E4- equipment and compression Flashcards
You are checking a demand regulator and find that the pressure gauge slowly drops to zero when the cylinder is switched off. What could be the cause?
There is a leak in the supply hose
What sort of material is best suited for the faceplate of a diving half mask
Toughened Glass
A typical buoyancy compensator will have a volume of approximately?
20 litres
Where on a demand regulator would you expect to find a HP seat?
In the pressure reducer (first stage)
Whilst fitting a DIN regulator to a cylinder, you find that you cannot get an airtight seal. Which of the following could be true?
The O ring is faulty
The cylinder is rated at 300 bar, the demand regulator 232 bar
When filling bailout cylinders from a HP bank using the cascade method, you can maximise efficiency by?
the lowest bank pressure tthat will fill the highest cylinder pressure
Diving information sheet 9 (issued by HSE) provides guidance on the interpretation of breathing air standards set out by BS EN 12021. Which of the following items has a maximum permitted level that varies according to the type of equipment being sampled?
Select one:
a.
Carbon Dioxide
b.
Carbon Monoxide
c.
Lubricant
d.
Water
e.
Oxygen
d- water
Duplex compressors have the advantage that they?
Select one:
a.
Produce a higher pressure than the conventional compressors
b.
Pump on both strokes of the cycle
c.
Produce HP and LP air for use from the same outlet
d.
Are much cheaper than the conventional compressors
e.
Are much quieter than conventional compressors
pump on both strokes on the cycle
What is Isothermal compression?
Select one:
a.
When the cylinder is compressed in a bath of water to keep it cool
b.
When the a cylinder stays the same temperature during filling
c.
When a cylinder gains pressure after filling
d.
When a cylinder heats up during filling and cools after
e.
When a cylinder cools during filling
stays at same temp
Which of the following removes oil as it passes through a filter?
Select one:
a.
Silica Gel
b.
Activated alumina
c.
Activated Charcoal
d.
Felt Pad
e.
Carbonated Feenam
c. activated charcol
What is the first thing to check if you have difficulty removing an air filter?
Select one:
a.
That you have the correct spanner
b.
That you are removing the correct container
c.
That the unit is depressurised
d.
That you have the correct filter
e.
That the compressor is topped up with oil
depressurised
What should you check before operating a portable electric HP compressor?
Select one:
a.
The position of the air intake
b.
The level of oil in the prime mover
c.
That all the drain valves are closed
d.
That there is sufficient petrol in the prime mover
e.
All of the above
the position of the air intake
Rattling in cylinder
Anti debris tube fallen out
Periodic inspection
2.5 years
periodici inspection and test (hydraullic)
5 years
(two wire )Simplex system
one way communication - radio
permanently monitored
more common than duplex- cheaper and simpler
(four wire) duplex system
Simultaneously - telephone
less common than simplex- expensive
advantages of hard wire communications
Surface can continuously monitor divers breathing
less affected by underwater environment
disadvantages of hard wire communications
communications cable restricts divers movement
advantages of through water communications
2 divers in water on same frequency can talk and listen to each other
can cover greater distances using an SMB rather than a lifeline
disadvantages of through water communications
surface cant monitor breathing or listen to diver at all times
divers can talk over each other
isothermal
temp remains constant
needs a slow fill
adiabatic
quick fill so drops back down
LP fill
under 50 bar
surface supplied diving and recompression chambers
HP fill
over 50 bar
diving cylinders
smaller compressor fills slower or faster
slower
compression stages
compressed
cooled
drained of water
pressure
repeat x 3
filter tower
charging panel
composition of breathing air
oxygen 21 +/- 1 %
composition of breathing air
carbon dioxide
<500 ml m-3 (ppm)
composition of breathing air
carbon monoxide
composition of breathing air
oil
< 0.5 mg m-3
composition of breathing air
water
25mg m-3
Filter tower
silica gel
water
Filter tower
activated charcoal
odour and oil
molecular sieve
oil and water
felt pads
particulates
In a filter tower why does the drying agent need to be first?
activated charcol doesnt work when wet
What oil should you use in a compressor?
manufactors recommendation
draeger tubes tets for
air purity
