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. For safety at high altitudes, it is essential to keep your gauge calibrated.
Analog gauges
Divers can use analog gauges to gauge dive. They are able to measure the depth of the water. They work by having a needle pivot around a graduated scale to indicate the depth. These gauges can be worn around the wrist or integrated into a dive computer. Although they are more reliable than the digital gauges, analog gauges can still be used. An analog gauge has one advantage: you won't run out of batteries.
The face of the gauge is designed to be easy to read. It offers numerical increments in depth of 10'-40', 20'-40', and 20'-150'. The gauge has a pressure indicator. It displays pressure ranging from 0 up to 5000psi. The screen displays reserve air and the green screen main air.
Digital models
Many divers want to stay long and dive deep, but a digital gauge won't help them do this. Temperature variations can alter the pressure differential between the gauge (and the ambient water). A mechanical gauge can be safer than an electronics gadget. A gauge not only keeps track of dive time and depth but it also calculates Nitrogen retention and helps prevent decompression illness.
There are two basic types digital gauge diving 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. You can also find this type of diving computer in console or wrist-mounted models.
Pneumofathometers
Pneumofathometers measure the depth of the air supply to a diver. These devices measure the air pressure at the surface, and indicate the depth in metres or feet. 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.
For gauge diving, divers should buy a gauge that is between 130-160 percent of the maximum operating temperature of their diving system. This range is sufficient for systems operating at 3,000 psi and more.
Submersible pressure gauges
A submersible Pressure Gauge (SPG), is a device that allows divers to track their air pressure. It displays the current depth as well as the direction that the diver is moving. The regulator is connected to the SPG via a high pressure hose. This arrangement reduces confusion and prevents the regulator from getting lost. A SPG measures the remaining air pressure per square inch. It is used to monitor your air supply while diving.
Scubapro produces an oil-filled analog depth gauge with a Bourdon tube design that measures to a depth of 200 feet. The console boot can also be attached to it with the C1 compass. This gauge is great for beginners as it is simple to use.
Compass
Easy to read compass is the best for gauge diving. It should be large enough that it can be read underwater, and the right markings. Look for a compass with a bezel with compass headings grouped in 30-degree increments and indicator marks every five degrees.
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 even in complete darkness to follow the course of the compass.