Sentry ST312A User manual

ST312A
Refrigerant
Leak Detector
Instruction Manual
Ver. 01 _20220622.

Table Content
1.
Introduction
1-1. Features
1-2. Applications
2.
Safety Information
2-1. Safety symbols
2-2. Warning
3.
Product Specifications
4.
General Descriptions
4-1. Parts and Control Panel
4-2. Lithium Battery Storage and Care
4-3. Charging the Lithium Battery
5. Operating Instructions
5-1. Main Function
5-1-1 Button Function -----------------------------
5-1-2 Low Battery Indicator ---------------------------
5-1-3 Sensor Failure Indicator -----------------------
5-2. Start with Auto/ Manual Reset Mode
5-2-1 Manual Reset Mode Inspection ---------------
5-2-2 Auto Reset Mode Inspection -----------
6. Maintenance
6-1. Leak Test Bottle
6-2. Probe Tip
6-3. Clean
6-4. Replacement Parts

1. Introduction
Thank you for purchasing the refrigerant leak detector.
Read through this instruction manual before operating the unit.
Please also store and retain this instruction manual for future reference.
1-1.Features
●LED Tip light ●3 adjustable sensitivity levels
●Mute function ●DC 3.7v rechargeable lithium battery
●USB power adaptor ●Extremely sensitive semiconductor sensor
●LED power indicator ●Multiple colors LED for leak level indictor
●Low battery indicator ●Detects R-22, R-32, R-134a, R-410a,andR-407c etc.
●Rugged flexible probe ●Automatic adjustment and reset to background
●Sensor failure indicator ●
Microcontroller circuitry that guarantees accuracy
and reliability
1-2.Applications
●Refrigeration ●Semiconductor production
●Air conditioning ●HVAC
●Laboratory accurate ●Automotive service
●Systems engineering ●Aircraft construction industry

2. Safety Information
Read the following safety information carefully before attempting to operate or
service the meter.
Only qualified personnel should perform repairs.
2-1.Safety symbols
Certification
This instrument conforms to the following standards:
EN61326-1:2021 : Electrical equipment formeasurement,control
and laboratory use
equipment EMC test.
IEC61000-4-2 : ESD immunity test.
IEC61000-4-3 : Radiated, radio-frequency,Electromagnetic field immunity test.
IEC61000-4-8 : Power frequency magnetic field immunity test.
RoHS
Restrict to use of ten substances within electrical and electronic equipment (EEE),
thereby contributing to the protection of human health and the environment.
REACH (SVHC)
The device of used materials content no following substances that list of proposed
REACH substances of very high concern.
The device may not be disposed of with the trash. It promotes the re-use
recycling and other forms of recovery of used materials and components, and
to improve the environmental performance of all operators (manufacturers, traders
and treatment facilities) involved in the life cycle of products. Dispose of the product
appropriately in accordance with the regulations in force in your country.

2-2.Warning
Please read the manual carefully to ensure safe and correct use of this meter before
using.
Please reread if necessary.
Be sure to adhere to the following points to avoid injury.
●Do not attempt to replace the sensor and LED.
●Do not attempt to repair it yourself if the meter is malfunction.
Only qualified personnel may do it.
●Do not force to bend the flexible probe over its limit of angle.
●Do not subject the probe tip to impact that could break the inside sensor.
●Do not use the meter in places where flammable or nearby the fire.
●Do not use this meter in environments outside this range: 32°F (0°C) to 122°F (50°C)
●Never use organic solvents to clean the meter.(Such as thinner, benzene, etc.)

3. Product Specifications
Model 312A
Sensor Semiconductor
Refrigerants R-22, R-32, R-134a, R-404a, R-410a,
and all CFCs, HCFCs and HFCs
Sensitivity levels High：0.15 oz/year(4g/year)
Medium：0.25 oz/year(7g/year)
Low：0.5 oz/year(14g/year)
Accuracy Compatibility with SAE J2791
Calibration Manually reset to background level
Automatic reset to background level
Response time Less than 0.5 second
Warm up time Approx. 50 seconds
Battery type 3.7V DC, 1960mAh rechargeable lithium
battery
Battery life Max. up to10 hours continuous use
after fully charged.
Sensor failure notification Yes
Audio alarm Yes(Buzzer)
Fan system Yes
Auto power off 10 minutes of idle.
Low battery indicator Yes (Battery Icon)
Tip light Yes
Flexible probe length 18”(450mm)
Operating temp. and %RH 32°F ~ 122°F(0°C ~ 50°C), ＜80%RH
Storage temp. and %RH 14°F ~ 140°F(-10°C ~ 60°C), ＜70%RH
Dimensions 7.2”x 2.8”x 1.6”(184 x 70 x 40 mm)
Weight 12 oz.(340g)
Accessories Included : Quick user's guide, USB cable, Leak test bottle
Option to buy: Charger, Rubber protector, Hard carrying case

4. General Descriptions
4-1. Parts and Control Panel
1. Power Button 9. Back Light ON/OFF Button
2. Sensitivity Level Indicator 10. Reset/Back Light Indicator
3. Leak Level Indicator 11. Reset Indicator
4. Sensor failure Indicator 12. MuteIndicator
5. Low Battery Indicator 13. Buzzer Output
6. Charging Indication 14. Mute Button
7. Reset Button 15.
Sensitivity Button(High、Medium、Low)
8. Tip Light LED ON/OFF Button 16. Flexible Probe
17. Tip Light

4-2.Lithium Battery Storage and Care
●Operating Temperature and Humidity:
Discharge : 32°F ~ 122°F(0°C ~ 50°C) ,less than 80% RH
Charging : 32°F ~ 113°F(0°C ~ 45°C) ,less than 80% RH
●Storage Humidity: Less than 70% RH
●Storage temperature and capacity recovery:
Temperature range Duration Capacity recovery
-4°F ~ 139°F (-20°C ~ +60°C) 1month 75%
-4°F ~ 113°F (-20°C ~ +45°C) 3months 70%
-4°F ~ 77°F (-20°C ~ +25°C ) 1year 80%
●In case of contacting the materials from the battery:
Skin Contact : Washing immediately with water and soap.
Eye Contact : Washing immediately with plenty of water for at least
15 minutes.
Get medical attention.
Ingestion : Get medical attention immediately.
Warning:
●When the battery has rust, bad smell or something abnormal at first-time-
using, do
not use and contact your dealer.
●
The battery is requested to be stored within a proper temperature range specified
in this specification.
●Do not disassemble or reconstruct battery.
●Do not give battery impact or fling it.
●Do not immerse the battery in water or sea water, or get it wet.
●Do use the specified charger and observe charging requirement.
●Do not continue to charge battery over specified time.
●Do not charge the battery near a fire or in a hot vehicle or direct sunlight.
●Do not use the battery with conspicuous damage or deformation.
●Charging temperature range is regulated between 32°F ~ 113°F(0°C ~ 45°C).
Do not charge the battery out of recommended temperature range.
Charging out of recommended range might cause the generating heat or serious
damage of battery.
And also, it might cause the deterioration of battery's characteristics and cycle life.
●Do not use or leave batter nearby fire, stove or heated place.
The battery may generate heat, smoke or flame.
And also, it might cause the deterioration of battery’s characteristics or cycle life.
●Avoid discharging the battery completely, it can
damage the performance of the
battery.

4-3.Charging the Lithium Battery
The detector will automatically turn off if the battery capacity is too low, charging it
when the LOW-BATT LED is lit.
It is highly recommended not to use the detector during charging, the battery may be
heated and dangerous.
The CHARGING LED be lit red color during charging, it will turn to green when
charging is completed.
Note: Always charge within the charging environment specifications of 32°F~113°F
(0°C~45°C), less than 80% RH.
The lithium battery is charged with AC power via AC adapter and USB cable:
(AC adapter/charger is not include)
1.
Use the AC adapter and plug mini B male into the mini B receptacle of the unit
(Fig. 1).
2. Plug the AC adapter to the wall jack (Fig. 2).
3.
Use the USB cable plug mini B receptacle of the unit and plug A male into PC or
Notebook USB port (Fig. 3).

5. Operating Instructions
5-1. Main Function
5-1-1 Button Function
●
Power Button
Turn ON:
Press and hold the Power button for 2 seconds to turn the detector on.
LCD screen will be lit with the start-up
buzzer beep (or, no buzzer beep under
MUTE mode).
Turn OFF:
Repeat to press and hold the Power button for 2 seconds again to turn the
detector off.
Warm-Up:
The detector will automatically start heating the sensor after power-on.
During the warm-up, the graphical Leak Level will be flashed.
After the warm-up, the leak level return to the lowest point, and the buzzer
beeps every 2 seconds (or, no buzzer beep under MUTE mode).
At this time the detector is ready to find leaks.
●
Sensitivity Button
Press the SENS button to change sensitivity.
High, Medium or Low sensitivity level is signed by its respective icons ,
and .
※The detector will automatically default
to previous sensitivity level after the
warm-up.
●
RESET Button
The reset modehas 2 kinds, Auto Rest Mode and Manual Rest Mode.
The factory default value is under Auto Rest Mode.
Press and hold the rest
button for 2 seconds to toggle to the
Auto/Manual reset mode.

Manual reset mode: The Reset Indicator on screen disappears and
will show for 2 secs.
Press the Rest button once to reset to background manually and the Reset
Indicator on screen flashes 1 sec. (Only in Manual reset mode.)
Auto reset Mode: TheReset Indicatoron screen appears and
will show for 2 secs.
Under auto reset mode,
pressing Rest Button is invalid, since the
detector will rest automatically.
●
MUTE Button
Press the Mute button to toggle the audio alarm on and off.
The buzzer alarm is turned off: The MUTE icon will be appeared.


The buzzer alarm is turned on: The MUTE icon will be off.
※
The detector will automatically default to previous MUTE ON/OFF setting
after re-start
The buzzer alarm is OFF
Under the MUTE mode, all audible beeps are off.
The buzzer alarm is ON
Button Tone
The buzzer gives one beep when any of button is pressed.
Detection Tone
The buzzer beeps every 2 seconds when no leak activity is found.
The buzzer becomes rapid when leak signal is approaching.
The fast beeps is given, the high density refrigerant is detected.
●
Tip Light LED Button

The tip light is always off after re-start.
Press the Tip Light LED Button to turn on/off the light of probe tip.

Backlight ON/OFF Button
Auto backlight Mode (Power-saving Mode)
When no leak activity is found and no buttonis pressedwithin 30secs, the
detector will enter Auto backlight Mode (Power-saving Mode
) to shutdown
LCD backlight. And thebacklight will be activated again after finding leak
activityor pressing any buttons.
※When detector entersAuto backlight Mode (Power-saving Mode),pressing
Backlight Button again, the detector will lit up the backlight on screen.
Manual backlight Mode
Under Manual backlight mode, pressing Backlight Button to toggle
backlight ON/OFF.
The backlight mode has 2 kinds, Auto backlight Mode and Manual backlight
Mode. The factory default value is under Auto backlight Mode.
Press and hold the Backlight Button for 2 seconds to toggle to the
Auto/Manual reset mode.
Manual backlight Mode:pressing and hold Backlight Button for 2 secs, and
will show on screen for 2 secs and the detector has enter
Manual backlight Mode.
Auto backlight Mode: pressing and hold Backlight Button for 2 secs, and
will show on screen for 2 secs and the detector has enter
Auto backlight Mode.
5-1-2 Low Battery Indicator
When the LOW-BATT icon is appeared：
Read the warning in the section 4-3 carefully and charge the battery by section 4-4.
If the battery capacity is too low, the detector will automatically turn off to protect
the lithium battery and electronics.

5-1-3 Sensor Failure Indicator
The sensor failure icon blinksand gives slow beep alarm when sensor was
misplaced or failure.
Please replace a new sensor by section 6-2 or contact your dealer.
5-2. Start with Auto/Manual Reset Mode
5-2-1
Manual Reset Mode Inspection
Reset manually to the background level in clear air, and then inspect the possible
leak point for at least 0.5 sec. The audio alarm sound
will become more rapid, when
close to the exact leak point.
Under Manual REST mode, please press button to rest the detector manually,
when the environment changes dramatically. (For example: Move the detector from
indoor to outdoor.)
5-2-2 Auto Reset Mode Inspection
1. Turn on the detector and wait until the warm-up is finished. After the warm-up,
toggle to high sensitivity level.
2. Open the seal cap of leak test bottle and take it to probe tip for a moment. If the
Leak Level Indicator on screenhas showed signal detection, the sensor and
electronics are working correctly.
3. Slowly move the probe tip to pass each possible point of leak at a rate of no faster
than 2 inches (5cm) per second.
Note: It is important to continually move the probe tip.
If held on a leak, the auto reset feature will reset this leak signal to the background
level.
4. When the detector discovers a leak source, the Leak Level Indicator will be lit
corresponding to the leak level and give beep alarm.
5. Move the probe tip away from the leak source for a moment (more than 2
seconds), then move it back to detect. Repeat to move back and forth, user can find
more accurate leakage area.
6. If user want to find exact leak point, user can use Auto Rest Mode to find the
leakage area first, and then toggle to manual reset mode.
Move the probe tip away from the leak source and reset manually in clear air, then
move it back to detect and compare with leak level to pinpoint the exactleak point.
If the refrigerant leak is large, toggling to lower sensitivity level will make it easier to

find the leak point.
※The manual reset mode can help user to find the leak point more exactly, but it may
also easily cause the false-trigger.
※The auto reset mode provides user with fast and convenient way to find the leak
area, but it is not proper to operate in following condition:
1.Detect a small leak in a higher refrigerant contaminated background.
2.Detect the leak level at fixed point.
Warning:
●Keep the detector away organic solvents (such as gases, alcohol).

6. Maintenance
6-1 Leak Test Bottle
Remember to close the seal cap of leak test bottle to avoid evaporating completely
after test.
6-2 Probe Tip
Replacement of the sensor or Tip Light LED (3V) is shown in the following figure :
Note: Turn off the detector before removing sensor.
1. The life of sensor is 1 year (normally use), if the sensors 100 PPM refrigerant,
exposed to characteristic may be affected.
2. Please mind there is no water drops, dusts in the surface of sensor.
6-3. Clean
Clean the Housing:
Never use organic solvents to clean the meter. (Such as thinner, benzene, etc.)
Warning:
The organic solvents might damage the sensor, please avoid the solvents contacts the
sensor.
6-4. Replacement Parts
●Sensor
●DC 3.7 V rechargeable lithium battery