NIDEK MARK-5 - NUVO M5C5 OXYGEN CONCENTRATOR - TROUBLESHOOTING - Medical Equipment
Capacitor Replacement.
The capacitor helps the compressor to start and run more
efficiently. If the compressor cannot start, the capacitor may be defective and
require replacement. The capacitor
should be replaced at each compressor service / module replacement. To replace
the capacitor, take the following steps:
- Set the unit’s I/0 (ON/OFF) switch to the 0 (OFF) position, and unplug the power cord.
- Remove the rear and front cabinets.
- Disconnect the two leads to the capacitor and remove the nut from the mounting screw.
- Remove the nut and washer below the capacitor.
- To install the new capacitor, connect the leads and replace the capacitor and associated hardware.
The Mark5 Nuvo uses a gear motor powered rotary cam-operated
puppet valve assembly to control the air separation process. There is a feed
port that connects to the air tank and an exhaust port that connects to the
exhaust muffler. There are three possible valve states as follows:
- Air feed connected to sieve bed A and exhaust connected to sieve bed B.
- Air feed connected to sieve bed B and exhaust connected to sieve bed A.
- Both ports closed; this is a very short time period during which air pressure builds in the air tank. The control valve of the Mark5 Nuvo unit requires no scheduled maintenance. If a valve does not function as required, it is best to replace the complete sieve module as it is probable that one or both of the beds has been damaged.
SIEVE BED REMOVAL
Do not expose molecular sieve (contents of bed) to air for
an extended period of time. Prolonged exposure of molecular sieve to the
moisture in room air results in contamination and permanent damage to the sieve
material. Keep all openings to the sieve beds sealed during periods of storage.
If replacement is necessary, you must replace both sieve
beds at the same time. It is recommended to replace the sieve beds and control
valve module as a complete assembly.
- Set the unit’s I/0 (ON/OFF) switch to the 0 (OFF) position and unplug the power cord.
- Remove the cabinet back.
- Disconnect the 1/4-inch product tube from the top of one of the beds.
- Remove the 4 tie-wraps ( 2 from each sieve bed ). Note their position and orientation.
- Remove two “Z” brackets; one from the top of each of the sieve beds.
- Lift the module up and out of the base plate cradle.
- Unplug the valve gear motor electrical leads at the in-line connections.
- Manipulate the module so that the black exhaust hose can be removed from the fitting on the valve.
- Loosen the hose clamp and remove the black feed hose from the fitting on the valve.
To install the sieve beds, follow the sieve bed removal
procedure in reverse order. It is very important to tighten all tubes to
eliminate leaks. However, do not over tighten.
To check for leaks, take the following steps:
- Plug in the unit.
- Set the unit’s I/0 (ON/OFF) switch to I (ON) for three minutes with the flow meter closed to pressurize the system.
- Apply soapy water around the hose connections at the valve and the air tank; check for leaks.
NOTE: Even small
leaks can affect concentrator performance and can cause contamination of the
sieve. Careful leak testing is important.
TROUBLESHOOTING
Air Pressure Test (P1)
Testing the operating pressure is a useful diagnostic tool
when a concentrator has low purity and requires servicing. Units functioning
normally do not require operating tests.
Use the following procedure to test the operating pressure of the unit.
- Set the I/0 (ON/OFF) switch to the 0 (OFF) position, and unplug the power cord.
- Remove the cabinet rear.
- Remove the test port plug at the top of the air tank.
- Connect the pressure test gauge to the test port.
- Plug in the power cord, and set the I/0 (ON/OFF) power switch to the ON position. Set the flow meter to 5 l/min, and allow the unit to run at least five minutes.
- Observe the maximum and minimum readings on the pressure test gauge.
- The maximum reading should not exceed 34 psig (235 kPa). The minimum reading should not be less than 16 psig (110 kPa).
Higher than normal operating pressure may indicate any of
the following:
► A restrictive exhaust
muffler, which does not allow the waste
(purge) gas to exit the system freely.
Operate the unit with the exhaust muffler disconnected to see if the operating
pressure returns to normal.
► An improperly operating
control valve, confirm that the control valve is turning at 4 rpm. Time the
exhaust pulse at 7.5 seconds.
► Contaminated sieve beds. Change the sieve beds.
Lower than normal operating pressure may indicate any of the
following:
► A restriction
in the suction resonator or
inlet air filter,
which limits the amount of room air available to the
compressor. Disconnect the suction tube at the compressor, and allow the unit
to operate without the suction resonator to see if normal operating pressure
returns.
► An improperly
operating control valve. Confirm that the control valve does not have a leak.
► A leak
in the unit, which allows
system pressure to
escape. Leak test
the unit.
► A compressor with
reduced output. Ensure that the
concentration level at the desired liter flow is within specifications
Product Pressure Test (P2)
Testing the product pressure is a useful diagnostic tool
when a concentrator has low purity and requires servicing. Units functioning
normally do not require operating tests.
Use the following procedure to test the product pressure of the unit.
- Set the I/0 (ON/OFF) switch to the 0 (OFF) position, and unplug the power cord.
- Remove the cabinet rear.
- Remove the test port plug from the tee at the top of the sieve bed.
- Connect the pressure test gauge to the P2 test port.
- Plug in the power cord, and set the I/0 (ON/OFF) power switch to the ON position. Set the flow meter to 5 l/min, and allow the unit to run at least five minutes.
- Observe the maximum and minimum readings on the pressure test gauge. The maximum reading should not exceed 16 psig (110 kPa). The minimum reading should not be less than 9 psig (62 kPa).
Lower than normal operating pressure may indicate any of the
following:
► An inlet
air filter that
limits the amount
of room air
available to the compressor. Disconnect the suction tube
at the compressor, and allow the unit to operate without the suction resonator
to see if normal operating pressure returns.
► An improperly
operating control valve. Confirm that the control valve does not have a leak.
► A leak
in the unit, which allows
system pressure to
escape. Leak test the unit.
► A compressor with
reduced output. Ensure that the
concentration level at the desired liter flow is within specifications.
High Product Pressure
Higher than normal operating pressure may indicate any of
the following:
► A restrictive exhaust
muffler, which does not allow the waste
(purge) gas to exit the system freely.
► Operate the unit with the exhaust muffler disconnected to
see if the operating pressure returns to normal.
► Check exhaust muffler and hoses for any restrictions.
► An improperly operating control valve, confirm that the
control valve is turning at 4 rpm. Time the exhaust pulse at 7.5 seconds.
► Contaminated sieve beds. Change the sieve beds.
