火焰原子吸收培训课程Chapt7

DAILY MAINTENANCE Uptake rate: < 5ml/min 5-6 ml/min > 6 ml/min QC Standard result: 5 ppm----------Abs Signed----------------------
Empty Waste Container
• Open fully THEN half a turn Back
The Dreaded Nitrous OxideAcetylene Flashback
Gas Flow and Burning Velocity
Flame Burning Down
Gas flowing Up
Nitrous Oxide-Acetylene Gas Flow
Check local and company regulations!
NEVER
NEVER
Acetylene
Nitrous Oxide
Nitrogen Hydrogen Argon
Oxygen
Cylinder Gauge Care
This ball cone is the seal
Ball socket outlet connector
Clean Windows
Clean Spills
Check O-rings
Lubricate with water or Non-ionic detergent i.e. Triton X-100 ONLY
Mark 7 Nebulizer
Impact Bead
SIPS Maintenance (1)
• Maintain instrument performance • Review safety issues
Results of Poor Maintenance
• Degradation of performance • Unsafe operation of the AA
Know your gas cylinders and plumbing!
• Avoid Spills • Avoid Acid Vapors • Proper Drainage
Check Exhaust
Clean Burner Compartment
Check Delivery Pressure
Normal
Tank Pressure
Delivery Pressure
Flame Atomic Absorption AA Maintenance & Safety
Objectives
• Identify a protocol for routine maintenance
• • • •
Gas Supplies Spray Chamber/ Nebulizer / Burner Instrument Body Accessories
SIPS Maintenance (2)
SIPS Maintenance (3)
• • • • •
Clean Rollers and Band regularly
•
Use Alcohol and tissue
Clean and rinse T piece Replace capillary tubing if blocked. Wipe down case with damp cloth. Ensure adequate ventilation around control unit
Low Uptake Rate
6 mL/min
3.4 mL/min
Mini-vacuum Cleaner
Lint or sample particle blockages
Aspirate D.I. Water
distilled water
Clean Burner
Keep slot clean and polished
Capillary to Autosampler
• Check Capillary Connection
Regulator Operation Check
Same Delivery Pressure
Overnight Leak Check
8:00 AM
5:00 PM
Don’t Over Do !
Use the correct fitting!
Nitrous oxide
Acetylene
Air
Acetylene (1)
• • • •
Gas dissolved in liquid Must have low phosphene content. Must be instrument grade Do not use for 24 hours if delivered when stored lying down
Daily Maintenance Tasks
• • • • •
Empty waste container Check Exhaust System Clean Burner Compartment & Instrument Check the gas delivery pressures Check the nebulizer uptake rate
20
1
30.0
Varian AA Safety Margins
• Over three times the minimum required flow • Safety Interlocks in Spray Chamber • Blow Out bung
A flashback just shouldn’t happen!
Nitrous Oxide Regulator
It may FREEZE NEVER Lubricate “O” rings with grease It is stored as liquid
Cylinder pressure does NOT indicate contents!
Open Valves Correctly
Keep Written Daily Log
DAILY MAINTENANCE Operator-----------------Date---------Time--------Gas lines OK Exhaust OK Instrument Cleaned Lamp % Gain---------SIPS pump tube changed SIPS pump band changed
Recommended Gas Delivery Pressures
This is at the REAR of the instrument NOT at the supply
GAS Acetylene Air Nitrous Oxide
kPa 63 420 420
psig 12 60 60
Measure Uptake Rate
Acetylene (2)
• • • •
MUST be Stabilized NEVER Operate with cylinder pressure below 700kPa (100 psig) Or line pressure above 105kPa (15psig). NEVER use copper lines or fittings
• Perform maintenance only as needed. • Not just to keep log filled.
Summary
• • • • • • •
Empty Waste Container Check Exhaust System Check Uptake Rate Check Gas Supplies Clean Dirty Components & Spills Maintain Accessories Aspirate 50 mL D.I. Water after analysis
Autosampler Maintenance (1)
源自文库
• •
Capillary Spills
SPS - 5
Autosampler Maintenance (2)
SPS - 2
SPS - 3
Autosampler Maintenance (3)
Capillary to Nebulizer Connection
Acetylene
2.0 1.8 1.6
1 5 10
Nitrous Oxide
1.4
Fuel/Oxidant Ratio
1.2 1.0 0.8
Flash Back Region
5
10
SpectrAA Gas Flow Region
15
0.6 0.4 0.2 0.0 0.0 5.0 10.0 15.0 Total Gas Flow Litre/Min 20.0 25.0