What Is An SPG ?

First off the SPG stands for Submersible Pressure Guage. SPGs let divers monitor their air supply (pressure) throughout the course of the dive. Such guages connect to the high pressure port on the regulator's first stage. Click on picture to take you to Leisure Pro Equipment.

You will learn to use the SPG to plan and control your dive so you return safely to the boat or shore without running out of air. The SPG is considered mandatory equipment when you dive, that is if you do not dive with a computer. Depending on the dive and type of dive, some divers dive with both an SPG and computer. The SPG of course is th back up.

A vital point to remember, that the SPG is a passive device. You have to read it, or it doesn't do any good. Develop the habit of looking at it frequently through out out the dive. When you dive alot you can get the feel of how fast you breathe air, and know about when you are to run out. So you may not need to check that often. But for the new divers, I recommend checking it often. Better too much than too little.

The most common type is an analog model with a spiral wound bourbon tube. Europeans SPGs go to 300 bar, while in North America SPGs range from 3500 - 4000 psi. On the dial the SPGs are color coded. In Europe for 0-35-70 bar and North America 500- 000 psi. The color is usually red and warns that you are dangerous low on air and need to return to surface immediately.