Riken Keiki SP-220 Series User manual

PT0E-1435
Portable Gas Leak Detector
SP-220 Series
SP-220(TYPE M)
SP-220(TYPE L)
SP-220(TYPE ML)
Operating Manual
(PT0-139)

- 2 -
Contents
1. Outline of the Product..................................................................................................................................... 3
Preface............................................................................................................................................................ 3
Purpose of use................................................................................................................................................ 3
Definition of DANGER, WARNING, CAUTION and NOTE............................................................................. 3
How to check the standards and explosion-proof specifications ................................................................... 4
2. Important Notices on Safety ........................................................................................................................... 5
2-1. Danger cases........................................................................................................................................... 5
2-2. Warning cases ......................................................................................................................................... 6
2-3. Precautions.............................................................................................................................................. 7
2-4. Safety information（for ATEX/IECEx specifications）............................................................................... 9
3. Product Components.................................................................................................................................... 10
3-1. Names and functions for each part .......................................................................................................10
4. How to Use ...................................................................................................................................................13
4-1. Before using the detector ......................................................................................................................13
4-2. Preparation for start-up.......................................................................................................................... 13
4-3. How to replace the batteries.................................................................................................................. 13
4-4. How to start the detector .......................................................................................................................15
4-5. Basic operating procedures...................................................................................................................17
4-6. How to detect......................................................................................................................................... 18
4-7. Change of the alarm setpoint ................................................................................................................ 19
4-8. Performing air calibration ...................................................................................................................... 20
4-9. Snap logger ...........................................................................................................................................21
4-10. Peak hold function ...............................................................................................................................22
4-11. Change of the alarm and operation sounds ........................................................................................22
4-12. How to turn on the illumination lamp ...................................................................................................23
4-13. Power-off .............................................................................................................................................23
5. How to Set Display Mode ............................................................................................................................. 24
5-1. Entering the display mode.....................................................................................................................24
5-2. Measured gas switching setting ............................................................................................................26
5-3. Log data display ....................................................................................................................................27
6. How to Set User Mode .................................................................................................................................28
6-1. Entering the user mode .........................................................................................................................28
6-2. Date/time setting.................................................................................................................................... 30
6-3. Clock function ON/OFF setting.............................................................................................................. 31
7. Alarm Function..............................................................................................................................................32
7-1. Gas alarm activation..............................................................................................................................32
7-2. Fault alarm activation ............................................................................................................................32
8. Maintenance .................................................................................................................................................33
8-1. Maintenance intervals and items...........................................................................................................33
8-2. How to clean ..........................................................................................................................................35
8-3. Parts replacement .................................................................................................................................35
9. Storage and Disposal ...................................................................................................................................38
9-1. Procedures to store the detector or leave it for a long time ..................................................................38
9-2. Procedures to use the detector again ................................................................................................... 38
9-3. Disposal of products ..............................................................................................................................39
10. Troubleshooting ..........................................................................................................................................40
11. Product Specifications ................................................................................................................................42
12. Appendix .....................................................................................................................................................43
12-1. Definition of terms................................................................................................................................43

1. Outline of the Product Preface
- 3 -
1
1. Outline of the Product
Preface
Thank you for choosing our portable gas leak detector SP-220 series (hereinafter referred to as the
detector). Please check that the model number of the product you purchased is included in the
specifications on this manual.
This manual explains how to use the detector and its specifications. It contains information required for
using the detector properly. Not only the first-time users but also the users who have already used the
product must read and understand the operating manual to enhance the knowledge and experience before
using the detector.
Note that the contents of this manual are subject to change without notice for product improvement. It is
also prohibited to copy or reproduce this manual, in whole or in part, without permission.
Regardless of warranty period, we shall not make any indemnification for accidents and damage caused by
using the detector.
Make sure to read the warranty policy specified on the warranty.
Purpose of use
This detector is used to detect a single channel, such as city gas, LP gas, etc., in air.
It provides three different specifications: TYPE M used to detect leakage of city gases, TYPE L used to
detect leakage of LP gases and TYPE ML used to detect leakage of city gases and LP gases with different
calibration available for each type of gases. Detection results are not intended to guarantee life or safety in
any way.
Definition of DANGER, WARNING, CAUTION and NOTE
Throughout this manual, the following indications are used to ensure safe and effective work.
DANGER This message indicates that improper handling may cause serious
damage on life, health or assets.
WARNING This message indicates that improper handling may cause serious
damage on health or assets.
CAUTION
This message indicates that improper handling may cause minor damage
on health or assets.
NOTE This message indicates advice on handling.

1. Outline of the Product How to check the standards and explosion-proof specifications
- 4 -
How to check the standards and explosion-proof
specifications
The detector has different specifications depending on the standards or explosion-proof certification type.
Check the specifications of the product you have before use. See the Declaration of Conformity at the end
of this operating manual for CE marking specifications.
For the product specifications, check the nameplate attached to the product shown in the following figure.
(1) Nameplate example of TIIS
specifications
(2) Nameplate example of CE marking
specifications
* The above nameplate (1) or (2) is
attached depending on the specified
explosion-proof specifications.
Ex mark
CE mark

2. Important Notices on Safety 2-1. Danger cases
- 5 -
2
2. Important Notices on
Safety
To maintain the performance and use the detector safely, observe the following instructions of DANGER,
WARNING and CAUTION.
2-1. Danger cases
DANGER
About use
While conducting measurement in a manhole or confined space, do not lean over or look into
the manhole or closed space. It may lead to dangers because oxygen-deficient air or other
gases may blow out.
Oxygen-deficient air or other gases may be discharged from the gas exhausting outlet of the
detector. Never inhale the air or gases.
High-concentration (100% LEL or higher) gases may be discharged from the gas exhausting
outlet of the detector. Never use fire near it.

2. Important Notices on Safety 2-2. Warning cases
- 6 -
2-2. Warning cases
WARNING
Sampling point pressure
The concentration meter is designed to draw gases under the atmospheric pressure. If
excessive pressure is applied to the gas inlet and outlet of the detector, measured gases may
leak out from its inside and may cause dangerous conditions. Be sure that excessive pressure
is not applied to them while used.
Air calibration in atmosphere
When air calibration is performed in the atmosphere, check the atmosphere for freshness
before beginning it. If interference gases or other gases exist, the adjustment cannot be
performed properly, thus leading to dangers when the gas leaks.
Response to gas alarm
A gas alarm is triggered by changes in temperature and humidity. In such a case, check the
atmosphere for freshness and perform air again in the measured atmosphere.
Example) If the detector is turned on in a room with a temperature of 20ºC and a humidity of
40% RH and taken outside (a temperature of 30ºC and a humidity of 60% RH), an alarm is
triggered by humidity changes. In such a case, perform air calibration outside and measure.
The detector performs air calibration automatically when it is turned on. Even in such a case,
check the atmosphere for freshness and perform air calibration again in the measured
atmosphere.
WARNING
Battery level check
Before use, check that there remains sufficient battery power. When the detector is not used for
a long period, the batteries may be exhausted. Never fail to replace them with new ones before
use.
If a low battery voltage alarm is triggered, gas detection cannot be conducted. If the alarm is
triggered during use, turn off the power and promptly replace the batteries in a safe area.
Others
Do not throw the detector into fire.
Do not wash the detector in a washing machine or ultrasonic cleaner, etc.
Do not block the buzzer sound opening. No alarm sound can be heard.
Do not remove the battery while the power is on.

2. Important Notices on Safety 2-3. Precautions
- 7 -
2-3. Precautions
CAUTION
Do not use the detector where it is exposed to oil, chemicals, etc. Do not submerge the detector
under water on purpose.
Do not use in a place where the detector is exposed to liquids such as oil and chemicals.
The detector is not water-pressure-resistant. Do not use the detector where a high water pressure is
applied to it (under a faucet, shower, etc.) or submerge it under water for a long time. The detector
is water-proof only in fresh water and running water, and not in hot water, salt water, detergent,
chemicals, human sweat, etc.
The gas inlet and outlet are not water-proof. Be careful not to let water such as rainwater, etc. get
into these parts. Because this may cause trouble and gas cannot be detected.
Do not place the detector where water or dirt gets accumulated. The detector placed at such a
location may cause malfunction due to water or dirt that gets into the buzzer opening, etc.
Note that drawing in dirty water, dust, metallic powder, etc. will significantly deteriorate the sensor
sensitivities. Be careful when the detector is used in an environment where these elements exist.
Do not use the detector in a place where the temperature drops below -20ºC or rises over 55ºC.
The operating temperature of the detector is -20 to +55ºC. Do not use the detector at higher
temperatures, humidities and pressures or at lower temperatures than the operating range.
Avoid long-term use of the detector in a place where it is exposed to direct sunlight.
Do not store the detector in a sun-heated car.
Avoid a sudden humidity or temperature change.
Do not leave the detector in a place with high temperature and humidity for a long time. The
performance of the unit may deteriorate.
Observe the operating restrictions to prevent condensation inside the concentration meter or gas
sampling hose.
Condensation formed on the detector or taper nozzle causes clogging, gas adsorption, etc., which
may disturb accurate gas detection. Thus, condensation must be avoided. In addition to the
installation environment, carefully monitor the temperature/humidity of the sampling point to prevent
condensation, etc. on the detector or taper nozzle. Please observe the operating restrictions.
Do not use a transceiver near the detector.
Radio wave from a transceiver or other device near the detector may disturb readings. If a
transceiver or other radio wave transmitting device is used, it must be used in a place where it
disturbs nothing.
Do not use the detector near a device that emits strong electromagnetic waves (high-frequency or
high-voltage devices).
Verify that the flow check display is rotating before using the detector.
If the flow check display is not rotating, gas detection cannot be performed properly. Check whether
the flow rate is lost.
Never fail to perform a regular maintenance.
Since this is a precision devices, a regular maintenance must be performed. Continuing to use the
detector without performing maintenance will compromise the sensitivity of the sensor, thus
resulting in inaccurate gas detection.

2. Important Notices on Safety 2-3. Precautions
- 8 -
CAUTION
Others
After a gas continuously comes into contact or a highly-concentrated gas comes into contact,
the alarm pattern may continue. In such a case, draw cleaned air for more than five minutes
(recommended) and perform air calibration again.
Pressing buttons unnecessarily may change the settings, preventing alarms from activating
correctly. Operate the detector using only the procedures described in this operating manual.
Do not drop or give shock to the detector. The accuracy of the detector may be deteriorated.
Do not jab the buzzer opening with a sharp-pointed item. Doing so may cause a failure or
damage.
Do not remove the panel sheet on the display. The water-proof and dust-proof performances
will be deteriorated.
Do not affix a label or the like on the infrared port. Infrared communications can no longer be
conducted.
The operating environment may include gases that have harmful effects on the sensor of the
detector. The detector cannot be used in the presence of the following gases:
(1) High-concentration sulfides (such as H2S, SO2, etc.)(2) Halogen gases (such as chloride
compounds, etc.)(3) Silicone (Si compounds)(4) High-concentration solvent gasesDo not use
the detector in the presence of the above (1), (2), and (3) gases (such as high-concentration
sulfides, halogen gases, silicone, etc.), which may shorten the sensor life significantly or cause
malfunctions such as inaccurate readings.
In case the detector is used for detection in the presence of silicone, etc., be sure to check the
gas sensitivities before using it again.
If the above (4) gas (high-concentration solvent gas) is exposed, a crack may occur in the unit.
Thus, do not use high-concentration solvent gases.
About battery replacement
Never fail to turn off the power of the detector before replacing the batteries.
Replace both of the two batteries with new ones at one time.
Pay attention to the polarities of the batteries.
Usage
In a low-temperature environment, the operating time is shortened due to the battery
performance property.
At low temperatures, the responses of the LCD display may slow down.
Perform air calibration under pressure and temperature/humidity conditions close to those in
the operating environment and in fresh air.
Perform air calibration after the reading is stabilized.
If there is a sudden temperature change of 15ºC or more between the storage and operational
locations, turn on the power of the detector, let it stand for more than 5 minutes in a similar
environment to the operational location, and perform air calibration in fresh air before using it.
When cleaning the detector, do not splash water over it or use organic solvents such as alcohol
and benzine on it. The surface of the detector may be discolored or damaged.
If the detector is not used for a long time, turn on the power at least once every six months and
check that the pump draws in air (about three minutes). The detector, when not activated for a
long time, may cease to work because of hardening of the grease in the pump motor.
If the detector is not used for a long time, store it after removing the batteries. Battery leaks
may result in fire, injury, etc.
When the detector is used again after a long-period storage, never fail to perform air
calibration. For information on readjustment including air calibration, please contact RIKEN
KEIKI.

2. Important Notices on Safety 2-4. Safety information（for ATEX/IECEx specifications）
- 9 -
2-4. Safety information（for ATEX/IECEx specifications）
Portable gas leak detector SP-220 is a gas detector to continuously detect combustible gases.
The detector draws gases with the internal micro pump.
Use only two TOSHIBA AA alkaline batteries (LR6T) connected in series for power supply.
Do not replace the dry batteries in a hazardous location.
Explosion-proof specifications
･Ex ia IIC T4 Ga
･Operating temperature range: -20 to +55°C
Electrical specifications
･Only TOSHIBA AA alkaline batteries (LR6T) can be used.
Certificate Number
･IECEx: IECEx PRE 15.0060
･ATEX: Presafe15 ATEX7188
Applied standards
･IEC 60079-0:2011 ･EN60079-0:2012
･IEC 60079-11:2011 ･EN60079-11:2012
Precautions
･Do not replace the battery unit in a hazardous location.
･Do not replace the dry batteries in a hazardous location.
･Do not disassemble/modify the unit.
･Use only TOSHIBA AA alkaline batteries (LR6T) for the dry battery unit.
INST. No. 0 0 0 0 0 0 0 0 0 0 0
AB C D E
A: Manufacturingyear(0-9)
B: Manufacturingmonth(1-9,XYZforOct.-Dec.)
C: Manufacturinglot
D: Serialnumber
E: Factorycode
Manufacturer
RIKEN KEIKI CO., LTD.
2-7-6 Azusawa, Itabashi-ku, Tokyo, 174-8744 Japan
Web site: http://www.rikenkeiki.co.jp/
NOTE
TOSHIBA AA alkaline batteries (LR6) can be used for TIIS specifications.
･II 1 G Ex ia IIC T4 Ga

3. Product Components 3-1. Names and functions for each part
- 10 -
3
3. Product Components
3-1. Names and functions for each part
This section describes names and functions of main unit and battery unit parts and LCD display.
Main unit
No. Name Function
(1) Gas inlet Collects gases.
(2) Alarm LED arrays Blinks or lights up in response to an alarm.
(3) LCD display Displays gas concentrations, measured gas name, alarms, etc.
(4) AIR button Keep this switch pressed to perform air calibration. Used to change the
screen and decrease numerical values in the setting mode.
(5) MODE button Press this switch to change between display modes. Used to change
the screen and increase numerical values in the setting mode.
(6) POWER button Turns the power ON or OFF. Used to change the screen and confirm
values in the setting mode.
(7) Gas outlet Exhausts the gas drawn into the detector. (Do not block it.)
(8) Alarm LED arrays Blinks or lights up in response to an alarm.
(9) Infrared port Used during infrared communications.
(10) Battery cover Protects the battery. Remove it to replace the batteries.
(11) LED light Provides you light for work.
(10)
(11)
(1)
(2)
(3)
(4) (5)
(6)
(7)
(8)
(9)

3. Product Components 3-1. Names and functions for each part
- 11 -
Standard accessories
Unpack and check the main unit and accessories.
AA alkaline battery (2 pcs) (installed)
Taper nozzle (1 pc)
Rubber protection cover (1 pc) (Protect the detector from shocks by being hit, etc.)
Hand strap (1 pc)
Waterproofing filter for exchange (5 pcs)
Product warranty (1 pc)
Operating manual (1 pc)
Name Appearance/
weight Quantity Name Appearance/ weight Quantity
Rubber
protection
cover
1 pc
(attached)
AA
alkaline battery
2 pcs
(installed)
Taper nozzle 1 pc Hand strap 1 pc
Water-proofing
filter for
exchange
1 bag
(5 pcs
included)
Operating
manual －1 pc
Product
warranty －1 pc
If there is anything missing, contact RIKEN KEIKI.
Approx. 9 g
Approx. 70 mm
Approx. 2 g
A
pp
rox. 150 mm
CAUTION
Do not remove the panel sheet on the display. The water-proof and dust-proof performances will
be deteriorated.
Do not affix a label or the like on the infrared port. Infrared communications can no longer be
conducted.
Approx.
42 g
Approx. 44 g
Approx. 14.5 mm
Approx.
47mm
Approx. 42.5 mm
Approx. 149 mm
A
pp
rox. 50 mm
Approx. 1g
Approx.
φ16 mm
Plastic bag

3. Product Components 3-1. Names and functions for each part
- 12 -
LCD display
No. Name Function
(1) Operating state display Displays the operating status in the detection mode. Normal: Blinking
(2) Flow check display Displays the drawing status. Normal: Rotating
(3) Gas concentration
display
Displays gas concentration and unit.
(4) Alarm sound display Displays the setting status of the alarm sound.
(5) Operation sound
display
Displays the setting status of the operation sound.
(6) Battery level icon Displays a reference of the battery level.
(7) Bar meter display Displays the level of gas concentration with the bar meter
(8) Mode display Displays the measuring mode status.
(9) Gas name and
message display
Displays the gas name and a message according to the function.
NOTE
The meanings of battery level icons are as follows:
: Sufficient/ : Low/ : Needs replacement If the battery level further drops, the
inside of the battery icon starts to blink ( ).
(7)
(1)
(2)
(3)
(4)
(5)
(6)
(8)
(9)

4. How to Use 4-1. Before using the detector
- 13 -
4
4. How to Use
4-1. Before using the detector
Not only the first-time users but also the users who have already used the detector must follow the
operating precautions.
Ignoring the precautions may damage the unit, resulting in inaccurate gas measurement.
4-2. Preparation for start-up
Before starting gas detection, check the followings.
Check that the protective film attached on the display from shipping is removed
The batteries are installed (with sufficient battery level).
Check that the taper nozzle and filter are not contaminated.
Check that the taper nozzle is not bent or has no hole.
Check that the nipple to which the taper nozzle is attached is not loose.
4-3. How to replace the batteries
When the detector is used for the first time, or when the battery level is low, attach two new AA alkaline
batteries according to the following procedures.
1 Check that the power of the
detector is turned off.
Turn off the power if it is turned on.
2 Turn the lock plate
counterclockwise and open
the battery cover.
3 Remove old batteries and
then put new batteries
while observing the correct
polarity.
4 Close the battery cover and
turn the lock plate
clockwise to lock.
Battery cover
Lock plate Dry batteries
Displaying battery
polarity
CAUTION
The display is covered by the protective film to prevent scratches from shipping.
Be sure to remove this film before use.
Gas monitor with this film will not satisfy the explosion-proof performance.

4. How to Use 4-3. How to replace the batteries
- 14 -
CAUTION
Never fail to turn off the power of the detector before replacing the batteries.
Replace the batteries in a safe place.
Replace both of the two batteries with new ones at one time.
Pay attention to the polarities during replacement. Replace while checking the battery polarities
stamped on the body.
If the battery cover is not completely locked, the dry batteries may drop off or water may get in
through the clearance. Water may also get in if a minute foreign substance is caught between
the detector and battery cover.

4. How to Use 4-4. How to start the detector
- 15 -
4-4. How to start the detector
When the power is turned on, a self-diagnostic starts, and then the detector enters the detection mode.
Power-on
Press and hold the POWER button until the buzzer blips (one second or longer) to turn on the power.
When the power is turned on, the LCD display changes automatically as shown below, and the detector
enters the detection mode.
(Display example: For city gases)
1 Press and hold the POWER button for one second or longer.
Hold it down until all the LCDs and alarm lamp light up and the buzzer blips.
All LCDs light
up Date/time display * Gas name/ full scale display Warm-up time
Display example:
Thursday,
October 01, 2015
12:34
Display example:
CH4
(Display for city
gases)
Detection mode Automatic air calibration
display
The buzzer blips
once and the
detection mode is
displayed.

4. How to Use 4-4. How to start the detector
- 16 -
* The date/time display is displayed only when the clock function is enabled. It is not displayed because the
clock function is disabled by default.
To enable the clock function, see "6-3. Clock function ON/OFF setting" on page 31.
NOTE
When powering on after leaving the detector for more than five minutes with the batteries removed,
such as when powering on for the first time, replacing the batteries, etc., or powering on with the
batteries inserted with incorrect polarities, a clock abnormality (FAIL CLOCK) may be triggered.
When it is reset using the MODE button, the detector moves to the date/time setting screen. See "6-2.
Date/time setting" on page 30 and set the date/time.
Warm-up time (WARM UP) is different depending on the stability status of the sensor.
If the detector is not used for a long period, warm-up time may be longer or a sensor abnormality
(FAIL SENSOR) may be displayed. In such a case, restart the detector.
The detector performs air calibration automatically on start-up. If an environment where the detector
is turned on is different from the measured atmosphere, perform air calibration again in the measured
atmosphere.
About LCD backlight
Pressing the AIR, MODE or POWER button turns on the LCD backlight. The LCD backlight goes off
after 30 seconds or so of no operation.
When an alarm is triggered, the LCD backlight lights up automatically.

4. How to Use 4-5. Basic operating procedures
- 17 -
4-5. Basic operating procedures
The detection mode is used after power-on.
(Display example: For city gases)
* Displayed only when the clock
function is enabled. See "6-3.
Clock function ON/OFF setting"
on page 31.
AIR + POWER buttons
Hold down for
3 secs
Illumination
lamp lights
up
<Operation/alarm sound ON/OFF>
MODE button
Hold down for
1 sec
Hold down for
3 secs
<Peak clear> <Peak hold ON/OFF> <Display mode>
AIR button
Hold down for
3 secs
<AIR calibration>
AIR + MODE buttons MODE + POWER buttons
<Alarm setpoint change> <Snap logger record>

4. How to Use 4-6. How to detect
- 18 -
4-6. How to detect
Put the tip of the taper nozzle close to the detection area in the detection mode and perform gas detection.
If a gas is drawn, the detected gas concentration is displayed with the bar meter on the LCD display.
CAUTION
Before performing gas detection, attach the taper nozzle provided with the detector to prevent
disturbances by air dust.
DANGER
While conducting measurement in a manhole or confined space, do not lean over or look into
the manhole or closed space. It may lead to dangers because oxygen-deficient air or other
gases may blow out.
Oxygen-deficient air or other gases may be discharged from the gas exhausting outlet of the
detector. Never inhale the air or gases.
High-concentration (100% LEL or higher) combustible gases may be discharged from the gas
exhausting outlet of the detector. Never use fire near it.
WARNING
The detector is designed to draw gases around it under the atmospheric pressure. If excessive
pressure is applied to the gas inlet and outlet of the detector, detected gases may leak out from
its inside and may cause dangerous conditions. Be sure that excessive pressure is not applied
to the detector while used.
When air calibration is performed in the atmosphere, check the atmosphere for freshness
before beginning it. If interference gases or other gases exist, the adjustment cannot be
performed properly, thus leading to dangers when the gas leaks.
Issuance of a gas alarm indicates that there are extreme dangers. Take proper actions based
on your judgment.
Before use, check that there remains sufficient battery power. When the detector is not used for
a long period, the batteries may be exhausted. Never fail to replace them with new ones before
use.
If a low battery alarm is triggered, gas detection cannot be conducted. If the alarm is triggered
during use, turn off the power and promptly replace the batteries in a safe area.
Do not block the buzzer sound opening. No alarm sound can be heard.
If the main unit is dropped or given a shock, the reading may rise and it may remain so. In such
a case, perform air calibration in a place where the surrounding air is fresh.

4. How to Use 4-7. Change of the alarm setpoint
- 19 -
4-7. Change of the alarm setpoint
In the detector, the alarm setpoint of city gas (CH4) and LP gas (LPG) is factory set to 30 ppm.
The alarm setpoint can be changed, depending on the purpose, in five levels.
How to change the alarm setpoint
1 In the detection mode, press the AIR and MODE buttons at the same time.
The alarm setpoint changes by five every time the AIR and MODE buttons are pressed.
NOTE
The alarm setpoint cannot be set to 10000 ppm.

4. How to Use 4-8. Performing air calibration
- 20 -
4-8. Performing air calibration
After a high-concentration gas is detected or an alarm is triggered by temperature/humidity changes,
perform air calibration in the measured atmosphere.
* Before performing air calibration, check that the surrounding air is fresh.
(Display example: For city gases)
1 In the detection mode,
hold down the AIR button.
(Display for city gases)
2 Release the AIR button
when the display
changes from "HOLD
AIR" to "RELEASE".
(Buzzer sound: Three times <blip,
blip, blip>)
▼
▼
The air calibration is done and the
detector returns to detection
mode.
(Buzzer sound: Once <blip>)
If air calibration fails, "FAIL AIR
CAL" is displayed.
Perform air calibration again in
fresh surrounding air.