There are many gauges on offer. There are three main types: Analog, Digital and Pneumofathometer models. A gauge that is right for you is key to a safe dive. Keeping your gauge calibrated is also vital for decompression safety, especially at altitudes.
Analog gauges
Analog gauges used for gauge diving are useful in helping divers determine the depth of water. You can use them to indicate the depth by turning a needle around a graduated scale. These gauges may be worn on the wrist, or integrated into the dive computers. The analog ones may be more reliable than digital gauges, but they are not completely accurate. One advantage of using an analog gauge is that you will never run out of batteries.
The gauge's face has been designed to be easy-to-read. It features numerical increments of depth from 10' to 40' and 20' to 150'. The gauge has a pressure indicator. It can display pressure from 0 - 5000 psi. The red screen represents reserve air, while green indicates main air.
Digital models
Divers want to dive long and deep. A digital gauge will not help them achieve this. Temperature fluctuations can alter the pressure difference between your gauge and the surrounding water. A mechanical gauge is safer than an electronic one. The gauge can keep track of your dive time, depth and will also calculate your Nitrogen retention to prevent you from getting decompression sickness.
There are two basic types for digital gauge dive computers. The hose technique is the simplest. It uses a hose for connecting the dive computer to a high-pressure port on stage 1. Wireless mode, on the contrary, attaches an electronic transmitter to the first stage to communicate to the computer. This type is also available in console and wrist-mounted models.
Pneumofathometers
Pneumofathometers are devices used to gauge the depth of air supplied to a diver. These devices measure surface air pressure and indicate depth in meters or feet. These devices were originally mounted on a hand-cranked pump that supplied breathing oxygen to the standard diving suit. The air supply was completely free-flowing, and there was no back-pressure.
A gauge should have a range between 130 and 160 percent of the maximum operating pressure for gauge diving. A gauge with this range would suffice for a system that operates at 3,000 psi or more.
Submersible pressure gauges
A submersible Pressure Gauge (SPG), is a device that allows divers to track their air pressure. It also displays the current depth and the direction the diver is moving. The SPG connects to the regulator using a high pressure line. This arrangement is useful for divers to avoid getting confused about the location of the gauge and helps prevent it from being lost. The SPG is a gauge that shows you the remaining air pressure in psi. It's useful for monitoring your air supply during diving.
Scubapro's oil-filled analog depth meter features a Bourdon Tube design. It measures to a depth 200 feet. You can attach the C1 compasses to your console boot for additional versatility. This gauge is best suited for beginners because it is simple and easy to use.
Compass
It is important to be able to read the compass easily when gauge diving. It should be large enough that it can be read underwater, and the right markings. Look for a compass bezel with compass headings that are grouped in 30-degree increments. Indicator marks appear every five degrees.
A side view window is an important feature of a compass that allows gauge diving. It lets the diver see the direction in which the compass point. This allows the diver even in complete darkness to follow the course of the compass.