Do you have practice questions for the DM exam?

[TheTrickster]

Ok...A few more questions for dm candidates.

Okay before I start - I'm going to convert the fsw to msw, as I'm a metric jockey!

#1) You are going on a dive to...let's make it easy...121fsw and you want to know the maximum oxygen mix you can use to maintain a PO2 of 1.4 ata. What is it?

EANx30

#2) You are diving with EAN30 to a depth of 121fsw. What is your PO2?

Umm... pp02 of 1.4

#3) You are diving with EAN30 and your PO2 is 1.4ata. What is your total absolute pressure? What is your depth?

4.67ATA
36.7m (121fsw)

#4) What gas law are you applying and what formula do you use to determine the above answers?

Daltons Law.

For Question1 the formula is: pp02 / ((Depth+10)/10) = 02%
For Question2 the formula is: ((Depth+10)/10) * 02% = pp02
For Question3 the formula is:

For the depth you use: ((1.4/(30/100))*10)-10
For the absolute pressure: ((Depth+10)/10)

10 point bonus question: This one is EXTREMELY DIFFICULT What is the MOD of EAN 50 and EAN100? What is the formula?

EANx50 - 18m (pp02.1.4) - 22m (pp02.1.6)
EANx100 (or Pure Oxygen) - 4m (pp02.1.4) - 6m (pp02.1.6)

MOD = ((pp02/(Mix/100))*10)-10

Step by step Formula

1. Mix / 100 = y
2. pp02 / y = x
3. x * 10 = z
4. z - 10 = MOD

These should be easy questions for those of you in a dm course and each of the answers is in the other questions, except for the extremely difficult bonus. If you find them difficult then study, study, study.

Mike and Trickster do not qualify for the Bonus question

Why not hehe I'm still a divemaster in training - I need all the help I can get!!

 

[elmo6s]

Here's an annoying one:

Describe the difference between a balanced and unbalanced first stage regulator, including how they each work.

 

[rawls]

Darn it Trickster...You confused me on those equations Easier way...t-formula


pg
_____

fg / pt


pg= partial pressure of gas
fg= fraction of gas
pt= total absolute pressure

If you know any 2 of these then you just solve for the other.

say pg is 1.4 and pt is 4.7 ata. To solve for fg you simply divide pg by pt...
1.4/4.7 = .30

say fg is .30 and pt is 4.7 ata then simply multiply fg x pt
.30 x 4.7 to get pg of 1.4 pO2....and so on...

MOD (Po2/EAN)x 33)-33....using 1.6 as pO2 and EAN50...

1.6/.5 = 3.2 x 33 = 105.6 - 33 = MOD of 72.6(73ft)

1.6/EAN100 = 1.6 x 33 = 52.8 - 33 = 19.8(20ft)

And you don't get the 10 bonus points

 

[drdirt]

Darn it Trickster...You confused me on those equations Easier way...t-formula


pg
_____

fg / pt


pg= partial pressure of gas
fg= fraction of gas
pt= total absolute pressure

I had to think about that formula. Watch that you don't interpret the fg/pt as division!

PG = FG*PT, so

PG
______

FG * PT​

Example:
PG = FG * PT
= 0.32 * 2 atm
= 0.64 atm
and

FG = PG/PT
= 0.64 atm / 2 atm note: depth about 33 feet
= 0.32 fraction So about 32% that gas

Right?

 

[Cacia]

pay special attention to rounding accurately, if I remember right. MC

 

[TheTrickster]

Hi Guys just got back from the Dive shop from doing my DM exams....

Phew!

Here are the results:

Divemaster Conducted Programs - 90% (18/20)
Assisting with Student Divers - 100% (20/20)
Supervising Certified Divers - 95% (19/20)
Physics - 100% (20/20)
Physiology - 90% (18/20)
Equipment - 100% (20/20)
Skills and Environment - 80% (16/20)
The RDP and Deco Theory - 100% (20/20)

Thank goodness that is all over!

 

[Lehmann108]

Hi Guys just got back from the Dive shop from doing my DM exams....

Phew!

Here are the results:

Divemaster Conducted Programs - 90% (18/20)
Assisting with Student Divers - 100% (20/20)
Supervising Certified Divers - 95% (19/20)
Physics - 100% (20/20)
Physiology - 90% (18/20)
Equipment - 100% (20/20)
Skills and Environment - 80% (16/20)
The RDP and Deco Theory - 100% (20/20)

Thank goodness that is all over!

Congrats!!!!!

 

[rawls]

I had to think about that formula. Watch that you don't interpret the fg/pt as division!

Yeah...I couldn't figure out a way to make a great big T...

Here's an annoying one:

Describe the difference between a balanced and unbalanced first stage regulator, including how they each work.

In an unbalanced first stage the valve seat sits right at the opening of the tank valve. When you inhale the gas in the intermediate pressure chamber decreases and cylinder pressure pushes against the valve seat which in turn opens the valve to allow you to take a breath. Thing is, the valve seat sits right at the opening of the cylinder valve. When the cylinder is full it is easy to open the valve via the pressure on the valve seat. When pressure decreases however, the force against the valve seat is decreased. This makes it more difficult to breathe when tank pressure gets low.
The balanced first stage, the tank pressure exerts no force on the piston directly, therefore it has no effect on the ease of breathing. Basically the function of the first stage is not dependent on tank pressure to open the valve.

Hi Guys just got back from the Dive shop from doing my DM exams....

Phew!

Here are the results:

Divemaster Conducted Programs - 90% (18/20)
Assisting with Student Divers - 100% (20/20)
Supervising Certified Divers - 95% (19/20)
Physics - 100% (20/20)
Physiology - 90% (18/20)
Equipment - 100% (20/20)
Skills and Environment - 80% (16/20)
The RDP and Deco Theory - 100% (20/20)

Thank goodness that is all over

CONGRATS Trickster....Fantastic!!!!

 

[martystoked]

I'm getting organized for my PADI DM final exam. I've gone throught the Knowledge Workbook and read the DM manual (cover to cover).

I've read throught the Encylopedia sections for things I was unsure about, and others I knew fairly well, but just wanted to get all I could. I've not read it cover to cover.

I've got good instructors.

I would like to test myself to see if I'm ready for the final exam. Anybody have sample questions from their own study? Any tips on reviewing?

With answers, it makes short work of assessing how well I've gotten the material, but questions alone work too. Looking up the answers can be a good study exercise.

Thanks for any an all assistance,

drdirt

I just started teaching a Physics Prep course because that has been what everyone seems to have to most trouble with. Attached you will find a list of 20 questions that I made up. If you would like the answers just email me and i can email you the solutions with the prolbems all worked out. Hope this helps

View attachment Physics Review Questions for the Dive Master and Instructor exams.doc