Figure 4-9. Test of high pressure cut-out switch

TM 5-4120-356-14

TEST

REFER TO FIGURE 4-8 FOR PRELIMINARY STEPS.

CONNECT A CIRCUIT TESTER ACROSS THE ELECTRICAL CONTACTS OF THE HIGH PRESSURE CUT-

OUT SWITCH.

SET THE CIRCUIT TESTER UP FOR CONTINUITY TESTING.

CONNECT A SOURCE OF VAPORIZED NITROGEN TO THE CAPILLARY TUBE FITTING. NITROGEN

SOURCE MUST BE EQUIPPED WITH A GAGE CALIBRATED FROM 0 TO 1000 PSIG (0 TO 100

ks/cm 2).

5. WHILE OBSERVING CIRCUIT TESTER, APPLY 415 PSIG (29 ks/cm2) NITROGEN PRESSURE TO

THE SWITCH. CIRCUIT TESTER SHOULD SHOW CONTINUITY BETWEEN THE ELECTRICAL CONTACTS

OF THE SWITCH.

6. WHILE OBSERVING CIRCUIT TESTER, SLOWLY INCREASE NITROGEN PRESSURE TO THE SWITCH.

SWITCH SHOULD TRIP (CIRCUIT TESTER SHOWS A BREAK IN CONTINUITY) WHEN NITROGEN

PRESSURE REACHES 450 TO 470 PSIG (31.6 TO 33 ks/cm2 ).

IF SWITCH DOES NOT TRIP AT ANY PRESSURE UP TO 550 PSIG (38.6 ks/cm2), REPLACE

THE SWITCH.

IF SWITCH TRIPS BETWEEN 450 AND 470 PSIG (31.6 TO 33ks/cm2) , DECREASE PRESSURE

TO 410 PSIG (48.8 ks/cm2) AND PUSH THE RESET BUTTON. CIRCUIT TESTER SHOULD AGAIN

SHOW CONTINUITY BETWEEN THE ELECTRICAL CONTACTS OF THE SWITCH.

9. IF THE SWITCH TRIPS BELOW 450 PSIG (31.6 ks/cm2) OR ABOVE 470 PSIG (33 ks/cm2),

THE SWITCH MUST BE CALIBRATED. TURNING THE CALIBRATION SCREW CLOCKWISE INCREASES

THE PRESSURE AT WHICH THE SWITCH WILL TRIP. TURNING THE CALIBRATION SCREW COUNTER-

CLOCKWISE DECREASES THE PRESSURE AT WHICH THE SWITCH WILL TRIP. CALIBRATE THE

SWITCH TO TRIP AT 460 PSIG (32.3 ks/cm2).

IF SWITCH CANNOT BE CALIBRATED AT 460 10 PSIG (32.3 ks/cm2), REPLACE SWITCH.

10.

DISCONNECT THE CIRCUIT TESTER LEADS FROM THE SWITCH CONTACTS AND DISCONNECT THE

11.

NITROGEN SOURCE FROM THE SWITCH CAPILLARY TUBE .

REFER TO PARAGRAPH 4-13a FOR FINAL STEPS IN MAINTENANCE OF THE HIGH PRESSURE

12.

CUT-OUT SWITCH.

TS5-4120-356-14/49

F i g u r e 4-9. Test of high pressure cut-out switch