Sunday, September 08, 2013

Oxygen Concentrator - NIDEK NUVO-8 - TROUBLESHOOTING - Low product pressure - High product pressure - General troubleshooting.

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.
  • Set the I/0 (ON/OFF) switch to the 0 (OFF) position, and unplug the power cord.
  • Remove the cabinet rear.
  • Remove the air supply tubing going to the control valve and install the test port T-fitting. Figures shows the normal operating configuration for the unit. and the installation of the test ports.
  • 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 8 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 40 psig (275 kPa). The minimum reading should not be less than 13 psig (90 kPa).
NOTE When you turn the unit on, it will take several minutes to reach normal operating pressures.
High Operating Air Pressure (P1)
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.
  • Contaminated sieve beds. Change the sieve beds.
Low Operating Air Pressure (P1)
Lower than normal operating pressure may indicate any of the following:
  • A restriction in the suction resonator or air intake filter, this 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 listed.
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 plug from the T-fitting atop the valve and install the test port tubing (1/4” OD tubing is required). Figure 1 above  shows the normal operating configuration for each unit. Figure 2 shows the installation of the test port tubing.
  • Connect a pressure test gauge to the P2 test port tubing.
  • Plug in the power cord, and set the I/0 (ON/OFF) power switch to the ON position. Set the flow meter to 8 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 40 psig (275kPa). The minimum reading should not be less than 13 psig (90 kPa).
Low Product Pressure (P2)
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 listed.
High Product Pressure (P2)
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.
  • Check exhaust muffler for any restrictions
  • Contaminated sieve beds. Change the sieve beds.
GENERAL TROUBLESHOOTING
Before reviewing the troubleshooting chart, the following steps may be useful to isolate any malfunctions:
  • Turn the concentrator on. If unit does not turn on, refer to troubleshooting chart.
  • Make sure all filters are clean.
  • Turn flow meter completely open, up to the highest setting. The ball should rest at the top of the scale. If setting is not greater than 8.5 l/min, adjust regulator so that the ball level exceeds 8.5 l/min with the flow meter completely open.
  • Connect test pressure gauge to the outlet fitting of the unit. The pressure should read approximately 17 psig (117 kPa).
  • Connect test pressure gauge to the P1 test port on the valve inlet. The pressure should be cycling between approximately 13 and 40 psig (90 and 275 kPa).
  • Make sure the unit is cycling properly by observing the pressure gauge cycle between a high and a low pressure. If the unit is not cycling properly, refer to troubleshooting chart.
  • Make sure that the unit is leak free by testing all tubing connections and fittings with leak testing solution. Protect circuit board from solution and start leak test at the compressor outlet, following the air flow through the unit to the oxygen outlet. Repair all leaks by tightening connections and fittings.
  • Set the concentrator at 8 l/min and connect pressure test gauge to P2 at the top of the sieve module. Determine pressure parameters by observing high and low pressure points on the gauge. It should cycle between approximately 13 psig and 40 psig (90 to 275 kPa). If pressures are high or low, refer to the troubleshooting chart.
  • Review troubleshooting chart to isolate and repair any other malfunctions.
The following diagnostic flow chart will help to isolate potential problems.

Click on the chart to Zoom.  Click ß at the top left of the browser to return.