Gas Handling

Question 1

Chamber Exhaust piping should be equipped with what?

Answer 1

Tee piece/Diffuser/Silencer

Question 2

Gas cylinders should be labeled with the following;

Answer 2

Gas Type
%
Chemical Symbol
Name of gas

O2% will be listed first in the gas content

Question 3

O2 can be stored in a confined space- T or F

Answer 3

False.

Never store O2 in a confined space.

Question 4

If storing gas below deck the room must have an O2 Hi/Low alarm-
True or False

Answer 4

True

Question 5

Identify the following gases by color code;
Brown
White
Black
Black/White
Brown/White
Grey
Pink

Answer 5

Brown - Helium
White - Oxygen
Black - Nitrogen
Black/White - Air
Brown/White - Heliox
Grey - Carbon Dioxide
Pink - Cal Gas

Question 6

O2 % above which should be treated as 100%

Answer 6

25% O2 content shall be treated same as 100%

Question 7

Are whip checks required on LP gas hoses?

Answer 7

Yes, check whips are required on all hoses under pressure

Question 8

When putting a new gas online it is required to a analyze at both the quad and the panel-
True or False

Answer 8

True,
when a new gas is put online it must be analyzed at the quad and the panel.

Question 9

State the max level of contaminants for BSEN12021
Oil
CO
CO2
Water

Answer 9

Oil - 0.5mg/m3
CO - 5ppm
CO2 - 500ppm
Water - 25mg/m3

Question 10

State the mechanism of action for the following analyzers;
O2 analyzers
CO2 analyzers
Draager Tubes

Answer 10

O2 analyzers;
Battery Fuel Cell

CO2 analyzers;
Radiation and Infrared Beams

Draager Tubes;
Colorimetric Tubes

Question 11

O2 should be reduced to X bar at the quad

Answer 11

As low as possible with
40bar max at quad

Question 12

All chambers require a ppO2 meter?
True or False?

Answer 12

True

Question 13

Considerations for O2 plumbing and valves;

Answer 13

Hard plumbing is preferred
Soft hose as short as possible
Use needle valves
Use O2 safe thread sealants no ptfe tape (phosgene gas)
O2 clean hoses and fittings

Question 14

Do compressors and pressure vessels require an PRV?

Answer 14

Yes

Question 15

Considerations for O2 storage location

Answer 15

Stored on upper deck
Clearly marked gas quads
Equipped with a fire or deluge system

Question 16

100% O2 can be pumped to Kelly’s;
True or False

Answer 16

False.
O2 cannot be pumped

Question 17

Give the approximate weight of a 50L cylinder and 16 bottle quad.

Answer 17

50L cylinder = 100kg
Therefore 16 bottle quad weighs at least 1.6T.

Question 18

What is the minimum allowable O2 content in an inert gas offshore?

Answer 18

2%

Lower percentage maybe allowed but with strict procedures in place.

Question 19

Who is responsible for analyzing divers gas before and during a dive?

Answer 19

The diving supervisor

Question 20

Can air be used as a scale gas on O2 analyzers?

Answer 20

Yes, but the sample must be taken outdoors not from inside a room and set to 20.9%

Question 21

How long must new gas mixes sit to ensure complete homogenization?

Answer 21

24hrs

Question 22

Gases can be mixed by these 2 methods;

Answer 22

Using a blender/mixer
Or
Decanting

Question 23

Which gas shall be added to the mix first;
2% or 20%

Answer 23

Start by mixing the rich mix first.
This lets the lean mix be pumped at a higher pressure.

Question 24

Which document states minimum gas requirements offshore?

Answer 24

IMCA D050

Question 25

Normal maximum working pressure for O2 at source to minimize fire risk?

Answer 25

40bar

Question 26

What is the purity standard for divers breathing gas?

Answer 26

BSEN 12021

Question 27

O2 content % should be marked before after other gases on the quad label?

Answer 27

O2 % should be shown first

Question 28

Gas cylinders used in diving must have marked on them;

Answer 28

Chemical formula of the contents and the color code.

Question 29

An O2 analyzer works by way of

Answer 29

Paramagnetism or using a fuel cell (battery) which generates electricity in proportion to the ppO2

Question 30

How often should bail out bottles have an internal and external visual examination for corrosion

Answer 30

Every 6 months
Internal/external

2 years: int/ext plus pressure test to max working pressure

4 years: hydraulic over pressure test 1.5x max working pressure plus the 2 yearly

Question 31

By which process do gas tubes work?

Answer 31

Colormetric

Question 32

Gas cylinder sets used underwater must have an hydraulic overpressure test to 1.5x the maximum working pressure every how often?

Answer 32

Every 5 years plus the int/ext examination.

2.5 years is pressure test to max working pressure plus int/ext visual

Question 33

IMCA D018 states a compressor should have a gas purity check every how often?

Answer 33

6 months
Vs
BSEN 12021
-3 monthly