Huvitz CDC-1 User manual

--------------------------------------------------------------------------------------------------------------------- CDC-1 User Manual
1
USER MANUAL
Automatic Visual Acuity Tester
CDC-1

2 CDC-1 -----------------------------------------------------------------------------------------------------------------------------------
IMPORTANT NOTICE
This product may malfunction due to electromagnetic waves caused by portable personal telephones, transceivers,
radio-controlled toys, etc. Be sure to avoid having objects such as, which affect this product, brought near the
product.
The information in this publication has been carefully checked and is believed to be entirely accurate at the time of
publication. SHANGHAI HUVITZ assumes no responsibility, however, for possible errors or omissions, or for any
consequences resulting from the use of the information contained herein.
SHANGHAI HUVITZ reserves the right to make changes in its products or product specifications at any time and
without prior notice, and is not required to update this documentation to reflect such changes.
V1.0 (9000ENG0113)
SHANGHAI HUVITZ Co., Ltd.
Building 1, No. 150, Renjie Road, Fengxian, Shanghai, 201401, China
EU Representative
LGMed Trades OY
Mikkolantie 19D, 00640 Helsinki,
Finland
Tel: [phone]
Fax: [phone]
All rights are reserved.
Under copyright laws, this manual may not be copied, in whole or in part, without the prior written consent of
SHANGHAI HUVITZ Co., Ltd.

--------------------------------------------------------------------------------------------------------------------- CDC-1 User Manual
3
CONTENTS
1. INTRODUCTION ......................................................................................................................6
1.1. OUTLINE OF PRODUCT ............................................................................................................................6
1.2. INTENDED USE ..........................................................................................................................................6
1.3. CLASSIFICATION.........................................................................................................................................6
1.4. PATIENT RESTRICTION .............................................................................................................................6
1.5. PATIENT REQUIREMENT...........................................................................................................................6
1.6. APPLIED STANDARD..................................................................................................................................7
2. INFORMATION REGARDING SAFETY.................................................................................8
2.1. INTRODUCTION ..........................................................................................................................................8
2.2. SAFETY SYMBOLS.....................................................................................................................................9
2.3. ENVIRONMENTA RELATED MATTERS.................................................................................................. 11
2.4. SAFETY PRECAUTIONS......................................................................................................................... 13
2.5. FCC WARNNING .................................................................................................................................... 14
3. CHARACTERISTICS.............................................................................................................15
4. USING THE DEVICE .............................................................................................................15
4.1. PREPERATION BEFORE USE ................................................................................................................ 15
4.2. USING THE DEVICE................................................................................................................................ 17
4.3. AFTER USING THE DEVICE .................................................................................................................. 17
5. PRECAUTIONS......................................................................................................................18
5.1. PRECAUTIONS FOR USE....................................................................................................................... 18
5.2. PRECAUTIONS FOR INSTALLATION...................................................................................................... 18
5.3. PRECAUTIONS FOR STROAGE............................................................................................................. 20
6. CONFIGRATION ....................................................................................................................21
6.1. MAIN BODY.............................................................................................................................................. 21
6.2. REMOTE CONTROLLER......................................................................................................................... 23
7. INSTALLIATION.....................................................................................................................28
7.1. PREPARATION ......................................................................................................................................... 28

4 CDC-1 -----------------------------------------------------------------------------------------------------------------------------------
7.2. INSTALLING THE MAIN BODY ............................................................................................................... 28
7.3. CONFIGURATION..................................................................................................................................... 29
7.4. CONNECTION WITH DIGITAL REFRACTOR......................................................................................... 29
8. USING MENU MODE AND FUNCTIONS ............................................................................29
8.1. EXECUTING AND OPERATING THE MENU MODE ............................................................................. 29
8.2. FUNCTIONS IN THE MEUN MODE........................................................................................................ 30
8.2.1. Vision Test .................................................................................................................................... 31
8.2.2. Movie/Photo ................................................................................................................................. 34
8.2.3. Setting ............................................................................................................................................ 35
8.3. OTHER FUNCTIONS................................................................................................................................ 38
8.3.1. Adjusting Contrast Sensitivity ................................................................................................ 38
8.3.2. Edit User Program ..................................................................................................................... 38
8.3.3. Set Remote Controller IR Channel ...................................................................................... 39
9. OPTOMETRIC TEST USING THE ACUITY TESTER.........................................................40
9.1. CYLINDER AXIS TEST............................................................................................................................ 40
9.2. CYLINDER POWER TEST ...................................................................................................................... 40
9.3. BINOCULAR CYLINDER AXIS TEST ..................................................................................................... 41
9.4. BINOCULAR CYLINDER POWER TEST................................................................................................ 41
9.5. RED/GREEN TEST ................................................................................................................................. 42
9.6. CROSS CYLINDER TEST FOR AXIS..................................................................................................... 42
9.7. CROSS CYLINDER TEST FOR POWER ............................................................................................... 43
9.8. BINOCULAR BALANCE TEST ................................................................................................................ 43
9.9. DOMINANT EYE TEST FOR PATIENTS WITH PHORIA....................................................................... 43
9.10. WORTH 4 DOT TEST......................................................................................................................... 44
9.11. POLARIZED CROSS TEST ................................................................................................................ 44
9.12. FIXATION DISPARITY TEST............................................................................................................... 44
9.13. COINCIDENCE TEST .......................................................................................................................... 45
9.14. SCHOBER TEST .................................................................................................................................. 45
9.15. VON GRAEFE TEST........................................................................................................................... 45
9.16. MADDOX ROD TEST & THORINGTON TEST ................................................................................. 46
9.17. ZEIGER TEST...................................................................................................................................... 47
9.18. STEREO TEST .................................................................................................................................... 47

--------------------------------------------------------------------------------------------------------------------- CDC-1 User Manual
5
9.19. MINUTE STEREO TEST..................................................................................................................... 48
10. MAINTENANCE .................................................................................................................49
10.1. REPLACEMENT BATTERY.................................................................................................................. 49
10.2. CLEANING............................................................................................................................................ 49
10.3. DISPOSAL............................................................................................................................................ 49
11. TROUBLE SHOOTING......................................................................................................50
11.1. PRESSED POWER SWITCH BUT THE SCREEN DOESN’T WORK.................................................. 50
11.2. CHART DISPLAYED AS BROKEN IMAGE .......................................................................................... 50
11.3. MAIN BODY DOESN’T RESPONSE TO REMOTE CONTROLLER.................................................... 50
11.4. THE SCREEN IS TOO BRIGHT OR TOO DARK ................................................................................. 50
11.5. VISUAL ACUITY TEST RESULTS IN OVERCORRECTION OR UNDERCORRECTION ................... 51
11.6. RED/GREEN TEST IS OVERCORRECTION OR UNDERCORRECTION ......................................... 51
11.7. RED/GREEN FILTER IS NOT FILTERING COMPLETELY ................................................................. 51
11.8. POLARIZER TEST IS NOT WORKING ................................................................................................ 51
12. ACCESSORIES..................................................................................................................52
13. PRODUCT SPECIFICATION.............................................................................................53
14.SERVICE INFORMATION .................................................................................................55

6 CDC-1 -----------------------------------------------------------------------------------------------------------------------------------
1.1. Outline of Product
The Shanghai Huvitz Automatic Visual Acuity Tester (CDC-1) is a computerized chart presenting device that provides
charts for refractive correction test and various functional tests such as cross cylinder, red/green, binocular balance,
fusion and suppression, heterophoria, associated phoria, aniseikonia, stereopsis, and dominant eye test for
heterophoria. Since the Digital Chart implements charts on the LCD panel by adopting the cutting edge digital
technology, it’s not only faster and quieter but also equipped with multifarious convenient functions. The contrast
sensitivity and the background luminance of the chart are adjustable for environmental needs. Also the image gallery
contains a dozen of image clips that the examiner could utilize during the examination. Various masking and random
functions would be helpful for a punctual vision test.
The examiner may execute all the charts and functions by using the remote controller and when it is connected to
Shanghai Huvitz Digital Refractor, the Operation Panel can also control this product.
1.2. Intended Use
Shanghai Huvitz Automatic Visual Acuity Tester displays optotypes or symbols on LCD for eyesight test within visible
distance using electronic power.
1.3. Classification
•Classfication of Product::
- EU –Class I according to Annex VIII (Rule 13) of the Medical Device Regulation MDR
•Resistance against electric shock: Class I
•Protection against harmful ingress of water: Ordinary, IPX0
•Degree of safety in the presence of a flammable anesthetics mixture with air or with oxygen or with nitrous
oxide: Not suitable for use in the presence of a flammable anesthetics mixture with air or with oxygen or
with nitrous oxide
•Mode of Operation: Continuous
1.4. Patient Restriction
• Patient who cannot keep a comfortable position.
1.5. Patient Requirement
Patient tested with this device should keep concentration for several minutes and follow below items.
-Keep eyes wide open.
1. Introduction

--------------------------------------------------------------------------------------------------------------------- CDC-1 User Manual
7
-During the test, understand and follow instructions.
When patient comply above conditions, would get a correct test result.
1.6. Applied Standard
•IEC/EN 60601-1: MEDICAL ELECTRICAL EQUIPMENT
–Part 1: General requirements for safety
•IEC/EN 60601-1-2: Medical electrical equipment Part1: General requirements for safety
- Collateral Standard: Electromagnetic Compatibility-Requirements and tests
ETSI EN 301 489-17: ElectroMagnetic Compatibility (EMC) standard for radio equipment and services; Part
17: Specific conditions for Broadband Data Transmission Systems; Harmonised Standard for
ElectroMagnetic Compatibility
•ISO15004-1: Ophthalmic instruments
–Fundamental requirements and test methods
General Requirements applicable to all Ophthalmic instrument

8 CDC-1 -----------------------------------------------------------------------------------------------------------------------------------
2.1. Introduction
Safety is everyone’s obligation and responsibility. Safe use of this device is important for everyone involved - installers,
users, operators and device managers. It is a must to study and to master this user manual individually prior to installing,
using, cleaning, repairing or controlling this device and its accessories. It does not suffice to emphasize the importance
of understanding the instructions found in this manual repeatedly in order to increase safety of patient or users. For this
reason, the following safety warning chart is included at the adequate place on this manual in order to highlight
information that requires special precaution or safety related information in particular. All the users or managers need
to pay special attention in addition to mastering “WARNING” or “CAUTION” in the manual.
“Warning“ indicates the presence of a hazard that could result in severe personal injury, death or substantial
property damage if ignored.
“Caution” indicates the presence for a hazard that could result in minor injury, or property damaged if ignored.
“Note” describes information for the installation, operation, or maintenance of which is important but hazard
related if ignored.
2. Information regarding Safety
!
WARNING
!
CAUTION
NOTE

--------------------------------------------------------------------------------------------------------------------- CDC-1 User Manual
9
2.2. Safety Symbols
The International Electro technical Commission (IEC) announced the symbols that warn when connecting electric
medical device’s power or that warn against calamity that may occur. Classification and symbol are as follows.
It indicates the year of manufacture and the manufacturer.
(Il indique l'année de fabrication et le fabricant.)
Manufacturer
(Fabricant)
CE Mark
(Marque CE)
Temperature Limitation
(Limitation de température)
Keep DRY
(Garder au sec)
WEEE mark
Disposal of your old appliance
When this crossed-out wheeled bin symbol is attached to a product it means
the product is covered by the European Directive 2002/96/EC.
All electrical and electronic products should be disposed of separately from the
municipal waste stream via designated collection facilities appointed by the
government or the local authorities.
The correct disposal of your old appliance will help prevent potential negative
consequences for the environment and human health.
For more detailed information about disposal of your old appliance, please
contact your city office, waste disposal service or the shop where you
purchased the product.
(Mise au rebut de votre ancien appareil
Lorsque ce symbole de poubelle barrée est joint à un produit, cela signifie que
le produit est couvert par la directive européenne 2002/96 / CE.
Tous les produits électriques et électroniques doivent être éliminés séparément
du flux des déchets municipaux via des installations de collecte désignées par
le gouvernement ou les autorités locales.
L'élimination correcte de votre ancien appareil aidera à prévenir les
conséquences négatives potentielles sur l'environnement et la santé humaine.
Pour plus d'informations sur l'élimination de votre ancien appareil, veuillez
contacter votre mairie, le service d'élimination des déchets ou le magasin où
vous avez acheté le produit.)
Atmospheric pressure limitation
(Limitation de pression atmosphérique)
Humidity limitation
(Limite d'humidité)

10 CDC-1 -----------------------------------------------------------------------------------------------------------------------------------
Stack direction
(Direction de la pile)
Fragile , handle with care
(Fragile, manipuler avec soin)
Stack layer limitation
(Limiter la couche de pile)
Use no hooks
(N'utilisez aucun crochet)
Alternating Current
(Courant alternative)
Direct Current
(Courant continu)
Consult instructions for use
(Consulter les instructions d'utilisation)
Serial Number Symbol
(Symbole du numéro de série)
Authorised Representative in the European Community
(Représentant autorisé dans la Communauté européenne)
Medical Device
Model Name
Unique Device Identifier

--------------------------------------------------------------------------------------------------------------------- CDC-1 User Manual
11
2.3. UDI Information
UDI structure: (01) Manufacturer prefix number: 697046148; (11) manufacture date;
(21) S/N code
2.4. Environmenta related Matters
The environment to avoid in operation and storage.
Place where device comes directly into contact with moisture
(do not operate the device with wet hand)
Place where device is exposed directly to sunlight.
A place where the equipment can be exposed to direct ultraviolet.
Place with severe temperature change.
Where there is a hot equipment nearby.
Where the humidity is extremely high or there is a ventilation problem.
Where the machine is exposed to excessive shocks or vibrations.

12 CDC-1 -----------------------------------------------------------------------------------------------------------------------------------
Where the machine is exposed to chemical material or explosive gas.
Be cautious so that things like dust and metal do not fall inside the machine.
Don’t disassemble or open the product. HUVITZ does not take responsibility for the
possible problems
Be careful not to block the fan of the machine.
Don’t plug the AC power cord into the outlet unless all parts of the machine are
completely connected. Otherwise, it will cause severe damage on the machine.
Pull out the power cord with holding the plug, not the cord.
Please keep below environment condition.
1. Operation: Ambient Temperature 10℃~ 40℃, Relative Humidity 30 ~ 90%, Atmosphere Pressure 800 ~
1060hpa.
2. Transportation: Ambient Temperature -40℃~ 70℃, Relative Humidity 10 ~ 95%, Atmoshpere Pressure 500
~ 1060hpa.
3. Storage: Ambient Temperature –10℃~ 55℃, Relative Humidity 10 ~ 95%, Atmosphere Pressure 700 ~
1060hpa.
Avoid environments where the equipment is exposed to excessive shocks or vibrations.

--------------------------------------------------------------------------------------------------------------------- CDC-1 User Manual
13
2.5. Safety Precautions
This device was developed and proven according to the domestic and international safety specs. This guarantees
this device’s high safety level. By law, a manufacturer is obligated to provide sufficient explanation of the matters
pertaining to the device safety to device users. Likewise, compliance with the contents of this device’s manual is
mandatory for safety sake. Thus, read the instructions in the manual sufficiently and understand prior to turning on
the power. For more information, inquire the distributor where you purchased the device.
1. This device is utilized with the accessories provided by Huvitz. If consumer wants to use other manufacturers’
accessories, safety of use must be proven and confirmed by Huvitz or by the accessories’ manufacturer.
2. This device should be operated by qualified personnel with sufficient training or under such personnel’s
supervision.
3. This device can be modified only by Huvitz’s service technician or a person with comparable qualifications.
4. Device management by customer should be carried out as explained in the user or service manual.
Management that requires more sophisticated skill set can be carried out only by Huvitz’s service technician
or a person with comparable qualifications.
5. Manufacturer assumes responsibility for this device’s safety, reliability and performance only when the
following conditions are satisfied: (1) When this device was installed at a viable space in accordance to this
manual’s regulations, and (2) when this device was used and maintained according to the procedure
regulated in this manual or service manual.
6. Only a person who completed adequate training or education program can install, operate and maintain this
device.
7. Store user or service manual at a place that is readily accessible by the person who manages and uses this
device.
8. Please do not pull on the device’s cable. Always hold the plug when disconnecting cables.
9. Always check the status of the device’s exterior and it’s functions before using the device.
10. Do NOT block the air vent for heat radiation.
11. Turn off the power immediately and take out the plug when there is smoke, spark, abnormal noise or smell.
12. This device should not be installed or stored in where having risk of explosion, volatile chemicals like alcohol ,
benzene or flammable, explosive substance.
13. The manufacturer is not liable for damages caused by unauthorized change of the device(s). Such change
will forfeit any rights of warranty.
14. Before connecting the cable of DC adapter to AC power source, makes sure the AC power meets the input
requirements of DC adapter.
15. The ground connection is important for safe operation. For providing power with proper voltage and frequency
to the device, it needs to be from outlet with ground.
16. Using medical certified DC adapter guarantees reliable ground. Check DC adapter regularly and do not use
it when damage is found.

14 CDC-1 -----------------------------------------------------------------------------------------------------------------------------------
17. Do not touch both signal input, output or other connectors, and the patient at the same time.
18. Use DC adapter and power cable supplied together to keep the reliability of the device.
19. IEC standard needs to be satisfied with in order to connect an outside device with input/output signal or other
connector. (IT equipment is IEC 60950, and electric equipment for medical use is IEC 60601). Moreover, all
the systems need to satisfy the safety requirement, IEC 60601-1 when it comes to the electric system for
medical use. Person who connects outside device with input/output signal or other connector has the
obligation to take responsibility in accordance to the IEC60601-1. Contact local technician or distributor if you
have doubts.
2.6. FCC Warnning
Any Changes or modifications not expressly approved by the party responsible for compliance could void the user's
authority to operate the equipment.
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions:
(1) This device may not cause harmful interference, and (2) this device must accept any interference received, including
interference that may cause undesired operation.
Caution: The user is cautioned that changes or modifications not expressly approved by the
party responsible for compliance could void the user's authority to operate the equipment.
Note: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part
15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a
residential installation. This equipment generates uses and can radiate radio frequency energy and, if not installed and
used in accordance with the instructions, may cause harmful interference to radio communications. However, there is
no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference
to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged
to try to correct the interference by one or more of the following measures:
-Reorient or relocate the receiving antenna.
-Increase the separation between the equipment and receiver.
-Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
-Consult the dealer or an experienced radio/TV technician for help.
The device has been evaluated to meet general RF exposure requirement. The device can be used in portable exposure
condition without restriction.
RF Exposure Statement：
This equipment complies with EU, FCC and IC RSS-102 radiation exposure limits set forth for an uncontrolled
environment. This equipment should be installed and operated with minimum distance 20cm between the radiator &
your body.

--------------------------------------------------------------------------------------------------------------------- CDC-1 User Manual
15
◼CDC-1 has LCD panel supporting polarization which enables various kinds of polarization test.
◼Through vision test can check color blindness/weakness.
◼Through Contrast Test can check color ability based on frequency and brightness of contrast.
◼Chart contrast can be easily adjusted by remote controller.
◼By using random chart function, user can prevents patients from remembering the order of charts
appearance.
◼Other various images can be used in optometry or help to explain to customer.
◼This device provides chart reverse. User can select white or black background color.
◼This device can connect to Shanghai HUVITZ digital refractor in wired or wireless. Once they are
connected, phoropter control panel can control charts and lens of phoropter conveniently.
4.1. Preperation before Use
Before using this product, please check below items and perform required actions refer to this user manual.
◼The device should be installed by qualified and trained person or under the guidance of such person.
◼Check any dust on the front screen, if does, clean it.
◼Use DC adapter and power cable that supplied with this device.
◼After connecting power by using DC adapter and power cable, perform simple device function check.
◼DC adapter cable should be fixed so it doesn’t shake
◼Check the remote controller has battery inside and the battery life is not over.
◼If environment such as room lightning were chagend from its first installation, adjust chart brightness,
red/green balance, etc. in setting menu before use.
3. Characteristics
4. Using the Device

16 CDC-1 -----------------------------------------------------------------------------------------------------------------------------------
Use only DC adapter and power cable provide by Shanghai HUVITZ.
DC adapter provided by Shanghai HUVITZ is qualified for medical device.
Manufacturer is NOT liable to any problem caused by using DC adapter or power cable which are not
provided by Shanghai HUVITZ.
!
WARNING

--------------------------------------------------------------------------------------------------------------------- CDC-1 User Manual
17
4.2. Using the Device
Operation procedures may differ from users. Followings are the most basic operation sequence.
◼Connect DC adapter to the device. Fix the adapter cable with cable tie to prevent it pulled off.
◼Push Power button on the lower part. Check device Logo on LCD.
◼Wait product’s initialization before C chart comes up.
◼Let patients be in the test distance, instruct to watch charts.
◼When necessary, adjust screen angle.
◼Using remote controller select charts and proceed test.
◼With programming function common used charts can be memorized in order which helps to finish test quickly.
◼After some idle time, the screen goes off or a screen saver is active. Press any button on the remote controller
to return to its original screen.
◼To turn off the device, keep press the power button till there is beep sounds then take the hand off.
When you hear another beep sound, the power is off.
4.3. After Using the Device
◼Using the power switch turn off the power, unplug the power cable.
◼When unplug a power cable, always hold a plug, not the cable. Especially care when unplug DC adapter
cable connected to the device.
◼Remove a power cable from an outlet when you’re not using the device for a long time.
◼Follow precautions of this manual for storage.
◼Maintain all parts and cables clean and arranged for next use.
◼Keep the device clean to not disturb using next time.
◼Do not tamper or open the product. The manufacturer is not liable for damages caused by such action.
◼Do not plug AC power cord to an outlet before all parts are connected completely. There is a risk of harming
the device.

18 CDC-1 -----------------------------------------------------------------------------------------------------------------------------------
◼Do not use organic solutions such as alcohol, thinner, benzene, etc. to clean a surface of this product. It may
damage the product
◼In case of not using the device for a long time, please put a dust cover on the device after plugging off.
◼When move the device, always turn off the power, disconnect DC adapter cable connected to the device,
and hold firmly with both hands.
5.1. Precautions for Use
When using this device, please be aware of the followings.
◼Avoid places where ambient temperature is too low or too high for normal operation.
◼Check the overall status of the device and any abnormally in the examinee persistently.
◼If any abnormality is observed, the operator is required to take appropriate measures such as stop the
operation of the device and let the examinee in a safe and stable condition.
◼Keep an examinee untocuh the device.
◼During an examination by this device, maintain the examinee in upright and correct position.
◼Carefully handle the device so as not to give impact on it or make it fall down.
◼Use the device under properly controlled ambient illumination. It could affect the test result.
◼To connect this device with other product, contact the dealer you purchased the device.
◼During the operation, if the device makes smokes, sparks, strange noises or odors, immediately turn off and
unplug the power. Contact the dealer you purchased the device.
5.2. Precautions for Installation
When install this device, should be aware of the followins.
◼Avoid places where the device is exposed to water vapor or moisture directly.
5. Precautions

--------------------------------------------------------------------------------------------------------------------- CDC-1 User Manual
19
◼Avoid places where the device could be affected by atmospheric pressure, humidity, temperature, ventilation,
sunlight or by the air containing dust, salinity, sulfur and etc..
◼Install the device on a place stable and leveled
◼Avoid places where the device is subject to excessive shocks or vibrations.
◼Avoid places where the device is exposed to chemicals or flammable gases.
◼Avoid places near a heating equipment.
◼Avoid places with high humidity or disturbing heat dissipation.
◼Be careful for the rated voltage (or rated power) when install.
◼Install the device with the proper ground connection.
◼Check if overall cables are connected completely. Especially DC adapter to the device. Use a cable tie to fix
the DC adapter cable to keep it from unplugging.
◼Using the devices jointly could result a risk.
NOTE
Fix the cable connecting the device and DC adapter to make it stable.
On a place tilted more than 10 degree, the device might fall to the side. Always install the device on flat
area.
!
WARNING

20 CDC-1 -----------------------------------------------------------------------------------------------------------------------------------
5.3. Precautions for Stroage
When sotre this device, please note the belowings.
◼Avoid places where the instrument is exposed to water vapor or moisture directly.
◼Avoid places where the instrument is exposed to direct sunlight.
◼Avoid places where the temperature changes extremely.
◼Avoid places near heating devices.
◼Avoid places with high humidity or disturbing heat dissipation.
◼Avoid places where the device is subject to excessive shocks or vibrations.
◼Avoid places where the device is exposed to chemicals or flammable gases.
◼Keep dust or metallic objects from getting into the inside.