Nidek Nuvo 8 Service manual

Nidek Medical Products, Inc
Nuvo 8 Oxygen Concentrator

Service Manual

Nidek Medical Products, Inc. 3949 Valley East Industrial Drive

Birmingham, Alabama 35217 USA

Telephone: [phone] • 24-Hour Fax: [phone]

Table of Contents

General Safety

Instructions

Section 1.0

Introduction

1.1

1.2

1.3

Section 2.0

Operational Check and Concentration Test

2.1

Section 3.0

Patient Instructions

3.1

Section 4.0

Home Service Provider Maintenance

4.1

4.2

Section 5.0

Service

5.1

5.2

2-4

Production and Use of Oxygen 5
Use and Maintenance of the Device 5
Standards and Regulations 5-6

Home Service Provider Responsibility 6-7
Important Notice and Symbol Explanations 7
Functional Specifications 8

2.2

2.3

2.4

3.2

Description of Operation
Operation Check
Alarm System

2.3.1 Battery Test

2.3.2 Power Failure Alarm test
Oxygen Concentration Test and Specification

General Instructions
Routine Maintenance by the Patient

3.2.1 Cleaning the Cabinet Air Filter

3.2.2 Checking the Alarm System Battery

Routine Maintenance 12

4.1.1 Cabinet Air Filter 12

4.1.2 Final Product Filter Replacement 12

4.1.3 Inlet Air Filter Replacement 13

4.1.4 Battery Replacement 13

4.1.5 Recording Maintenance 13
Cleaning and Infection Control 13-14

4.2.1 Preparing for New Patient Use 14

10
10

10-11

11
11
11
12

8
9
9

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Components 14-15
Cabinet Removal 15

5.2.1 Removing Cabinet Back 15

5.2.2 Removing Cabinet Front 15

5.2.3 Removing Control Panel 15

5.2.4 Main Structure 15

5.2.5 Caster Replacement 15

5.3

Compressor 15

5.4

5.5

5.6

5.7

5.8

5.9

5.10

5.11

5.12

5.13

5.14

5.15

6.1

6.2

6.3

6.4

6.5

5.3.1 Compressor Replacement 15-16

5.3.2 Capacitor Replacement 17
Process Control Valve 17

Sieve Module Replacement 18

5.5.1 Sieve Module Removal 28

5.5.2 Sieve Module Installation 18
Cabinet Fan Replacement 19
Circuit Board Replacement 19-20

5.7.1 Circuit Board Removal 20

5.7.2 Circuit Board Installation 20

5.7.3 Timing Board Removal 20

5.7.4 Timing Board Installation 21
Product Regulator Check and Setting 21

5.8.1 Product regulator cleaning or rebuilding 21
Pressure Switch Replacement 22
Circuit Breaker Replacement 22

5.10.1 Circuit Breaker Removal 22

5.10.2 Circuit Breaker Installation 22
I/0 (ON/OFF) Power Switch Replacement 22

5.11.1 I/0 (ON/OFF) Power Switch Removal 22

5.11.2 I/0 (ON/OFF) Power Switch Installation 23
Buzzer Replacement 23
Hour Meter Replacement 23
Flow Meter Replacement 23

5.14.1 Flow Meter Removal 23

5.14.2 Flow Meter Installation 23
Power Cord Replacement 23-24

Section 6.0

Troubleshooting

Air Pressure Test (P1) 24-25

6.1.1 High Air Pressure 26

6.1.2 Low Air Pressure 26
Product Pressure Test (P2) 26-27

6.2.1 High Product Pressure 27

6.2.2 Low Product Pressure 27
General Troubleshooting 27-29
Troubleshooting Chart 30-32
Tool Kit and Pressure Test Gauge 33

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Appendices

Exploded

Drawings

A-1: Pneumatic Flow Chart 34
A-2: Electrical Schematic, 230 Volt Unit 35

A-3: Electrical Schematic, 115 Volt Unit 36
A-4: Base Assembly 37
A-5: Main Structure Assembly Front View
A-5.1: Main Structure Assembly Rear View
A-6: Regulator Assembly 40
A-7: Compressor Assembly, 115 Volt Unit 41
A-7.1: Compressor Assembly, 230 Volt Unit 42
A-8: Control Panel Assembly; Front View 43
A-8.1: Control Panel Assembly; Rear View 44
A-9: Front Cabinet Assembly 45
A-10: Rear Cabinet Assembly 46
A-11: Module Assembly 47
A-12: Maintenance Log 48-49

38
39

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General Safety Instructions

Production and use of oxygen

Oxygen is not a flammable gas, but accelerates the combustion of materials. To
prevent fire risks, the Nuvo 8 should be kept away from flames, incandescent
sources or sources of heat (cigarettes) and combustible products such as oil,
grease, solvents, aerosols, etc.

Do not use in an explosive atmosphere.
Prevent oxygen from accumulating on upholstered seats or any other fabric. If the

concentrator operates without being administered to a patient, locate it so that the
flow of gas generated is dissipated into the air.

Locate the equipment in a free space (filter to the rear and below) which is well
ventilated and free of fumes or atmospheric pollution.

Use and Maintenance of the Device

Use the electric cable provided and check that the voltage of the mains socket used
complies with the electrical characteristics of the appliance indicated on the
manufacturers plate on the rear of the appliance.

Do not use an extension cord or multiple sockets which can create sparks and
therefore pose a fire risk.

Use of the Nuvo 8 must be restricted solely to oxygen therapy on medical
prescription in compliance with the daily rate and duration.

Use in other circumstances may represent a hazard to patient health.
Do not use in a specifically magnetic environment (MRI, etc.).

The Nuvo 8 has an audible alarm intended to warn the user of any problems. The
user must determine the maximum distance away from the Nuvo 8based on the

sound levels in the environment, to ensure that the alarm is always audible.

Standards & Regulations
In compliance with UL60601-1 [EN60601-1] (para 6.82.b):

“The manufacturer, assembler, installer or importer are not considered to be
responsible for consequences or the safety, reliability and characteristics of a
device unless,

● the assembly, extensions, adjustments modifications or repairs have been

performed by persons authorized by the manufacturer,

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● the electrical installation of the corresponding premises complies with

appropriate regulations and codes,

● the device is used in accordance with the instructions for its use.

If the replacement parts used for periodic servicing by an approved technician do
not comply with the manufacturer’s specifications, the manufacturer is absolved of
all liability in the event of an incident.

Do not open the equipment when it is powered on: risk of electrocution.

This device complies with the requirements of the FDA Quality System Regulation
and EU Directive 93/42/EEC, but its operation may be affected by the use in the
surrounding area of appliances such as diathermy, high frequency electro-surgical
instruments, defibrillators, short wave treatment appliances, cell-phones, CB
devices and other portables, microwave ovens, induction hot plates or remote
control toys, and more generally, by electromagnetic interference exceeding the
levels specified in standard IEC(EN) 60601-1-2.

1.0 Introduction

1.1 Home Service Provider Responsibility

All Home Service Providers of the Nidek Medical Nuvo 8 Oxygen Concentrator must
assume responsibilities for handling, operational check-out, patient instruction, and
maintenance. These responsibilities are outlined below and throughout this manual.

WARNING
Nuvo 8 units must not be used for or with any life-supporting or life sustaining

applications. Patients unable to communicate discomfort while using this device
may require additional monitoring. Advise patients to immediately notify their Home
Service Provider(s) and/or physician(s) in case of an alarm or any discomfort.

As a Home Service Provider, you must do all of the following:

● Inspect the condition of each Nuvo 8 unit immediately upon delivery to
your business location. Note any sign of damage, external or internal, on
the delivery receipt, and report it directly to both the freight company and
Nidek Medical Products, Inc. immediately.

● Check the operation of each Nuvo 8 before delivery to a patient. Always
operate the unit for a reasonable length of time and check that the oxygen
concentration level is within specifications as referred to in Section 2.4.
Test the battery and power disconnect alarm as described in Section 2.3
of this manual.

● Deliver Nuvo 8 units only to patients authorized by a physician’s
prescription. The Nuvo 8 must not be used as a life-supporting or life
sustaining device. A backup supply of oxygen must be available.

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● Instruct patients how to use the Nuvo 8 in conjunction with the Patient

a hazard or unsafe practice that can result

Describes a hazard or unsafe practice that can result

Provides information important enough to emphasize

Manual.

● Instruct patients to notify their physicians and/or Home Service Providers

if they experience any signs of discomfort.

● Instruct each patient how to perform routine maintenance of the cabinet

air filter and how to check the alarm system battery, if equipped. (Refer to
Section 3.2.)
Be available to service each patient at any time. Maintain the Nuvo 8 in
accordance with Section 4.0.

Repair components and replace parts only as outlined in this manual. Use only
Nidek Medical parts for replacement in Nuvo 8 Oxygen Concentrators.

● Refer to the Nuvo 8 Product Warranty if parts replacement is required
within the warranty period.

1.2 Important Notice and Symbol Explanations

As you read the manual, pay special attention to the WARNING, CAUTION, and
NOTE messages. They identify safety guidelines or other important information as
follows:

WARNING:

CAUTION:

NOTE:

The following harmonized symbols (pictograms), used for non-English language
countries, will be located on the exterior of the Nuvo 8 unit:

Read the accompanying documents; particularly the patient
operating guide.

Store, ship and use the device in an upright condition.

No smoking within five feet of this device, oxygen-carrying tubing, or
accessories.

Indicates an alarm signal.

Do not use any oil or grease on or near the device

Describes
in severe bodily injury or death.

in minor bodily injury or property damage.

or repeat.

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1.3 Functional Specifications

Dimensions: 15.5 in. long, 15.6 in. wide, 27.8 in. tall

(394 mm long, 396 mm wide, 706 mm high)
Weight: 50 to 54 Ib (22.5 to 24.5 kg)
Electrical 120 VAC, 60 Hz, 4.4-5.0 amps, 500 watts avg

Requirements: 230 VAC, 50 Hz, 1.8-2.1 amps, 490 watts avg

230 VAC, 60 Hz, 2.4-2.7 amps, 585 watts avg
Capacity: 8 liters per minute at 90% oxygen

(Based on 70°F [21°C] at sea level)
Accuracy: Flow meter ±5% full scale. (Based on pre-calibrated

analysis.)
Concentration: 2-8 liters per minute at 90% + 6.5 / - 3%
Response Time: Acceptable concentration is normally achieved in about

90 seconds; allow 5 minutes to attain full concentration.
Positioning: Operate the unit in an upright position, maintaining at

least six inches of open space on all sides for ventilation.

2.0 Operational Check and Concentration Test

2.1 Description of Operation

Air enters the Nuvo 8 Oxygen Concentrator through an external cooling air intake
filter. This filtered air enters the compressor via a suction resonator and fine filter,
which quiets the suction sounds made by the compressor. Pressurized air then exits
the compressor and passes through a heat exchanger, which reduces the
temperature of the compressed air. Next, an electronic valve system directs the air
into one of two sieve beds that contain molecular sieve. The special characteristic
property of molecular sieve is that it physically attracts (adsorbs) nitrogen when air
passes through this material, thus enabling the production of high purity oxygen.

There are two sieve beds or adsorbent columns; while one produces high purity
oxygen, the other is purged of the nitrogen it adsorbed (collected) while it was
producing oxygen. Each column produces oxygen for approximately 5.5 seconds
and delivers it to the product storage volume in the end of the column. Oxygen exits
the adsorbent column through a pressure regulator, flow control valve, flow meter,
and final product filter. The flow control valve, which is part of the flow meter,
controls the flow rate of oxygen delivered to the patient. The Nuvo 8 unit delivers up
to 95% oxygen concentration at flow rates from 2 to 8 l/min. The remaining
constituents of the product gas stream are nitrogen and argon, both of which are
part of the air we breathe, are inert and are completely safe.

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2.2 Operational Check

Nidek Medical runs each device through a burn in period and tests every Nuvo 8
Oxygen Concentrator thoroughly after manufacture before releasing for shipment.
As the home service provider, it is your responsibility to perform the following test to
ensure that no damage occurred in shipping or handling.

1. Open and inspect all concentrator cartons upon receipt. Unpack each

unit and remove it from its carton. Inspect the unit itself for damage. If
the exterior of the carton is damaged, or the unit itself is damaged,
note it on the freight bill signed by the driver.

● Before plugging the unit into the wall outlet, actuate the I/0

(ON/OFF) switch to the I (ON) position and note that the audible
alarm sounds continuously. (See Section 2.3). Move the switch to
the 0 (OFF) position.

2. Plug in the power cord of the unit, and set the I/0 (ON/OFF) switch to

the I (ON) position. Check to see that the following occurs:

● The compressor runs, listen for the sound.

● Exhaust air flows out of the bottom of the unit.

● OPTIONAL for Units Equipped with Oxygen Concentration Status

Indicator (OCSI): The OCSI green light remains off until the oxygen
concentration reaches 85% @ 60 Hz and 83% @ 50 Hz.
(approximately two minutes).

3. Turn the flow meter adjustment knob counterclockwise until it stops

(wide open). The flow meter should register in excess of 8.5 liters/min.
If not, refer to Section 5.8 to adjust the product regulator.

4 Perform an oxygen concentration test, as described in Section 2.4.

2.3 Alarm System

The Nuvo 8 Oxygen Concentrator is equipped with an alarm system, which sounds
a continuous and loud alarm when a power failure occurs or when one or more
cycle variables are not within specification. It sounds an alarm if the high or low
pressure indicators are activated (standard models only) or if the optional OCSI
detects lower than predetermined levels of oxygen concentration. The alarm
remains on until you correct the alarm condition or you set the I/0 (ON/OFF) switch
to the 0 (OFF) position. Refer to Section 6.0 for a list of probable alarm causes.

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2.3.1 Battery Test

If equipped, the Nuvo 8 battery should be checked by observing that the continuous
alarm sounds when the I/0 (ON/OFF) switch is moved to the I (ON) position when
the unit is unplugged from the wall outlet.

2.3.2 Power Failure Alarm Test

To test the power failure alarm, perform the following actions:
Unplug the power cord from the wall outlet, and set the I/0 (ON/OFF) switch to the I

(ON) position.
This should immediately activate the audible alarm. If it doesn’t, refer to the

troubleshooting chart in Section 6.0 of this manual.

2.4 Oxygen Concentration Test and Specification

To ensure that the output of oxygen from the device is within specification, you must
perform an oxygen concentration test. Test the unit upon delivery to a patient and at
periodic intervals. Home Service Providers, based on their expertise and
documentation, may establish and implement their own plans for checking oxygen
concentration. Consult Nidek Medical’s Service and Maintenance Log (A-12) for the
recommended intervals for testing.

1. If an oxygen humidifier bottle is used, remove it from the oxygen outlet.

2. Connect a calibrated oxygen concentration analyzer to the oxygen outlet.

3. Set the I/0 (ON/OFF) power switch to the I (ON) position. (It takes
approximately five minutes for the oxygen concentration to stabilize.) Take
oxygen concentration readings over a period of several minutes to reduce
any cyclic variations

4. Verify that the product flow rate delivered by the unit matches the patient’s
prescription and does not exceed the capacity of the unit.

5. Disconnect the oxygen analyzer, and reconnect the humidifier bottle (if used)
and any other equipment / accessories that may be required.

6. Adjust the flow meter adjustment knob to the prescribed flow rate.

NOTE:

Do not measure oxygen concentration output after the product stream passes
through a humidifier bottle, erroneous readings will result and your oxygen
concentration measuring device might be damaged.

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Nidek Medical Nuvo 8 Concentration Specifications

Remove the dirty cabinet air filter from the back of the

Wash the dirty filter in warm water with household

Reinstall the clean cabinet air filter on the grille in the

Liter Flow Specification Within Specification
2 to 8 l/min 90% + 6.5 / - 3% 87% or higher

3.0 Patient Instructions

3.1 General Instructions

It is important that patients thoroughly understand how to operate the Nidek Medical
Nuvo 8 unit. This enables proper treatment as prescribed by a qualified, licensed
physician. You must explain that the purpose of this therapy is to alleviate
symptoms. If patients experience any discomfort or the unit alarms, they must notify
their Home Service Provider and/or physician immediately. You, as the Home
Service Provider, are responsible to see that each patient receives the Patient
Manual. Explain each step in the operation of the unit to the patient in reference to
this manual.

3.2 Routine Maintenance by the Patient

To ensure accurate output and efficient operation of the unit, the patient must
perform two simple routine maintenance tasks:

• Clean the cabinet air filter

• Check the alarm system

3.2.1 Cleaning the Cabinet Air Filter

NOTE:

The patient must clean this filter weekly, as described below. The filter may require
daily cleaning if the Nuvo 8 unit operates in a harsh environment such as a house
heated by wood, kerosene, or oil, or one with excessive cigarette smoke.

1

Nuvo 8 unit.

2

detergent, and rinse.
3 Use a soft absorbent towel to remove excess water.
4

back of the unit.

3.2.2 Checking the Alarm System Battery

See Procedure described in Paragraph 2.3.1
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4.0 Home Service Provider Maintenance

4.1 Routine Maintenance

The Nuvo 8 unit has two filters and a 9-volt battery, if equipped, that require
scheduled maintenance and replacement.

To ensure that the output of oxygen from the unit is within specification, you must
perform an oxygen concentration test. Test the unit upon delivery to a patient and at
periodic intervals. Home Service Providers, based on their expertise and
documentation, may establish and implement their own practices for checking
oxygen concentration. The interval established may be longer or shorter than 90
days, which is the default time period recommended for providers who do not
choose to establish their method.

Nidek Medical does not require preventive maintenance on the concentrator. You
do not need to perform any maintenance as long as the Nuvo 8 unit remains within
specifications at the prescribed flow rate. (Refer to Section 2.4)

4.1.1 Cabinet Air Filter

The external cabinet air filter is located on the back of the unit; it is easily removed
by hand. Instruct the patient to clean this filter weekly. (Refer to Section 3.2.1.)

NOTE:

The filter may require more frequent cleaning if the Nuvo 8 unit operates in a harsh
environment such as a house heated by wood, kerosene, or oil, or one with
excessive cooking, cigarette smoke or atmospheric dust.

4.1.2 Final Product Filter Replacement

The final product filter does not require periodic replacement; it needs to be
replaced only if it restricts oxygen flow. It is suggested that it be replaced whenever
the sieve module is repaired or replaced and after the compressor is rebuilt.

1. Set the I/0 (ON/OFF) switch to the 0 (OFF) position, and unplug the power
cord.

2. Remove the cabinet back to locate the final product filter. NOTE: Observe
the flow direction of the filter before removal.

3. Separate the silicone tubing from both sides of the filter.

4. Install the new filter with the inlet side in the same position as before. Push
the tubing together so that it overlaps the barbs of the final product filter
connections.

5. Record information about the final product filter replacement in Appendix 12
of this manual and online at www.nidekmedical.com under the ‘Maintenance
Log’ tab.

6. Reinstall the cabinet back.

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4.1.3 Inlet Air Filter Replacement

The inlet air filter requires inspection at each patient visit. The filter should be
replaced annually, or more often depending on the environment.

1. Set the unit I/0 (ON/OFF) switch to the 0 (OFF) position, and unplug the
power cord.

2. Remove the rear cabinet access panel to locate the intake filter.

3. Remove filter from the unit, and replace with a new filter.

4. Record information about the filter replacement in Appendix 12 of this
manual and online at www.nidekmedical.com under the ‘Maintenance Log’
tab.

5. Reinstall the access panel.

4.1.4 Battery Replacement

Each time the Nuvo 8 unit is turned on, the alarm must sound loudly for
approximately five seconds to indicate a good battery. An alarm that does anything
other than sound loudly for five seconds indicates a weak battery and requires
replacement. For units with OCSI, actuate the switch with the power cord
unplugged to test the battery. To replace the battery, take the following steps:

1. Set the I/0 (ON/OFF) switch to the 0 (OFF) position, and unplug the power
cord.

2. Remove the access panel in the cabinet back.

3. Pull the battery from the mounting slot and remove the connection wires.

4. Attach the new battery to the connector and reinsert it into the mounting slot.

5. Set the I/0 (ON/OFF) switch to the I (ON) position to test the alarm.

6. Record the battery replacement information in Appendix 12 of this manual
and online at www.nidekmedical.com under the ‘Maintenance Log’ tab.

7. Reinstall the access panel.

4.1.5 Recording Maintenance

As the Home Service Provider, it is suggested that you record all routine
maintenance and repairs performed on the Nuvo 8 unit, including hours and dates
of service in Appendix 12 of this manual and online at www.nidekmedical.com
under the ‘Maintenance Log’ tab.

4.2 Cleaning and Infection Control

With the growing concern about possible cross infection from home oxygen
equipment (i.e.. oxygen concentrators) from one home care patient to another,
appropriate cautions should be exercised. The organisms of most concern are M.
Tuberculosis, HIV, and Viral Hepatitis. These are potentially pathogenic.

Tuberculosis can survive outside of the human body, but its mode of transmission is
by droplet nuclei. When infected individuals cough, they release droplet nuclei into

2010-2229 Rev - B Page 13 of 52

the air, and these carry the Tuberculosis organism. Another person may breathe in
these droplet nuclei, but prolonged exposure to the infected person is usually
necessary for infection to occur.

HIV and Viral Hepatitis are both viruses, which are not living cells themselves but
which can duplicate when in a living “host” cell. Both of these organisms are usually
passed on by person-to-person contact, and both need to be in the human body to
survive. Once outside the body, viruses can survive for only a short period of time.

4.2.1 Preparing for New Patient Use

When you remove the Nuvo 8 from a patient’s home, always dispose of the used
nasal cannula and humidifier bottle. Clean the exterior of the Nuvo 8 with a soapy
water solution or commercial detergent cleaner to remove any debris, organic or
otherwise. Be careful not to get any liquid into the interior of the unit.

Next, clean the exterior with either a common chemical disinfectant or a bleach
solution* and allow it to air dry. For the bleach solution, wear eye and skin
protection to prevent exposure to the chlorine. Retest the Nuvo 8 before you return
it to your inventory.

Replace the cabinet air filter between each patient’s use or clean with warm soapy
water if it is in good condition. Clean this filter at least once per week or more
frequently if operated in a dusty environment.

*Make the bleach solution a 1:100 dilution of 5.25% sodium hypochlorite. Mix one
part household bleach (e.g.. Clorox) with 99 parts cold tap water. To measure the
solution easily, take 1/4 cup of household bleach, and mix it with a gallon of cold tap
water. Allow the mixture to sit on potentially contaminated surfaces for 10 minutes.

5.0 Service

5.1 Components

The design of the Nidek Medical Nuvo 8 Oxygen Concentrator allows for easy
access and removal of most components. This allows you to perform scheduled
maintenance, repair, and replacement of parts with minimal time and effort. The
inlet air filter and battery are conveniently located inside the small access panel in
the cabinet back.

CAUTION:

For your safety, be sure to set the I/0 (ON/OFF) switch to the 0 (OFF) position and
unplug the power cord before you service the Nuvo 8 Oxygen Concentrator.

NOTE:

Record all scheduled maintenance. (Refer to Section 4.1.5.)

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5.2 Cabinet Removal

5.2.1 Removing Cabinet Back

To remove the cabinet back, remove two screws near the base (one on each side)
and two inset screws at the top just under the handle.

5.2.2 Removing Cabinet Front

To remove the cabinet front, remove two screws near the base (one on each side)
adjacent to the rear cabinet screws and two inset screws at the top just under the
handle. It is necessary to remove the cabinet back to access the top screws.

5.2.3 Removing Control Panel

Eight screws hold the control panel in place; the front cover must be removed to
access these screws. It is necessary to remove the electrical wiring and pneumatic
tubing to fully release the control panel.

5.2.4 Main Structure

The weight and forces of the internal components rest solely on four parts: the main
structure, the compressor plate, the base-plate and the base. These parts were
specially designed and formed. They should never require replacement under
normal use.

5.2.5 Caster Replacement

The casters are a push in type that do not require any fasteners. Lay the device on
its back to access the casters from the bottom. Pull them straight out away from the
bottom.

5.3 Compressor

The compressor is the pump within the oxygen concentrator that supplies air to the
separation process performed by the sieve beds. The pressure generated by the
compressor forces oxygen to flow out of the top of the sieve columns.

The compressor is the likely cause of two potential specific problems:

a. An insufficient amount of air is supplied to the process.
b. An excessive sound level.

● Air Supply

Compressor output refers to how much compressed air the compressor can
produce. This depends upon the model of the compressor, length of stroke, piston
diameter, speed of rotation and condition of seals. The cup seals form the seal
between the piston and the cylinder wall. As the cup seals wear, the output begins

2010-2229 Rev - B Page 15 of 52

to gradually decrease. This reduction in compressor output results in less air, and
thus less oxygen, entering the sieve beds. Therefore, the production of oxygen
decreases.

Because this drop in oxygen production occurs over a long period of time,
preventive maintenance on the compressor is not required.

You can continue a patient’s therapy on the Nuvo 8 unit as long as the oxygen
concentration level at the prescribed liter flow rate is within Nidek Medical’s
specification limits. Refer to Section 2.4.

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Air Flow

Meter

0 to 100 l/min

Pressure

Restrictor

1 bar

Pressure

Gauge

Flow

Compressor

Air

Filter

● Sound Level

The sound level is largely determined by the condition of the compressor’s
bearings.

There are four bearings located within the compressor that allow the inner
components of the compressor to rotate. If the bearings wear to the point that they
become loose and noisy, the compressor becomes noticeably loud and needs
servicing. The life of a compressor is determined primarily by its operating
temperature. It is extremely important that the inlet cooling air filters are cleaned
and replaced as required.

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