Gas Blender Courses
A qualification that may mark you out from the other new instructors is an Equipment Service Technician, this will enable you to service and repair equipment for the dive center you work for and could be classed as a valuable skill. PADI do not hold such a course so you will have to take it with a techincal diving agency like TDI or SDI. Here as some things you need to know:
Technical Diving Service Technician Exam Questions
1. List 7 methods of oxygen cleaning equipment.
a) Steam Cleaning.
b) Hot water cleaning.
c) Caustic cleaning.
d) Acid cleaning.
e) Solvent washing (including ultrasonic cleaning).
f) Vapor degreasing.
g) Mechanical Cleaning.
2. Cylinders with liners must have their liners removed before they can be certified for EAN use.
True I False
3. When drying oxygen cleaned cylinders, always rinse steel cylinders with hot water and purge with: nitrogen.
4. Hydrocarbons in a compressor system of 1.2 mg/m3 are too high for producing EAN compatible air. True I False
5 What is the main reason quick opening (ball or ¼ turn) valves are not used in an oxygen containment or transfer system?
a) Gas travelling at sonic velocity may reach auto-ignition temperatures at an abrupt turn, obstruction or down-sizing in the containment materials.
b) Quick opening valves may create heat of compression which causes flashing.
c) Quick opening valves may cause adiabatic compression.
d) Both a and c are correct.
6. What should soft components (Le. o-rings and high pressure seats) be made of if they will be exposed to O2 concentrations higher than 40%?
a) Fluorocarbon rubber.
b) Nitrile rubber.
d) Both a and c are correct.
7. What are 3 ways a service technician might degrease scuba equipment:
a) Ultrasonic solvent cleaning, steam, purge with oxygen.
b) Vacuum, flush with hot water, purge with hydrocarbon free air.
c) Hotwater cleaning, TCA, steam or hot water.
d) Hot water cleaning, Solvent washing, and Mechanical cleaning.
8. Of the T methods listed in question 1, the two cleaning methods most used for oxygen cleaning scuba equipment are:
a) Hot water cleaning.
b) Mechanical Cleaning.
9. List 4 inspection procedures for assuring the technician that oxygen cleaning was done successfully.
a) Direct visual inspection (white light).
b) Direct visual inspection (black light).
c) Wipe test.
d) Water break test.
10. Fluorinated grease, when exposed to temperatures above 500°F can produce toxic
True / False
11. Carbon steel can only be used in pure oxygen delivery systems at pressures below 1000 psi (68 bar).
True / False
12. Grade ‘E’ or diving quality air is an acceptable standard for the production of oxygen compatible air systems.
True / False
13. The acceptable level for hydrocarbon contamination within a clean air system for the production of oxygen compatible air is:
14. Describe the complete process for cleaning an aluminium scuba cylinder and its valve for oxygen certification.
Remove the valve and perform standard visual inspection. Remove all visual contaminants manually and re-inspect visually if necessary. Clean the cylinder threads manually with a toothbrush dipped in full strength cleaner. Warm 1 gallon of cleaning solution and pour into cylinder, cap and tumble or shake end to end.
Rinse cylinder with warm water and flush continuously until no foaming is present in rinse water. Invert cylinder on drying rack and dry thoroughly. Inspect for hydrocarbons using black-light or other prescribed method.
Disassemble valve in accordance with the manufacturer’s recommendations and service manual steps. Mechanically remove all visual contaminants paying special attention to areas between bearing surfaces, washers, packing, etc. If valve is contaminated by salt water or other corrosion then clean in accordance with standard practices. Place parts in basket and clean in warm cleaning solution and / or ultrasonic bath. Rinse with clean water and dry using oil free compressed air.
Examine for any remaining hydrocarbons using black-light and water bead tests, reclean if necessary. Reassemble using Viton or EDPM style o-rings that match manufacturer’s recommended replacement parts. lightly lubricate o-rings and valve stem and all moving parts with Krytox or ChristoLube lubricants. Re-install the valve into the cylinder (or store in plastic bag if not to be used right away).
15. Describe the complete process for cleaning a regulator for oxygen certification.
Disassemble in accordance with the manufacturer’s recommendations.
Inspect all parts and replace any if necessary in accordance with normal procedures. Mechanically clean all parts prior to solution cleaning. Remove all heavy deposits of greases and other contamination. If regulator parts have heavy contamination or corrosion from salt water, first clean in accordance with normal techniques prior to oxygen cleaning. Place all parts in a basket and-clean in warm cleaning solution and/or ultrasonic bath. Dry using oil-free compressed air. Examine for any remaining hydrocarbons using black-light, water bead or other prescribed tests. Reassemble using Viton or EPDM o-rings or seats, matching all original o-ring or seat parameters or use the manufacturer’s ean service kit. Viton or EPDM parts, moving parts, or other normally lubricated areas should be lubricated with Krytox or ChristoLube.
When completely assembled test in accordance with manufacturer’s guidelines with hydrocarbon free air. Log maintenance as required.