GT-324 Manual
Page 18
GT-324-9800 Rev B
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:
1. Attach zero count filter to the inlet nozzle (PN G3111).
2. Configure the unit as follows: Samples = MANUAL, Sample Time = 60 seconds,
Volume = Total Count (TC)
3. Start and complete a sample.
4. The smallest particle size should have a count <= 1.
desired.
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.