Casella CEL DryCal DC-Lite flow calibrator - Manual (Page 7)

accurately mirroring the transient internal vibrations of the gauge. This type of
gauge must be isolated from the DryCal by inserting a suitable restriction between
the gauge and the calibrator
8.0 Maintenance, Quality Assurance
Although the DryCal DC-Lite is a rugged instrument, certain care and maintenance
requirements must still be met.
Current service and calibration information and pricing can be found at
www.biosint.com/service/dclite.htm.
8.1 Maintenance
When not in use always store your DC-Lite in a clean, dry environment. When
possible leave the unit on charge. Wipe only with a damp cloth and do not spray
with liquid solvents or use abrasive cleaners.
8.2 Leak-Test Procedure
A quality assurance self-test feature is provided to verify proper integrity
of the flow cell. It is recommended that the self-check leakage test be conducted
periodically as part of an on-going quality assurance program.
Passing the leak test does not ensure proper function of the DC-Lite. It does
ensure that total leakage is within the product’s allowable limits. To ensure proper
function of the DC-Lite annual factory calibration is recommended.
To Initiate the Leak-Test
The leak-test tubing accessory is a short piece of latex tubing with a red plug
that is found in the tubing kit shipped with your DC-Lite. Place the leak-test
tubing accessory over the top (inlet) air boss. The low flow range DC-Lite requires
a miniature leak-test tubing accessory that is supplied in addition to the
standard tubing kit. Any maintenance to the DryCal must be performed by Bios
maintenance personnel.
1 Press and hold the Stop button while pressing the On button. If the DC-Lite
is already on, press and hold the Stop button while pressing the hard reset
button on the back of the unit as described in Section 5.10. After a leak-test is
initiated, the display will read “Leak Test, Invert & Push Read.”
2 Invert the DC-Lite so the piston moves to the top of the cell. While the piston
is resting at the top of the cell press the Read button and the internal
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pressure spike is invisible to the flow source; however, it can cause an interaction
with some instruments (example: some mass flow controllers, Magnehelic
manometers and rotameters). The most common solution is to isolate the DryCal
with a restriction as described in Sections 7.1–7.4.
7.1 Use with Instruments that Contain Internal
Mass Flow Controllers (MFCs)
For some flow instruments with MFCs and large dead volumes (example: some
PM 2.5 monitors) results may not correlate between the instrument’s display and
the DryCal. To eliminate these discrepancies, Bios offers an active regulation
device, part DC-IR-H, to provide a constant insertion pressure.
7.2 Use with Personal Air Samplers
The DryCal DC-Lite may be used to calibrate or check the flow rate of personal air
samplers. To ensure accurate flow calibrations, Bios recommends the use of an
isolating flow restriction as described in Section 7.0. A standard MSHA approved
respirable dust filter or equivalent 25–37 mm 0.5 micron casette should be suffi-
cient to provide an appopriate isolation.
7.3 Calibrating Rotameters
When calibrating rotameters the DryCal DC-Lite should be used as a transfer
standard only. Do not use the DC-Lite in series with a rotameter. For optimum
accuracy, use a rotameter over its mid-range.
1 Attach an isolating load or sample medium, with a pressure drop of about
8 to 12 inches of water column, in series with a stable pump and a DryCal.
2 Calibrate the sampling pump at the desired flow setting (ie: 2.00 Lpm)
with the DryCal. When the desired flow setting is obtained, disconnect the
DryCal and attach the tubing to the outlet boss of the rotameter.
3 When the rotameter ball stabilizes, mark the rotameter for the true flow
rate (2.00 Lpm for example) using tape and a permanent marker to denote
the calibrated flow setting or note the point on a rotameter flow chart.
Repeat this procedure for any additional flow settings.
7.4 Use with Magnehelic Manometers
High-capacitance spring-loaded gauges such as Magnehelic manometers can
cause vibration of the DryCal piston. This is not a defect in the DryCal. The piston is
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