There are many different types of gauges that are available. There are three types of gauges available: Analog, Digital, and Pneumofathometer models. A gauge that is right for you is key to a safe dive. For safety at high altitudes, it is essential to keep your gauge calibrated.
Analog gauges
Analog gauges for gauge diving can help divers understand the depth in the water. A graduated scale is used to indicate depth. These gauges are worn on the wrist or can be integrated into the dive computer. While the analog gauges are more reliable than digital ones, they may not be as accurate. An advantage of an analog gauge over digital is the fact that you never run out.
The gauge's face is easy to read. It has numerical increments of depth ranging from 10'-40' and 20’ to 150'. The gauge also includes a pressure gauge. It displays pressure from 0 to 5000 psi. A red screen indicates reserve air, while the green screen shows main air.
Digital models
Divers desire to be able dive deeper and for longer periods of time, but a digital gauge doesn't allow them to do that. Temperature changes can cause the difference in pressure between gauge and ambient water to change. Fortunately, a mechanical gauge is much safer than an electronic gadget. Not only will it keep track of your dive times and depth but also calculate Nitrogen retention, which can help prevent decompression sickness.
There are two types of digital gauge dive computers. The hose method is a simple method, using a hose to connect the dive computer to the high-pressure port on the first stage. Wireless mode, however, connects the first stage with an electronic transmitter. This type of diving computer is also available in wrist-mounted and console models.
Pneumofathometers
Pneumofathometers measure the depth of the air supply to a diver. These devices measure the air pressure near the surface and then display the depth in feet (or metres). These devices were previously mounted on the hand-cranked compressor that supplied air to standard diving suits. The air supply was free flowing, with 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
Submersible pressure gauges (SPG) are devices that allow divers to monitor their air pressure. It can display current depth and indicate the direction in which the diver is moving. The SPG is usually attached to the regulator via a high-pressure hose. This arrangement helps the diver avoid confusion and keeps the gauge from getting lost. A SPG shows the remaining air pressure in pounds per square inch and is useful for monitoring your air supply while diving.
Scubapro's oil-filled analog depth meter features a Bourdon Tube design. It measures to a depth 200 feet. It comes with a C1 Compass, which attaches directly to the console boot. This gauge is ideal to beginners, as it is simple and straightforward to use.
Compass
A compass that is easy-to-read is the best compass to use for gauge diving. It should be large enough that it can be read underwater, and the right markings. Look for a compasse with a bezel that includes indicator marks and compass headings.
A gauge diver's compass should have a side view window to allow them to see the direction it is pointing. This allows the diver see the direction that the compass is pointed even in complete darkness.