![]() SAC rate is nothing more than RMV adjusted for ambient pressure at sea level. This is where Surface Air Consumption or SAC rate comes in. In order to make RMV usable, we need to convert it to something else. For example, at a depth of four atmospheres - that’s 30 meters or just under 100 feet - our RMV will be twice what it would be at a depth of two atmospheres or ten meters/33 feet. The thing about RMV is that it varies with depth. Therefore, it’s important for us to be able to project RMV in terms of volume, so that we can apply it to any size cylinder we may happen to be using. It’s possible for open-circuit divers to measure RMV in bars or psi - but this is only useful if, like many sport divers, you consistently use just a single size cylinder, like an 11-liter Aluminum 80.Īs cave and technical divers, we use a wide variety of cylinders. In this article, we’re going to focus on how RMV affects open-circuit divers. The lower the RMV, the less carbon dioxide passes through the scrubber material, and the longer it will last. They use RMV chiefly for projecting scrubber canister life. CCR divers, on the other hand, don’t “consume” gas the way open-circuit divers do.For open-circuit divers, RMV is a way of projecting gas consumption at depth.Open-circuit and CCR divers use RMV for very different purposes. Note that it doesn’t matter whether you use metric or Imperial units of measure - so just use whatever you are most comfortable with. Respiratory Minute Volume or RMV is exactly what the name implies: The volume of gas, in either liters or cubic feet, that moves in to or out of your lungs over the course of a minute. In reality, the underlying concept is actually fairly simple.Ī friend of mine, former Dive Training magazine Senior Editor Dr. It doesn’t help that, in many tech diver courses, any discussion of RMV and SAC rate is coupled with a lot of complex math. Of course, everyone of these statements is wrong. RMV is for CCR diving SAC is for open circuit.You measure SAC in psi and RMV in cubic feet.Here are some of the things I’ve had tech Instructor candidates tell me when I asked them to explain the difference between the two: This entry was posted in Diver Training Instructor Training Uncategorized on Septemby Adminįew topics seem to generate more confusion among divers and instructors than Respiratory Minute Volume, better known as RMV, and Surface Air Consumption rate, commonly referred to as SAC rate. This article will tell you what you need to know in simple, easy-to-understand language.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |