GT-324
MANUAL
GT-324 Handheld Particle Counter
Copyright Notice
© Copyright 2018 Met One Instruments, Inc. All Rights Reserved Worldwide. No part of this publication may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any other language in any form by any means without the express written permission of Met One Instruments, Inc.
Technical Support
Should you require support, please consult your printed documentation to resolve your problem. If you are still experiencing difficulty, you may contact a Technical Service representative during normal business hours—7:00 a.m. to 4:00 p.m. Pacific Time,
Monday through Friday.
Voice: 541-471-7111
Fax: 541-471-7116
E-Mail: service@metone.com
Mail: Technical Services Department
Met One Instruments, Inc.
1600 NW Washington Boulevard
Grants Pass, OR 97526
NOTICE
CAUTION— Use of controls or adjustments or performance of procedures other than those specified herein may result in hazardous radiation exposure.
WARNING— This product, when properly installed and operated, is considered a Class I laser product. Class I products are not considered to be hazardous.
There are no user serviceable parts located inside the cover of this device.
Do not attempt to remove the cover of this product. Failure to comply with this instruction could cause accidental exposure to laser radiation.
Introduction
The GT-324 is a small lightweight four channel hand held particle counter. Key features include:
- Simple user interface with multifunction rotary dial (rotate and press)
- 8 hours continuous operation
- 4 count channels. All channels are user selectable to 1 of 7 preset sizes: (0.3μm, 0.5μm, 0.7μm, 1.0μm, 2.5μm, 5.0μm and 10μm)
- Concentration and total count modes
- Fully integrated temperature/relative humidity sensor
- Password protection for user settings
Setup
The following sections cover unpacking, layout and performing a test run to verify operation.
2.1. Unpacking
When unpacking the GT-324 and accessories, inspect the carton for obvious damage.
If the carton is damaged notify the carrier. Unpack everything and make a visual inspection of the contents. Standard items (included) are shown in
Figure 1 – Standard Accessories. Optional accessories are shown in
Figure 2 – Optional Accessories.
ATTENTION:
A Silicon Labs CP210x Driver for the USB connection must be installed before connecting the GT-324 USB port to your computer. If this driver is not installed first,
Windows may install generic drivers that are not compatible with this product. See section 6.1.
Driver download weblink: https://metone.com/usb-drivers/
2.2. Layout
The following figure shows the layout of the GT-324 and provides a description of the components.
| Component | Description |
| Display | 2X16 character LCD display |
| Keyboard | 2 key membrane keypad |
| Rotary dial | Multifunction dial (rotate and press) |
| Charger Jack | Input jack for external battery charger. This jack charges the internal batteries and provides continuous operating power for the unit. |
| Flow Adjust | Adjusts the sample flow rate |
| Inlet Nozzle | Sample nozzle |
| USB Port | USB communication port |
| Temp/RH Sensor | Integrated sensor that measures ambient temperature and relative humidity. |
2.3. Default Settings
The GT-324 comes with the user settings configured as follows.
| Parameter | Value |
| Sizes | 0.3, 0.5, 5.0, 10 mm |
| Temperature | C |
| Sample Location | 1 |
| Sample Mode | Manual |
| Sample Time | 60 seconds |
| Count Units | CF |
2.4. Initial Operation
The battery should be charged for 2.5 hours prior to use. Refer to Section 7.1 of this manual for battery charging information.
Complete the following steps to verify proper operation.
- Press the Power key for 0.5 seconds or more to turn on power.
- Observe the Startup screen for 3 seconds then the Sample screen (Section 4.2)
- Press Start / Stop key. The GT-324 will sample for 1 minute and stop.
- Observe the counts on the display
- Rotate the Select dial to view other sizes
- The unit is ready for use
User Interface
The GT-324 user interface is composed of a rotary dial, 2 button keypad and an LCD display. The keypad and rotary dial are described in the following table.
| Control | Description | |
| Power Key | Power the unit on or off. For power on, press for 0.5 seconds or more. | |
| Start / Stop Key | Sample Screen | START / STOP a sample event |
| Settings Menu | Return to Sample screen | |
| Edit Settings | Cancel edit mode and return to the Settings Menu | |
| Select Dial | Rotate the dial to scroll through selections or change values. Press the dial to select item or value. | |
Operation
The following sections cover the basic operation of GT-324.
4.1. Power Up
Press the Power key to power up the GT-324. The first screen shown is the Startup Screen (Figure 4). The Startup Screen displays the product type and company website for approximately 3 seconds before loading the Sample Screen.
4.1.1. Auto Power Off
The GT-324 will power down after 5 minutes to preserve battery power providing the unit is stopped (not counting) and there is no keyboard activity or serial communications.
4.2. Sample Screen
The Sample Screen displays sizes, counts, count units, and time remaining. The time remaining is displayed during sample events. The Sample Screen is shown in Figure 5 below.
Channel 1 (0.3) is displayed on Sample Screen Line 1. Rotate the Select dial to display channels 2-4, battery status, ambient temperature, and relative humidity on line 2 (Figure 6).
4.2.1. Warnings / Errors
The GT-324 has internal diagnostics to monitor critical functions such as low battery, system noise and an optical engine failure. Warnings / errors are displayed on Sample Screen Line 2. When this occurs, simply rotate the Select dial to view any size on the top line.
A low battery warning occurs when there is approximately 15 minutes of sampling remaining before the unit stops sampling. A low battery condition is shown in Figure 7 below.
Excessive system noise can result in false counts and reduced accuracy. The GT-324 automatically monitors system noise and displays a warning when the noise level is high. The primary cause of this condition is contamination in the optical engine. Figure 7 shows the Sample screen with a System Noise warning.
A sensor error is reported when the GT-324 detects a failure in the optical sensor.
Figure 9 shows a sensor error.
4.3. Sampling
The following sub-sections cover sample related functions.
4.3.1. Starting/Stopping
Press the START/STOP key to start or stop a sample from the Sample Screen.
Depending on the sample mode, the unit will either run a single sample or continuous samples. Sample modes are discussed in Section 4.3.2.
4.3.2. Sample Mode
The sample mode controls single or continuous sampling. The Manual setting configures the unit for a single sample. The Continuous setting configures the unit for
nonstop sampling.
4.3.3. Count Units
The GT-324 supports total counts (TC), particles per cubic foot (CF), particles per cubic meter (M3) and particles per liter (/L). Concentration values (CF, /L, M3) are time dependent. These values may fluctuate early in the sample; however, after several seconds the measurement will stabilize. Longer samples (e.g. 60 seconds) will improve concentration measurement accuracy.
4.3.4. Sample Time
Sample time determines the sample duration. Sample time is user settable from 3 to 60 seconds and is discussed in Sample Timing below.
4.3.5. Hold Time
The hold time is used when Samples is set for more than one sample. The hold time represents the time from the completion of the last sample to the start of the next
sample. The hold time is user settable from 0 – 9999 seconds.
4.3.6. Sample Timing
The following figures depict the sample timing sequence for both manual and continuous sampling. Figure 10 shows the timing for manual sample mode. Figure 11
shows the timing for continuous sample mode. The Start section includes a 3 second purge time.
Use the Settings Menu to view or change configuration options.
5.1. View Settings
Press the Select dial to navigate to the Settings Menu. Rotate the Select dial to scroll through the settings in the following table. To return to the Sample screen, press
Start/Stop or wait 7 seconds.
The Settings menu contains the following items.
| Function | Description |
| LOCATION | Assign a unique number to a location or area. Range = 1 – 999 |
| SIZES | The GT-324 has four (4) programmable count channels. The operator can assign one of seven preset sizes to each count channel. Standard sizes: 0.3, 0.5, 0.7, 1.0, 2.5, 5.0, 10. |
| MODE | Manual or Continuous. The Manual setting configures the unit for a single sample. The Continuous setting configures the unit for nonstop sampling. |
| COUNT UNITS | Total Count (TC), Particles / cubic foot (CF), particles / L (/L), particles / cubic meter (M3). See Section 4.3.3. |
| TEMP UNITS | Celsius (C) or Fahrenheit (F) temperature units. See Section 5.2.6 |
| HISTORY | Display previous samples. See Section 5.1.1 |
| SAMPLE TIME | See Section 4.3.4. Range = 3 – 60 seconds |
| HOLD TIME | See Section 4.3.5. Range 0 – 9999. |
| TIME | Display / enter time. Time format is HH:MM:SS (HH = Hours, MM = Minutes, SS = Seconds). |
| DATE | Display / enter date. Date format is DD/MMM/YYYY (DD = Day, MMM = Month, YYYY = Year) |
| FREE MEMORY | Display the percentage of memory space which is available for data storage. When Free Memory = 0%, the oldest data will be overwritten with new data. |
| PASSWORD | Enter a four (4) digit numeric number to prevent unauthorized changes to the user settings. |
| ABOUT | Display model number and firmware version |
5.1.1. View Sample History
Press the Select dial to navigate to the Settings Menu. Rotate the Select dial to the History selection. Follow the steps below to view sample history. To return to the Settings Menu, press Start/Stop or wait 7 seconds.
| Press to View HISTORY |
Press Select to view history. |
 |
GT-324 will display the last record (Date, Time, Location, and Record Number). Rotate dial to scroll through records. Press to view record. |
 |
Rotate dial to scroll through record data (counts, date, time, alarms). Press Start/Stop to return to previous screen. |
5.2. Edit Settings
Press the Select dial to navigate to the Settings Menu. Rotate the Select dial to scroll to the desired setting then press the Select dial to edit the Setting. A blinking cursor will indicate edit mode. To cancel edit mode and return to the Settings Menu, press Start/Stop.
Edit mode is disabled when the GT-324 is sampling (see below).
| Sampling… Press Stop Key | Screen displayed for 3 seconds then return to Settings Menu |
5.2.1. Password Feature
The following screen is displayed if you attempt to edit a setting when the password feature is enabled. The unit will remain unlocked for a period of 5 minutes after a successful password unlock code is entered.
 |
Press Select to enter Edit mode. Return to Sample screen if no Select key in 3 seconds |
 |
Blinking cursor indicates Edit mode. Rotate dial to scroll value. Press dial to select next value. Repeat action until last digit. |
 |
Rotate dial to scroll value. Press dial to exit Edit Mode. |
| Incorrect Password! | Screen displayed for 3 seconds if the password is incorrect. |
5.2.2. Edit Location Number
 |
View screen. Press Select to enter Edit mode. |
 |
Blinking cursor indicates Edit mode. Rotate dial to scroll value. Press dial to select next value. Repeat action until last digit. |
 |
Rotate dial to scroll value. Press dial to exit Edit Mode and return to view screen. |
5.2.3. Edit Sizes
| Press to View CHANNEL SIZES |
Press Select to view Sizes. |
 |
Sizes view screen. Rotate dial to view channel sizes. Press dial to change setting. |
 |
Blinking cursor indicates Edit mode. Rotate dial to scroll values. Press dial to exit Edit mode and return to view screen. |
5.2.4. Edit Sample Mode
 |
View screen. Press Select to enter edit mode. |
 |
Blinking cursor indicates Edit mode. Rotate dial to toggle value. Press dial to exit Edit mode and return to view screen. |
5.2.5. Edit Count Units
 |
View screen. Press Select to enter edit mode. |
 |
Blinking cursor indicates Edit mode. Rotate dial to toggle value. Press dial to exit Edit mode and return to view screen. |
5.2.6. Edit Temp Units
 |
View screen. Press Select to enter edit mode. |
 |
Blinking cursor indicates Edit mode. Rotate dial to toggle value. Press dial to exit Edit mode and return to view screen. |
5.2.7. Edit Sample Time
 |
View screen. Press Select to enter Edit mode. |
 |
Blinking cursor indicates Edit mode. Rotate dial to scroll value. Press dial to select next value. |
 |
Rotate dial to scroll value. Press dial to exit Edit Mode and return to view screen. |
5.2.8. Edit Hold Time
 |
View screen. Press Select to enter Edit mode. |
 |
Blinking cursor indicates Edit mode. Rotate dial to scroll value. Press dial to select next value. Repeat action until last digit. |
5.2.9. Edit Time
 |
View screen. Time is real time. Press Select to enter edit mode. |
 |
Blinking cursor indicates Edit mode. Rotate dial to scroll values. Press dial to select next value. Repeat action until last digit. |
 |
Last digit. Rotate dial to scroll values. Press dial to exit Edit mode and return to view screen. |
5.2.10.Edit Date
 |
View screen. Date is real time. Press Select to enter edit mode. |
 |
Blinking cursor indicates Edit mode. Rotate dial to scroll values. Press dial to select next value. Repeat action until last digit. |
 |
Rotate dial to scroll values. Press dial to exit Edit mode and return to view screen. |
5.2.11. Clear Memory
 |
View screen. Available memory. Press Select to enter edit mode. |
 |
Hold Select dial for 3 seconds to clear memory and return to view screen. Return to view screen if no action for 3 seconds or key hold time is less than 3 seconds. |
5.2.12. Edit Password
 |
View screen. #### = Hidden password. Press Select to enter Edit mode. Enter 0000 to disable password (0000 = NONE). |
 |
Blinking cursor indicates Edit mode. Rotate dial to scroll value. Press dial to select next value. Repeat action until last digit. |
 |
Rotate dial to scroll value. Press dial to exit Edit Mode and return to view screen. |
Serial Communications
Serial communications, firmware field upgrades and real time output are provided via the USB port located on the side of the unit.
6.1. Connection
ATTENTION:
A Silicon Labs CP210x Driver for the USB connection must be installed before connecting the GT-324 USB port to your computer.
Driver download weblink: https://metone.com/usb-drivers/
6.2. Comet Software
The Comet software is a utility for extracting information (data, alarms, settings, etc.) from Met One Instruments products. The software is designed for the user to easily access information within a product without having to know underlying communications protocol for that device.
The Comet software can be downloaded at https://metone.com/software/ .
6.3. Commands
The GT-324 provides serial commands for accessing stored data and settings. The protocol is compatible with terminal programs such as Comet, Putty or Windows HyperTerminal.
The unit returns a prompt (‘*’) when it receives a carriage return to indicate a good connection. The following table lists the available commands and descriptions.
| SERIAL COMMANDS | ||
| Protocol Summary: · 38,400 Baud, 8 Data bits, No Parity, 1 Stop Bit · Commands (CMD) are UPPER or lower case · Commands are terminated with a carriage return <CR> · To view setting = CMD <CR> · To change setting = CMD <SPACE> <Value> <CR> |
||
| CMD | Type | DESCRIPTION |
| ?,H | Help | View the help menu |
| 1 | Settings | View the settings |
| 2 | All data | Returns all available records. |
| 3 | New data | Returns all records since last ‘2’ or ‘3’ command. |
| 4 | Last data | Returns the last record or last n records (n = <Value>) |
| D | Date | Change date. Date is format is MM/DD/YY |
| T | Time | Change time. Time format is HH:MM:SS |
| C | Clear data | Displays a prompt for clearing the stored unit data. |
| S | Start | Start a sample |
| E | End | Ends a sample (abort the sample, no data record) |
| ST | Sample time | View / change the sample time. Range 3-60 seconds. |
| ID | Location | View / change the location number. Range 1-999. |
| CS w x y z | Channel Sizes | View / change channel sizes where w=Size1, x=Size2, y=Size3 and z=Size4. Values (w x y z) are 1=0.3, 2=0.5, 3=0.7, 4=1.0, 5=2.5, 6=5.0, 7=10 |
| SH | Hold Time | View / change the hold time. Values are 0 – 9999 seconds. |
| SM | Sample mode | View / change sample mode. (0=Manual, 1= Continuous) |
| CU | Count units | View / change count units. Values are 0=CF, 1=/L, 2=TC |
| OP | Op Status | Replies OP x, where x is “S” Stopped or “R” Running |
| RV | Revision | View Software Revision |
| DT | Date Time | View / change date and time. Format = DD-MM-YY HH:MM:SS |
6.4. Real Time Output
The GT-324 outputs real time data at the end of each sample. The output format is a comma separated values (CSV). The following sections show the format.
6.5. Comma Separated Value (CSV)
A CSV header is included for multiple record transfers like Display All Data (2) or Display New Data (3).
CSV Header:
Time, Location, Sample Time, Size1, Count1 (units), Size2, Count2 (units), Size3, Count3 (units), Size4, Count4 (units), Ambient Temperature, RH, Status
CSV Example Record:
31/AUG/2010 14:12:21, 001,060,0.3,12345,0.5,12345,5.0,12345,10,12345,22.3, 58,000<CR><LF>
Note: Status bits: 000 = Normal, 016 = Low Battery, 032 = Sensor Error, 048 = Low battery and Sensor Error.
Maintenance
WARNING: There are no user serviceable components inside this instrument. The covers on this instrument should not be removed or opened for servicing, calibration or any other purpose except by a factory-authorized person. To do so may result in exposure to invisible laser radiation that can cause eye injury.
7.1. Charging the Battery
Caution:
The provided battery charger is designed to work safely with this device. Do not attempt to connect any other charger or adapter to this device. Doing so may
result in equipment damage.
To charge the battery, connect the battery charger module AC power cord to an AC power outlet and the battery charger DC plug to the socket on the side of the GT-324.
The universal battery charger will work with power line voltages of 100 to 240 volts, at 50/60 Hz. The battery charger LED indicator will be Red when charging and Green when fully charged. A discharged battery pack will take approximately 2.5 hours to fully charge.
There is no need to disconnect the charger between charging cycles because the charger enters a maintenance mode (trickle charge) when the battery is fully charged.
7.2. Service Schedule
Although there are no customer serviceable components, there are service items which ensure the proper operation of the instrument. Table 1 shows the recommended service schedule for the GT-324.
| Item To Service | Frequency | Done By |
| Flow rate test | Monthly | Customer or Factory Service |
| Zero test | Optional | Customer or Factory Service |
| Inspect pump | Yearly | Factory service only |
| Test battery pack | Yearly | Factory service only |
| Calibrate Sensor | Yearly | Factory service only |
Table 1 Service Schedule
7.2.1. Flow Rate Test
The sample flow rate is factory set to 0.1cfm (2.83 lpm). Continued use can cause minor changes in flow which can reduce measurement accuracy. A flow calibration kit is available separately that includes everything needed to test and adjust the flow rate.
To test the flow rate: remove the Isokinetic inlet. Attach the tubing connected to the flow meter (MOI# 9801) to the instrument inlet. Start a sample, and note the flow meter reading. The flow rate should be 0.10 CFM (2.83 LPM) ±5%.
If the flow is not within this tolerance, it can be adjusted by a trim pot located in an access hole in the side of the unit. Turn the adjustment pot clockwise to increase the
flow and counter-clockwise to decrease the flow.
7.2.1. Zero Count Test
Air leaks or debris in the particle sensor can cause false counts which may result in significant count errors when sampling in clean environments. Perform the following zero count test weekly to ensure proper operation:
- Attach zero count filter to the inlet nozzle (PN G3111).
- Configure the unit as follows: Samples = MANUAL, Sample Time = 60 seconds, Volume = Total Count (TC)
- Start and complete a sample.
- The smallest particle size should have a count <= 1.
7.2.2. Annual Calibration
The GT-324 should be sent back to Met One Instruments yearly for calibration and inspection. Particle counter calibration requires specialized equipment and training.
The Met One Instruments calibration facility uses industry accepted methods such as ISO.
In addition to calibration, the annual calibration includes the following preventative maintenance items to reduce unexpected failures:
- Inspect filter
- Inspect / clean optical sensor
- Inspect pump and tubing
- Cycle and test the battery
- Verify RH and Temperature measurements
7.3. Flash Upgrade
Firmware can be field upgraded via the USB port. Binary files and the flash program must be provided by Met One Instruments.
Troubleshooting
WARNING: There are no user serviceable components inside this instrument. The covers on this instrument should not be removed or opened for servicing, calibration or any other purpose except by a factory-authorized person. To do so may result in exposure to invisible laser radiation that can eye injury.
The following table covers some common failure symptoms, causes and solutions.
| Symptom | Possible Cause | Correction |
| Low battery message | Low battery | Charge battery 2.5 hrs |
| System noise message | Contamination | 1. Blow clean air into nozzle (low pressure, do not connect via tubing) 2. Send to service center |
| Sensor error message | Sensor failure | Send to service center |
| Does not turn on, no display | 1. Dead battery 2. Defective Battery |
1. Charge battery 2.5 hrs 2. Send to service center |
| Display turns on but pump does not | 1. Low Battery 2. Defective pump |
1. Charge battery 2.5 hrs 2. Send to service center |
| No counts | 1. Pump stopped 2. Laser diode bad |
1. Send to service center 2. Send to service center |
| Low counts | 1. Incorrect flow rate 2. Calibration drift |
1. Check flow rate 2. Send to service center |
| High counts | 1. Incorrect flow rate 2. Calibration drift |
1. Check flow rate 2. Send to service center |
| Battery pack does not hold a charge | 1. Defective battery pack 2. Defective charger module |
1. Send to service center 2. Replace charger |
Specifications
Features:
| Size Range: | 0.3 to 10.0 microns |
| Count Channels: | 4 channels preset to 0.3, 0.5, 5.0 and 10.0 μm |
| Size Selections: | 0.3, 0.5, 0.7, 1.0, 2.5, 5.0 and 10.0 μm |
| Accuracy: | ± 10% to traceable standard |
| Concentration Limit: | 3,000,000 particles/ft³ |
| Temperature | ± 3 °C |
| Relative Humidity | ± 5% |
| Flow Rate: | 0.1 CFM (2.83 L/min) |
| Sampling Mode: | Single or Continuous |
| Sampling Time: | 3 – 60 seconds |
| Data Storage: | 2200 records |
| Display: | 2 line by 16-character LCD |
| Keyboard: | 2 button with rotary dial |
| Status Indicators: | Low Battery |
| Calibration | NIST, ISO |
Measurement:
| Method: | Light scatter |
| Light Source: | Laser Diode, 35 mW, 780 nm |
Electrical:
| AC Adapter/Charger: | AC to DC module, 100 – 240 VAC to 8.4 VDC |
| Battery Type: | Li-ion rechargeable Battery |
| Battery Operating Time: | 8 hours continuous use |
| Battery Recharge Time: | 2.5 hours typical |
| Communication: | USB Mini B Type |
Physical:
| Height: | 6.25” (15.9 cm) |
| Width: | 3.65” (9.3 cm) |
| Thickness: | 2.00” (5.1 cm) |
| Weight | 1.6 lbs – (0.73 kg) |
Environmental:
| Operating Temperature: | 0º C to +50º C |
| Humidity | 0 – 90%, noncondensing |
| Storage Temperature: | -20º C to +60º C |
Warranty / Service Information
Warranty
Products manufactured by Met One Instruments, Inc. are warranted against defects and workmanship for a period of one (1) year from the ship date.
Any product found to be defective during the warranty period will, at the option of Met One Instruments. Inc.. be replaced or repaired. In no case shall the liability of Met One Instruments. Inc. exceed the purchase price of the product.
This warranty may not apply to products that have been subject to misuse, negligence, accident. acts of nature, or that have been altered or modified other than by Met One Instruments, Inc. Consumable items such as filters, bearings pumps and batteries are not covered under this warranty.
Other than the warranty set forth herein, there shall be no other warranties, whether expressed, implied or statutory, including warranties of fitness of merchantability.
Service
Any product being returned to Met One Instruments, Inc. for service, repair or calibration, including items sent for warranty repair, must be assigned a return authorization (R AI number. Please call 541-471-7111 or send an email to servicea@metone.com requesting an RA number and shipping instructions.
All returns must be shipped to the factory. freight pre-paid. Met One Instruments. Inc. will pay the shipping charge to return the product to the end user after repair or replacement of an item covered by warranty.
All instruments sent to the factory for repair or calibration must be free of contamination resulting from sampling chemicals, biological matter, or radioactive materials. Any items received with such contamination will be disposed and the customer will be billed a disposal fee.
Replacement parts or service/repair work performed by Met One Instruments, Inc. are warranted against defects in material and workmanship for a period of ninety (90) days from the date of shipment, under the same conditions as stated above.
GT-324 Manual
GT-324-9800 Rev E
Documents / Resources
 |
MET ONE INSTRUMENTS GT-324 Handheld Particle Counter [pdf] User Manual GT-324-9800, GT-324, GT-324 Handheld Particle Counter, Handheld Particle Counter, Particle Counter |