The VPM (Varying Permeability Model) and the BUHLMANN model in SCUBA diving planning


Scuba diving is a popular recreational activity that allows people to explore the underwater world. However, it is a dangerous activity that requires proper training and equipment to ensure the safety of the divers. One important aspect of diving is the calculation of dive profiles, which involves determining the amount of time that a diver can safely spend at different depths.

There are two main models used for calculating dive profiles: the VPM (Varying Permeability Model) and the BUHLMANN model. Both models are used to predict the maximum operating depth (MOD) and the no-decompression limit (NDL) for a diver.

The VPM model was developed by Dr. Bill Stone and Dr. Pete Ekstrom in the 1980s. It is based on the idea that the permeability of gases in the body changes with depth and time. The model takes into account the effect of tissue compartments on the absorption and elimination of gases, and it predicts the risk of decompression sickness (DCS) based on the diver's dive profile.

The BUHLMANN model, on the other hand, was developed by Dr. Albert A. Buhlmann in the 1970s. It is based on the idea that the body has a limited capacity to absorb and eliminate gases, and it predicts the risk of DCS based on the amount of gas that is absorbed and eliminated by the body during a dive.

Both the VPM and BUHLMANN models are widely used in the scuba diving industry, and they are considered to be accurate and reliable for predicting dive profiles. However, there are some differences between the two models that divers should be aware of.

The VPM model is considered to be more conservative, which means that it predicts shorter dive times and lower maximum operating depths. This is because the model takes into account the effect of tissue compartments on gas absorption and elimination, which can be more complex than the BUHLMANN model. However, the VPM model is also considered to be more flexible, as it allows for the customization of dive profiles based on the individual diver's physiology and diving experience.

The BUHLMANN model, on the other hand, is considered to be more lenient, as it predicts longer dive times and higher maximum operating depths. This is because the model is based on the assumption that the body has a limited capacity to absorb and eliminate gases, and it does not take into account the effect of tissue compartments on gas absorption and elimination. However, the BUHLMANN model is also considered to be more straightforward and easy to use, as it does not require the customization of dive profiles for individual divers.

In conclusion, both the VPM and BUHLMANN models are widely used in the scuba diving industry for predicting dive profiles. The VPM model is more conservative and flexible, while the BUHLMANN model is more lenient and straightforward. Divers should choose the model that best fits their needs and abilities, and they should always follow the guidelines and recommendations provided by their dive training agencies.

Thank you for reading my blog. I hope you found the information and insights we shared to be valuable. Your thoughts and feedback are important to me, so please don't hesitate to leave a comment below. I'd love to hear your thoughts on the topic and any questions you may have. Additionally, if you found this blog helpful, please consider sharing it with your friends and colleagues on social media. Your support helps me to continue providing valuable content like this. Thanks again for reading!


Antonio CIGLIOLA
PADI Instructor IDC-S No. 358644
Mobile: (+39) 392 2921903
E: cigliolaa@gmail.com 

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