How Dive Stores Create Nitrox

May 23, 2024BlogNo Comments »

Mark Tozer

Today, I’m going to explain how dive stores make Nitrox, a technical topic with lots of details to cover. Let’s break it down into simpler terms. If you’re a diver interested in using Nitrox, you might wonder how a dive store gets that 32% oxygen mix into your tank. They don’t buy it pre-made in boxes; they create it on-site using various methods. Here’s how they do it.

Methods for Producing Nitrox

  1. Pre-Bottled Nitrox
    • Easiest Method: Dive stores can buy pre-bottled Nitrox, just like they buy other gases such as carbon dioxide or oxygen. They’d order, for example, two large bottles of 32% Nitrox.
    • How it Works: When you need a refill, the store connects your tank to these bottles, fills it with the 32% Nitrox, and you’re good to go.
    • Drawbacks: This method is the most expensive. The dive store won’t make as much money, and they may need additional equipment like a booster to match the pressure required.
  2. Partial Pressure Blending
    • Common Method: This involves calculating the required pressure for each gas in the mix to achieve the desired 32% oxygen.
    • How it Works: The dive store owner uses Dalton’s Law of Partial Pressures to determine how much oxygen to add to your tank. They fill part of the tank with pure oxygen and then top it off with regular air.
    • Drawbacks: Requires oxygen-clean equipment because pure oxygen can be hazardous if the tank isn’t clean. Also, the method isn’t perfect and may need additional equipment if the oxygen supply pressure is low.
  3. Continuous Blending (The Stick Method)
    • High Volume, Low Maintenance: This method, often referred to by the brand name “The Stick,” allows dive stores to produce Nitrox continuously and in large volumes.
    • How it Works: The system mixes air with pure oxygen in a device called the stick. The mixture is monitored to ensure it has the right percentage of oxygen before being compressed into your tank.
    • Drawbacks: This method requires significant initial investment. Equipment such as the stick, a reliable oxygen supply, a compressor capable of handling enriched air, and proper monitoring systems are essential. Additionally, the compressor must be oxygen-ready, using synthetic oil instead of normal oil.

Considerations for Dive Store Owners

Choosing the right method depends on various factors:

  • Volume of Nitrox Sales: Stores selling large volumes might benefit more from continuous blending.
  • Initial Investment: Pre-bottled Nitrox has a lower upfront cost but higher ongoing expenses. Continuous blending has a higher initial cost but is more economical in the long run.
  • Technical Expertise: Some methods require more technical knowledge and maintenance.

In summary, dive stores have multiple ways to produce Nitrox, each with its pros and cons. Pre-bottled Nitrox is simple but costly. Partial pressure blending is common but needs oxygen-clean equipment. Continuous blending, using the stick method, is efficient but requires significant investment. Understanding these methods can help divers appreciate the complexities behind getting that perfect Nitrox mix.

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