressurizing air filter 8 is under normal condition. At the time of developing clogging in the pressurizing air filter 8, what is reached to the quality control limit at shorter time than setting value of the contact point indication 13a for pressurizing time, is read by the sequencer 16 and the alarm lamp 18 and the alarm buzzer 19 are worked, and then it is checked that the pressurizing air filter 8 is developed to the clogging of the filter, to know the exchanging time.
SASAKI HIROSHI
YAEGASHI AKIO
ISHIKAWA MASAAKI
