Thermo 48i, Instruction Manual

Page: 153 / 302

Calibration
References
Thermo Electron Corporation Model 48 i Instruction Manual 4-7
2. Periodically challenging the instrument with a CO level of
approximately 80% of the URL. The 80% URL level may be obtained
by dilution of a higher level of CO using a system similar to that of
Figure 4-1, or by using a low level cylinder of CO containing CO in air
at a concentration of approximately 80% of the URL. In either case the
cylinder of CO should be checked against an SRM or CRM. It should
also be true for a cylinder of low level CO.
The Quality Assurance Handbook
1
should be referred to for the cylinder
checking procedure.
Record the instrument’s response in % of scale as A
80
. Compute the
span error from the following equation:
Where:
Z = Recorder response obtained at the last calibration for zero air, % scale.
[CO] = Span concentration
3. Latest copy of the Quality Assurance Handbook for Air Pollution
Measurement Systems
1
should be consulted to determine the level of
acceptance of zero and span errors.
For detailed guidance in setting up a quality assurance program, refer to
the
Code of Federal Regulations
3
and the EPA Handbook on Quality
Assurance
1
.
References
1. QUALITY ASSURANCE HANDBOOK FOR AIR POLLUTION
MEASUREMENT SYSTEMS, Volume II - Ambient Air Specific
Methods EPA 600/4-77-027a, May 1977 and 40 CFR 50, Appendix C.
HI and LO Multi-Point
Calibration
The instrument can also be calibrated using a dual three-point calibration.
The calibration points are divided into a “low” range and a “high” range
consisting of three points each
• Cal Point 1
• Cal Point 2
• Cal Point 3
Span Error, % = ([A
80
- Z)URL/100] - [CO]) X 100/[CO]