Alicat PCU Portable Calibration Unit - Manual (Page 25)

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Slower response than specified.
PCU meters feature an RS-232 programmable Geometric Running Average (GRA). Depending on the
full scale range of the meter, it may have the GRA set to enhance the stability/readability of the display,
which would result in slower perceived response time. If you require the fastest possible response time,
please consult the factory for written instructions on adjusting the GRA.
Jumps to zero at low flow.
PCU meters feature an RS-232 programmable zero deadband. The factory setting is usually 0.5% of
full scale. This can be adjusted via RS-232 programming between NONE and 6.375% of full scale.
Contact the factory for more information.
Discrepancies between old and new units.
Please see “Standard Gas Data Tables” explanation on page 21.
Maintenance and Recalibration
General: The PCU requires minimal maintenance. It has no moving parts. The single most important
thing that affects the life and accuracy of these devices is the quality of the gas being measured. The
meters are designed to measure CLEAN, DRY, NON-CORROSIVE gases. A 20 micron filter (50 micron
for 50 LPM and up) mounted upstream of the meter is highly recommended. Moisture, oil, and other
contaminants can affect the laminar flow elements and/or reduce the area that is used to calculate the
flow rate. This directly affects the accuracy.
Recalibration: The recommended period for recalibration is once every year. Providing that the CLEAN,
DRY, and NON-CORROSIVE mantra is observed, this periodic recalibration is sufficient. A label located
on the control panel of the device lists the recalibration due date. The device should be returned to the
factory for recalibration near the listed due date. Before calling to schedule a recalibration, please note
the serial number of the device. The Serial Number, Model Number, and Date of Manufacture are also
available on the Manufacture Data 2 screen (page 11).
Cleaning: The PCU requires no periodic cleaning. The outside of the case can be washed as necessary.
The control panel and displays may be cleaned with a soft dry rag. Avoid excess moisture or solvents.
For repairs, recalibrations, or recycling of this product, contact:
Alicat Scientific, Inc.
7641 N Business Park Drive
Tucson, Arizona 85743
USA
Ph. 520-290-6060
Fax 520-290-0109
email: [email protected]
Web site: www.alicatscientific.com