Question Zhl-16c questions

[Hihihello]

Dear all,

I am writing to seek help from professionals regarding ZHL-16C.

My questions are as follows:

1. Where can I find the \(a\) and \(b\) values for the 16 tissues of ZHL-16C?

2. Does ZHL-16C have 17 tissues? (Is that correct?)

3. Is the \(a\) and \(b\) constant information on [this Wikipedia page](https://en.m.wikipedia.org/wiki/B%C3%BChlmann_decompression_algorithm) accurate for ZHL-16C, and does it provide the correct formulas for ZHL-16C?

4. Should I follow the formulas in "Deco for Divers" or those on this link?

5. Assuming a diver is using air and starts diving from sea level (0 m) with a descent rate of 22 m/min, reaching a depth of 30 m and a bottom time of 30 minutes, can someone explain how to calculate the diver's decompression obligations using ZHL-16C with a gradient factor (GF) of 30/70? How can I calculate the necessary stops using mathematical formulas?

6. Could someone explain the meaning of variables and constants in the formulas?

As a new open water diver, I am unfamiliar with these concepts. I would greatly appreciate your assistance. Thank you!

Since English is not my first language, I apologize for any mistakes in my message.

Best regards,

HiHi

 

[Mobulai]

Hi HiHi,

Take a look at this thread for a and b coefficients:

Thread 'I'm having trouble understanding/deriving Bühlmann coefficients "a" and "b".'

Jan 5, 2025

I am trying to derive a and b coefficients for ZH-L16 using the Nitrogen M values in "Understanding M-values" by Erik Baker. I can find already computed coefficients published here and in An Explanation of Buehlmann's ZH-L16 Algorithm by Paul Chapman, so I am able to check my work.

I will take tissue compartment 2 for my examples (just to avoid the potential compartment 1/1b confusion and because M_0 is the same for ZH-L16A, B, and C).

Calculating b for tissue compartment 2
Baker's paper says b is just the inverse of the "ΔM slope"...

• ThisSurfaceIntervalSucks
• Replies: 33
• Forum: Technical Diving

• 

 

[Hihihello]

@Mobulai
Thank you very much indeed

 

[inquis]

2. Does ZHL-16C have 17 tissues? (Is that correct?)

No, there are 16 tissue compartments (which is why the "16" is in the name. The "C" denotes the third revision, which is the most recent and widely used.

 

[Hihihello]

@inquis Thanks for your reply. I saw something called 1b in the authors book, so I am thinking why the name is zhl 16 but not 17.

 

[inquis]

1a and 1b are the two possible values for the first tissue compartment. Pick one. (I would personally pick the larger value.) The off-gassing rate of either is so fast that it won't really matter. (Other compartments will likely control the ascent.)

 

[Hihihello]

@inquis Thank you very much indeed as I am a ow diver, I know nothing about it thanks but I will try to use both of them and see how it works thanks

 

[tursiops]

.

 

[tursiops]

Dear all,

I am writing to seek help from professionals regarding ZHL-16C.

My questions are as follows:

1. Where can I find the \(a\) and \(b\) values for the 16 tissues of ZHL-16C?

2. Does ZHL-16C have 17 tissues? (Is that correct?)

3. Is the \(a\) and \(b\) constant information on [this Wikipedia page](https://en.m.wikipedia.org/wiki/B%C3%BChlmann_decompression_algorithm) accurate for ZHL-16C, and does it provide the correct formulas for ZHL-16C?

4. Should I follow the formulas in "Deco for Divers" or those on this link?

5. Assuming a diver is using air and starts diving from sea level (0 m) with a descent rate of 22 m/min, reaching a depth of 30 m and a bottom time of 30 minutes, can someone explain how to calculate the diver's decompression obligations using ZHL-16C with a gradient factor (GF) of 30/70? How can I calculate the necessary stops using mathematical formulas?

6. Could someone explain the meaning of variables and constants in the formulas?

As a new open water diver, I am unfamiliar with these concepts. I would greatly appreciate your assistance. Thank you!

Since English is not my first language, I apologize for any mistakes in my message.

Best regards,

HiHi

Why are you doing this? do you ahve a Buhlmann computer?
Is this just for fun, or are you planning to actually dive using your calculations?

 

[inquis]

Subsurface is an open source planner with a full implementation of Buhlmann with Gradient Factors. Looking at that code may be helpful.