Huntleigh AlphaBed, Service Manual

Page: 78 / 94

Low Pressure Indicator Test (Mechanical Units Only)
1.5 With the test equipment set up as in Section 1.1, set the pressure control knob in the mid
position and use the flowmeter valve to adjust the pressure slowly up and down.
1.6 Observe the LOW PRESSURE warning light to indicate the operation of the Micro switch.
1.7 The micro switch should activate at or before the pressure reaches 5 mmHg descending and
deactivate at or before the pressure reaches 20 mmHg ascending.
Low Pressure Indicator Test (Electronic units only)
WARNING
DANGER OF ELECTRIC SHOCK. DURING THE FOLLOWING TESTS, LIVE
TERMINALS AND CONDUCTORS MAY BE EXPOSED. EXERCISE EXTREME
CAUTION.
Note: Pump units fitted with an alarm monitoring PCB should have the low pressure alarm
settings tested within 60 seconds of switching the pump on.
1.8 Remove the rear case assembly (Refer to Chap 3, Section 6).
1.8.1 Fit snap-lock connectors to both outlet ports. Connect the pressure gauge and a
bleed valve to the duty port.
1.8.2 Connect a buzzer or LED to the microswitch terminals to indicate microswitch
operation (see Chap 4, Fig 24 for microswitch terminal connections).
1.8.3 Ensure that the bleed valve is fully closed, Ensure that the low pressure adjustment
screw (on the upper flap) is fully disengaged. Turn the arbour clockwise and
counter-clockwise over the full range three or four times. Leave it in the fully
counter-clockwise position.
1.8.4 Turn the pressure control knob until the indicated pressure is 50 mmHg (maximum
setting for Aura models only).
1.8.5 Open the bleed valve to induce a leak, until the pressure is 10 mmHg (60 mmHg for
Aura models only).
1.8.6 The microswitch should activate before the pressure reaches X mmHg descending
and deactivate before the pressure reaches Y mmHg ascending, as specified in
Table 34.
1.8.7 Set the low pressure adjustment screw so that the microswitch activates at this set
level. Do this very slowly. Adjust the pressure up and down by means of the bleed
valve and verify that the microswitch goes on and off accordingly.
1.8.8 Replace the rear cover (Refer to Chap 3, Section 7).
Chap 5 Issue 2
Page 4 SER0004 Nov 2001
Testing Mini Pump Service Manual